version 0.9.0

Framework/Info.plist

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>en</string>
+	<key>CFBundleExecutable</key>
+	<string>$(EXECUTABLE_NAME)</string>
+	<key>CFBundleIdentifier</key>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>$(PRODUCT_NAME)</string>
+	<key>CFBundlePackageType</key>
+	<string>FMWK</string>
+	<key>CFBundleShortVersionString</key>
+	<string>0.9.0</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>$(CURRENT_PROJECT_VERSION)</string>
+	<key>NSPrincipalClass</key>
+	<string></string>
+</dict>
+</plist>

Framework/YYWebImage-Static.xcodeproj/project.xcworkspace/contents.xcworkspacedata

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "self:/Users/ibireme/Dev/Project/YYKitNew/Projects/YYWebImage/Framework/Fake/YYWebImage/YYWebImage-Static.xcodeproj">
+   </FileRef>
+</Workspace>

Framework/YYWebImage.xcodeproj/project.pbxproj

@@ -0,0 +1,498 @@
+// !$*UTF8*$!
+{
+	archiveVersion = 1;
+	classes = {
+	};
+	objectVersion = 46;
+	objects = {
+
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+}

Framework/YYWebImage.xcodeproj/project.xcworkspace/contents.xcworkspacedata

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "self:YYWebImage.xcodeproj">
+   </FileRef>
+</Workspace>

Framework/YYWebImage.xcodeproj/xcshareddata/xcschemes/YYWebImage.xcscheme

@@ -0,0 +1,80 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "0700"
+   version = "1.3">
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+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
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+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "D975395F1BD2970400C6F4B8"
+               BuildableName = "YYWebImage.framework"
+               BlueprintName = "YYWebImage"
+               ReferencedContainer = "container:YYWebImage.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES">
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+            BuildableIdentifier = "primary"
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+            BlueprintName = "YYWebImage"
+            ReferencedContainer = "container:YYWebImage.xcodeproj">
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+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
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+      debugDocumentVersioning = "YES">
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+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "D975395F1BD2970400C6F4B8"
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+            ReferencedContainer = "container:YYWebImage.xcodeproj">
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LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2015 Yaoyuan Guo
+Copyright (c) 2015 ibireme <ibireme@gmail.com>
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -1,2 +1,22 @@
-# YYWebImage
-Asynchronous image fetch and display framework.
+YYWebImage <a href="#中文介绍">中文介绍</a>
+==============
+[![License MIT](https://img.shields.io/badge/license-MIT-green.svg?style=flat)](https://raw.githubusercontent.com/ibireme/YYWebImage/master/LICENSE)&nbsp;
+[![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)&nbsp;
+[![Cocoapods](http://img.shields.io/cocoapods/v/YYWebImage.svg?style=flat)](http://cocoapods.org/?q= YYWebImage)&nbsp;
+[![Cocoapods](http://img.shields.io/cocoapods/p/YYWebImage.svg?style=flat)](http://cocoapods.org/?q= YYWebImage)&nbsp;
+[![Support](https://img.shields.io/badge/support-iOS%206%2B%20-blue.svg?style=flat)](https://www.apple.com/nl/ios/)
+
+Asynchronous image loading framework.<br/>
+(It's a component of [YYKit](https://github.com/ibireme/YYKit))
+
+
+Features
+==============
+- Asynchronous image load from remote or local URL.
+- Animated WebP, APNG, GIF support.
+- Baseline/progressive/interlaced image decode support.
+- Image loading category for UIImageView, UIButton, MKAnnotationView and CALayer.
+- High performance memory and disk image cache.
+- High performance image loader to avoid main thread blocked.
+
+<img src="https://raw.github.com/ibireme/YYWebImage/Demo/Demo.gif" width="320">

Vendor/WebP.framework/Headers/config.h

@@ -0,0 +1,142 @@
+/* src/webp/config.h.  Generated from config.h.in by configure.  */
+/* src/webp/config.h.in.  Generated from configure.ac by autoheader.  */
+
+/* Define if building universal (internal helper macro) */
+/* #undef AC_APPLE_UNIVERSAL_BUILD */
+
+/* Set to 1 if __builtin_bswap16 is available */
+#define HAVE_BUILTIN_BSWAP16 1
+
+/* Set to 1 if __builtin_bswap32 is available */
+#define HAVE_BUILTIN_BSWAP32 1
+
+/* Set to 1 if __builtin_bswap64 is available */
+#define HAVE_BUILTIN_BSWAP64 1
+
+/* Define to 1 if you have the <dlfcn.h> header file. */
+#define HAVE_DLFCN_H 1
+
+/* Define to 1 if you have the <GLUT/glut.h> header file. */
+/* #undef HAVE_GLUT_GLUT_H */
+
+/* Define to 1 if you have the <GL/glut.h> header file. */
+/* #undef HAVE_GL_GLUT_H */
+
+/* Define to 1 if you have the <inttypes.h> header file. */
+#define HAVE_INTTYPES_H 1
+
+/* Define to 1 if you have the <memory.h> header file. */
+#define HAVE_MEMORY_H 1
+
+/* Define to 1 if you have the <OpenGL/glut.h> header file. */
+/* #undef HAVE_OPENGL_GLUT_H */
+
+/* Have PTHREAD_PRIO_INHERIT. */
+#define HAVE_PTHREAD_PRIO_INHERIT 1
+
+/* Define to 1 if you have the <shlwapi.h> header file. */
+/* #undef HAVE_SHLWAPI_H */
+
+/* Define to 1 if you have the <stdint.h> header file. */
+#define HAVE_STDINT_H 1
+
+/* Define to 1 if you have the <stdlib.h> header file. */
+#define HAVE_STDLIB_H 1
+
+/* Define to 1 if you have the <strings.h> header file. */
+#define HAVE_STRINGS_H 1
+
+/* Define to 1 if you have the <string.h> header file. */
+#define HAVE_STRING_H 1
+
+/* Define to 1 if you have the <sys/stat.h> header file. */
+#define HAVE_SYS_STAT_H 1
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#define HAVE_SYS_TYPES_H 1
+
+/* Define to 1 if you have the <unistd.h> header file. */
+#define HAVE_UNISTD_H 1
+
+/* Define to 1 if you have the <wincodec.h> header file. */
+/* #undef HAVE_WINCODEC_H */
+
+/* Define to 1 if you have the <windows.h> header file. */
+/* #undef HAVE_WINDOWS_H */
+
+/* Define to the sub-directory in which libtool stores uninstalled libraries.
+   */
+#define LT_OBJDIR ".libs/"
+
+/* Name of package */
+#define PACKAGE "libwebp"
+
+/* Define to the address where bug reports for this package should be sent. */
+#define PACKAGE_BUGREPORT "http://code.google.com/p/webp/issues"
+
+/* Define to the full name of this package. */
+#define PACKAGE_NAME "libwebp"
+
+/* Define to the full name and version of this package. */
+#define PACKAGE_STRING "libwebp 0.4.3"
+
+/* Define to the one symbol short name of this package. */
+#define PACKAGE_TARNAME "libwebp"
+
+/* Define to the home page for this package. */
+#define PACKAGE_URL "http://developers.google.com/speed/webp"
+
+/* Define to the version of this package. */
+#define PACKAGE_VERSION "0.4.3"
+
+/* Define to necessary symbol if this constant uses a non-standard name on
+   your system. */
+/* #undef PTHREAD_CREATE_JOINABLE */
+
+/* Define to 1 if you have the ANSI C header files. */
+#define STDC_HEADERS 1
+
+/* Version number of package */
+#define VERSION "0.4.3"
+
+/* Enable experimental code */
+/* #undef WEBP_EXPERIMENTAL_FEATURES */
+
+/* Define to 1 to force aligned memory operations */
+/* #undef WEBP_FORCE_ALIGNED */
+
+/* Set to 1 if AVX2 is supported */
+/* #undef WEBP_HAVE_AVX2 */
+
+/* Set to 1 if GIF library is installed */
+/* #undef WEBP_HAVE_GIF */
+
+/* Set to 1 if OpenGL is supported */
+/* #undef WEBP_HAVE_GL */
+
+/* Set to 1 if JPEG library is installed */
+/* #undef WEBP_HAVE_JPEG */
+
+/* Set to 1 if PNG library is installed */
+/* #undef WEBP_HAVE_PNG */
+
+/* Set to 1 if SSE2 is supported */
+/* #undef WEBP_HAVE_SSE2 */
+
+/* Set to 1 if TIFF library is installed */
+/* #undef WEBP_HAVE_TIFF */
+
+/* Undefine this to disable thread support. */
+#define WEBP_USE_THREAD 1
+
+/* Define WORDS_BIGENDIAN to 1 if your processor stores words with the most
+   significant byte first (like Motorola and SPARC, unlike Intel). */
+#if defined AC_APPLE_UNIVERSAL_BUILD
+# if defined __BIG_ENDIAN__
+#  define WORDS_BIGENDIAN 1
+# endif
+#else
+# ifndef WORDS_BIGENDIAN
+/* #  undef WORDS_BIGENDIAN */
+# endif
+#endif

Vendor/WebP.framework/Headers/decode.h

@@ -0,0 +1,503 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+//  Main decoding functions for WebP images.
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_WEBP_DECODE_H_
+#define WEBP_WEBP_DECODE_H_
+
+#include "./types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define WEBP_DECODER_ABI_VERSION 0x0203    // MAJOR(8b) + MINOR(8b)
+
+// Note: forward declaring enumerations is not allowed in (strict) C and C++,
+// the types are left here for reference.
+// typedef enum VP8StatusCode VP8StatusCode;
+// typedef enum WEBP_CSP_MODE WEBP_CSP_MODE;
+typedef struct WebPRGBABuffer WebPRGBABuffer;
+typedef struct WebPYUVABuffer WebPYUVABuffer;
+typedef struct WebPDecBuffer WebPDecBuffer;
+typedef struct WebPIDecoder WebPIDecoder;
+typedef struct WebPBitstreamFeatures WebPBitstreamFeatures;
+typedef struct WebPDecoderOptions WebPDecoderOptions;
+typedef struct WebPDecoderConfig WebPDecoderConfig;
+
+// Return the decoder's version number, packed in hexadecimal using 8bits for
+// each of major/minor/revision. E.g: v2.5.7 is 0x020507.
+WEBP_EXTERN(int) WebPGetDecoderVersion(void);
+
+// Retrieve basic header information: width, height.
+// This function will also validate the header and return 0 in
+// case of formatting error.
+// Pointers 'width' and 'height' can be passed NULL if deemed irrelevant.
+WEBP_EXTERN(int) WebPGetInfo(const uint8_t* data, size_t data_size,
+                             int* width, int* height);
+
+// Decodes WebP images pointed to by 'data' and returns RGBA samples, along
+// with the dimensions in *width and *height. The ordering of samples in
+// memory is R, G, B, A, R, G, B, A... in scan order (endian-independent).
+// The returned pointer should be deleted calling free().
+// Returns NULL in case of error.
+WEBP_EXTERN(uint8_t*) WebPDecodeRGBA(const uint8_t* data, size_t data_size,
+                                     int* width, int* height);
+
+// Same as WebPDecodeRGBA, but returning A, R, G, B, A, R, G, B... ordered data.
+WEBP_EXTERN(uint8_t*) WebPDecodeARGB(const uint8_t* data, size_t data_size,
+                                     int* width, int* height);
+
+// Same as WebPDecodeRGBA, but returning B, G, R, A, B, G, R, A... ordered data.
+WEBP_EXTERN(uint8_t*) WebPDecodeBGRA(const uint8_t* data, size_t data_size,
+                                     int* width, int* height);
+
+// Same as WebPDecodeRGBA, but returning R, G, B, R, G, B... ordered data.
+// If the bitstream contains transparency, it is ignored.
+WEBP_EXTERN(uint8_t*) WebPDecodeRGB(const uint8_t* data, size_t data_size,
+                                    int* width, int* height);
+
+// Same as WebPDecodeRGB, but returning B, G, R, B, G, R... ordered data.
+WEBP_EXTERN(uint8_t*) WebPDecodeBGR(const uint8_t* data, size_t data_size,
+                                    int* width, int* height);
+
+
+// Decode WebP images pointed to by 'data' to Y'UV format(*). The pointer
+// returned is the Y samples buffer. Upon return, *u and *v will point to
+// the U and V chroma data. These U and V buffers need NOT be free()'d,
+// unlike the returned Y luma one. The dimension of the U and V planes
+// are both (*width + 1) / 2 and (*height + 1)/ 2.
+// Upon return, the Y buffer has a stride returned as '*stride', while U and V
+// have a common stride returned as '*uv_stride'.
+// Return NULL in case of error.
+// (*) Also named Y'CbCr. See: http://en.wikipedia.org/wiki/YCbCr
+WEBP_EXTERN(uint8_t*) WebPDecodeYUV(const uint8_t* data, size_t data_size,
+                                    int* width, int* height,
+                                    uint8_t** u, uint8_t** v,
+                                    int* stride, int* uv_stride);
+
+// These five functions are variants of the above ones, that decode the image
+// directly into a pre-allocated buffer 'output_buffer'. The maximum storage
+// available in this buffer is indicated by 'output_buffer_size'. If this
+// storage is not sufficient (or an error occurred), NULL is returned.
+// Otherwise, output_buffer is returned, for convenience.
+// The parameter 'output_stride' specifies the distance (in bytes)
+// between scanlines. Hence, output_buffer_size is expected to be at least
+// output_stride x picture-height.
+WEBP_EXTERN(uint8_t*) WebPDecodeRGBAInto(
+    const uint8_t* data, size_t data_size,
+    uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
+WEBP_EXTERN(uint8_t*) WebPDecodeARGBInto(
+    const uint8_t* data, size_t data_size,
+    uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
+WEBP_EXTERN(uint8_t*) WebPDecodeBGRAInto(
+    const uint8_t* data, size_t data_size,
+    uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
+
+// RGB and BGR variants. Here too the transparency information, if present,
+// will be dropped and ignored.
+WEBP_EXTERN(uint8_t*) WebPDecodeRGBInto(
+    const uint8_t* data, size_t data_size,
+    uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
+WEBP_EXTERN(uint8_t*) WebPDecodeBGRInto(
+    const uint8_t* data, size_t data_size,
+    uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
+
+// WebPDecodeYUVInto() is a variant of WebPDecodeYUV() that operates directly
+// into pre-allocated luma/chroma plane buffers. This function requires the
+// strides to be passed: one for the luma plane and one for each of the
+// chroma ones. The size of each plane buffer is passed as 'luma_size',
+// 'u_size' and 'v_size' respectively.
+// Pointer to the luma plane ('*luma') is returned or NULL if an error occurred
+// during decoding (or because some buffers were found to be too small).
+WEBP_EXTERN(uint8_t*) WebPDecodeYUVInto(
+    const uint8_t* data, size_t data_size,
+    uint8_t* luma, size_t luma_size, int luma_stride,
+    uint8_t* u, size_t u_size, int u_stride,
+    uint8_t* v, size_t v_size, int v_stride);
+
+//------------------------------------------------------------------------------
+// Output colorspaces and buffer
+
+// Colorspaces
+// Note: the naming describes the byte-ordering of packed samples in memory.
+// For instance, MODE_BGRA relates to samples ordered as B,G,R,A,B,G,R,A,...
+// Non-capital names (e.g.:MODE_Argb) relates to pre-multiplied RGB channels.
+// RGBA-4444 and RGB-565 colorspaces are represented by following byte-order:
+// RGBA-4444: [r3 r2 r1 r0 g3 g2 g1 g0], [b3 b2 b1 b0 a3 a2 a1 a0], ...
+// RGB-565: [r4 r3 r2 r1 r0 g5 g4 g3], [g2 g1 g0 b4 b3 b2 b1 b0], ...
+// In the case WEBP_SWAP_16BITS_CSP is defined, the bytes are swapped for
+// these two modes:
+// RGBA-4444: [b3 b2 b1 b0 a3 a2 a1 a0], [r3 r2 r1 r0 g3 g2 g1 g0], ...
+// RGB-565: [g2 g1 g0 b4 b3 b2 b1 b0], [r4 r3 r2 r1 r0 g5 g4 g3], ...
+
+typedef enum WEBP_CSP_MODE {
+  MODE_RGB = 0, MODE_RGBA = 1,
+  MODE_BGR = 2, MODE_BGRA = 3,
+  MODE_ARGB = 4, MODE_RGBA_4444 = 5,
+  MODE_RGB_565 = 6,
+  // RGB-premultiplied transparent modes (alpha value is preserved)
+  MODE_rgbA = 7,
+  MODE_bgrA = 8,
+  MODE_Argb = 9,
+  MODE_rgbA_4444 = 10,
+  // YUV modes must come after RGB ones.
+  MODE_YUV = 11, MODE_YUVA = 12,  // yuv 4:2:0
+  MODE_LAST = 13
+} WEBP_CSP_MODE;
+
+// Some useful macros:
+static WEBP_INLINE int WebPIsPremultipliedMode(WEBP_CSP_MODE mode) {
+  return (mode == MODE_rgbA || mode == MODE_bgrA || mode == MODE_Argb ||
+          mode == MODE_rgbA_4444);
+}
+
+static WEBP_INLINE int WebPIsAlphaMode(WEBP_CSP_MODE mode) {
+  return (mode == MODE_RGBA || mode == MODE_BGRA || mode == MODE_ARGB ||
+          mode == MODE_RGBA_4444 || mode == MODE_YUVA ||
+          WebPIsPremultipliedMode(mode));
+}
+
+static WEBP_INLINE int WebPIsRGBMode(WEBP_CSP_MODE mode) {
+  return (mode < MODE_YUV);
+}
+
+//------------------------------------------------------------------------------
+// WebPDecBuffer: Generic structure for describing the output sample buffer.
+
+struct WebPRGBABuffer {    // view as RGBA
+  uint8_t* rgba;    // pointer to RGBA samples
+  int stride;       // stride in bytes from one scanline to the next.
+  size_t size;      // total size of the *rgba buffer.
+};
+
+struct WebPYUVABuffer {              // view as YUVA
+  uint8_t* y, *u, *v, *a;     // pointer to luma, chroma U/V, alpha samples
+  int y_stride;               // luma stride
+  int u_stride, v_stride;     // chroma strides
+  int a_stride;               // alpha stride
+  size_t y_size;              // luma plane size
+  size_t u_size, v_size;      // chroma planes size
+  size_t a_size;              // alpha-plane size
+};
+
+// Output buffer
+struct WebPDecBuffer {
+  WEBP_CSP_MODE colorspace;  // Colorspace.
+  int width, height;         // Dimensions.
+  int is_external_memory;    // If true, 'internal_memory' pointer is not used.
+  union {
+    WebPRGBABuffer RGBA;
+    WebPYUVABuffer YUVA;
+  } u;                       // Nameless union of buffer parameters.
+  uint32_t       pad[4];     // padding for later use
+
+  uint8_t* private_memory;   // Internally allocated memory (only when
+                             // is_external_memory is false). Should not be used
+                             // externally, but accessed via the buffer union.
+};
+
+// Internal, version-checked, entry point
+WEBP_EXTERN(int) WebPInitDecBufferInternal(WebPDecBuffer*, int);
+
+// Initialize the structure as empty. Must be called before any other use.
+// Returns false in case of version mismatch
+static WEBP_INLINE int WebPInitDecBuffer(WebPDecBuffer* buffer) {
+  return WebPInitDecBufferInternal(buffer, WEBP_DECODER_ABI_VERSION);
+}
+
+// Free any memory associated with the buffer. Must always be called last.
+// Note: doesn't free the 'buffer' structure itself.
+WEBP_EXTERN(void) WebPFreeDecBuffer(WebPDecBuffer* buffer);
+
+//------------------------------------------------------------------------------
+// Enumeration of the status codes
+
+typedef enum VP8StatusCode {
+  VP8_STATUS_OK = 0,
+  VP8_STATUS_OUT_OF_MEMORY,
+  VP8_STATUS_INVALID_PARAM,
+  VP8_STATUS_BITSTREAM_ERROR,
+  VP8_STATUS_UNSUPPORTED_FEATURE,
+  VP8_STATUS_SUSPENDED,
+  VP8_STATUS_USER_ABORT,
+  VP8_STATUS_NOT_ENOUGH_DATA
+} VP8StatusCode;
+
+//------------------------------------------------------------------------------
+// Incremental decoding
+//
+// This API allows streamlined decoding of partial data.
+// Picture can be incrementally decoded as data become available thanks to the
+// WebPIDecoder object. This object can be left in a SUSPENDED state if the
+// picture is only partially decoded, pending additional input.
+// Code example:
+//
+//   WebPInitDecBuffer(&buffer);
+//   buffer.colorspace = mode;
+//   ...
+//   WebPIDecoder* idec = WebPINewDecoder(&buffer);
+//   while (has_more_data) {
+//     // ... (get additional data)
+//     status = WebPIAppend(idec, new_data, new_data_size);
+//     if (status != VP8_STATUS_SUSPENDED ||
+//       break;
+//     }
+//
+//     // The above call decodes the current available buffer.
+//     // Part of the image can now be refreshed by calling to
+//     // WebPIDecGetRGB()/WebPIDecGetYUVA() etc.
+//   }
+//   WebPIDelete(idec);
+
+// Creates a new incremental decoder with the supplied buffer parameter.
+// This output_buffer can be passed NULL, in which case a default output buffer
+// is used (with MODE_RGB). Otherwise, an internal reference to 'output_buffer'
+// is kept, which means that the lifespan of 'output_buffer' must be larger than
+// that of the returned WebPIDecoder object.
+// The supplied 'output_buffer' content MUST NOT be changed between calls to
+// WebPIAppend() or WebPIUpdate() unless 'output_buffer.is_external_memory' is
+// set to 1. In such a case, it is allowed to modify the pointers, size and
+// stride of output_buffer.u.RGBA or output_buffer.u.YUVA, provided they remain
+// within valid bounds.
+// All other fields of WebPDecBuffer MUST remain constant between calls.
+// Returns NULL if the allocation failed.
+WEBP_EXTERN(WebPIDecoder*) WebPINewDecoder(WebPDecBuffer* output_buffer);
+
+// This function allocates and initializes an incremental-decoder object, which
+// will output the RGB/A samples specified by 'csp' into a preallocated
+// buffer 'output_buffer'. The size of this buffer is at least
+// 'output_buffer_size' and the stride (distance in bytes between two scanlines)
+// is specified by 'output_stride'.
+// Additionally, output_buffer can be passed NULL in which case the output
+// buffer will be allocated automatically when the decoding starts. The
+// colorspace 'csp' is taken into account for allocating this buffer. All other
+// parameters are ignored.
+// Returns NULL if the allocation failed, or if some parameters are invalid.
+WEBP_EXTERN(WebPIDecoder*) WebPINewRGB(
+    WEBP_CSP_MODE csp,
+    uint8_t* output_buffer, size_t output_buffer_size, int output_stride);
+
+// This function allocates and initializes an incremental-decoder object, which
+// will output the raw luma/chroma samples into a preallocated planes if
+// supplied. The luma plane is specified by its pointer 'luma', its size
+// 'luma_size' and its stride 'luma_stride'. Similarly, the chroma-u plane
+// is specified by the 'u', 'u_size' and 'u_stride' parameters, and the chroma-v
+// plane by 'v' and 'v_size'. And same for the alpha-plane. The 'a' pointer
+// can be pass NULL in case one is not interested in the transparency plane.
+// Conversely, 'luma' can be passed NULL if no preallocated planes are supplied.
+// In this case, the output buffer will be automatically allocated (using
+// MODE_YUVA) when decoding starts. All parameters are then ignored.
+// Returns NULL if the allocation failed or if a parameter is invalid.
+WEBP_EXTERN(WebPIDecoder*) WebPINewYUVA(
+    uint8_t* luma, size_t luma_size, int luma_stride,
+    uint8_t* u, size_t u_size, int u_stride,
+    uint8_t* v, size_t v_size, int v_stride,
+    uint8_t* a, size_t a_size, int a_stride);
+
+// Deprecated version of the above, without the alpha plane.
+// Kept for backward compatibility.
+WEBP_EXTERN(WebPIDecoder*) WebPINewYUV(
+    uint8_t* luma, size_t luma_size, int luma_stride,
+    uint8_t* u, size_t u_size, int u_stride,
+    uint8_t* v, size_t v_size, int v_stride);
+
+// Deletes the WebPIDecoder object and associated memory. Must always be called
+// if WebPINewDecoder, WebPINewRGB or WebPINewYUV succeeded.
+WEBP_EXTERN(void) WebPIDelete(WebPIDecoder* idec);
+
+// Copies and decodes the next available data. Returns VP8_STATUS_OK when
+// the image is successfully decoded. Returns VP8_STATUS_SUSPENDED when more
+// data is expected. Returns error in other cases.
+WEBP_EXTERN(VP8StatusCode) WebPIAppend(
+    WebPIDecoder* idec, const uint8_t* data, size_t data_size);
+
+// A variant of the above function to be used when data buffer contains
+// partial data from the beginning. In this case data buffer is not copied
+// to the internal memory.
+// Note that the value of the 'data' pointer can change between calls to
+// WebPIUpdate, for instance when the data buffer is resized to fit larger data.
+WEBP_EXTERN(VP8StatusCode) WebPIUpdate(
+    WebPIDecoder* idec, const uint8_t* data, size_t data_size);
+
+// Returns the RGB/A image decoded so far. Returns NULL if output params
+// are not initialized yet. The RGB/A output type corresponds to the colorspace
+// specified during call to WebPINewDecoder() or WebPINewRGB().
+// *last_y is the index of last decoded row in raster scan order. Some pointers
+// (*last_y, *width etc.) can be NULL if corresponding information is not
+// needed.
+WEBP_EXTERN(uint8_t*) WebPIDecGetRGB(
+    const WebPIDecoder* idec, int* last_y,
+    int* width, int* height, int* stride);
+
+// Same as above function to get a YUVA image. Returns pointer to the luma
+// plane or NULL in case of error. If there is no alpha information
+// the alpha pointer '*a' will be returned NULL.
+WEBP_EXTERN(uint8_t*) WebPIDecGetYUVA(
+    const WebPIDecoder* idec, int* last_y,
+    uint8_t** u, uint8_t** v, uint8_t** a,
+    int* width, int* height, int* stride, int* uv_stride, int* a_stride);
+
+// Deprecated alpha-less version of WebPIDecGetYUVA(): it will ignore the
+// alpha information (if present). Kept for backward compatibility.
+static WEBP_INLINE uint8_t* WebPIDecGetYUV(
+    const WebPIDecoder* idec, int* last_y, uint8_t** u, uint8_t** v,
+    int* width, int* height, int* stride, int* uv_stride) {
+  return WebPIDecGetYUVA(idec, last_y, u, v, NULL, width, height,
+                         stride, uv_stride, NULL);
+}
+
+// Generic call to retrieve information about the displayable area.
+// If non NULL, the left/right/width/height pointers are filled with the visible
+// rectangular area so far.
+// Returns NULL in case the incremental decoder object is in an invalid state.
+// Otherwise returns the pointer to the internal representation. This structure
+// is read-only, tied to WebPIDecoder's lifespan and should not be modified.
+WEBP_EXTERN(const WebPDecBuffer*) WebPIDecodedArea(
+    const WebPIDecoder* idec, int* left, int* top, int* width, int* height);
+
+//------------------------------------------------------------------------------
+// Advanced decoding parametrization
+//
+//  Code sample for using the advanced decoding API
+/*
+     // A) Init a configuration object
+     WebPDecoderConfig config;
+     CHECK(WebPInitDecoderConfig(&config));
+
+     // B) optional: retrieve the bitstream's features.
+     CHECK(WebPGetFeatures(data, data_size, &config.input) == VP8_STATUS_OK);
+
+     // C) Adjust 'config', if needed
+     config.no_fancy_upsampling = 1;
+     config.output.colorspace = MODE_BGRA;
+     // etc.
+
+     // Note that you can also make config.output point to an externally
+     // supplied memory buffer, provided it's big enough to store the decoded
+     // picture. Otherwise, config.output will just be used to allocate memory
+     // and store the decoded picture.
+
+     // D) Decode!
+     CHECK(WebPDecode(data, data_size, &config) == VP8_STATUS_OK);
+
+     // E) Decoded image is now in config.output (and config.output.u.RGBA)
+
+     // F) Reclaim memory allocated in config's object. It's safe to call
+     // this function even if the memory is external and wasn't allocated
+     // by WebPDecode().
+     WebPFreeDecBuffer(&config.output);
+*/
+
+// Features gathered from the bitstream
+struct WebPBitstreamFeatures {
+  int width;          // Width in pixels, as read from the bitstream.
+  int height;         // Height in pixels, as read from the bitstream.
+  int has_alpha;      // True if the bitstream contains an alpha channel.
+  int has_animation;  // True if the bitstream is an animation.
+  int format;         // 0 = undefined (/mixed), 1 = lossy, 2 = lossless
+
+  // Unused for now:
+  int no_incremental_decoding;  // if true, using incremental decoding is not
+                                // recommended.
+  int rotate;                   // TODO(later)
+  int uv_sampling;              // should be 0 for now. TODO(later)
+  uint32_t pad[2];              // padding for later use
+};
+
+// Internal, version-checked, entry point
+WEBP_EXTERN(VP8StatusCode) WebPGetFeaturesInternal(
+    const uint8_t*, size_t, WebPBitstreamFeatures*, int);
+
+// Retrieve features from the bitstream. The *features structure is filled
+// with information gathered from the bitstream.
+// Returns VP8_STATUS_OK when the features are successfully retrieved. Returns
+// VP8_STATUS_NOT_ENOUGH_DATA when more data is needed to retrieve the
+// features from headers. Returns error in other cases.
+static WEBP_INLINE VP8StatusCode WebPGetFeatures(
+    const uint8_t* data, size_t data_size,
+    WebPBitstreamFeatures* features) {
+  return WebPGetFeaturesInternal(data, data_size, features,
+                                 WEBP_DECODER_ABI_VERSION);
+}
+
+// Decoding options
+struct WebPDecoderOptions {
+  int bypass_filtering;               // if true, skip the in-loop filtering
+  int no_fancy_upsampling;            // if true, use faster pointwise upsampler
+  int use_cropping;                   // if true, cropping is applied _first_
+  int crop_left, crop_top;            // top-left position for cropping.
+                                      // Will be snapped to even values.
+  int crop_width, crop_height;        // dimension of the cropping area
+  int use_scaling;                    // if true, scaling is applied _afterward_
+  int scaled_width, scaled_height;    // final resolution
+  int use_threads;                    // if true, use multi-threaded decoding
+  int dithering_strength;             // dithering strength (0=Off, 100=full)
+#if WEBP_DECODER_ABI_VERSION > 0x0203
+  int flip;                           // flip output vertically
+#endif
+#if WEBP_DECODER_ABI_VERSION > 0x0204
+  int alpha_dithering_strength;       // alpha dithering strength in [0..100]
+#endif
+
+  // Unused for now:
+  int force_rotation;                 // forced rotation (to be applied _last_)
+  int no_enhancement;                 // if true, discard enhancement layer
+#if WEBP_DECODER_ABI_VERSION < 0x0203
+  uint32_t pad[5];                    // padding for later use
+#elif WEBP_DECODER_ABI_VERSION < 0x0204
+  uint32_t pad[4];                    // padding for later use
+#else
+  uint32_t pad[3];                    // padding for later use
+#endif
+};
+
+// Main object storing the configuration for advanced decoding.
+struct WebPDecoderConfig {
+  WebPBitstreamFeatures input;  // Immutable bitstream features (optional)
+  WebPDecBuffer output;         // Output buffer (can point to external mem)
+  WebPDecoderOptions options;   // Decoding options
+};
+
+// Internal, version-checked, entry point
+WEBP_EXTERN(int) WebPInitDecoderConfigInternal(WebPDecoderConfig*, int);
+
+// Initialize the configuration as empty. This function must always be
+// called first, unless WebPGetFeatures() is to be called.
+// Returns false in case of mismatched version.
+static WEBP_INLINE int WebPInitDecoderConfig(WebPDecoderConfig* config) {
+  return WebPInitDecoderConfigInternal(config, WEBP_DECODER_ABI_VERSION);
+}
+
+// Instantiate a new incremental decoder object with the requested
+// configuration. The bitstream can be passed using 'data' and 'data_size'
+// parameter, in which case the features will be parsed and stored into
+// config->input. Otherwise, 'data' can be NULL and no parsing will occur.
+// Note that 'config' can be NULL too, in which case a default configuration
+// is used.
+// The return WebPIDecoder object must always be deleted calling WebPIDelete().
+// Returns NULL in case of error (and config->status will then reflect
+// the error condition).
+WEBP_EXTERN(WebPIDecoder*) WebPIDecode(const uint8_t* data, size_t data_size,
+                                       WebPDecoderConfig* config);
+
+// Non-incremental version. This version decodes the full data at once, taking
+// 'config' into account. Returns decoding status (which should be VP8_STATUS_OK
+// if the decoding was successful).
+WEBP_EXTERN(VP8StatusCode) WebPDecode(const uint8_t* data, size_t data_size,
+                                      WebPDecoderConfig* config);
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_WEBP_DECODE_H_ */

Vendor/WebP.framework/Headers/demux.h

@@ -0,0 +1,224 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Demux API.
+// Enables extraction of image and extended format data from WebP files.
+
+// Code Example: Demuxing WebP data to extract all the frames, ICC profile
+// and EXIF/XMP metadata.
+/*
+  WebPDemuxer* demux = WebPDemux(&webp_data);
+
+  uint32_t width = WebPDemuxGetI(demux, WEBP_FF_CANVAS_WIDTH);
+  uint32_t height = WebPDemuxGetI(demux, WEBP_FF_CANVAS_HEIGHT);
+  // ... (Get information about the features present in the WebP file).
+  uint32_t flags = WebPDemuxGetI(demux, WEBP_FF_FORMAT_FLAGS);
+
+  // ... (Iterate over all frames).
+  WebPIterator iter;
+  if (WebPDemuxGetFrame(demux, 1, &iter)) {
+    do {
+      // ... (Consume 'iter'; e.g. Decode 'iter.fragment' with WebPDecode(),
+      // ... and get other frame properties like width, height, offsets etc.
+      // ... see 'struct WebPIterator' below for more info).
+    } while (WebPDemuxNextFrame(&iter));
+    WebPDemuxReleaseIterator(&iter);
+  }
+
+  // ... (Extract metadata).
+  WebPChunkIterator chunk_iter;
+  if (flags & ICCP_FLAG) WebPDemuxGetChunk(demux, "ICCP", 1, &chunk_iter);
+  // ... (Consume the ICC profile in 'chunk_iter.chunk').
+  WebPDemuxReleaseChunkIterator(&chunk_iter);
+  if (flags & EXIF_FLAG) WebPDemuxGetChunk(demux, "EXIF", 1, &chunk_iter);
+  // ... (Consume the EXIF metadata in 'chunk_iter.chunk').
+  WebPDemuxReleaseChunkIterator(&chunk_iter);
+  if (flags & XMP_FLAG) WebPDemuxGetChunk(demux, "XMP ", 1, &chunk_iter);
+  // ... (Consume the XMP metadata in 'chunk_iter.chunk').
+  WebPDemuxReleaseChunkIterator(&chunk_iter);
+  WebPDemuxDelete(demux);
+*/
+
+#ifndef WEBP_WEBP_DEMUX_H_
+#define WEBP_WEBP_DEMUX_H_
+
+#include "./mux_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define WEBP_DEMUX_ABI_VERSION 0x0101    // MAJOR(8b) + MINOR(8b)
+
+// Note: forward declaring enumerations is not allowed in (strict) C and C++,
+// the types are left here for reference.
+// typedef enum WebPDemuxState WebPDemuxState;
+// typedef enum WebPFormatFeature WebPFormatFeature;
+typedef struct WebPDemuxer WebPDemuxer;
+typedef struct WebPIterator WebPIterator;
+typedef struct WebPChunkIterator WebPChunkIterator;
+
+//------------------------------------------------------------------------------
+
+// Returns the version number of the demux library, packed in hexadecimal using
+// 8bits for each of major/minor/revision. E.g: v2.5.7 is 0x020507.
+WEBP_EXTERN(int) WebPGetDemuxVersion(void);
+
+//------------------------------------------------------------------------------
+// Life of a Demux object
+
+typedef enum WebPDemuxState {
+  WEBP_DEMUX_PARSE_ERROR    = -1,  // An error occurred while parsing.
+  WEBP_DEMUX_PARSING_HEADER =  0,  // Not enough data to parse full header.
+  WEBP_DEMUX_PARSED_HEADER  =  1,  // Header parsing complete,
+                                   // data may be available.
+  WEBP_DEMUX_DONE           =  2   // Entire file has been parsed.
+} WebPDemuxState;
+
+// Internal, version-checked, entry point
+WEBP_EXTERN(WebPDemuxer*) WebPDemuxInternal(
+    const WebPData*, int, WebPDemuxState*, int);
+
+// Parses the full WebP file given by 'data'.
+// Returns a WebPDemuxer object on successful parse, NULL otherwise.
+static WEBP_INLINE WebPDemuxer* WebPDemux(const WebPData* data) {
+  return WebPDemuxInternal(data, 0, NULL, WEBP_DEMUX_ABI_VERSION);
+}
+
+// Parses the possibly incomplete WebP file given by 'data'.
+// If 'state' is non-NULL it will be set to indicate the status of the demuxer.
+// Returns NULL in case of error or if there isn't enough data to start parsing;
+// and a WebPDemuxer object on successful parse.
+// Note that WebPDemuxer keeps internal pointers to 'data' memory segment.
+// If this data is volatile, the demuxer object should be deleted (by calling
+// WebPDemuxDelete()) and WebPDemuxPartial() called again on the new data.
+// This is usually an inexpensive operation.
+static WEBP_INLINE WebPDemuxer* WebPDemuxPartial(
+    const WebPData* data, WebPDemuxState* state) {
+  return WebPDemuxInternal(data, 1, state, WEBP_DEMUX_ABI_VERSION);
+}
+
+// Frees memory associated with 'dmux'.
+WEBP_EXTERN(void) WebPDemuxDelete(WebPDemuxer* dmux);
+
+//------------------------------------------------------------------------------
+// Data/information extraction.
+
+typedef enum WebPFormatFeature {
+  WEBP_FF_FORMAT_FLAGS,  // Extended format flags present in the 'VP8X' chunk.
+  WEBP_FF_CANVAS_WIDTH,
+  WEBP_FF_CANVAS_HEIGHT,
+  WEBP_FF_LOOP_COUNT,
+  WEBP_FF_BACKGROUND_COLOR,
+  WEBP_FF_FRAME_COUNT    // Number of frames present in the demux object.
+                         // In case of a partial demux, this is the number of
+                         // frames seen so far, with the last frame possibly
+                         // being partial.
+} WebPFormatFeature;
+
+// Get the 'feature' value from the 'dmux'.
+// NOTE: values are only valid if WebPDemux() was used or WebPDemuxPartial()
+// returned a state > WEBP_DEMUX_PARSING_HEADER.
+WEBP_EXTERN(uint32_t) WebPDemuxGetI(
+    const WebPDemuxer* dmux, WebPFormatFeature feature);
+
+//------------------------------------------------------------------------------
+// Frame iteration.
+
+struct WebPIterator {
+  int frame_num;
+  int num_frames;          // equivalent to WEBP_FF_FRAME_COUNT.
+  int fragment_num;
+  int num_fragments;
+  int x_offset, y_offset;  // offset relative to the canvas.
+  int width, height;       // dimensions of this frame or fragment.
+  int duration;            // display duration in milliseconds.
+  WebPMuxAnimDispose dispose_method;  // dispose method for the frame.
+  int complete;   // true if 'fragment' contains a full frame. partial images
+                  // may still be decoded with the WebP incremental decoder.
+  WebPData fragment;  // The frame or fragment given by 'frame_num' and
+                      // 'fragment_num'.
+  int has_alpha;      // True if the frame or fragment contains transparency.
+  WebPMuxAnimBlend blend_method;  // Blend operation for the frame.
+
+  uint32_t pad[2];         // padding for later use.
+  void* private_;          // for internal use only.
+};
+
+// Retrieves frame 'frame_number' from 'dmux'.
+// 'iter->fragment' points to the first fragment on return from this function.
+// Individual fragments may be extracted using WebPDemuxSelectFragment().
+// Setting 'frame_number' equal to 0 will return the last frame of the image.
+// Returns false if 'dmux' is NULL or frame 'frame_number' is not present.
+// Call WebPDemuxReleaseIterator() when use of the iterator is complete.
+// NOTE: 'dmux' must persist for the lifetime of 'iter'.
+WEBP_EXTERN(int) WebPDemuxGetFrame(
+    const WebPDemuxer* dmux, int frame_number, WebPIterator* iter);
+
+// Sets 'iter->fragment' to point to the next ('iter->frame_num' + 1) or
+// previous ('iter->frame_num' - 1) frame. These functions do not loop.
+// Returns true on success, false otherwise.
+WEBP_EXTERN(int) WebPDemuxNextFrame(WebPIterator* iter);
+WEBP_EXTERN(int) WebPDemuxPrevFrame(WebPIterator* iter);
+
+// Sets 'iter->fragment' to reflect fragment number 'fragment_num'.
+// Returns true if fragment 'fragment_num' is present, false otherwise.
+WEBP_EXTERN(int) WebPDemuxSelectFragment(WebPIterator* iter, int fragment_num);
+
+// Releases any memory associated with 'iter'.
+// Must be called before any subsequent calls to WebPDemuxGetChunk() on the same
+// iter. Also, must be called before destroying the associated WebPDemuxer with
+// WebPDemuxDelete().
+WEBP_EXTERN(void) WebPDemuxReleaseIterator(WebPIterator* iter);
+
+//------------------------------------------------------------------------------
+// Chunk iteration.
+
+struct WebPChunkIterator {
+  // The current and total number of chunks with the fourcc given to
+  // WebPDemuxGetChunk().
+  int chunk_num;
+  int num_chunks;
+  WebPData chunk;    // The payload of the chunk.
+
+  uint32_t pad[6];   // padding for later use
+  void* private_;
+};
+
+// Retrieves the 'chunk_number' instance of the chunk with id 'fourcc' from
+// 'dmux'.
+// 'fourcc' is a character array containing the fourcc of the chunk to return,
+// e.g., "ICCP", "XMP ", "EXIF", etc.
+// Setting 'chunk_number' equal to 0 will return the last chunk in a set.
+// Returns true if the chunk is found, false otherwise. Image related chunk
+// payloads are accessed through WebPDemuxGetFrame() and related functions.
+// Call WebPDemuxReleaseChunkIterator() when use of the iterator is complete.
+// NOTE: 'dmux' must persist for the lifetime of the iterator.
+WEBP_EXTERN(int) WebPDemuxGetChunk(const WebPDemuxer* dmux,
+                                   const char fourcc[4], int chunk_number,
+                                   WebPChunkIterator* iter);
+
+// Sets 'iter->chunk' to point to the next ('iter->chunk_num' + 1) or previous
+// ('iter->chunk_num' - 1) chunk. These functions do not loop.
+// Returns true on success, false otherwise.
+WEBP_EXTERN(int) WebPDemuxNextChunk(WebPChunkIterator* iter);
+WEBP_EXTERN(int) WebPDemuxPrevChunk(WebPChunkIterator* iter);
+
+// Releases any memory associated with 'iter'.
+// Must be called before destroying the associated WebPDemuxer with
+// WebPDemuxDelete().
+WEBP_EXTERN(void) WebPDemuxReleaseChunkIterator(WebPChunkIterator* iter);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_WEBP_DEMUX_H_ */

Vendor/WebP.framework/Headers/encode.h

@@ -0,0 +1,520 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+//   WebP encoder: main interface
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_WEBP_ENCODE_H_
+#define WEBP_WEBP_ENCODE_H_
+
+#include "./types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define WEBP_ENCODER_ABI_VERSION 0x0202    // MAJOR(8b) + MINOR(8b)
+
+// Note: forward declaring enumerations is not allowed in (strict) C and C++,
+// the types are left here for reference.
+// typedef enum WebPImageHint WebPImageHint;
+// typedef enum WebPEncCSP WebPEncCSP;
+// typedef enum WebPPreset WebPPreset;
+// typedef enum WebPEncodingError WebPEncodingError;
+typedef struct WebPConfig WebPConfig;
+typedef struct WebPPicture WebPPicture;   // main structure for I/O
+typedef struct WebPAuxStats WebPAuxStats;
+typedef struct WebPMemoryWriter WebPMemoryWriter;
+
+// Return the encoder's version number, packed in hexadecimal using 8bits for
+// each of major/minor/revision. E.g: v2.5.7 is 0x020507.
+WEBP_EXTERN(int) WebPGetEncoderVersion(void);
+
+//------------------------------------------------------------------------------
+// One-stop-shop call! No questions asked:
+
+// Returns the size of the compressed data (pointed to by *output), or 0 if
+// an error occurred. The compressed data must be released by the caller
+// using the call 'free(*output)'.
+// These functions compress using the lossy format, and the quality_factor
+// can go from 0 (smaller output, lower quality) to 100 (best quality,
+// larger output).
+WEBP_EXTERN(size_t) WebPEncodeRGB(const uint8_t* rgb,
+                                  int width, int height, int stride,
+                                  float quality_factor, uint8_t** output);
+WEBP_EXTERN(size_t) WebPEncodeBGR(const uint8_t* bgr,
+                                  int width, int height, int stride,
+                                  float quality_factor, uint8_t** output);
+WEBP_EXTERN(size_t) WebPEncodeRGBA(const uint8_t* rgba,
+                                   int width, int height, int stride,
+                                   float quality_factor, uint8_t** output);
+WEBP_EXTERN(size_t) WebPEncodeBGRA(const uint8_t* bgra,
+                                   int width, int height, int stride,
+                                   float quality_factor, uint8_t** output);
+
+// These functions are the equivalent of the above, but compressing in a
+// lossless manner. Files are usually larger than lossy format, but will
+// not suffer any compression loss.
+WEBP_EXTERN(size_t) WebPEncodeLosslessRGB(const uint8_t* rgb,
+                                          int width, int height, int stride,
+                                          uint8_t** output);
+WEBP_EXTERN(size_t) WebPEncodeLosslessBGR(const uint8_t* bgr,
+                                          int width, int height, int stride,
+                                          uint8_t** output);
+WEBP_EXTERN(size_t) WebPEncodeLosslessRGBA(const uint8_t* rgba,
+                                           int width, int height, int stride,
+                                           uint8_t** output);
+WEBP_EXTERN(size_t) WebPEncodeLosslessBGRA(const uint8_t* bgra,
+                                           int width, int height, int stride,
+                                           uint8_t** output);
+
+//------------------------------------------------------------------------------
+// Coding parameters
+
+// Image characteristics hint for the underlying encoder.
+typedef enum WebPImageHint {
+  WEBP_HINT_DEFAULT = 0,  // default preset.
+  WEBP_HINT_PICTURE,      // digital picture, like portrait, inner shot
+  WEBP_HINT_PHOTO,        // outdoor photograph, with natural lighting
+  WEBP_HINT_GRAPH,        // Discrete tone image (graph, map-tile etc).
+  WEBP_HINT_LAST
+} WebPImageHint;
+
+// Compression parameters.
+struct WebPConfig {
+  int lossless;           // Lossless encoding (0=lossy(default), 1=lossless).
+  float quality;          // between 0 (smallest file) and 100 (biggest)
+  int method;             // quality/speed trade-off (0=fast, 6=slower-better)
+
+  WebPImageHint image_hint;  // Hint for image type (lossless only for now).
+
+  // Parameters related to lossy compression only:
+  int target_size;        // if non-zero, set the desired target size in bytes.
+                          // Takes precedence over the 'compression' parameter.
+  float target_PSNR;      // if non-zero, specifies the minimal distortion to
+                          // try to achieve. Takes precedence over target_size.
+  int segments;           // maximum number of segments to use, in [1..4]
+  int sns_strength;       // Spatial Noise Shaping. 0=off, 100=maximum.
+  int filter_strength;    // range: [0 = off .. 100 = strongest]
+  int filter_sharpness;   // range: [0 = off .. 7 = least sharp]
+  int filter_type;        // filtering type: 0 = simple, 1 = strong (only used
+                          // if filter_strength > 0 or autofilter > 0)
+  int autofilter;         // Auto adjust filter's strength [0 = off, 1 = on]
+  int alpha_compression;  // Algorithm for encoding the alpha plane (0 = none,
+                          // 1 = compressed with WebP lossless). Default is 1.
+  int alpha_filtering;    // Predictive filtering method for alpha plane.
+                          //  0: none, 1: fast, 2: best. Default if 1.
+  int alpha_quality;      // Between 0 (smallest size) and 100 (lossless).
+                          // Default is 100.
+  int pass;               // number of entropy-analysis passes (in [1..10]).
+
+  int show_compressed;    // if true, export the compressed picture back.
+                          // In-loop filtering is not applied.
+  int preprocessing;      // preprocessing filter:
+                          // 0=none, 1=segment-smooth, 2=pseudo-random dithering
+  int partitions;         // log2(number of token partitions) in [0..3]. Default
+                          // is set to 0 for easier progressive decoding.
+  int partition_limit;    // quality degradation allowed to fit the 512k limit
+                          // on prediction modes coding (0: no degradation,
+                          // 100: maximum possible degradation).
+  int emulate_jpeg_size;  // If true, compression parameters will be remapped
+                          // to better match the expected output size from
+                          // JPEG compression. Generally, the output size will
+                          // be similar but the degradation will be lower.
+  int thread_level;       // If non-zero, try and use multi-threaded encoding.
+  int low_memory;         // If set, reduce memory usage (but increase CPU use).
+
+  uint32_t pad[5];        // padding for later use
+};
+
+// Enumerate some predefined settings for WebPConfig, depending on the type
+// of source picture. These presets are used when calling WebPConfigPreset().
+typedef enum WebPPreset {
+  WEBP_PRESET_DEFAULT = 0,  // default preset.
+  WEBP_PRESET_PICTURE,      // digital picture, like portrait, inner shot
+  WEBP_PRESET_PHOTO,        // outdoor photograph, with natural lighting
+  WEBP_PRESET_DRAWING,      // hand or line drawing, with high-contrast details
+  WEBP_PRESET_ICON,         // small-sized colorful images
+  WEBP_PRESET_TEXT          // text-like
+} WebPPreset;
+
+// Internal, version-checked, entry point
+WEBP_EXTERN(int) WebPConfigInitInternal(WebPConfig*, WebPPreset, float, int);
+
+// Should always be called, to initialize a fresh WebPConfig structure before
+// modification. Returns false in case of version mismatch. WebPConfigInit()
+// must have succeeded before using the 'config' object.
+// Note that the default values are lossless=0 and quality=75.
+static WEBP_INLINE int WebPConfigInit(WebPConfig* config) {
+  return WebPConfigInitInternal(config, WEBP_PRESET_DEFAULT, 75.f,
+                                WEBP_ENCODER_ABI_VERSION);
+}
+
+// This function will initialize the configuration according to a predefined
+// set of parameters (referred to by 'preset') and a given quality factor.
+// This function can be called as a replacement to WebPConfigInit(). Will
+// return false in case of error.
+static WEBP_INLINE int WebPConfigPreset(WebPConfig* config,
+                                        WebPPreset preset, float quality) {
+  return WebPConfigInitInternal(config, preset, quality,
+                                WEBP_ENCODER_ABI_VERSION);
+}
+
+#if WEBP_ENCODER_ABI_VERSION > 0x0202
+// Activate the lossless compression mode with the desired efficiency level
+// between 0 (fastest, lowest compression) and 9 (slower, best compression).
+// A good default level is '6', providing a fair tradeoff between compression
+// speed and final compressed size.
+// This function will overwrite several fields from config: 'method', 'quality'
+// and 'lossless'. Returns false in case of parameter error.
+WEBP_EXTERN(int) WebPConfigLosslessPreset(WebPConfig* config, int level);
+#endif
+
+// Returns true if 'config' is non-NULL and all configuration parameters are
+// within their valid ranges.
+WEBP_EXTERN(int) WebPValidateConfig(const WebPConfig* config);
+
+//------------------------------------------------------------------------------
+// Input / Output
+// Structure for storing auxiliary statistics (mostly for lossy encoding).
+
+struct WebPAuxStats {
+  int coded_size;         // final size
+
+  float PSNR[5];          // peak-signal-to-noise ratio for Y/U/V/All/Alpha
+  int block_count[3];     // number of intra4/intra16/skipped macroblocks
+  int header_bytes[2];    // approximate number of bytes spent for header
+                          // and mode-partition #0
+  int residual_bytes[3][4];  // approximate number of bytes spent for
+                             // DC/AC/uv coefficients for each (0..3) segments.
+  int segment_size[4];    // number of macroblocks in each segments
+  int segment_quant[4];   // quantizer values for each segments
+  int segment_level[4];   // filtering strength for each segments [0..63]
+
+  int alpha_data_size;    // size of the transparency data
+  int layer_data_size;    // size of the enhancement layer data
+
+  // lossless encoder statistics
+  uint32_t lossless_features;  // bit0:predictor bit1:cross-color transform
+                               // bit2:subtract-green bit3:color indexing
+  int histogram_bits;          // number of precision bits of histogram
+  int transform_bits;          // precision bits for transform
+  int cache_bits;              // number of bits for color cache lookup
+  int palette_size;            // number of color in palette, if used
+  int lossless_size;           // final lossless size
+
+  uint32_t pad[4];        // padding for later use
+};
+
+// Signature for output function. Should return true if writing was successful.
+// data/data_size is the segment of data to write, and 'picture' is for
+// reference (and so one can make use of picture->custom_ptr).
+typedef int (*WebPWriterFunction)(const uint8_t* data, size_t data_size,
+                                  const WebPPicture* picture);
+
+// WebPMemoryWrite: a special WebPWriterFunction that writes to memory using
+// the following WebPMemoryWriter object (to be set as a custom_ptr).
+struct WebPMemoryWriter {
+  uint8_t* mem;       // final buffer (of size 'max_size', larger than 'size').
+  size_t   size;      // final size
+  size_t   max_size;  // total capacity
+  uint32_t pad[1];    // padding for later use
+};
+
+// The following must be called first before any use.
+WEBP_EXTERN(void) WebPMemoryWriterInit(WebPMemoryWriter* writer);
+
+#if WEBP_ENCODER_ABI_VERSION > 0x0203
+// The following must be called to deallocate writer->mem memory. The 'writer'
+// object itself is not deallocated.
+WEBP_EXTERN(void) WebPMemoryWriterClear(WebPMemoryWriter* writer);
+#endif
+// The custom writer to be used with WebPMemoryWriter as custom_ptr. Upon
+// completion, writer.mem and writer.size will hold the coded data.
+#if WEBP_ENCODER_ABI_VERSION > 0x0203
+// writer.mem must be freed by calling WebPMemoryWriterClear.
+#else
+// writer.mem must be freed by calling 'free(writer.mem)'.
+#endif
+WEBP_EXTERN(int) WebPMemoryWrite(const uint8_t* data, size_t data_size,
+                                 const WebPPicture* picture);
+
+// Progress hook, called from time to time to report progress. It can return
+// false to request an abort of the encoding process, or true otherwise if
+// everything is OK.
+typedef int (*WebPProgressHook)(int percent, const WebPPicture* picture);
+
+// Color spaces.
+typedef enum WebPEncCSP {
+  // chroma sampling
+  WEBP_YUV420  = 0,        // 4:2:0
+  WEBP_YUV420A = 4,        // alpha channel variant
+  WEBP_CSP_UV_MASK = 3,    // bit-mask to get the UV sampling factors
+  WEBP_CSP_ALPHA_BIT = 4   // bit that is set if alpha is present
+} WebPEncCSP;
+
+// Encoding error conditions.
+typedef enum WebPEncodingError {
+  VP8_ENC_OK = 0,
+  VP8_ENC_ERROR_OUT_OF_MEMORY,            // memory error allocating objects
+  VP8_ENC_ERROR_BITSTREAM_OUT_OF_MEMORY,  // memory error while flushing bits
+  VP8_ENC_ERROR_NULL_PARAMETER,           // a pointer parameter is NULL
+  VP8_ENC_ERROR_INVALID_CONFIGURATION,    // configuration is invalid
+  VP8_ENC_ERROR_BAD_DIMENSION,            // picture has invalid width/height
+  VP8_ENC_ERROR_PARTITION0_OVERFLOW,      // partition is bigger than 512k
+  VP8_ENC_ERROR_PARTITION_OVERFLOW,       // partition is bigger than 16M
+  VP8_ENC_ERROR_BAD_WRITE,                // error while flushing bytes
+  VP8_ENC_ERROR_FILE_TOO_BIG,             // file is bigger than 4G
+  VP8_ENC_ERROR_USER_ABORT,               // abort request by user
+  VP8_ENC_ERROR_LAST                      // list terminator. always last.
+} WebPEncodingError;
+
+// maximum width/height allowed (inclusive), in pixels
+#define WEBP_MAX_DIMENSION 16383
+
+// Main exchange structure (input samples, output bytes, statistics)
+struct WebPPicture {
+  //   INPUT
+  //////////////
+  // Main flag for encoder selecting between ARGB or YUV input.
+  // It is recommended to use ARGB input (*argb, argb_stride) for lossless
+  // compression, and YUV input (*y, *u, *v, etc.) for lossy compression
+  // since these are the respective native colorspace for these formats.
+  int use_argb;
+
+  // YUV input (mostly used for input to lossy compression)
+  WebPEncCSP colorspace;     // colorspace: should be YUV420 for now (=Y'CbCr).
+  int width, height;         // dimensions (less or equal to WEBP_MAX_DIMENSION)
+  uint8_t *y, *u, *v;        // pointers to luma/chroma planes.
+  int y_stride, uv_stride;   // luma/chroma strides.
+  uint8_t* a;                // pointer to the alpha plane
+  int a_stride;              // stride of the alpha plane
+  uint32_t pad1[2];          // padding for later use
+
+  // ARGB input (mostly used for input to lossless compression)
+  uint32_t* argb;            // Pointer to argb (32 bit) plane.
+  int argb_stride;           // This is stride in pixels units, not bytes.
+  uint32_t pad2[3];          // padding for later use
+
+  //   OUTPUT
+  ///////////////
+  // Byte-emission hook, to store compressed bytes as they are ready.
+  WebPWriterFunction writer;  // can be NULL
+  void* custom_ptr;           // can be used by the writer.
+
+  // map for extra information (only for lossy compression mode)
+  int extra_info_type;    // 1: intra type, 2: segment, 3: quant
+                          // 4: intra-16 prediction mode,
+                          // 5: chroma prediction mode,
+                          // 6: bit cost, 7: distortion
+  uint8_t* extra_info;    // if not NULL, points to an array of size
+                          // ((width + 15) / 16) * ((height + 15) / 16) that
+                          // will be filled with a macroblock map, depending
+                          // on extra_info_type.
+
+  //   STATS AND REPORTS
+  ///////////////////////////
+  // Pointer to side statistics (updated only if not NULL)
+  WebPAuxStats* stats;
+
+  // Error code for the latest error encountered during encoding
+  WebPEncodingError error_code;
+
+  // If not NULL, report progress during encoding.
+  WebPProgressHook progress_hook;
+
+  void* user_data;        // this field is free to be set to any value and
+                          // used during callbacks (like progress-report e.g.).
+
+  uint32_t pad3[3];       // padding for later use
+
+  // Unused for now
+  uint8_t *pad4, *pad5;
+  uint32_t pad6[8];       // padding for later use
+
+  // PRIVATE FIELDS
+  ////////////////////
+  void* memory_;          // row chunk of memory for yuva planes
+  void* memory_argb_;     // and for argb too.
+  void* pad7[2];          // padding for later use
+};
+
+// Internal, version-checked, entry point
+WEBP_EXTERN(int) WebPPictureInitInternal(WebPPicture*, int);
+
+// Should always be called, to initialize the structure. Returns false in case
+// of version mismatch. WebPPictureInit() must have succeeded before using the
+// 'picture' object.
+// Note that, by default, use_argb is false and colorspace is WEBP_YUV420.
+static WEBP_INLINE int WebPPictureInit(WebPPicture* picture) {
+  return WebPPictureInitInternal(picture, WEBP_ENCODER_ABI_VERSION);
+}
+
+//------------------------------------------------------------------------------
+// WebPPicture utils
+
+// Convenience allocation / deallocation based on picture->width/height:
+// Allocate y/u/v buffers as per colorspace/width/height specification.
+// Note! This function will free the previous buffer if needed.
+// Returns false in case of memory error.
+WEBP_EXTERN(int) WebPPictureAlloc(WebPPicture* picture);
+
+// Release the memory allocated by WebPPictureAlloc() or WebPPictureImport*().
+// Note that this function does _not_ free the memory used by the 'picture'
+// object itself.
+// Besides memory (which is reclaimed) all other fields of 'picture' are
+// preserved.
+WEBP_EXTERN(void) WebPPictureFree(WebPPicture* picture);
+
+// Copy the pixels of *src into *dst, using WebPPictureAlloc. Upon return, *dst
+// will fully own the copied pixels (this is not a view). The 'dst' picture need
+// not be initialized as its content is overwritten.
+// Returns false in case of memory allocation error.
+WEBP_EXTERN(int) WebPPictureCopy(const WebPPicture* src, WebPPicture* dst);
+
+// Compute PSNR, SSIM or LSIM distortion metric between two pictures.
+// Result is in dB, stores in result[] in the Y/U/V/Alpha/All order.
+// Returns false in case of error (src and ref don't have same dimension, ...)
+// Warning: this function is rather CPU-intensive.
+WEBP_EXTERN(int) WebPPictureDistortion(
+    const WebPPicture* src, const WebPPicture* ref,
+    int metric_type,           // 0 = PSNR, 1 = SSIM, 2 = LSIM
+    float result[5]);
+
+// self-crops a picture to the rectangle defined by top/left/width/height.
+// Returns false in case of memory allocation error, or if the rectangle is
+// outside of the source picture.
+// The rectangle for the view is defined by the top-left corner pixel
+// coordinates (left, top) as well as its width and height. This rectangle
+// must be fully be comprised inside the 'src' source picture. If the source
+// picture uses the YUV420 colorspace, the top and left coordinates will be
+// snapped to even values.
+WEBP_EXTERN(int) WebPPictureCrop(WebPPicture* picture,
+                                 int left, int top, int width, int height);
+
+// Extracts a view from 'src' picture into 'dst'. The rectangle for the view
+// is defined by the top-left corner pixel coordinates (left, top) as well
+// as its width and height. This rectangle must be fully be comprised inside
+// the 'src' source picture. If the source picture uses the YUV420 colorspace,
+// the top and left coordinates will be snapped to even values.
+// Picture 'src' must out-live 'dst' picture. Self-extraction of view is allowed
+// ('src' equal to 'dst') as a mean of fast-cropping (but note that doing so,
+// the original dimension will be lost). Picture 'dst' need not be initialized
+// with WebPPictureInit() if it is different from 'src', since its content will
+// be overwritten.
+// Returns false in case of memory allocation error or invalid parameters.
+WEBP_EXTERN(int) WebPPictureView(const WebPPicture* src,
+                                 int left, int top, int width, int height,
+                                 WebPPicture* dst);
+
+// Returns true if the 'picture' is actually a view and therefore does
+// not own the memory for pixels.
+WEBP_EXTERN(int) WebPPictureIsView(const WebPPicture* picture);
+
+// Rescale a picture to new dimension width x height.
+// If either 'width' or 'height' (but not both) is 0 the corresponding
+// dimension will be calculated preserving the aspect ratio.
+// No gamma correction is applied.
+// Returns false in case of error (invalid parameter or insufficient memory).
+WEBP_EXTERN(int) WebPPictureRescale(WebPPicture* pic, int width, int height);
+
+// Colorspace conversion function to import RGB samples.
+// Previous buffer will be free'd, if any.
+// *rgb buffer should have a size of at least height * rgb_stride.
+// Returns false in case of memory error.
+WEBP_EXTERN(int) WebPPictureImportRGB(
+    WebPPicture* picture, const uint8_t* rgb, int rgb_stride);
+// Same, but for RGBA buffer.
+WEBP_EXTERN(int) WebPPictureImportRGBA(
+    WebPPicture* picture, const uint8_t* rgba, int rgba_stride);
+// Same, but for RGBA buffer. Imports the RGB direct from the 32-bit format
+// input buffer ignoring the alpha channel. Avoids needing to copy the data
+// to a temporary 24-bit RGB buffer to import the RGB only.
+WEBP_EXTERN(int) WebPPictureImportRGBX(
+    WebPPicture* picture, const uint8_t* rgbx, int rgbx_stride);
+
+// Variants of the above, but taking BGR(A|X) input.
+WEBP_EXTERN(int) WebPPictureImportBGR(
+    WebPPicture* picture, const uint8_t* bgr, int bgr_stride);
+WEBP_EXTERN(int) WebPPictureImportBGRA(
+    WebPPicture* picture, const uint8_t* bgra, int bgra_stride);
+WEBP_EXTERN(int) WebPPictureImportBGRX(
+    WebPPicture* picture, const uint8_t* bgrx, int bgrx_stride);
+
+// Converts picture->argb data to the YUV420A format. The 'colorspace'
+// parameter is deprecated and should be equal to WEBP_YUV420.
+// Upon return, picture->use_argb is set to false. The presence of real
+// non-opaque transparent values is detected, and 'colorspace' will be
+// adjusted accordingly. Note that this method is lossy.
+// Returns false in case of error.
+WEBP_EXTERN(int) WebPPictureARGBToYUVA(WebPPicture* picture,
+                                       WebPEncCSP /*colorspace = WEBP_YUV420*/);
+
+// Same as WebPPictureARGBToYUVA(), but the conversion is done using
+// pseudo-random dithering with a strength 'dithering' between
+// 0.0 (no dithering) and 1.0 (maximum dithering). This is useful
+// for photographic picture.
+WEBP_EXTERN(int) WebPPictureARGBToYUVADithered(
+    WebPPicture* picture, WebPEncCSP colorspace, float dithering);
+
+#if WEBP_ENCODER_ABI_VERSION > 0x0204
+// Performs 'smart' RGBA->YUVA420 downsampling and colorspace conversion.
+// Downsampling is handled with extra care in case of color clipping. This
+// method is roughly 2x slower than WebPPictureARGBToYUVA() but produces better
+// YUV representation.
+// Returns false in case of error.
+WEBP_EXTERN(int) WebPPictureSmartARGBToYUVA(WebPPicture* picture);
+#endif
+
+// Converts picture->yuv to picture->argb and sets picture->use_argb to true.
+// The input format must be YUV_420 or YUV_420A.
+// Note that the use of this method is discouraged if one has access to the
+// raw ARGB samples, since using YUV420 is comparatively lossy. Also, the
+// conversion from YUV420 to ARGB incurs a small loss too.
+// Returns false in case of error.
+WEBP_EXTERN(int) WebPPictureYUVAToARGB(WebPPicture* picture);
+
+// Helper function: given a width x height plane of RGBA or YUV(A) samples
+// clean-up the YUV or RGB samples under fully transparent area, to help
+// compressibility (no guarantee, though).
+WEBP_EXTERN(void) WebPCleanupTransparentArea(WebPPicture* picture);
+
+// Scan the picture 'picture' for the presence of non fully opaque alpha values.
+// Returns true in such case. Otherwise returns false (indicating that the
+// alpha plane can be ignored altogether e.g.).
+WEBP_EXTERN(int) WebPPictureHasTransparency(const WebPPicture* picture);
+
+// Remove the transparency information (if present) by blending the color with
+// the background color 'background_rgb' (specified as 24bit RGB triplet).
+// After this call, all alpha values are reset to 0xff.
+WEBP_EXTERN(void) WebPBlendAlpha(WebPPicture* pic, uint32_t background_rgb);
+
+//------------------------------------------------------------------------------
+// Main call
+
+// Main encoding call, after config and picture have been initialized.
+// 'picture' must be less than 16384x16384 in dimension (cf WEBP_MAX_DIMENSION),
+// and the 'config' object must be a valid one.
+// Returns false in case of error, true otherwise.
+// In case of error, picture->error_code is updated accordingly.
+// 'picture' can hold the source samples in both YUV(A) or ARGB input, depending
+// on the value of 'picture->use_argb'. It is highly recommended to use
+// the former for lossy encoding, and the latter for lossless encoding
+// (when config.lossless is true). Automatic conversion from one format to
+// another is provided but they both incur some loss.
+WEBP_EXTERN(int) WebPEncode(const WebPConfig* config, WebPPicture* picture);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_WEBP_ENCODE_H_ */

Vendor/WebP.framework/Headers/format_constants.h

@@ -0,0 +1,88 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+//  Internal header for constants related to WebP file format.
+//
+// Author: Urvang (urvang@google.com)
+
+#ifndef WEBP_WEBP_FORMAT_CONSTANTS_H_
+#define WEBP_WEBP_FORMAT_CONSTANTS_H_
+
+// Create fourcc of the chunk from the chunk tag characters.
+#define MKFOURCC(a, b, c, d) ((uint32_t)(a) | (b) << 8 | (c) << 16 | (d) << 24)
+
+// VP8 related constants.
+#define VP8_SIGNATURE 0x9d012a              // Signature in VP8 data.
+#define VP8_MAX_PARTITION0_SIZE (1 << 19)   // max size of mode partition
+#define VP8_MAX_PARTITION_SIZE  (1 << 24)   // max size for token partition
+#define VP8_FRAME_HEADER_SIZE 10  // Size of the frame header within VP8 data.
+
+// VP8L related constants.
+#define VP8L_SIGNATURE_SIZE          1      // VP8L signature size.
+#define VP8L_MAGIC_BYTE              0x2f   // VP8L signature byte.
+#define VP8L_IMAGE_SIZE_BITS         14     // Number of bits used to store
+                                            // width and height.
+#define VP8L_VERSION_BITS            3      // 3 bits reserved for version.
+#define VP8L_VERSION                 0      // version 0
+#define VP8L_FRAME_HEADER_SIZE       5      // Size of the VP8L frame header.
+
+#define MAX_PALETTE_SIZE             256
+#define MAX_CACHE_BITS               11
+#define HUFFMAN_CODES_PER_META_CODE  5
+#define ARGB_BLACK                   0xff000000
+
+#define DEFAULT_CODE_LENGTH          8
+#define MAX_ALLOWED_CODE_LENGTH      15
+
+#define NUM_LITERAL_CODES            256
+#define NUM_LENGTH_CODES             24
+#define NUM_DISTANCE_CODES           40
+#define CODE_LENGTH_CODES            19
+
+#define MIN_HUFFMAN_BITS             2  // min number of Huffman bits
+#define MAX_HUFFMAN_BITS             9  // max number of Huffman bits
+
+#define TRANSFORM_PRESENT            1  // The bit to be written when next data
+                                        // to be read is a transform.
+#define NUM_TRANSFORMS               4  // Maximum number of allowed transform
+                                        // in a bitstream.
+typedef enum {
+  PREDICTOR_TRANSFORM      = 0,
+  CROSS_COLOR_TRANSFORM    = 1,
+  SUBTRACT_GREEN           = 2,
+  COLOR_INDEXING_TRANSFORM = 3
+} VP8LImageTransformType;
+
+// Alpha related constants.
+#define ALPHA_HEADER_LEN            1
+#define ALPHA_NO_COMPRESSION        0
+#define ALPHA_LOSSLESS_COMPRESSION  1
+#define ALPHA_PREPROCESSED_LEVELS   1
+
+// Mux related constants.
+#define TAG_SIZE           4     // Size of a chunk tag (e.g. "VP8L").
+#define CHUNK_SIZE_BYTES   4     // Size needed to store chunk's size.
+#define CHUNK_HEADER_SIZE  8     // Size of a chunk header.
+#define RIFF_HEADER_SIZE   12    // Size of the RIFF header ("RIFFnnnnWEBP").
+#define ANMF_CHUNK_SIZE    16    // Size of an ANMF chunk.
+#define ANIM_CHUNK_SIZE    6     // Size of an ANIM chunk.
+#define FRGM_CHUNK_SIZE    6     // Size of a FRGM chunk.
+#define VP8X_CHUNK_SIZE    10    // Size of a VP8X chunk.
+
+#define MAX_CANVAS_SIZE     (1 << 24)     // 24-bit max for VP8X width/height.
+#define MAX_IMAGE_AREA      (1ULL << 32)  // 32-bit max for width x height.
+#define MAX_LOOP_COUNT      (1 << 16)     // maximum value for loop-count
+#define MAX_DURATION        (1 << 24)     // maximum duration
+#define MAX_POSITION_OFFSET (1 << 24)     // maximum frame/fragment x/y offset
+
+// Maximum chunk payload is such that adding the header and padding won't
+// overflow a uint32_t.
+#define MAX_CHUNK_PAYLOAD (~0U - CHUNK_HEADER_SIZE - 1)
+
+#endif  /* WEBP_WEBP_FORMAT_CONSTANTS_H_ */

Vendor/WebP.framework/Headers/mux.h

@@ -0,0 +1,399 @@
+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+//  RIFF container manipulation for WebP images.
+//
+// Authors: Urvang (urvang@google.com)
+//          Vikas (vikasa@google.com)
+
+// This API allows manipulation of WebP container images containing features
+// like color profile, metadata, animation and fragmented images.
+//
+// Code Example#1: Create a WebPMux object with image data, color profile and
+// XMP metadata.
+/*
+  int copy_data = 0;
+  WebPMux* mux = WebPMuxNew();
+  // ... (Prepare image data).
+  WebPMuxSetImage(mux, &image, copy_data);
+  // ... (Prepare ICCP color profile data).
+  WebPMuxSetChunk(mux, "ICCP", &icc_profile, copy_data);
+  // ... (Prepare XMP metadata).
+  WebPMuxSetChunk(mux, "XMP ", &xmp, copy_data);
+  // Get data from mux in WebP RIFF format.
+  WebPMuxAssemble(mux, &output_data);
+  WebPMuxDelete(mux);
+  // ... (Consume output_data; e.g. write output_data.bytes to file).
+  WebPDataClear(&output_data);
+*/
+
+// Code Example#2: Get image and color profile data from a WebP file.
+/*
+  int copy_data = 0;
+  // ... (Read data from file).
+  WebPMux* mux = WebPMuxCreate(&data, copy_data);
+  WebPMuxGetFrame(mux, 1, &image);
+  // ... (Consume image; e.g. call WebPDecode() to decode the data).
+  WebPMuxGetChunk(mux, "ICCP", &icc_profile);
+  // ... (Consume icc_data).
+  WebPMuxDelete(mux);
+  free(data);
+*/
+
+#ifndef WEBP_WEBP_MUX_H_
+#define WEBP_WEBP_MUX_H_
+
+#include "./mux_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define WEBP_MUX_ABI_VERSION 0x0101        // MAJOR(8b) + MINOR(8b)
+
+// Note: forward declaring enumerations is not allowed in (strict) C and C++,
+// the types are left here for reference.
+// typedef enum WebPMuxError WebPMuxError;
+// typedef enum WebPChunkId WebPChunkId;
+typedef struct WebPMux WebPMux;   // main opaque object.
+typedef struct WebPMuxFrameInfo WebPMuxFrameInfo;
+typedef struct WebPMuxAnimParams WebPMuxAnimParams;
+
+// Error codes
+typedef enum WebPMuxError {
+  WEBP_MUX_OK                 =  1,
+  WEBP_MUX_NOT_FOUND          =  0,
+  WEBP_MUX_INVALID_ARGUMENT   = -1,
+  WEBP_MUX_BAD_DATA           = -2,
+  WEBP_MUX_MEMORY_ERROR       = -3,
+  WEBP_MUX_NOT_ENOUGH_DATA    = -4
+} WebPMuxError;
+
+// IDs for different types of chunks.
+typedef enum WebPChunkId {
+  WEBP_CHUNK_VP8X,     // VP8X
+  WEBP_CHUNK_ICCP,     // ICCP
+  WEBP_CHUNK_ANIM,     // ANIM
+  WEBP_CHUNK_ANMF,     // ANMF
+  WEBP_CHUNK_FRGM,     // FRGM
+  WEBP_CHUNK_ALPHA,    // ALPH
+  WEBP_CHUNK_IMAGE,    // VP8/VP8L
+  WEBP_CHUNK_EXIF,     // EXIF
+  WEBP_CHUNK_XMP,      // XMP
+  WEBP_CHUNK_UNKNOWN,  // Other chunks.
+  WEBP_CHUNK_NIL
+} WebPChunkId;
+
+//------------------------------------------------------------------------------
+
+// Returns the version number of the mux library, packed in hexadecimal using
+// 8bits for each of major/minor/revision. E.g: v2.5.7 is 0x020507.
+WEBP_EXTERN(int) WebPGetMuxVersion(void);
+
+//------------------------------------------------------------------------------
+// Life of a Mux object
+
+// Internal, version-checked, entry point
+WEBP_EXTERN(WebPMux*) WebPNewInternal(int);
+
+// Creates an empty mux object.
+// Returns:
+//   A pointer to the newly created empty mux object.
+//   Or NULL in case of memory error.
+static WEBP_INLINE WebPMux* WebPMuxNew(void) {
+  return WebPNewInternal(WEBP_MUX_ABI_VERSION);
+}
+
+// Deletes the mux object.
+// Parameters:
+//   mux - (in/out) object to be deleted
+WEBP_EXTERN(void) WebPMuxDelete(WebPMux* mux);
+
+//------------------------------------------------------------------------------
+// Mux creation.
+
+// Internal, version-checked, entry point
+WEBP_EXTERN(WebPMux*) WebPMuxCreateInternal(const WebPData*, int, int);
+
+// Creates a mux object from raw data given in WebP RIFF format.
+// Parameters:
+//   bitstream - (in) the bitstream data in WebP RIFF format
+//   copy_data - (in) value 1 indicates given data WILL be copied to the mux
+//               object and value 0 indicates data will NOT be copied.
+// Returns:
+//   A pointer to the mux object created from given data - on success.
+//   NULL - In case of invalid data or memory error.
+static WEBP_INLINE WebPMux* WebPMuxCreate(const WebPData* bitstream,
+                                          int copy_data) {
+  return WebPMuxCreateInternal(bitstream, copy_data, WEBP_MUX_ABI_VERSION);
+}
+
+//------------------------------------------------------------------------------
+// Non-image chunks.
+
+// Note: Only non-image related chunks should be managed through chunk APIs.
+// (Image related chunks are: "ANMF", "FRGM", "VP8 ", "VP8L" and "ALPH").
+// To add, get and delete images, use WebPMuxSetImage(), WebPMuxPushFrame(),
+// WebPMuxGetFrame() and WebPMuxDeleteFrame().
+
+// Adds a chunk with id 'fourcc' and data 'chunk_data' in the mux object.
+// Any existing chunk(s) with the same id will be removed.
+// Parameters:
+//   mux - (in/out) object to which the chunk is to be added
+//   fourcc - (in) a character array containing the fourcc of the given chunk;
+//                 e.g., "ICCP", "XMP ", "EXIF" etc.
+//   chunk_data - (in) the chunk data to be added
+//   copy_data - (in) value 1 indicates given data WILL be copied to the mux
+//               object and value 0 indicates data will NOT be copied.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux, fourcc or chunk_data is NULL
+//                               or if fourcc corresponds to an image chunk.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxSetChunk(
+    WebPMux* mux, const char fourcc[4], const WebPData* chunk_data,
+    int copy_data);
+
+// Gets a reference to the data of the chunk with id 'fourcc' in the mux object.
+// The caller should NOT free the returned data.
+// Parameters:
+//   mux - (in) object from which the chunk data is to be fetched
+//   fourcc - (in) a character array containing the fourcc of the chunk;
+//                 e.g., "ICCP", "XMP ", "EXIF" etc.
+//   chunk_data - (out) returned chunk data
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux, fourcc or chunk_data is NULL
+//                               or if fourcc corresponds to an image chunk.
+//   WEBP_MUX_NOT_FOUND - If mux does not contain a chunk with the given id.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxGetChunk(
+    const WebPMux* mux, const char fourcc[4], WebPData* chunk_data);
+
+// Deletes the chunk with the given 'fourcc' from the mux object.
+// Parameters:
+//   mux - (in/out) object from which the chunk is to be deleted
+//   fourcc - (in) a character array containing the fourcc of the chunk;
+//                 e.g., "ICCP", "XMP ", "EXIF" etc.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or fourcc is NULL
+//                               or if fourcc corresponds to an image chunk.
+//   WEBP_MUX_NOT_FOUND - If mux does not contain a chunk with the given fourcc.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxDeleteChunk(
+    WebPMux* mux, const char fourcc[4]);
+
+//------------------------------------------------------------------------------
+// Images.
+
+// Encapsulates data about a single frame/fragment.
+struct WebPMuxFrameInfo {
+  WebPData    bitstream;  // image data: can be a raw VP8/VP8L bitstream
+                          // or a single-image WebP file.
+  int         x_offset;   // x-offset of the frame.
+  int         y_offset;   // y-offset of the frame.
+  int         duration;   // duration of the frame (in milliseconds).
+
+  WebPChunkId id;         // frame type: should be one of WEBP_CHUNK_ANMF,
+                          // WEBP_CHUNK_FRGM or WEBP_CHUNK_IMAGE
+  WebPMuxAnimDispose dispose_method;  // Disposal method for the frame.
+  WebPMuxAnimBlend   blend_method;    // Blend operation for the frame.
+  uint32_t    pad[1];     // padding for later use
+};
+
+// Sets the (non-animated and non-fragmented) image in the mux object.
+// Note: Any existing images (including frames/fragments) will be removed.
+// Parameters:
+//   mux - (in/out) object in which the image is to be set
+//   bitstream - (in) can be a raw VP8/VP8L bitstream or a single-image
+//               WebP file (non-animated and non-fragmented)
+//   copy_data - (in) value 1 indicates given data WILL be copied to the mux
+//               object and value 0 indicates data will NOT be copied.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux is NULL or bitstream is NULL.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxSetImage(
+    WebPMux* mux, const WebPData* bitstream, int copy_data);
+
+// Adds a frame at the end of the mux object.
+// Notes: (1) frame.id should be one of WEBP_CHUNK_ANMF or WEBP_CHUNK_FRGM
+//        (2) For setting a non-animated non-fragmented image, use
+//            WebPMuxSetImage() instead.
+//        (3) Type of frame being pushed must be same as the frames in mux.
+//        (4) As WebP only supports even offsets, any odd offset will be snapped
+//            to an even location using: offset &= ~1
+// Parameters:
+//   mux - (in/out) object to which the frame is to be added
+//   frame - (in) frame data.
+//   copy_data - (in) value 1 indicates given data WILL be copied to the mux
+//               object and value 0 indicates data will NOT be copied.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or frame is NULL
+//                               or if content of 'frame' is invalid.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxPushFrame(
+    WebPMux* mux, const WebPMuxFrameInfo* frame, int copy_data);
+
+// Gets the nth frame from the mux object.
+// The content of 'frame->bitstream' is allocated using malloc(), and NOT
+// owned by the 'mux' object. It MUST be deallocated by the caller by calling
+// WebPDataClear().
+// nth=0 has a special meaning - last position.
+// Parameters:
+//   mux - (in) object from which the info is to be fetched
+//   nth - (in) index of the frame in the mux object
+//   frame - (out) data of the returned frame
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or frame is NULL.
+//   WEBP_MUX_NOT_FOUND - if there are less than nth frames in the mux object.
+//   WEBP_MUX_BAD_DATA - if nth frame chunk in mux is invalid.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxGetFrame(
+    const WebPMux* mux, uint32_t nth, WebPMuxFrameInfo* frame);
+
+// Deletes a frame from the mux object.
+// nth=0 has a special meaning - last position.
+// Parameters:
+//   mux - (in/out) object from which a frame is to be deleted
+//   nth - (in) The position from which the frame is to be deleted
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux is NULL.
+//   WEBP_MUX_NOT_FOUND - If there are less than nth frames in the mux object
+//                        before deletion.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxDeleteFrame(WebPMux* mux, uint32_t nth);
+
+//------------------------------------------------------------------------------
+// Animation.
+
+// Animation parameters.
+struct WebPMuxAnimParams {
+  uint32_t bgcolor;  // Background color of the canvas stored (in MSB order) as:
+                     // Bits 00 to 07: Alpha.
+                     // Bits 08 to 15: Red.
+                     // Bits 16 to 23: Green.
+                     // Bits 24 to 31: Blue.
+  int loop_count;    // Number of times to repeat the animation [0 = infinite].
+};
+
+// Sets the animation parameters in the mux object. Any existing ANIM chunks
+// will be removed.
+// Parameters:
+//   mux - (in/out) object in which ANIM chunk is to be set/added
+//   params - (in) animation parameters.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or params is NULL.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxSetAnimationParams(
+    WebPMux* mux, const WebPMuxAnimParams* params);
+
+// Gets the animation parameters from the mux object.
+// Parameters:
+//   mux - (in) object from which the animation parameters to be fetched
+//   params - (out) animation parameters extracted from the ANIM chunk
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or params is NULL.
+//   WEBP_MUX_NOT_FOUND - if ANIM chunk is not present in mux object.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxGetAnimationParams(
+    const WebPMux* mux, WebPMuxAnimParams* params);
+
+//------------------------------------------------------------------------------
+// Misc Utilities.
+
+#if WEBP_MUX_ABI_VERSION > 0x0101
+// Sets the canvas size for the mux object. The width and height can be
+// specified explicitly or left as zero (0, 0).
+// * When width and height are specified explicitly, then this frame bound is
+//   enforced during subsequent calls to WebPMuxAssemble() and an error is
+//   reported if any animated frame does not completely fit within the canvas.
+// * When unspecified (0, 0), the constructed canvas will get the frame bounds
+//   from the bounding-box over all frames after calling WebPMuxAssemble().
+// Parameters:
+//   mux - (in) object to which the canvas size is to be set
+//   width - (in) canvas width
+//   height - (in) canvas height
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux is NULL; or
+//                               width or height are invalid or out of bounds
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxSetCanvasSize(WebPMux* mux,
+                                               int width, int height);
+#endif
+
+// Gets the canvas size from the mux object.
+// Note: This method assumes that the VP8X chunk, if present, is up-to-date.
+// That is, the mux object hasn't been modified since the last call to
+// WebPMuxAssemble() or WebPMuxCreate().
+// Parameters:
+//   mux - (in) object from which the canvas size is to be fetched
+//   width - (out) canvas width
+//   height - (out) canvas height
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux, width or height is NULL.
+//   WEBP_MUX_BAD_DATA - if VP8X/VP8/VP8L chunk or canvas size is invalid.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxGetCanvasSize(const WebPMux* mux,
+                                               int* width, int* height);
+
+// Gets the feature flags from the mux object.
+// Note: This method assumes that the VP8X chunk, if present, is up-to-date.
+// That is, the mux object hasn't been modified since the last call to
+// WebPMuxAssemble() or WebPMuxCreate().
+// Parameters:
+//   mux - (in) object from which the features are to be fetched
+//   flags - (out) the flags specifying which features are present in the
+//           mux object. This will be an OR of various flag values.
+//           Enum 'WebPFeatureFlags' can be used to test individual flag values.
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or flags is NULL.
+//   WEBP_MUX_BAD_DATA - if VP8X/VP8/VP8L chunk or canvas size is invalid.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxGetFeatures(const WebPMux* mux,
+                                             uint32_t* flags);
+
+// Gets number of chunks with the given 'id' in the mux object.
+// Parameters:
+//   mux - (in) object from which the info is to be fetched
+//   id - (in) chunk id specifying the type of chunk
+//   num_elements - (out) number of chunks with the given chunk id
+// Returns:
+//   WEBP_MUX_INVALID_ARGUMENT - if mux, or num_elements is NULL.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxNumChunks(const WebPMux* mux,
+                                           WebPChunkId id, int* num_elements);
+
+// Assembles all chunks in WebP RIFF format and returns in 'assembled_data'.
+// This function also validates the mux object.
+// Note: The content of 'assembled_data' will be ignored and overwritten.
+// Also, the content of 'assembled_data' is allocated using malloc(), and NOT
+// owned by the 'mux' object. It MUST be deallocated by the caller by calling
+// WebPDataClear(). It's always safe to call WebPDataClear() upon return,
+// even in case of error.
+// Parameters:
+//   mux - (in/out) object whose chunks are to be assembled
+//   assembled_data - (out) assembled WebP data
+// Returns:
+//   WEBP_MUX_BAD_DATA - if mux object is invalid.
+//   WEBP_MUX_INVALID_ARGUMENT - if mux or assembled_data is NULL.
+//   WEBP_MUX_MEMORY_ERROR - on memory allocation error.
+//   WEBP_MUX_OK - on success.
+WEBP_EXTERN(WebPMuxError) WebPMuxAssemble(WebPMux* mux,
+                                          WebPData* assembled_data);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_WEBP_MUX_H_ */

Vendor/WebP.framework/Headers/mux_types.h

@@ -0,0 +1,97 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Data-types common to the mux and demux libraries.
+//
+// Author: Urvang (urvang@google.com)
+
+#ifndef WEBP_WEBP_MUX_TYPES_H_
+#define WEBP_WEBP_MUX_TYPES_H_
+
+#include <stdlib.h>  // free()
+#include <string.h>  // memset()
+#include "./types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Note: forward declaring enumerations is not allowed in (strict) C and C++,
+// the types are left here for reference.
+// typedef enum WebPFeatureFlags WebPFeatureFlags;
+// typedef enum WebPMuxAnimDispose WebPMuxAnimDispose;
+// typedef enum WebPMuxAnimBlend WebPMuxAnimBlend;
+typedef struct WebPData WebPData;
+
+// VP8X Feature Flags.
+typedef enum WebPFeatureFlags {
+  FRAGMENTS_FLAG  = 0x00000001,
+  ANIMATION_FLAG  = 0x00000002,
+  XMP_FLAG        = 0x00000004,
+  EXIF_FLAG       = 0x00000008,
+  ALPHA_FLAG      = 0x00000010,
+  ICCP_FLAG       = 0x00000020
+} WebPFeatureFlags;
+
+// Dispose method (animation only). Indicates how the area used by the current
+// frame is to be treated before rendering the next frame on the canvas.
+typedef enum WebPMuxAnimDispose {
+  WEBP_MUX_DISPOSE_NONE,       // Do not dispose.
+  WEBP_MUX_DISPOSE_BACKGROUND  // Dispose to background color.
+} WebPMuxAnimDispose;
+
+// Blend operation (animation only). Indicates how transparent pixels of the
+// current frame are blended with those of the previous canvas.
+typedef enum WebPMuxAnimBlend {
+  WEBP_MUX_BLEND,              // Blend.
+  WEBP_MUX_NO_BLEND            // Do not blend.
+} WebPMuxAnimBlend;
+
+// Data type used to describe 'raw' data, e.g., chunk data
+// (ICC profile, metadata) and WebP compressed image data.
+struct WebPData {
+  const uint8_t* bytes;
+  size_t size;
+};
+
+// Initializes the contents of the 'webp_data' object with default values.
+static WEBP_INLINE void WebPDataInit(WebPData* webp_data) {
+  if (webp_data != NULL) {
+    memset(webp_data, 0, sizeof(*webp_data));
+  }
+}
+
+// Clears the contents of the 'webp_data' object by calling free(). Does not
+// deallocate the object itself.
+static WEBP_INLINE void WebPDataClear(WebPData* webp_data) {
+  if (webp_data != NULL) {
+    free((void*)webp_data->bytes);
+    WebPDataInit(webp_data);
+  }
+}
+
+// Allocates necessary storage for 'dst' and copies the contents of 'src'.
+// Returns true on success.
+static WEBP_INLINE int WebPDataCopy(const WebPData* src, WebPData* dst) {
+  if (src == NULL || dst == NULL) return 0;
+  WebPDataInit(dst);
+  if (src->bytes != NULL && src->size != 0) {
+    dst->bytes = (uint8_t*)malloc(src->size);
+    if (dst->bytes == NULL) return 0;
+    memcpy((void*)dst->bytes, src->bytes, src->size);
+    dst->size = src->size;
+  }
+  return 1;
+}
+
+#ifdef __cplusplus
+}    // extern "C"
+#endif
+
+#endif  /* WEBP_WEBP_MUX_TYPES_H_ */

Vendor/WebP.framework/Headers/types.h

@@ -0,0 +1,48 @@
+// Copyright 2010 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+//  Common types
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_WEBP_TYPES_H_
+#define WEBP_WEBP_TYPES_H_
+
+#include <stddef.h>  // for size_t
+
+#ifndef _MSC_VER
+#include <inttypes.h>
+#if defined(__cplusplus) || !defined(__STRICT_ANSI__) || \
+    (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L)
+#define WEBP_INLINE inline
+#else
+#define WEBP_INLINE
+#endif
+#else
+typedef signed   char int8_t;
+typedef unsigned char uint8_t;
+typedef signed   short int16_t;
+typedef unsigned short uint16_t;
+typedef signed   int int32_t;
+typedef unsigned int uint32_t;
+typedef unsigned long long int uint64_t;
+typedef long long int int64_t;
+#define WEBP_INLINE __forceinline
+#endif  /* _MSC_VER */
+
+#ifndef WEBP_EXTERN
+// This explicitly marks library functions and allows for changing the
+// signature for e.g., Windows DLL builds.
+#define WEBP_EXTERN(type) extern type
+#endif  /* WEBP_EXTERN */
+
+// Macro to check ABI compatibility (same major revision number)
+#define WEBP_ABI_IS_INCOMPATIBLE(a, b) (((a) >> 8) != ((b) >> 8))
+
+#endif  /* WEBP_WEBP_TYPES_H_ */

Vendor/WebP.sh

@@ -0,0 +1,135 @@
+#!/bin/bash
+#
+# This script generates 'WebP.framework' (static library).
+# An iOS app can decode WebP images by including 'WebP.framework'.
+#
+# 1. Download the latest libwebp source code from
+#    http://downloads.webmproject.org/releases/webp/index.html
+# 2. Use this script instead of the original 'iosbuild.sh' to build the WebP.framework.
+#    It will build all modules, include mux, demux, coder and decoder.
+#
+# Notice: You should use Xcode 7 (or above) to support bitcode.
+
+set -e
+
+# Extract the latest SDK version from the final field of the form: iphoneosX.Y
+readonly SDK=$(xcodebuild -showsdks \
+  | grep iphoneos | sort | tail -n 1 | awk '{print substr($NF, 9)}'
+)
+# Extract Xcode version.
+readonly XCODE=$(xcodebuild -version | grep Xcode | cut -d " " -f2)
+if [[ -z "${XCODE}" ]]; then
+  echo "Xcode not available"
+  exit 1
+fi
+
+readonly OLDPATH=${PATH}
+
+# Add iPhoneOS-V6 to the list of platforms below if you need armv6 support.
+# Note that iPhoneOS-V6 support is not available with the iOS6 SDK.
+PLATFORMS="iPhoneSimulator iPhoneSimulator64"
+PLATFORMS+=" iPhoneOS-V7 iPhoneOS-V7s iPhoneOS-V7-arm64"
+readonly PLATFORMS
+readonly SRCDIR=$(dirname $0)
+readonly TOPDIR=$(pwd)
+readonly BUILDDIR="${TOPDIR}/iosbuild"
+readonly TARGETDIR="${TOPDIR}/WebP.framework"
+readonly DEVELOPER=$(xcode-select --print-path)
+readonly PLATFORMSROOT="${DEVELOPER}/Platforms"
+readonly LIPO=$(xcrun -sdk iphoneos${SDK} -find lipo)
+LIBLIST=''
+
+if [[ -z "${SDK}" ]]; then
+  echo "iOS SDK not available"
+  exit 1
+elif [[ ${SDK} < 6.0 ]]; then
+  echo "You need iOS SDK version 6.0 or above"
+  exit 1
+else
+  echo "iOS SDK Version ${SDK}"
+fi
+
+rm -rf ${BUILDDIR}
+rm -rf ${TARGETDIR}
+mkdir -p ${BUILDDIR}
+mkdir -p ${TARGETDIR}/Headers/
+
+if [[ ! -e ${SRCDIR}/configure ]]; then
+  if ! (cd ${SRCDIR} && sh autogen.sh); then
+    cat <<EOT
+Error creating configure script!
+This script requires the autoconf/automake and libtool to build. MacPorts can
+be used to obtain these:
+http://www.macports.org/install.php
+EOT
+    exit 1
+  fi
+fi
+
+for PLATFORM in ${PLATFORMS}; do
+  ARCH2=""
+  if [[ "${PLATFORM}" == "iPhoneOS-V7-arm64" ]]; then
+    PLATFORM="iPhoneOS"
+    ARCH="aarch64"
+    ARCH2="arm64"
+  elif [[ "${PLATFORM}" == "iPhoneOS-V7s" ]]; then
+    PLATFORM="iPhoneOS"
+    ARCH="armv7s"
+  elif [[ "${PLATFORM}" == "iPhoneOS-V7" ]]; then
+    PLATFORM="iPhoneOS"
+    ARCH="armv7"
+  elif [[ "${PLATFORM}" == "iPhoneOS-V6" ]]; then
+    PLATFORM="iPhoneOS"
+    ARCH="armv6"
+  elif [[ "${PLATFORM}" == "iPhoneSimulator64" ]]; then
+    PLATFORM="iPhoneSimulator"
+    ARCH="x86_64"
+  else
+    ARCH="i386"
+  fi
+
+  ROOTDIR="${BUILDDIR}/${PLATFORM}-${SDK}-${ARCH}"
+  mkdir -p "${ROOTDIR}"
+
+  DEVROOT="${DEVELOPER}/Toolchains/XcodeDefault.xctoolchain"
+  SDKROOT="${PLATFORMSROOT}/"
+  SDKROOT+="${PLATFORM}.platform/Developer/SDKs/${PLATFORM}${SDK}.sdk/"
+  CFLAGS="-arch ${ARCH2:-${ARCH}} -pipe -isysroot ${SDKROOT} -O3 -DNDEBUG"
+  CFLAGS+=" -miphoneos-version-min=6.0 -fembed-bitcode"
+
+  set -x
+  export PATH="${DEVROOT}/usr/bin:${OLDPATH}"
+  ${SRCDIR}/configure --host=${ARCH}-apple-darwin --prefix=${ROOTDIR} \
+    --build=$(${SRCDIR}/config.guess) \
+    --disable-shared --enable-static \
+    --enable-libwebpmux \
+    --enable-libwebpdemux \
+    --enable-libwebpdecoder \
+    --enable-swap-16bit-csp \
+    CFLAGS="${CFLAGS}"
+  set +x
+
+  # run make only in the src/ directory to create libwebpdecoder.a
+  cd src/
+  make V=0
+  make install
+
+  MAKEPATH=$(pwd)
+  cd ${ROOTDIR}/lib/
+  ar x libwebp.a
+  ar x libwebpmux.a
+  ar x libwebpdemux.a
+  ar x libwebpdecoder.a
+  ar q webp.a *.o
+
+  LIBLIST+=" ${ROOTDIR}/lib/webp.a"
+  cd ${MAKEPATH}
+
+  make clean
+  cd ..
+
+  export PATH=${OLDPATH}
+done
+
+cp -a ${SRCDIR}/src/webp/*.h ${TARGETDIR}/Headers/
+${LIPO} -create ${LIBLIST} -output ${TARGETDIR}/WebP

YYWebImage.podspec

@@ -0,0 +1,21 @@
+Pod::Spec.new do |s|
+  s.name         = 'YYWebImage'
+  s.summary      = 'Asynchronous image loading framework.'
+  s.version      = '0.9.0'
+  s.license      = { :type => 'MIT', :file => 'LICENSE' }
+  s.authors      = { 'ibireme' => 'ibireme@gmail.com' }
+  s.social_media_url = 'http://blog.ibireme.com'
+  s.homepage     = 'https://github.com/ibireme/YYWebImage'
+  s.platform     = :ios, '6.0'
+  s.ios.deployment_target = '6.0'
+  s.source       = { :git => 'https://github.com/ibireme/YYWebImage.git', :tag => s.version.to_s }
+  
+  s.requires_arc = true
+  s.source_files = 'YYWebImage/*.{h,m}'
+  s.public_header_files = 'YYWebImage/*.{h}'
+  
+  s.libraries = 'z'
+  s.frameworks = 'UIKit', 'CoreFoundation', 'QuartzCore', 'AssetsLibrary', 'ImageIO', 'Accelerate', 'MobileCoreServices'
+  s.ios.vendored_frameworks = 'Vendor/WebP.framework'
+
+end

YYWebImage/Cache/YYCache.h

@@ -0,0 +1,176 @@
+//
+//  YYCache.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/13.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <Foundation/Foundation.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYMemoryCache.h>
+#import <YYWebImage/YYDiskCache.h>
+#import <YYWebImage/YYKVStorage.h>
+#else
+#import "YYMemoryCache.h"
+#import "YYDiskCache.h"
+#import "YYKVStorage.h"
+#endif
+
+
+
+/**
+ `YYCache` is a thread safe key-value cache.
+ 
+ It use `YYMemoryCache` to store objects in a small and fast memory cache,
+ and use `YYDiskCache` to persisting objects to a large and slow disk cache.
+ See `YYMemoryCache` and `YYDiskCache` for more information.
+ */
+@interface YYCache : NSObject
+
+/** The name of the cache, readonly. */
+@property (copy, readonly) NSString *name;
+
+/** The underlying memory cache. see `YYMemoryCache` for more information.*/
+@property (strong, readonly) YYMemoryCache *memoryCache;
+
+/** The underlying disk cache. see `YYDiskCache` for more information.*/
+@property (strong, readonly) YYDiskCache *diskCache;
+
+/**
+ Create a new instance with the specified name.
+ Multiple instances with the same name will make the cache unstable.
+ 
+ @param name  The name of the cache. It will create a dictionary with the name in
+     the app's caches dictionary for disk cache. Once initialized you should not 
+     read and write to this directory.
+ @result A new cache object, or nil if an error occurs.
+ @warning Multiple instances with the same name will make the storage unstable.
+ */
+- (instancetype)initWithName:(NSString *)name;
+
+/**
+ Create a new instance with the specified name.
+ Multiple instances with the same name will make the cache unstable.
+ 
+ @param path  Full path of a directory in which the cache will write data.
+     Once initialized you should not read and write to this directory.
+ @result A new cache object, or nil if an error occurs.
+ @warning Multiple instances with the same path will make the storage unstable.
+ */
+- (instancetype)initWithPath:(NSString *)path;
+
+- (instancetype)init UNAVAILABLE_ATTRIBUTE;
++ (instancetype)new UNAVAILABLE_ATTRIBUTE;
+
+#pragma mark - Access Methods
+///=============================================================================
+/// @name Access Methods
+///=============================================================================
+
+/**
+ Returns a boolean value that indicates whether a given key is in cache.
+ This method may blocks the calling thread until file read finished.
+ 
+ @param key A string identifying the value. If nil, just return NO.
+ @return Whether the key is in cache.
+ */
+- (BOOL)containsObjectForKey:(NSString *)key;
+
+/**
+ Returns a boolean value with the block that indicates whether a given key is in cache.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param key   A string identifying the value. If nil, just return NO.
+ @param block A block which will be revoked in background queue when finished.
+ */
+- (void)containsObjectForKey:(NSString *)key withBlock:(void(^)(NSString *key, BOOL contains))block;
+
+/**
+ Returns the value associated with a given key.
+ This method may blocks the calling thread until file read finished.
+ 
+ @param key A string identifying the value. If nil, just return nil.
+ @return The value associated with key, or nil if no value is associated with key.
+ */
+- (id<NSCoding>)objectForKey:(NSString *)key;
+
+/**
+ Returns the value associated with a given key.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param key A string identifying the value. If nil, just return nil.
+ @param block A block which will be revoked in background queue when finished.
+ */
+- (void)objectForKey:(NSString *)key withBlock:(void(^)(NSString *key, id<NSCoding> object))block;
+
+/**
+ Sets the value of the specified key in the cache.
+ This method may blocks the calling thread until file write finished.
+ 
+ @param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.
+ @param key    The key with which to associate the value. If nil, this method has no effect.
+ */
+- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key;
+
+/**
+ Sets the value of the specified key in the cache.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key withBlock:(void(^)(void))block;
+
+/**
+ Removes the value of the specified key in the cache.
+ This method may blocks the calling thread until file delete finished.
+ 
+ @param key The key identifying the value to be removed. If nil, this method has no effect.
+ */
+- (void)removeObjectForKey:(NSString *)key;
+
+/**
+ Removes the value of the specified key in the cache.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param key The key identifying the value to be removed. If nil, this method has no effect.
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)removeObjectForKey:(NSString *)key withBlock:(void(^)(NSString *key))block;
+
+/**
+ Empties the cache.
+ This method may blocks the calling thread until file delete finished.
+ */
+- (void)removeAllObjects;
+
+/**
+ Empties the cache.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)removeAllObjectsWithBlock:(void(^)(void))block;
+
+/**
+ Empties the cache with block.
+ This method returns immediately and executes the clear operation with block in background.
+ 
+ @warning You should not send message to this instance in these blocks.
+ @param progress This block will be revoked during removing, pass nil to ignore.
+ @param end      This block will be revoked at the end, pass nil to ignore.
+ */
+- (void)removeAllObjectsWithProgressBlock:(void(^)(int removedCount, int totalCount))progress
+                                 endBlock:(void(^)(BOOL error))end;
+
+@end

YYWebImage/Cache/YYCache.m

@@ -0,0 +1,128 @@
+//
+//  YYCache.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/13.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYCache.h"
+#import "YYMemoryCache.h"
+#import "YYDiskCache.h"
+
+@implementation YYCache
+
+- (instancetype) init {
+    self = [super init];
+    NSLog(@"Use \"initWithName\" or \"initWithPath\" to create YYCache instance.");
+    return self;
+}
+
+- (instancetype)initWithName:(NSString *)name {
+    if (name.length == 0) return nil;
+    self = [super init];
+    NSString *cacheFolder = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];
+    NSString *path = [cacheFolder stringByAppendingPathComponent:name];
+    return [self initWithPath:path];
+}
+
+- (instancetype)initWithPath:(NSString *)path {
+    if (path.length == 0) return nil;
+    YYDiskCache *diskCache = [[YYDiskCache alloc] initWithPath:path];
+    if (!diskCache) return nil;
+    NSString *name = [path lastPathComponent];
+    YYMemoryCache *memoryCache = [YYMemoryCache new];
+    memoryCache.name = name;
+    
+    self = [super init];
+    _name = name;
+    _diskCache = diskCache;
+    _memoryCache = memoryCache;
+    return self;
+}
+
+- (BOOL)containsObjectForKey:(NSString *)key {
+    return [_memoryCache containsObjectForKey:key] || [_diskCache containsObjectForKey:key];
+}
+
+- (void)containsObjectForKey:(NSString *)key withBlock:(void (^)(NSString *key, BOOL contains))block {
+    if (!block) return;
+    
+    if ([_memoryCache containsObjectForKey:key]) {
+        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+            block(key, YES);
+        });
+    } else  {
+        [_diskCache containsObjectForKey:key withBlock:block];
+    }
+}
+
+- (id<NSCoding>)objectForKey:(NSString *)key {
+    id<NSCoding> object = [_memoryCache objectForKey:key];
+    if (!object) {
+        object = [_diskCache objectForKey:key];
+        if (object) {
+            [_memoryCache setObject:object forKey:key];
+        }
+    }
+    return object;
+}
+
+- (void)objectForKey:(NSString *)key withBlock:(void (^)(NSString *key, id<NSCoding> object))block {
+    if (!block) return;
+    id<NSCoding> object = [_memoryCache objectForKey:key];
+    if (object) {
+        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+            block(key, object);
+        });
+    } else {
+        [_diskCache objectForKey:key withBlock:block];
+    }
+}
+
+- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key {
+    [_memoryCache setObject:object forKey:key];
+    [_diskCache setObject:object forKey:key];
+}
+
+- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key withBlock:(void (^)(void))block {
+    [_memoryCache setObject:object forKey:key];
+    [_diskCache setObject:object forKey:key withBlock:block];
+}
+
+- (void)removeObjectForKey:(NSString *)key {
+    [_memoryCache removeObjectForKey:key];
+    [_diskCache removeObjectForKey:key];
+}
+
+- (void)removeObjectForKey:(NSString *)key withBlock:(void (^)(NSString *key))block {
+    [_memoryCache removeObjectForKey:key];
+    [_diskCache removeObjectForKey:key withBlock:block];
+}
+
+- (void)removeAllObjects {
+    [_memoryCache removeAllObjects];
+    [_diskCache removeAllObjects];
+}
+
+- (void)removeAllObjectsWithBlock:(void(^)(void))block {
+    [_memoryCache removeAllObjects];
+    [_diskCache removeAllObjectsWithBlock:block];
+}
+
+- (void)removeAllObjectsWithProgressBlock:(void(^)(int removedCount, int totalCount))progress
+                                 endBlock:(void(^)(BOOL error))end {
+    [_memoryCache removeAllObjects];
+    [_diskCache removeAllObjectsWithProgressBlock:progress endBlock:end];
+    
+}
+
+- (NSString *)description {
+    if (_name) return [NSString stringWithFormat:@"<%@: %p> (%@)", self.class, self, _name];
+    else return [NSString stringWithFormat:@"<%@: %p>", self.class, self];
+}
+
+@end

YYWebImage/Cache/YYDiskCache.h

@@ -0,0 +1,402 @@
+//
+//  YYDiskCache.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/11.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <Foundation/Foundation.h>
+
+/**
+ YYDiskCache is a thread-safe cache that stores key-value pairs backed by SQLite
+ and file system (similar to NSURLCache's disk cache).
+ 
+ YYDiskCache has these features:
+ 
+ * It use LRU (least-recently-used) to remove objects.
+ * It can be controlled by cost, count, and age.
+ * It can be configured to automatically evict objects when there's no free disk space.
+ * It can automatically decide the storage type (sqlite/file) for each object to get
+      better performance.
+ 
+ You may compile the lastest version of sqlite and ignore the libsqlite3.dylib in
+ iOS system to get 2x~4x speed up.
+ */
+@interface YYDiskCache : NSObject
+
+#pragma mark - Attribute
+///=============================================================================
+/// @name Attribute
+///=============================================================================
+
+/** The name of the cache. Default is nil. */
+@property (copy) NSString *name;
+
+/** The path of the cache (read-only). */
+@property (readonly) NSString *path;
+
+/**
+ If the object's data size (in bytes) is larger than this value, then object will
+ be stored as a file, otherwise the object will be stored in sqlite.
+ 
+ 0 means all objects will be stored as separated files, NSUIntegerMax means all
+ objects will be stored in sqlite. 
+ 
+ The default value is 20480 (20KB).
+ */
+@property (readonly) NSUInteger inlineThreshold;
+
+/**
+ If this block in not nil, then the block will be used to archive object instead
+ of NSKeyedArchiver. You can use this block to support the objects which do not
+ conform to the `NSCoding` protocol.
+ 
+ The default value is nil.
+ */
+@property (copy) NSData *(^customArchiveBlock)(id object);
+
+/**
+ If this block in not nil, then the block will be used to unarchive object instead
+ of NSKeyedUnarchiver. You can use this block to support the objects which do not
+ conform to the `NSCoding` protocol.
+ 
+ The default value is nil.
+ */
+@property (copy) id (^customUnarchiveBlock)(NSData *data);
+
+/**
+ When an object needs to be saved as a file, this block will be revoked to generate
+ a file name for a specified key. If the block is nil, the cache use md5(key) as 
+ default file name.
+ 
+ The default value is nil.
+ */
+@property (copy) NSString *(^customFilenameBlock)(NSString *key);
+
+
+
+#pragma mark - Limit
+///=============================================================================
+/// @name Limit
+///=============================================================================
+
+/**
+ The maximum number of objects the cache should hold.
+ 
+ @discussion The default value is NSUIntegerMax, which means no limit.
+ This is not a strict limit—if the cache goes over the limit, some objects in the
+ cache could be evicted later in backgound queue.
+ */
+@property (assign) NSUInteger countLimit;
+
+/**
+ The maximum total cost that the cache can hold before it starts evicting objects.
+ 
+ @discussion The default value is NSUIntegerMax, which means no limit.
+ This is not a strict limit—if the cache goes over the limit, some objects in the
+ cache could be evicted later in backgound queue.
+ */
+@property (assign) NSUInteger costLimit;
+
+/**
+ The maximum expiry time of objects in cache.
+ 
+ @discussion The default value is DBL_MAX, which means no limit.
+ This is not a strict limit—if an object goes over the limit, the objects could
+ be evicted later in backgound queue.
+ */
+@property (assign) NSTimeInterval ageLimit;
+
+/**
+ The minimum free disk space (in bytes) which the cache should kept.
+ 
+ @discussion The default value is 0, which means no limit.
+ If the free disk space is lower than this value, the cache will remove objects
+ to free some disk space. This is not a strict limit—if the free disk space goes
+ over the limit, the objects could be evicted later in background queue.
+ */
+@property (assign) NSUInteger freeDiskSpaceLimit;
+
+/**
+ The auto trim check time interval in seconds. Default is 60 (1 minute).
+ 
+ @discussion The cache holds an internal timer to check whether the cache reaches
+ its limits, and if the limit is reached, it begins to evict objects.
+ */
+@property (assign) NSTimeInterval autoTrimInterval;
+
+
+#pragma mark - Initializer
+///=============================================================================
+/// @name Initializer
+///=============================================================================
+- (instancetype)init UNAVAILABLE_ATTRIBUTE;
++ (instancetype)new UNAVAILABLE_ATTRIBUTE;
+
+/**
+ Create a new cache based on the specified path.
+ 
+ @param path Full path of a directory in which the cache will write data.
+     Once initialized you should not read and write to this directory.
+ 
+ @return A new cache object, or nil if an error occurs.
+ 
+ @warning Multiple instances with the same path will make the storage unstable.
+ */
+- (instancetype)initWithPath:(NSString *)path;
+
+/**
+ The designated initializer.
+ 
+ @param path       Full path of a directory in which the cache will write data.
+     Once initialized you should not read and write to this directory.
+ 
+ @param threshold  The data store inline threshold in bytes. If the object's data
+     size (in bytes) is larger than this value, then object will be stored as a 
+     file, otherwise the object will be stored in sqlite. 0 means all objects will 
+     be stored as separated files, NSUIntegerMax means all objects will be stored 
+     in sqlite. If you don't know your object's size, 20480 is a good choice.
+     After first initialized you should not change this value of the specified path.
+ 
+ @return A new cache object, or nil if an error occurs.
+ 
+ @warning Multiple instances with the same path will make the storage unstable.
+ */
+- (instancetype)initWithPath:(NSString *)path
+             inlineThreshold:(NSUInteger)threshold NS_DESIGNATED_INITIALIZER;
+
+
+#pragma mark - Access Methods
+///=============================================================================
+/// @name Access Methods
+///=============================================================================
+
+/**
+ Returns a boolean value that indicates whether a given key is in cache.
+ This method may blocks the calling thread until file read finished.
+ 
+ @param key A string identifying the value. If nil, just return NO.
+ @return Whether the key is in cache.
+ */
+- (BOOL)containsObjectForKey:(NSString *)key;
+
+/**
+ Returns a boolean value with the block that indicates whether a given key is in cache.
+ This method returns immediately and revoke the passed block in background queue 
+ when the operation finished.
+ 
+ @param key   A string identifying the value. If nil, just return NO.
+ @param block A block which will be revoked in background queue when finished.
+ */
+- (void)containsObjectForKey:(NSString *)key withBlock:(void(^)(NSString *key, BOOL contains))block;
+
+/**
+ Returns the value associated with a given key.
+ This method may blocks the calling thread until file read finished.
+ 
+ @param key A string identifying the value. If nil, just return nil.
+ @return The value associated with key, or nil if no value is associated with key.
+ */
+- (id<NSCoding>)objectForKey:(NSString *)key;
+
+/**
+ Returns the value associated with a given key.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param key A string identifying the value. If nil, just return nil.
+ @param block A block which will be revoked in background queue when finished.
+ */
+- (void)objectForKey:(NSString *)key withBlock:(void(^)(NSString *key, id<NSCoding> object))block;
+
+/**
+ Sets the value of the specified key in the cache.
+ This method may blocks the calling thread until file write finished.
+ 
+ @param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.
+ @param key    The key with which to associate the value. If nil, this method has no effect.
+ */
+- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key;
+
+/**
+ Sets the value of the specified key in the cache.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key withBlock:(void(^)(void))block;
+
+/**
+ Removes the value of the specified key in the cache.
+ This method may blocks the calling thread until file delete finished.
+ 
+ @param key The key identifying the value to be removed. If nil, this method has no effect.
+ */
+- (void)removeObjectForKey:(NSString *)key;
+
+/**
+ Removes the value of the specified key in the cache.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param key The key identifying the value to be removed. If nil, this method has no effect.
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)removeObjectForKey:(NSString *)key withBlock:(void(^)(NSString *key))block;
+
+/**
+ Empties the cache.
+ This method may blocks the calling thread until file delete finished.
+ */
+- (void)removeAllObjects;
+
+/**
+ Empties the cache.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)removeAllObjectsWithBlock:(void(^)(void))block;
+
+/**
+ Empties the cache with block.
+ This method returns immediately and executes the clear operation with block in background.
+ 
+ @warning You should not send message to this instance in these blocks.
+ @param progress This block will be revoked during removing, pass nil to ignore.
+ @param end      This block will be revoked at the end, pass nil to ignore.
+ */
+- (void)removeAllObjectsWithProgressBlock:(void(^)(int removedCount, int totalCount))progress
+                                 endBlock:(void(^)(BOOL error))end;
+
+
+/**
+ Returns the number of objects in this cache.
+ This method may blocks the calling thread until file read finished.
+ 
+ @return The total objects count.
+ */
+- (NSInteger)totalCount;
+
+/**
+ Get the number of objects in this cache.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)totalCountWithBlock:(void(^)(NSInteger totalCount))block;
+
+/**
+ Returns the total cost (in bytes) of objects in this cache.
+ This method may blocks the calling thread until file read finished.
+ 
+ @return The total objects cost in bytes.
+ */
+- (NSInteger)totalCost;
+
+/**
+ Get the total cost (in bytes) of objects in this cache.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)totalCostWithBlock:(void(^)(NSInteger totalCost))block;
+
+
+#pragma mark - Trim
+///=============================================================================
+/// @name Trim
+///=============================================================================
+
+/**
+ Removes objects from the cache use LRU, until the `totalCount` is below the specified value.
+ This method may blocks the calling thread until operation finished.
+ 
+ @param count  The total count allowed to remain after the cache has been trimmed.
+ */
+- (void)trimToCount:(NSUInteger)count;
+
+/**
+ Removes objects from the cache use LRU, until the `totalCount` is below the specified value.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param count  The total count allowed to remain after the cache has been trimmed.
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)trimToCount:(NSUInteger)count withBlock:(void(^)(void))block;
+
+/**
+ Removes objects from the cache use LRU, until the `totalCost` is below the specified value.
+ This method may blocks the calling thread until operation finished.
+ 
+ @param cost The total cost allowed to remain after the cache has been trimmed.
+ */
+- (void)trimToCost:(NSUInteger)cost;
+
+/**
+ Removes objects from the cache use LRU, until the `totalCost` is below the specified value.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param cost The total cost allowed to remain after the cache has been trimmed.
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)trimToCost:(NSUInteger)cost withBlock:(void(^)(void))block;
+
+/**
+ Removes objects from the cache use LRU, until all expiry objects removed by the specified value.
+ This method may blocks the calling thread until operation finished.
+ 
+ @param age  The maximum age of the object.
+ */
+- (void)trimToAge:(NSTimeInterval)age;
+
+/**
+ Removes objects from the cache use LRU, until all expiry objects removed by the specified value.
+ This method returns immediately and revoke the passed block in background queue
+ when the operation finished.
+ 
+ @param age  The maximum age of the object.
+ @param block  A block which will be revoked in background queue when finished.
+ */
+- (void)trimToAge:(NSTimeInterval)age withBlock:(void(^)(void))block;
+
+
+#pragma mark - Extended Data
+///=============================================================================
+/// @name Extended Data
+///=============================================================================
+
+/**
+ Get extended data from an object.
+ 
+ @discussion See 'setExtendedData:toObject:' for more information.
+ 
+ @param object An object.
+ @return The extended data.
+ */
++ (NSData *)getExtendedDataFromObject:(id)object;
+
+/**
+ Set extended data to an object.
+ 
+ @discussion You can set any extended data to an object before you save the object
+ to disk cache. The extended data will also be saved with this object. You can get
+ the extended data later with "getExtendedDataFromObject:".
+ 
+ @param extendedData The extended data (pass nil to remove).
+ @param object       The object.
+ */
++ (void)setExtendedData:(NSData *)extendedData toObject:(id)object;
+
+@end

YYWebImage/Cache/YYDiskCache.m

@@ -0,0 +1,398 @@
+//
+//  YYDiskCache.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/11.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYDiskCache.h"
+#import "YYKVStorage.h"
+#import <CommonCrypto/CommonCrypto.h>
+#import <objc/runtime.h>
+#import <time.h>
+
+#define Lock() dispatch_semaphore_wait(_lock, DISPATCH_TIME_FOREVER)
+#define Unlock() dispatch_semaphore_signal(_lock)
+
+static const int extended_data_key;
+
+/// Free disk space in bytes.
+static int64_t _YYDiskSpaceFree() {
+    NSError *error = nil;
+    NSDictionary *attrs = [[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:&error];
+    if (error) return -1;
+    int64_t space =  [[attrs objectForKey:NSFileSystemFreeSize] longLongValue];
+    if (space < 0) space = -1;
+    return space;
+}
+
+/// String's md5 hash.
+static NSString *_YYNSStringMD5(NSString *string) {
+    if (!string) return nil;
+    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
+    unsigned char result[CC_MD5_DIGEST_LENGTH];
+    CC_MD5(data.bytes, (CC_LONG)data.length, result);
+    return [NSString stringWithFormat:
+                @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
+                result[0],  result[1],  result[2],  result[3],
+                result[4],  result[5],  result[6],  result[7],
+                result[8],  result[9],  result[10], result[11],
+                result[12], result[13], result[14], result[15]
+            ];
+}
+
+
+@implementation YYDiskCache {
+    YYKVStorage *_kv;
+    dispatch_semaphore_t _lock;
+    dispatch_queue_t _queue;
+}
+
+- (void)_trimRecursively {
+    __weak typeof(self) _self = self;
+    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(_autoTrimInterval * NSEC_PER_SEC)), dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
+        __strong typeof(_self) self = _self;
+        if (!self) return;
+        [self _trimInBackground];
+        [self _trimRecursively];
+    });
+}
+
+- (void)_trimInBackground {
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        if (!self) return;
+        dispatch_semaphore_wait(self->_lock, DISPATCH_TIME_FOREVER);
+        [self _trimToCost:self.countLimit];
+        [self _trimToCount:self.countLimit];
+        [self _trimToAge:self.ageLimit];
+        [self _trimToFreeDiskSpace:self.freeDiskSpaceLimit];
+        dispatch_semaphore_signal(self->_lock);
+    });
+}
+
+- (void)_trimToCost:(NSUInteger)costLimit {
+    if (costLimit >= INT_MAX) return;
+    [_kv removeItemsToFitSize:(int)costLimit];
+    
+}
+
+- (void)_trimToCount:(NSUInteger)countLimit {
+    if (countLimit >= INT_MAX) return;
+    [_kv removeItemsToFitCount:(int)countLimit];
+}
+
+- (void)_trimToAge:(NSTimeInterval)ageLimit {
+    if (ageLimit <= 0) {
+        [_kv removeAllItems];
+        return;
+    }
+    long timestamp = time(NULL);
+    if (timestamp <= ageLimit) return;
+    long age = timestamp - ageLimit;
+    if (age >= INT_MAX) return;
+    [_kv removeItemsEarlierThanTime:(int)age];
+}
+
+- (void)_trimToFreeDiskSpace:(NSUInteger)targetFreeDiskSpace {
+    if (targetFreeDiskSpace == 0) return;
+    int64_t totalBytes = [_kv getItemsSize];
+    if (totalBytes <= 0) return;
+    int64_t diskFreeBytes = _YYDiskSpaceFree();
+    if (diskFreeBytes < 0) return;
+    int64_t needTrimBytes = targetFreeDiskSpace - diskFreeBytes;
+    if (needTrimBytes <= 0) return;
+    int64_t costLimit = totalBytes - needTrimBytes;
+    if (costLimit < 0) costLimit = 0;
+    [self _trimToCost:(int)costLimit];
+}
+
+- (NSString *)_filenameForKey:(NSString *)key {
+    NSString *filename = nil;
+    if (_customFilenameBlock) filename = _customFilenameBlock(key);
+    if (!filename) filename = _YYNSStringMD5(key);
+    return filename;
+}
+
+#pragma mark - public
+
+- (instancetype)init {
+    @throw [NSException exceptionWithName:@"YYDiskCache init error" reason:@"YYDiskCache must be initialized with a path. Use 'initWithPath:' or 'initWithPath:inlineThreshold:' instead." userInfo:nil];
+    return [self initWithPath:nil inlineThreshold:0];
+}
+
+- (instancetype)initWithPath:(NSString *)path {
+    return [self initWithPath:path inlineThreshold:1024 * 20]; // 20KB
+}
+
+- (instancetype)initWithPath:(NSString *)path
+             inlineThreshold:(NSUInteger)threshold {
+    self = [super init];
+    if (!self) return nil;
+    
+    YYKVStorageType type;
+    if (threshold == 0) {
+        type = YYKVStorageTypeFile;
+    } else if (threshold == NSUIntegerMax) {
+        type = YYKVStorageTypeSQLite;
+    } else {
+        type = YYKVStorageTypeMixed;
+    }
+    
+    YYKVStorage *kv = [[YYKVStorage alloc] initWithPath:path type:type];
+    if (!kv) return nil;
+    
+    _kv = kv;
+    _path = path;
+    _lock = dispatch_semaphore_create(1);
+    _queue = dispatch_queue_create("com.ibireme.yykit.cache.disk", DISPATCH_QUEUE_CONCURRENT);
+    _inlineThreshold = threshold;
+    _countLimit = NSUIntegerMax;
+    _costLimit = NSUIntegerMax;
+    _ageLimit = DBL_MAX;
+    _freeDiskSpaceLimit = 0;
+    _autoTrimInterval = 60;
+    
+    [self _trimRecursively];
+    return self;
+}
+
+- (BOOL)containsObjectForKey:(NSString *)key {
+    if (!key) return NO;
+    Lock();
+    BOOL contains = [_kv itemExistsForKey:key];
+    Unlock();
+    return contains;
+}
+
+- (void)containsObjectForKey:(NSString *)key withBlock:(void(^)(NSString *key, BOOL contains))block {
+    if (!block) return;
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        BOOL contains = [self containsObjectForKey:key];
+        block(key, contains);
+    });
+}
+
+- (id<NSCoding>)objectForKey:(NSString *)key {
+    if (!key) return nil;
+    Lock();
+    YYKVStorageItem *item = [_kv getItemForKey:key];
+    Unlock();
+    if (!item.value) return nil;
+    
+    id object = nil;
+    if (_customUnarchiveBlock) {
+        object = _customUnarchiveBlock(item.value);
+    } else {
+        @try {
+            object = [NSKeyedUnarchiver unarchiveObjectWithData:item.value];
+        }
+        @catch (NSException *exception) {
+            // nothing to do...
+        }
+    }
+    if (object && item.extendedData) {
+        [YYDiskCache setExtendedData:item.extendedData toObject:object];
+    }
+    return object;
+}
+
+- (void)objectForKey:(NSString *)key withBlock:(void(^)(NSString *key, id<NSCoding> object))block {
+    if (!block) return;
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        id<NSCoding> object = [self objectForKey:key];
+        block(key, object);
+    });
+}
+
+- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key {
+    if (!key) return;
+    if (!object) {
+        [self removeObjectForKey:key];
+        return;
+    }
+    
+    NSData *extendedData = [YYDiskCache getExtendedDataFromObject:object];
+    NSData *value = nil;
+    if (_customArchiveBlock) {
+        value = _customArchiveBlock(object);
+    } else {
+        @try {
+            value = [NSKeyedArchiver archivedDataWithRootObject:object];
+        }
+        @catch (NSException *exception) {
+            // nothing to do...
+        }
+    }
+    if (!value) return;
+    NSString *filename = nil;
+    if (_kv.type != YYKVStorageTypeSQLite) {
+        if (value.length > _inlineThreshold) {
+            filename = [self _filenameForKey:key];
+        }
+    }
+    
+    Lock();
+    [_kv saveItemWithKey:key value:value filename:filename extendedData:extendedData];
+    Unlock();
+}
+
+- (void)setObject:(id<NSCoding>)object forKey:(NSString *)key withBlock:(void(^)(void))block {
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        [self setObject:object forKey:key];
+        if (block) block();
+    });
+}
+
+- (void)removeObjectForKey:(NSString *)key {
+    if (!key) return;
+    Lock();
+    [_kv removeItemForKey:key];
+    Unlock();
+}
+
+- (void)removeObjectForKey:(NSString *)key withBlock:(void(^)(NSString *key))block {
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        [self removeObjectForKey:key];
+        if (block) block(key);
+    });
+}
+
+- (void)removeAllObjects {
+    Lock();
+    [_kv removeAllItems];
+    Unlock();
+}
+
+- (void)removeAllObjectsWithBlock:(void(^)(void))block {
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        [self removeAllObjects];
+        if (block) block();
+    });
+}
+
+- (void)removeAllObjectsWithProgressBlock:(void(^)(int removedCount, int totalCount))progress
+                                 endBlock:(void(^)(BOOL error))end {
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        if (!self) {
+            if (end) end(YES);
+            return;
+        }
+        dispatch_semaphore_wait(self->_lock, DISPATCH_TIME_FOREVER);
+        [_kv removeAllItemsWithProgressBlock:progress endBlock:end];
+        dispatch_semaphore_signal(self->_lock);
+    });
+}
+
+- (NSInteger)totalCount {
+    Lock();
+    int count = [_kv getItemsCount];
+    Unlock();
+    return count;
+}
+
+- (void)totalCountWithBlock:(void(^)(NSInteger totalCount))block {
+    if (!block) return;
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        NSInteger totalCount = [self totalCount];
+        block(totalCount);
+    });
+}
+
+- (NSInteger)totalCost {
+    Lock();
+    int count = [_kv getItemsSize];
+    Unlock();
+    return count;
+}
+
+- (void)totalCostWithBlock:(void(^)(NSInteger totalCost))block {
+    if (!block) return;
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        NSInteger totalCost = [self totalCost];
+        block(totalCost);
+    });
+}
+
+- (void)trimToCount:(NSUInteger)count {
+    Lock();
+    [self _trimToCount:count];
+    Unlock();
+}
+
+- (void)trimToCount:(NSUInteger)count withBlock:(void(^)(void))block {
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        [self trimToCount:count];
+        if (block) block();
+    });
+}
+
+- (void)trimToCost:(NSUInteger)cost {
+    Lock();
+    [self _trimToCost:cost];
+    Unlock();
+}
+
+- (void)trimToCost:(NSUInteger)cost withBlock:(void(^)(void))block {
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        [self trimToCost:cost];
+        if (block) block();
+    });
+}
+
+- (void)trimToAge:(NSTimeInterval)age {
+    Lock();
+    [self _trimToAge:age];
+    Unlock();
+}
+
+- (void)trimToAge:(NSTimeInterval)age withBlock:(void(^)(void))block {
+    __weak typeof(self) _self = self;
+    dispatch_async(_queue, ^{
+        __strong typeof(_self) self = _self;
+        [self trimToAge:age];
+        if (block) block();
+    });
+}
+
++ (NSData *)getExtendedDataFromObject:(id)object {
+    if (!object) return nil;
+    return (NSData *)objc_getAssociatedObject(object, &extended_data_key);
+}
+
++ (void)setExtendedData:(NSData *)extendedData toObject:(id)object {
+    if (!object) return;
+    objc_setAssociatedObject(object, &extended_data_key, extendedData, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+}
+
+- (NSString *)description {
+    if (_name) return [NSString stringWithFormat:@"<%@: %p> (%@:%@)", self.class, self, _name, _path];
+    else return [NSString stringWithFormat:@"<%@: %p> (%@)", self.class, self, _path];
+}
+
+@end

YYWebImage/Cache/YYKVStorage.h

@@ -0,0 +1,319 @@
+//
+//  YYKVStorage.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/4/22.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <Foundation/Foundation.h>
+
+/**
+ YYKVStorageItem is used by `YYKVStorage` to store key-value pair and meta data.
+ */
+@interface YYKVStorageItem : NSObject
+@property (nonatomic, strong) NSString *key;        ///< key
+@property (nonatomic, strong) NSData *value;        ///< value
+@property (nonatomic, strong) NSString *filename;   ///< filename (nil if inline)
+@property (nonatomic, assign) int size;             ///< value's size in bytes
+@property (nonatomic, assign) int modTime;          ///< modification unix timestamp
+@property (nonatomic, assign) int accessTime;       ///< last access unix timestamp
+@property (nonatomic, strong) NSData *extendedData; ///< extended data (nil if no extended data)
+@end
+
+/**
+ Storage type, indicated where the `YYKVStorageItem.value` stored.
+ 
+ @discussion Typically, write data to sqlite is faster than extern file, but 
+ reading performance is dependent on data size. In my test (on iPhone 6 64G), 
+ read data from extern file is faster than from sqlite when the data is larger 
+ than 20KB.
+ 
+ * If you want to store large number of small datas (such as contacts cache), 
+   use YYKVStorageTypeSQLite to get better performance.
+ * If you want to store large files (such as image cache),
+   use YYKVStorageTypeFile to get better performance.
+ * You can use YYKVStorageTypeMixed and choice your storage type for each item.
+ 
+ See <http://www.sqlite.org/intern-v-extern-blob.html> for more information.
+ */
+typedef NS_ENUM(NSUInteger, YYKVStorageType) {
+    
+    /// The `value` is stored as a file in file system.
+    YYKVStorageTypeFile = 0,
+    
+    /// The `value` is stored in sqlite with blob type.
+    YYKVStorageTypeSQLite = 1,
+    
+    /// The `value` is stored in file system or sqlite based on your choice.
+    YYKVStorageTypeMixed = 2,
+};
+
+
+
+/**
+ YYKVStorage is a key-value storage based on sqlite and file system.
+ 
+ @discussion The designated initializer for YYKVStorage is `initWithPath:type:`. 
+ After initialized, a directory is created based on the `path` to hold key-value data.
+ Once initialized you should not read or write this directory without the instance.
+ 
+ You may compile the lastest version of sqlite and ignore the libsqlite3.dylib in
+ iOS system to get 2x~4x speed up.
+ 
+ @warning The instance of this class is *NOT* thread safe, you need to make sure 
+ that there's only one thread to access the instance at the same time. If you really 
+ need to process large amounts of data in multi-thread, you should split the data
+ to multiple KVStorage instance (sharding).
+ */
+@interface YYKVStorage : NSObject
+
+#pragma mark - Attribute
+///=============================================================================
+/// @name Attribute
+///=============================================================================
+
+@property (nonatomic, readonly) NSString *path;        ///< The path of this storage.
+@property (nonatomic, readonly) YYKVStorageType type;  ///< The type of this storage.
+@property (nonatomic, assign) BOOL errorLogsEnabled;   ///< Set `YES` to enable error logs for debug.
+
+#pragma mark - Initializer
+///=============================================================================
+/// @name Initializer
+///=============================================================================
+- (instancetype)init UNAVAILABLE_ATTRIBUTE;
++ (instancetype)new UNAVAILABLE_ATTRIBUTE;
+
+/**
+ The designated initializer. 
+ 
+ @param path  Full path of a directory in which the storage will write data. If
+    the directory is not exists, it will try to create one, otherwise it will 
+    read the data in this directory.
+ @param type  The storage type. After first initialized you should not change the 
+    type of the specified path.
+ @return  A new storage object, or nil if an error occurs.
+ @warning Multiple instances with the same path will make the storage unstable.
+ */
+- (instancetype)initWithPath:(NSString *)path type:(YYKVStorageType)type NS_DESIGNATED_INITIALIZER;
+
+
+#pragma mark - Save Items
+///=============================================================================
+/// @name Save Items
+///=============================================================================
+
+/**
+ Save an item or update the item with 'key' if it already exists.
+ 
+ @discussion This method will save the item.key, item.value, item.filename and
+ item.extendedData to disk or sqlite, other properties will be ignored. item.key 
+ and item.value should not be empty (nil or zero length).
+ 
+ If the `type` is YYKVStorageTypeFile, then the item.filename should not be empty.
+ If the `type` is YYKVStorageTypeSQLite, then the item.filename will be ignored.
+ It the `type` is YYKVStorageTypeMixed, then the item.value will be saved to file 
+ system if the item.filename is not empty, otherwise it will be saved to sqlite.
+ 
+ @param item  An item.
+ @return Whether succeed.
+ */
+- (BOOL)saveItem:(YYKVStorageItem *)item;
+
+/**
+ Save an item or update the item with 'key' if it already exists.
+ 
+ @discussion This method will save the key-value pair to sqlite. If the `type` is
+ YYKVStorageTypeFile, then this method will failed.
+ 
+ @param key   The key, should not be empty (nil or zero length).
+ @param value The key, should not be empty (nil or zero length).
+ @return Whether succeed.
+ */
+- (BOOL)saveItemWithKey:(NSString *)key value:(NSData *)value;
+
+/**
+ Save an item or update the item with 'key' if it already exists.
+ 
+ @discussion
+ If the `type` is YYKVStorageTypeFile, then the `filename` should not be empty.
+ If the `type` is YYKVStorageTypeSQLite, then the `filename` will be ignored.
+ It the `type` is YYKVStorageTypeMixed, then the `value` will be saved to file
+ system if the `filename` is not empty, otherwise it will be saved to sqlite.
+ 
+ @param key           The key, should not be empty (nil or zero length).
+ @param value         The key, should not be empty (nil or zero length).
+ @param filename      The filename.
+ @param extendedData  The extended data for this item (pass nil to ignore it).
+ 
+ @return Whether succeed.
+ */
+- (BOOL)saveItemWithKey:(NSString *)key
+                  value:(NSData *)value
+               filename:(NSString *)filename
+           extendedData:(NSData *)extendedData;
+
+#pragma mark - Remove Items
+///=============================================================================
+/// @name Remove Items
+///=============================================================================
+
+/**
+ Remove an item with 'key'.
+ 
+ @param key The item's key.
+ @return Whether succeed.
+ */
+- (BOOL)removeItemForKey:(NSString *)key;
+
+/**
+ Remove items with an array of keys.
+ 
+ @param keys An array of specified keys.
+ 
+ @return Whether succeed.
+ */
+- (BOOL)removeItemForKeys:(NSArray *)keys;
+
+/**
+ Remove all items which `value` is larger than a specified size.
+ 
+ @param size  The maximum size in bytes.
+ @return Whether succeed.
+ */
+- (BOOL)removeItemsLargerThanSize:(int)size;
+
+/**
+ Remove all items which last access time is earlier than a specified timestamp.
+ 
+ @param time  The specified unix timestamp.
+ @return Whether succeed.
+ */
+- (BOOL)removeItemsEarlierThanTime:(int)time;
+
+/**
+ Remove items to make the total size not larger than a specified size.
+ The least recently used (LRU) items will be removed first.
+ 
+ @param maxSize The specified size in bytes.
+ @return Whether succeed.
+ */
+- (BOOL)removeItemsToFitSize:(int)maxSize;
+
+/**
+ Remove items to make the total count not larger than a specified count.
+ The least recently used (LRU) items will be removed first.
+ 
+ @param maxCount The specified item count.
+ @return Whether succeed.
+ */
+- (BOOL)removeItemsToFitCount:(int)maxCount;
+
+/**
+ Remove all items in background queue.
+ 
+ @discussion This method will remove the files and sqlite database to a trash
+ folder, and then clear the folder in background queue. So this method is much 
+ faster than `removeAllItemsWithProgressBlock:endBlock:`.
+ 
+ @return Whether succeed.
+ */
+- (BOOL)removeAllItems;
+
+/**
+ Remove all items.
+ 
+ @warning You should not send message to this instance in these blocks.
+ @param progress This block will be revoked during removing, pass nil to ignore.
+ @param end      This block will be revoked at the end, pass nil to ignore.
+ */
+- (void)removeAllItemsWithProgressBlock:(void(^)(int removedCount, int totalCount))progress
+                               endBlock:(void(^)(BOOL error))end;
+
+
+#pragma mark - Get Items
+///=============================================================================
+/// @name Get Items
+///=============================================================================
+
+/**
+ Get item with a specified key.
+ 
+ @param key A specified key.
+ @return Item for the key, or nil if not exists / error occurs.
+ */
+- (YYKVStorageItem *)getItemForKey:(NSString *)key;
+
+/**
+ Get item information with a specified key.
+ The `value` in this item will be ignored.
+ 
+ @param key A specified key.
+ @return Item information for the key, or nil if not exists / error occurs.
+ */
+- (YYKVStorageItem *)getItemInfoForKey:(NSString *)key;
+
+/**
+ Get item value with a specified key.
+ 
+ @param key  A specified key.
+ @return Item's value, or nil if not exists / error occurs.
+ */
+- (NSData *)getItemValueForKey:(NSString *)key;
+
+/**
+ Get items with an array of keys.
+ 
+ @param keys  An array of specified keys.
+ @return An array of `YYKVStorageItem`, or nil if not exists / error occurs.
+ */
+- (NSArray *)getItemForKeys:(NSArray *)keys;
+
+/**
+ Get item infomartions with an array of keys.
+ The `value` in items will be ignored.
+ 
+ @param keys  An array of specified keys.
+ @return An array of `YYKVStorageItem`, or nil if not exists / error occurs.
+ */
+- (NSArray *)getItemInfoForKeys:(NSArray *)keys;
+
+/**
+ Get items value with an array of keys.
+ 
+ @param keys  An array of specified keys.
+ @return A dictionary which key is 'key' and value is 'value', or nil if not 
+    exists / error occurs.
+ */
+- (NSDictionary *)getItemValueForKeys:(NSArray *)keys;
+
+#pragma mark - Get Storage Status
+///=============================================================================
+/// @name Get Storage Status
+///=============================================================================
+
+/**
+ Whether an item exists for a specified key.
+ 
+ @param key  A specified key.
+ 
+ @return `YES` if there's an item exists for the key, `NO` if not exists or an error occurs.
+ */
+- (BOOL)itemExistsForKey:(NSString *)key;
+
+/**
+ Get total item count.
+ @return Total item count, -1 when an error occurs.
+ */
+- (int)getItemsCount;
+
+/**
+ Get item value's total size in bytes.
+ @return Total size in bytes, -1 when an error occurs.
+ */
+- (int)getItemsSize;
+
+@end

YYWebImage/Cache/YYKVStorage.m

@@ -0,0 +1,1012 @@
+//
+//  YYKVStorage.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/4/22.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYKVStorage.h"
+#import <UIKit/UIKit.h>
+#import <libkern/OSAtomic.h>
+#import <time.h>
+
+#if __has_include(<sqlite3.h>)
+#import <sqlite3.h>
+#else
+#import "sqlite3.h"
+#endif
+
+static const int kPathLengthMax = PATH_MAX - 64;
+static NSString *const kDBFileName = @"manifest.sqlite";
+static NSString *const kDBShmFileName = @"manifest.sqlite-shm";
+static NSString *const kDBWalFileName = @"manifest.sqlite-wal";
+static NSString *const kDataDirectoryName = @"data";
+static NSString *const kTrashDirectoryName = @"trash";
+
+/*
+ SQL:
+ create table if not exists manifest (
+    key                 text,
+    filename            text,
+    size                integer,
+    inline_data         blob,
+    modification_time   integer,
+    last_access_time    integer,
+    extended_data       blob,
+    primary key(key)
+ ); 
+ create index if not exists last_access_time_idx on manifest(last_access_time);
+ */
+
+@implementation YYKVStorageItem
+@end
+
+@implementation YYKVStorage {
+    dispatch_queue_t _trashQueue;
+    
+    NSString *_path;
+    NSString *_dbPath;
+    NSString *_dataPath;
+    NSString *_trashPath;
+    
+    sqlite3 *_db;
+    CFMutableDictionaryRef _dbStmtCache;
+    
+    BOOL _invalidated; ///< If YES, then the db should not open again, all read/write should be ignored.
+    BOOL _dbIsClosing; ///< If YES, then the db is during closing.
+    OSSpinLock _dbStateLock;
+}
+
+
+#pragma mark - db
+
+- (BOOL)_dbOpen {
+    BOOL shouldOpen = YES;
+    OSSpinLockLock(&_dbStateLock);
+    if (_invalidated) {
+        shouldOpen = NO;
+    } else if (_dbIsClosing) {
+        shouldOpen = NO;
+    } else if (_db){
+        shouldOpen = NO;
+    }
+    OSSpinLockUnlock(&_dbStateLock);
+    if (!shouldOpen) return YES;
+    
+    int result = sqlite3_open(_dbPath.UTF8String, &_db);
+    if (result == SQLITE_OK) {
+        CFDictionaryKeyCallBacks keyCallbacks = kCFTypeDictionaryKeyCallBacks;
+        CFDictionaryValueCallBacks valueCallbacks = {0};
+        _dbStmtCache = CFDictionaryCreateMutable(CFAllocatorGetDefault(), 0, &keyCallbacks, &valueCallbacks);
+        return YES;
+    } else {
+        NSLog(@"%s line:%d sqlite open failed (%d).", __FUNCTION__, __LINE__, result);
+        return NO;
+    }
+}
+
+- (BOOL)_dbClose {
+    BOOL needClose = YES;
+    OSSpinLockLock(&_dbStateLock);
+    if (!_db) {
+        needClose = NO;
+    } else if (_invalidated) {
+        needClose = NO;
+    } else if (_dbIsClosing) {
+        needClose = NO;
+    } else {
+        _dbIsClosing = YES;
+    }
+    OSSpinLockUnlock(&_dbStateLock);
+    if (!needClose) return YES;
+    
+    int  result = 0;
+    BOOL retry = NO;
+    BOOL stmtFinalized = NO;
+    
+    if (_dbStmtCache) CFRelease(_dbStmtCache);
+    _dbStmtCache = NULL;
+    
+    do {
+        retry = NO;
+        result = sqlite3_close(_db);
+        if (result == SQLITE_BUSY || result == SQLITE_LOCKED) {
+            if (!stmtFinalized) {
+                stmtFinalized = YES;
+                sqlite3_stmt *stmt;
+                while ((stmt = sqlite3_next_stmt(_db, nil)) != 0) {
+                    sqlite3_finalize(stmt);
+                    retry = YES;
+                }
+            }
+        } else if (result != SQLITE_OK) {
+            NSLog(@"%s line:%d sqlite close failed (%d).", __FUNCTION__, __LINE__, result);
+        }
+    } while (retry);
+    _db = NULL;
+    
+    OSSpinLockLock(&_dbStateLock);
+    _dbIsClosing = NO;
+    OSSpinLockUnlock(&_dbStateLock);
+    
+    return YES;
+}
+
+- (BOOL)_dbIsReady {
+    return (_db && !_dbIsClosing && !_invalidated);
+}
+
+- (BOOL)_dbInitialize {
+    NSString *sql = @"pragma journal_mode = wal; pragma synchronous = normal; create table if not exists manifest (key text, filename text, size integer, inline_data blob, modification_time integer, last_access_time integer, extended_data blob, primary key(key)); create index if not exists last_access_time_idx on manifest(last_access_time);";
+    return [self _dbExecute:sql];
+}
+
+- (BOOL)_dbExecute:(NSString *)sql {
+    if (sql.length == 0) return NO;
+    if (![self _dbIsReady]) return NO;
+    
+    char *error = NULL;
+    int result = sqlite3_exec(_db, sql.UTF8String, NULL, NULL, &error);
+    if (error) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite exec error (%d): %s", __FUNCTION__, __LINE__, result, error);
+        sqlite3_free(error);
+    }
+    
+    return result == SQLITE_OK;
+}
+
+- (sqlite3_stmt *)_dbPrepareStmt:(NSString *)sql {
+    if (![self _dbIsReady]) return NULL;
+    sqlite3_stmt *stmt = (sqlite3_stmt *)CFDictionaryGetValue(_dbStmtCache, (__bridge const void *)(sql));
+    if (!stmt) {
+        int result = sqlite3_prepare_v2(_db, sql.UTF8String, -1, &stmt, NULL);
+        if (result != SQLITE_OK) {
+            if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite stmt prepare error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+            return NULL;
+        }
+        CFDictionarySetValue(_dbStmtCache, (__bridge const void *)(sql), stmt);
+    } else {
+        sqlite3_reset(stmt);
+    }
+    return stmt;
+}
+
+- (BOOL)_dbSaveWithKey:(NSString *)key value:(NSData *)value fileName:(NSString *)fileName extendedData:(NSData *)extendedData {
+    NSString *sql = @"insert or replace into manifest (key, filename, size, inline_data, modification_time, last_access_time, extended_data) values (?1, ?2, ?3, ?4, ?5, ?6, ?7);";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return NO;
+    
+    int timestamp = (int)time(NULL);
+    sqlite3_bind_text(stmt, 1, key.UTF8String, -1, NULL);
+    sqlite3_bind_text(stmt, 2, fileName.UTF8String, -1, NULL);
+    sqlite3_bind_int(stmt, 3, (int)value.length);
+    if (fileName.length == 0) {
+        sqlite3_bind_blob(stmt, 4, value.bytes, (int)value.length, 0);
+    } else {
+        sqlite3_bind_blob(stmt, 4, NULL, 0, 0);
+    }
+    sqlite3_bind_int(stmt, 5, timestamp);
+    sqlite3_bind_int(stmt, 6, timestamp);
+    sqlite3_bind_blob(stmt, 7, extendedData.bytes, (int)extendedData.length, 0);
+    
+    int result = sqlite3_step(stmt);
+    if (result != SQLITE_DONE) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite insert error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return NO;
+    }
+    return YES;
+}
+
+- (BOOL)_dbUpdateAccessTimeWithKey:(NSString *)key {
+    NSString *sql = @"update manifest set last_access_time = ?1 where key = ?2;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return NO;
+    sqlite3_bind_int(stmt, 1, (int)time(NULL));
+    sqlite3_bind_text(stmt, 2, key.UTF8String, -1, NULL);
+    int result = sqlite3_step(stmt);
+    if (result != SQLITE_DONE) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite update error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return NO;
+    }
+    return YES;
+}
+
+- (BOOL)_dbUpdateAccessTimeWithKeys:(NSArray *)keys {
+    if (![self _dbIsReady]) return NO;
+    int t = (int)time(NULL);
+     NSString *sql = [NSString stringWithFormat:@"update manifest set last_access_time = %d where key in (%@);", t, [keys componentsJoinedByString:@","]];
+    
+    sqlite3_stmt *stmt = NULL;
+    int result = sqlite3_prepare_v2(_db, sql.UTF8String, -1, &stmt, NULL);
+    if (result != SQLITE_OK) {
+        if (_errorLogsEnabled)  NSLog(@"%s line:%d sqlite stmt prepare error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return NO;
+    }
+    
+    result = sqlite3_step(stmt);
+    sqlite3_finalize(stmt);
+    if (result != SQLITE_DONE) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite update error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return NO;
+    }
+    return YES;
+}
+
+- (BOOL)_dbDeleteItemWithKey:(NSString *)key {
+    NSString *sql = @"delete from manifest where key = ?1;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return NO;
+    sqlite3_bind_text(stmt, 1, key.UTF8String, -1, NULL);
+    
+    int result = sqlite3_step(stmt);
+    if (result != SQLITE_DONE) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d db delete error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return NO;
+    }
+    return YES;
+}
+
+- (BOOL)_dbDeleteItemWithKeys:(NSArray *)keys {
+    if (![self _dbIsReady]) return NO;
+    NSString *sql =  [NSString stringWithFormat:@"delete from manifest where key in (%@);", [keys componentsJoinedByString:@","]];
+    sqlite3_stmt *stmt = NULL;
+    int result = sqlite3_prepare_v2(_db, sql.UTF8String, -1, &stmt, NULL);
+    if (result != SQLITE_OK) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite stmt prepare error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return NO;
+    }
+    
+    result = sqlite3_step(stmt);
+    sqlite3_finalize(stmt);
+    if (result == SQLITE_ERROR) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite delete error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return NO;
+    }
+    return YES;
+}
+
+- (BOOL)_dbDeleteItemsWithSizeLargerThan:(int)size {
+    NSString *sql = @"delete from manifest where size > ?1;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return NO;
+    sqlite3_bind_int(stmt, 1, size);
+    int result = sqlite3_step(stmt);
+    if (result != SQLITE_DONE) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite delete error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return NO;
+    }
+    return YES;
+}
+
+- (BOOL)_dbDeleteItemsWithTimeEarlierThan:(int)time {
+    NSString *sql = @"delete from manifest where last_access_time < ?1;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return NO;
+    sqlite3_bind_int(stmt, 1, time);
+    int result = sqlite3_step(stmt);
+    if (result != SQLITE_DONE) {
+        if (_errorLogsEnabled)  NSLog(@"%s line:%d sqlite delete error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return NO;
+    }
+    return YES;
+}
+
+- (YYKVStorageItem *)_dbGetItemFromStmt:(sqlite3_stmt *)stmt excludeInlineData:(BOOL)excludeInlineData {
+    int i = 0;
+    char *key = (char *)sqlite3_column_text(stmt, i++);
+    char *filename = (char *)sqlite3_column_text(stmt, i++);
+    int size = sqlite3_column_int(stmt, i++);
+    const void *inline_data = excludeInlineData ? NULL : sqlite3_column_blob(stmt, i);
+    int inline_data_bytes = excludeInlineData ? 0 : sqlite3_column_bytes(stmt, i++);
+    int modification_time = sqlite3_column_int(stmt, i++);
+    int last_access_time = sqlite3_column_int(stmt, i++);
+    const void *extended_data = sqlite3_column_blob(stmt, i);
+    int extended_data_bytes = sqlite3_column_bytes(stmt, i++);
+    
+    YYKVStorageItem *item = [YYKVStorageItem new];
+    if (key) item.key = [NSString stringWithUTF8String:key];
+    if (filename && *filename != 0) item.filename = [NSString stringWithUTF8String:filename];
+    item.size = size;
+    if (inline_data_bytes > 0 && inline_data) item.value = [NSData dataWithBytes:inline_data length:inline_data_bytes];
+    item.modTime = modification_time;
+    item.accessTime = last_access_time;
+    if (extended_data_bytes > 0 && extended_data) item.extendedData = [NSData dataWithBytes:extended_data length:extended_data_bytes];
+    return item;
+}
+
+- (YYKVStorageItem *)_dbGetItemWithKey:(NSString *)key excludeInlineData:(BOOL)excludeInlineData {
+    NSString *sql = excludeInlineData ? @"select key, filename, size, modification_time, last_access_time, extended_data from manifest where key = ?1;" : @"select key, filename, size, inline_data, modification_time, last_access_time, extended_data from manifest where key = ?1;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return nil;
+    sqlite3_bind_text(stmt, 1, key.UTF8String, -1, NULL);
+    
+    YYKVStorageItem *item = nil;
+    int result = sqlite3_step(stmt);
+    if (result == SQLITE_ROW) {
+        item = [self _dbGetItemFromStmt:stmt excludeInlineData:excludeInlineData];
+    } else {
+        if (result != SQLITE_DONE) {
+            if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        }
+    }
+    return item;
+}
+
+- (NSMutableArray *)_dbGetItemWithKeys:(NSArray *)keys excludeInlineData:(BOOL)excludeInlineData {
+    if (![self _dbIsReady]) return nil;
+    NSString *sql;
+    if (excludeInlineData) {
+        sql = [NSString stringWithFormat:@"select key, filename, size, modification_time, last_access_time, extended_data from manifest where key in (%@);", [keys componentsJoinedByString:@","]];
+    } else {
+        sql = [NSString stringWithFormat:@"select key, filename, size, inline_data, modification_time, last_access_time, extended_data from manifest where key in (%@)", [keys componentsJoinedByString:@","]];
+    }
+    
+    sqlite3_stmt *stmt = NULL;
+    int result = sqlite3_prepare_v2(_db, sql.UTF8String, -1, &stmt, NULL);
+    if (result != SQLITE_OK) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite stmt prepare error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return nil;
+    }
+    
+    NSMutableArray *items = [NSMutableArray new];
+    do {
+        result = sqlite3_step(stmt);
+        if (result == SQLITE_ROW) {
+            YYKVStorageItem *item = [self _dbGetItemFromStmt:stmt excludeInlineData:excludeInlineData];
+            if (item) [items addObject:item];
+        } else if (result == SQLITE_DONE) {
+            break;
+        } else {
+            if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+            items = nil;
+            break;
+        }
+    } while (1);
+    sqlite3_finalize(stmt);
+    return items;
+}
+
+- (NSData *)_dbGetValueWithKey:(NSString *)key {
+    NSString *sql = @"select inline_data from manifest where key = ?1;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return nil;
+    sqlite3_bind_text(stmt, 1, key.UTF8String, -1, NULL);
+    
+    int result = sqlite3_step(stmt);
+    if (result == SQLITE_ROW) {
+        const void *inline_data = sqlite3_column_blob(stmt, 0);
+        int inline_data_bytes = sqlite3_column_bytes(stmt, 0);
+        if (!inline_data || inline_data_bytes <= 0) return nil;
+        return [NSData dataWithBytes:inline_data length:inline_data_bytes];
+    } else {
+        if (result != SQLITE_DONE) {
+            if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        }
+        return nil;
+    }
+}
+
+- (NSString *)_dbGetFilenameWithKey:(NSString *)key {
+    NSString *sql = @"select filename from manifest where key = ?1;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return nil;
+    sqlite3_bind_text(stmt, 1, key.UTF8String, -1, NULL);
+    int result = sqlite3_step(stmt);
+    if (result == SQLITE_ROW) {
+        char *filename = (char *)sqlite3_column_text(stmt, 0);
+        if (filename && *filename != 0) {
+            return [NSString stringWithUTF8String:filename];
+        }
+    } else {
+        if (result != SQLITE_DONE) {
+            if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        }
+    }
+    return nil;
+}
+
+- (NSMutableArray *)_dbGetFilenameWithKeys:(NSArray *)keys {
+    if (![self _dbIsReady]) return nil;
+    NSString *sql = [NSString stringWithFormat:@"select filename from manifest where key in (%@);", [keys componentsJoinedByString:@","]];
+    sqlite3_stmt *stmt = NULL;
+    int result = sqlite3_prepare_v2(_db, sql.UTF8String, -1, &stmt, NULL);
+    if (result != SQLITE_OK) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite stmt prepare error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return nil;
+    }
+    
+    NSMutableArray *filenames = [NSMutableArray new];
+    do {
+        result = sqlite3_step(stmt);
+        if (result == SQLITE_ROW) {
+            char *filename = (char *)sqlite3_column_text(stmt, 0);
+            if (filename && *filename != 0) {
+                NSString *name = [NSString stringWithUTF8String:filename];
+                if (name) [filenames addObject:name];
+            }
+        } else if (result == SQLITE_DONE) {
+            break;
+        } else {
+            if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+            filenames = nil;
+            break;
+        }
+    } while (1);
+    sqlite3_finalize(stmt);
+    return filenames;
+}
+
+- (NSMutableArray *)_dbGetFilenamesWithSizeLargerThan:(int)size {
+    NSString *sql = @"select filename from manifest where size > ?1 and filename is not null;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return nil;
+    sqlite3_bind_int(stmt, 1, size);
+    
+    NSMutableArray *filenames = [NSMutableArray new];
+    do {
+        int result = sqlite3_step(stmt);
+        if (result == SQLITE_ROW) {
+            char *filename = (char *)sqlite3_column_text(stmt, 0);
+            if (filename && *filename != 0) {
+                NSString *name = [NSString stringWithUTF8String:filename];
+                if (name) [filenames addObject:name];
+            }
+        } else if (result == SQLITE_DONE) {
+            break;
+        } else {
+            if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+            filenames = nil;
+            break;
+        }
+    } while (1);
+    return filenames;
+}
+
+- (NSMutableArray *)_dbGetFilenamesWithTimeEarlierThan:(int)time {
+    NSString *sql = @"select filename from manifest where last_access_time < ?1 and filename is not null;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return nil;
+    sqlite3_bind_int(stmt, 1, time);
+    
+    NSMutableArray *filenames = [NSMutableArray new];
+    do {
+        int result = sqlite3_step(stmt);
+        if (result == SQLITE_ROW) {
+            char *filename = (char *)sqlite3_column_text(stmt, 0);
+            if (filename && *filename != 0) {
+                NSString *name = [NSString stringWithUTF8String:filename];
+                if (name) [filenames addObject:name];
+            }
+        } else if (result == SQLITE_DONE) {
+            break;
+        } else {
+            if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+            filenames = nil;
+            break;
+        }
+    } while (1);
+    return filenames;
+}
+
+- (NSMutableArray *)_dbGetItemSizeInfoOrderByTimeDescWithLimit:(int)count {
+    NSString *sql = @"select key, filename, size from manifest order by last_access_time desc limit ?1;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return nil;
+    sqlite3_bind_int(stmt, 1, count);
+    
+    NSMutableArray *items = [NSMutableArray new];
+    do {
+        int result = sqlite3_step(stmt);
+        if (result == SQLITE_ROW) {
+            char *key = (char *)sqlite3_column_text(stmt, 0);
+            char *filename = (char *)sqlite3_column_text(stmt, 1);
+            int size = sqlite3_column_int(stmt, 2);
+            YYKVStorageItem *item = [YYKVStorageItem new];
+            item.key = key ? [NSString stringWithUTF8String:key] : nil;
+            item.filename = filename ? [NSString stringWithUTF8String:filename] : nil;
+            item.size = size;
+            [items addObject:item];
+        } else if (result == SQLITE_DONE) {
+            break;
+        } else {
+            if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+            items = nil;
+            break;
+        }
+    } while (1);
+    return items;
+}
+
+- (int)_dbGetItemCountWithKey:(NSString *)key {
+    NSString *sql = @"select count(key) from manifest where key = ?1;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return -1;
+    sqlite3_bind_text(stmt, 1, key.UTF8String, -1, NULL);
+    int result = sqlite3_step(stmt);
+    if (result != SQLITE_ROW) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return -1;
+    }
+    return sqlite3_column_int(stmt, 0);
+}
+
+- (int)_dbGetTotalItemSize {
+    NSString *sql = @"select sum(size) from manifest;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return -1;
+    int result = sqlite3_step(stmt);
+    if (result != SQLITE_ROW) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return -1;
+    }
+    return sqlite3_column_int(stmt, 0);
+}
+
+- (int)_dbGetTotalItemCount {
+    NSString *sql = @"select count(*) from manifest;";
+    sqlite3_stmt *stmt = [self _dbPrepareStmt:sql];
+    if (!stmt) return -1;
+    int result = sqlite3_step(stmt);
+    if (result != SQLITE_ROW) {
+        if (_errorLogsEnabled) NSLog(@"%s line:%d sqlite query error (%d): %s", __FUNCTION__, __LINE__, result, sqlite3_errmsg(_db));
+        return -1;
+    }
+    return sqlite3_column_int(stmt, 0);
+}
+
+
+#pragma mark - file
+
+- (BOOL)_fileWriteWithName:(NSString *)filename data:(NSData *)data {
+    if (_invalidated) return NO;
+    NSString *path = [_dataPath stringByAppendingPathComponent:filename];
+    return [data writeToFile:path atomically:NO];
+}
+
+- (NSData *)_fileReadWithName:(NSString *)filename {
+    if (_invalidated) return nil;
+    NSString *path = [_dataPath stringByAppendingPathComponent:filename];
+    NSData *data = [NSData dataWithContentsOfFile:path];
+    return data;
+}
+
+- (BOOL)_fileDeleteWithName:(NSString *)filename {
+    if (_invalidated) return NO;
+    NSString *path = [_dataPath stringByAppendingPathComponent:filename];
+    return [[NSFileManager defaultManager] removeItemAtPath:path error:NULL];
+}
+
+- (BOOL)_fileMoveAllToTrash {
+    if (_invalidated) return NO;
+    CFUUIDRef uuidRef = CFUUIDCreate(NULL);
+    CFStringRef uuid = CFUUIDCreateString(NULL, uuidRef);
+    CFRelease(uuidRef);
+    NSString *tmpPath = [_trashPath stringByAppendingPathComponent:(__bridge NSString *)(uuid)];
+    BOOL suc = [[NSFileManager defaultManager] moveItemAtPath:_dataPath toPath:tmpPath error:nil];
+    if (suc) {
+        suc = [[NSFileManager defaultManager] createDirectoryAtPath:_dataPath withIntermediateDirectories:YES attributes:nil error:NULL];
+    }
+    CFRelease(uuid);
+    return suc;
+}
+
+- (void)_fileEmptyTrashInBackground {
+    if (_invalidated) return;
+    NSString *trashPath = _trashPath;
+    dispatch_queue_t queue = _trashQueue;
+    dispatch_async(queue, ^{
+        NSFileManager *manager = [NSFileManager new];
+        NSArray *directoryContents = [manager contentsOfDirectoryAtPath:trashPath error:NULL];
+        for (NSString *path in directoryContents) {
+            NSString *fullPath = [trashPath stringByAppendingPathComponent:path];
+            [manager removeItemAtPath:fullPath error:NULL];
+        }
+    });
+}
+
+
+#pragma mark - private
+
+/**
+ Delete all files and empty in background.
+ Make sure the db is closed.
+ */
+- (void)_reset {
+    [[NSFileManager defaultManager] removeItemAtPath:[_path stringByAppendingPathComponent:kDBFileName] error:nil];
+    [[NSFileManager defaultManager] removeItemAtPath:[_path stringByAppendingPathComponent:kDBShmFileName] error:nil];
+    [[NSFileManager defaultManager] removeItemAtPath:[_path stringByAppendingPathComponent:kDBWalFileName] error:nil];
+    [self _fileMoveAllToTrash];
+    [self _fileEmptyTrashInBackground];
+}
+
+- (void)_appWillBeTerminated {
+    OSSpinLockLock(&_dbStateLock);
+    _invalidated = YES;
+    OSSpinLockUnlock(&_dbStateLock);
+}
+
+#pragma mark - public
+
+- (instancetype)init {
+    @throw [NSException exceptionWithName:@"YYKVStorage init error" reason:@"Please use the designated initializer and pass the 'path' and 'type'." userInfo:nil];
+    return [self initWithPath:nil type:YYKVStorageTypeFile];
+}
+
+- (instancetype)initWithPath:(NSString *)path type:(YYKVStorageType)type {
+    if (path.length == 0 || path.length > kPathLengthMax) {
+        NSLog(@"YYKVStorage init error: invalid path: [%@].", path);
+        return nil;
+    }
+    if (type > YYKVStorageTypeMixed) {
+        NSLog(@"YYKVStorage init error: invalid type: %lu.", (unsigned long)type);
+        return nil;
+    }
+    
+    self = [super init];
+    _path = path.copy;
+    _type = type;
+    _dataPath = [path stringByAppendingPathComponent:kDataDirectoryName];
+    _trashPath = [path stringByAppendingPathComponent:kTrashDirectoryName];
+    _trashQueue = dispatch_queue_create("com.ibireme.yykit.cache.disk.trash", DISPATCH_QUEUE_SERIAL);
+    _dbPath = [path stringByAppendingPathComponent:kDBFileName];
+    _dbStateLock = OS_SPINLOCK_INIT;
+    _errorLogsEnabled = YES;
+    NSError *error = nil;
+    if (![[NSFileManager defaultManager] createDirectoryAtPath:path
+                                   withIntermediateDirectories:YES
+                                                    attributes:nil
+                                                         error:&error] ||
+        ![[NSFileManager defaultManager] createDirectoryAtPath:[path stringByAppendingPathComponent:kDataDirectoryName]
+                                   withIntermediateDirectories:YES
+                                                    attributes:nil
+                                                         error:&error] ||
+        ![[NSFileManager defaultManager] createDirectoryAtPath:[path stringByAppendingPathComponent:kTrashDirectoryName]
+                                   withIntermediateDirectories:YES
+                                                    attributes:nil
+                                                         error:&error]) {
+        NSLog(@"YYKVStorage init error:%@", error);
+        return nil;
+    }
+    
+    if (![self _dbOpen] || ![self _dbInitialize]) {
+        // db file may broken...
+        [self _dbClose];
+        [self _reset]; // rebuild
+        if (![self _dbOpen] || ![self _dbInitialize]) {
+            [self _dbClose];
+            NSLog(@"YYKVStorage init error: fail to open sqlite db.");
+        }
+        return nil;
+    }
+    [self _fileEmptyTrashInBackground]; // empty the trash if failed at last time
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_appWillBeTerminated) name:UIApplicationWillTerminateNotification object:nil];
+    return self;
+}
+
+- (void)dealloc {
+    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationWillTerminateNotification object:nil];
+    [self _dbClose];
+}
+
+- (BOOL)saveItem:(YYKVStorageItem *)item {
+    return [self saveItemWithKey:item.key value:item.value filename:item.filename extendedData:item.extendedData];
+}
+
+- (BOOL)saveItemWithKey:(NSString *)key value:(NSData *)value {
+    return [self saveItemWithKey:key value:value filename:nil extendedData:nil];
+}
+
+- (BOOL)saveItemWithKey:(NSString *)key value:(NSData *)value filename:(NSString *)filename extendedData:(NSData *)extendedData {
+    if (key.length == 0 || value.length == 0) return NO;
+    if (_type == YYKVStorageTypeFile && filename.length == 0) {
+        return NO;
+    }
+    
+    if (filename.length) {
+        if (![self _fileWriteWithName:filename data:value]) {
+            return NO;
+        }
+        if (![self _dbSaveWithKey:key value:value fileName:filename extendedData:extendedData]) {
+            [self _fileDeleteWithName:filename];
+            return NO;
+        }
+        return YES;
+    } else {
+        if (_type != YYKVStorageTypeSQLite) {
+            NSString *filename = [self _dbGetFilenameWithKey:key];
+            if (filename) {
+                [self _fileDeleteWithName:filename];
+            }
+        }
+        return [self _dbSaveWithKey:key value:value fileName:nil extendedData:extendedData];
+    }
+}
+
+- (BOOL)removeItemForKey:(NSString *)key {
+    if (key.length == 0) return NO;
+    switch (_type) {
+        case YYKVStorageTypeSQLite: {
+            return [self _dbDeleteItemWithKey:key];
+        } break;
+        case YYKVStorageTypeFile:
+        case YYKVStorageTypeMixed: {
+            NSString *filename = [self _dbGetFilenameWithKey:key];
+            if (filename) {
+                [self _fileDeleteWithName:filename];
+            }
+            return [self _dbDeleteItemWithKey:key];
+        } break;
+        default: return NO;
+    }
+}
+
+- (BOOL)removeItemForKeys:(NSArray *)keys {
+    if (keys.count == 0) return NO;
+    switch (_type) {
+        case YYKVStorageTypeSQLite: {
+            return [self _dbDeleteItemWithKeys:keys];
+        } break;
+        case YYKVStorageTypeFile:
+        case YYKVStorageTypeMixed: {
+            NSArray *filenames = [self _dbGetFilenameWithKeys:keys];
+            for (NSString *filename in filenames) {
+                [self _fileDeleteWithName:filename];
+            }
+            return [self _dbDeleteItemWithKeys:keys];
+        } break;
+        default: return NO;
+    }
+}
+
+- (BOOL)removeItemsLargerThanSize:(int)size {
+    if (size == INT_MAX) return YES;
+    if (size <= 0) return [self removeAllItems];
+    
+    switch (_type) {
+        case YYKVStorageTypeSQLite: {
+            return [self _dbDeleteItemsWithSizeLargerThan:size];
+        } break;
+        case YYKVStorageTypeFile:
+        case YYKVStorageTypeMixed: {
+            NSArray *filenames = [self _dbGetFilenamesWithSizeLargerThan:size];
+            for (NSString *name in filenames) {
+                [self _fileDeleteWithName:name];
+            }
+            return [self _dbDeleteItemsWithSizeLargerThan:size];
+        } break;
+    }
+    return NO;
+}
+
+- (BOOL)removeItemsEarlierThanTime:(int)time {
+    if (time <= 0) return YES;
+    if (time == INT_MAX) return [self removeAllItems];
+    
+    switch (_type) {
+        case YYKVStorageTypeSQLite: {
+            return [self _dbDeleteItemsWithTimeEarlierThan:time];
+        } break;
+        case YYKVStorageTypeFile:
+        case YYKVStorageTypeMixed: {
+            NSArray *filenames = [self _dbGetFilenamesWithTimeEarlierThan:time];
+            for (NSString *name in filenames) {
+                [self _fileDeleteWithName:name];
+            }
+            return [self _dbDeleteItemsWithTimeEarlierThan:time];
+        } break;
+    }
+    return NO;
+}
+
+- (BOOL)removeItemsToFitSize:(int)maxSize {
+    if (maxSize == INT_MAX) return YES;
+    if (maxSize <= 0) return [self removeAllItems];
+    
+    int total = [self _dbGetTotalItemSize];
+    if (total < 0) return NO;
+    if (total <= maxSize) return YES;
+    
+    NSArray *items = nil;
+    BOOL suc = NO;
+    do {
+        int perCount = 16;
+        items = [self _dbGetItemSizeInfoOrderByTimeDescWithLimit:perCount];
+        for (YYKVStorageItem *item in items) {
+            if (total > maxSize) {
+                if (item.filename) {
+                    [self _fileDeleteWithName:item.filename];
+                }
+                suc = [self _dbDeleteItemWithKey:item.key];
+                total -= item.size;
+            } else {
+                break;
+            }
+            if (!suc) break;
+        }
+    } while (total > maxSize && items.count > 0 && suc);
+    return suc;
+}
+
+- (BOOL)removeItemsToFitCount:(int)maxCount {
+    if (maxCount == INT_MAX) return YES;
+    if (maxCount <= 0) return [self removeAllItems];
+    
+    int total = [self _dbGetTotalItemCount];
+    if (total < 0) return NO;
+    if (total <= maxCount) return YES;
+    
+    NSArray *items = nil;
+    BOOL suc = NO;
+    do {
+        int perCount = 16;
+        items = [self _dbGetItemSizeInfoOrderByTimeDescWithLimit:perCount];
+        for (YYKVStorageItem *item in items) {
+            if (total > maxCount) {
+                if (item.filename) {
+                    [self _fileDeleteWithName:item.filename];
+                }
+                suc = [self _dbDeleteItemWithKey:item.key];
+                total--;
+            } else {
+                break;
+            }
+            if (!suc) break;
+        }
+    } while (total > maxCount && items.count > 0 && suc);
+    return suc;
+}
+
+- (BOOL)removeAllItems {
+    if (![self _dbClose]) return NO;
+    [self _reset];
+    if (![self _dbOpen]) return NO;
+    if (![self _dbInitialize]) return NO;
+    return YES;
+}
+
+- (void)removeAllItemsWithProgressBlock:(void(^)(int removedCount, int totalCount))progress
+                               endBlock:(void(^)(BOOL error))end {
+    
+    int total = [self _dbGetTotalItemCount];
+    if (total <= 0) {
+        if (end) end(total < 0);
+    } else {
+        int left = total;
+        int perCount = 32;
+        NSArray *items = nil;
+        BOOL suc = NO;
+        do {
+            items = [self _dbGetItemSizeInfoOrderByTimeDescWithLimit:perCount];
+            for (YYKVStorageItem *item in items) {
+                if (left > 0) {
+                    if (item.filename) {
+                        [self _fileDeleteWithName:item.filename];
+                    }
+                    suc = [self _dbDeleteItemWithKey:item.key];
+                    left--;
+                } else {
+                    break;
+                }
+                if (!suc) break;
+            }
+            if (progress) progress(total - left, total);
+        } while (left > 0 && items.count > 0 && suc);
+        if (end) end(!suc);
+    }
+}
+
+- (YYKVStorageItem *)getItemForKey:(NSString *)key {
+    if (key.length == 0) return nil;
+    YYKVStorageItem *item = [self _dbGetItemWithKey:key excludeInlineData:NO];
+    if (item) {
+        [self _dbUpdateAccessTimeWithKey:key];
+        if (item.filename) {
+            item.value = [self _fileReadWithName:item.filename];
+            if (!item.value) {
+                [self _dbDeleteItemWithKey:key];
+                item = nil;
+            }
+        }
+    }
+    return item;
+}
+
+- (YYKVStorageItem *)getItemInfoForKey:(NSString *)key {
+    if (key.length == 0) return nil;
+    YYKVStorageItem *item = [self _dbGetItemWithKey:key excludeInlineData:YES];
+    return item;
+}
+
+- (NSData *)getItemValueForKey:(NSString *)key {
+    if (key.length == 0) return nil;
+    NSData *value = nil;
+    switch (_type) {
+        case YYKVStorageTypeFile: {
+            NSString *filename = [self _dbGetFilenameWithKey:key];
+            if (filename) {
+                value = [self _fileReadWithName:filename];
+                if (!value) {
+                    [self _dbDeleteItemWithKey:key];
+                    value = nil;
+                }
+            }
+        } break;
+        case YYKVStorageTypeSQLite: {
+            value = [self _dbGetValueWithKey:key];
+        } break;
+        case YYKVStorageTypeMixed: {
+            NSString *filename = [self _dbGetFilenameWithKey:key];
+            if (filename) {
+                value = [self _fileReadWithName:filename];
+                if (!value) {
+                    [self _dbDeleteItemWithKey:key];
+                    value = nil;
+                }
+            } else {
+                value = [self _dbGetValueWithKey:key];
+            }
+        } break;
+    }
+    if (value) {
+        [self _dbUpdateAccessTimeWithKey:key];
+    }
+    return value;
+}
+
+- (NSArray *)getItemForKeys:(NSArray *)keys {
+    if (keys.count == 0) return nil;
+    NSMutableArray *items = [self _dbGetItemWithKeys:keys excludeInlineData:NO];
+    if (_type != YYKVStorageTypeSQLite) {
+        for (NSInteger i = 0, max = items.count; i < max; i++) {
+            YYKVStorageItem *item = items[i];
+            if (item.filename) {
+                item.value = [self _fileReadWithName:item.filename];
+                if (!item.value) {
+                    if (item.key) [self _dbDeleteItemWithKey:item.key];
+                    [items removeObjectAtIndex:i];
+                    i--;
+                    max--;
+                }
+            }
+        }
+    }
+    if (items.count > 0) {
+        [self _dbUpdateAccessTimeWithKeys:keys];
+    }
+    return items.count ? items : nil;
+}
+
+- (NSArray *)getItemInfoForKeys:(NSArray *)keys {
+    if (keys.count == 0) return nil;
+    return [self _dbGetItemWithKeys:keys excludeInlineData:YES];
+}
+
+- (NSDictionary *)getItemValueForKeys:(NSArray *)keys {
+    NSMutableArray *items = (NSMutableArray *)[self getItemForKeys:keys];
+    NSMutableDictionary *kv = [NSMutableDictionary new];
+    for (YYKVStorageItem *item in items) {
+        if (item.key && item.value) {
+            [kv setObject:item.value forKey:item.key];
+        }
+    }
+    return kv.count ? kv : nil;
+}
+
+- (BOOL)itemExistsForKey:(NSString *)key {
+    if (key.length == 0) return NO;
+    return [self _dbGetItemCountWithKey:key] > 0;
+}
+
+- (int)getItemsCount {
+    return [self _dbGetTotalItemCount];
+}
+
+- (int)getItemsSize {
+    return [self _dbGetTotalItemSize];
+}
+
+@end

YYWebImage/Cache/YYMemoryCache.h

@@ -0,0 +1,202 @@
+//
+//  YYMemoryCache.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/7.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <Foundation/Foundation.h>
+
+/**
+ YYMemoryCache is a fast in-memory cache that stores key-value pairs.
+ In contrast to NSDictionary, keys are retained and not copied.
+ The API and performance is similar to `NSCache`, all methods are thread-safe.
+ 
+ YYMemoryCache objects differ from NSCache in a few ways:
+ 
+ * It use LRU (least-recently-used) to remove objects; NSCache's eviction method 
+   is non-deterministic.
+ * It can be controlled by cost, count and age; NSCache's limits are imprecise.
+ * It can be configured to automatically evict objects when receive memory 
+   warning or app enter background.
+ 
+ The time of `Access Methods` in YYMemoryCache is typically in constant time (O(1)).
+ */
+@interface YYMemoryCache : NSObject
+
+#pragma mark - Attribute
+///=============================================================================
+/// @name Attribute
+///=============================================================================
+
+/** The name of the cache. Default is nil. */
+@property (copy) NSString *name;
+
+/** The number of objects in the cache (read-only) */
+@property (readonly) NSUInteger totalCount;
+
+/** The total cost of objects in the cache (read-only). */
+@property (readonly) NSUInteger totalCost;
+
+
+#pragma mark - Limit
+///=============================================================================
+/// @name Limit
+///=============================================================================
+
+/**
+ The maximum number of objects the cache should hold.
+ 
+ @discussion The default value is NSUIntegerMax, which means no limit.
+ This is not a strict limit—if the cache goes over the limit, some objects in the
+ cache could be evicted later in backgound thread.
+ */
+@property (assign) NSUInteger countLimit;
+
+/**
+ The maximum total cost that the cache can hold before it starts evicting objects.
+ 
+ @discussion The default value is NSUIntegerMax, which means no limit.
+ This is not a strict limit—if the cache goes over the limit, some objects in the
+ cache could be evicted later in backgound thread.
+ */
+@property (assign) NSUInteger costLimit;
+
+/**
+ The maximum expiry time of objects in cache.
+ 
+ @discussion The default value is DBL_MAX, which means no limit.
+ This is not a strict limit—if an object goes over the limit, the object could 
+ be evicted later in backgound thread.
+ */
+@property (assign) NSTimeInterval ageLimit;
+
+/**
+ The auto trim check time interval in seconds. Default is 5.0.
+ 
+ @discussion The cache holds an internal timer to check whether the cache reaches 
+ its limits, and if the limit is reached, it begins to evict objects.
+ */
+@property (assign) NSTimeInterval autoTrimInterval;
+
+/**
+ If `YES`, the cache will remove all objects when the app receives a memory warning.
+ The default value is `YES`.
+ */
+@property (assign) BOOL shouldRemoveAllObjectsOnMemoryWarning;
+
+/**
+ If `YES`, The cache will remove all objects when the app enter background.
+ The default value is `YES`.
+ */
+@property (assign) BOOL shouldRemoveAllObjectsWhenEnteringBackground;
+
+/**
+ A block to be executed when the app receives a memory warning.
+ The default value is nil.
+ */
+@property (copy) void(^didReceiveMemoryWarningBlock)(YYMemoryCache *cache);
+
+/**
+ A block to be executed when the app enter background.
+ The default value is nil.
+ */
+@property (copy) void(^didEnterBackgroundBlock)(YYMemoryCache *cache);
+
+/**
+ If `YES`, the key-value object will be released on main thread, otherwise on
+ background thread. Default is NO. 
+ 
+ @discussion You may set this value to `YES` if the key-value object contains
+ the instance which should be released in main thread (such as UIView/CALayer).
+ */
+@property (assign) BOOL releaseOnMainThread;
+
+
+#pragma mark - Access Methods
+///=============================================================================
+/// @name Access Methods
+///=============================================================================
+
+/**
+ Returns a Boolean value that indicates whether a given key is in cache.
+ 
+ @param key An object identifying the value. If nil, just return `NO`.
+ @return Whether the key is in cache.
+ */
+- (BOOL)containsObjectForKey:(id)key;
+
+/**
+ Returns the value associated with a given key.
+ 
+ @param key An object identifying the value. If nil, just return nil.
+ @return The value associated with key, or nil if no value is associated with key.
+ */
+- (id)objectForKey:(id)key;
+
+/**
+ Sets the value of the specified key in the cache (0 cost).
+ 
+ @param object The object to be stored in the cache. If nil, it calls `removeObjectForKey:`.
+ @param key    The key with which to associate the value. If nil, this method has no effect.
+ @discussion Unlike an NSMutableDictionary object, a cache does not copy the key 
+ objects that are put into it.
+ */
+- (void)setObject:(id)object forKey:(id)key;
+
+/**
+ Sets the value of the specified key in the cache, and associates the key-value 
+ pair with the specified cost.
+ 
+ @param object The object to store in the cache. If nil, it calls `removeObjectForKey`.
+ @param key    The key with which to associate the value. If nil, this method has no effect.
+ @param cost   The cost with which to associate the key-value pair.
+ @discussion Unlike an NSMutableDictionary object, a cache does not copy the key
+ objects that are put into it.
+ */
+- (void)setObject:(id)object forKey:(id)key withCost:(NSUInteger)cost;
+
+/**
+ Removes the value of the specified key in the cache.
+ 
+ @param key The key identifying the value to be removed. If nil, this method has no effect.
+ */
+- (void)removeObjectForKey:(id)key;
+
+/**
+ Empties the cache immediately.
+ */
+- (void)removeAllObjects;
+
+
+#pragma mark - Trim
+///=============================================================================
+/// @name Trim
+///=============================================================================
+
+/**
+ Removes objects from the cache with LRU, until the `totalCount` is below or equal to
+ the specified value.
+ @param count  The total count allowed to remain after the cache has been trimmed.
+ */
+- (void)trimToCount:(NSUInteger)count;
+
+/**
+ Removes objects from the cache with LRU, until the `totalCost` is or equal to
+ the specified value.
+ @param cost The total cost allowed to remain after the cache has been trimmed.
+ */
+- (void)trimToCost:(NSUInteger)cost;
+
+/**
+ Removes objects from the cache with LRU, until all expiry objects removed by the
+ specified value.
+ @param age  The maximum age (in seconds) of objects.
+ */
+- (void)trimToAge:(NSTimeInterval)age;
+
+@end

YYWebImage/Cache/YYMemoryCache.m

@@ -0,0 +1,479 @@
+//
+//  YYMemoryCache.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/7.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYMemoryCache.h"
+#import <UIKit/UIKit.h>
+#import <CoreFoundation/CoreFoundation.h>
+#import <QuartzCore/QuartzCore.h>
+#import <libkern/OSAtomic.h>
+
+#if __has_include("YYDispatchQueuePool.h")
+#import "YYDispatchQueuePool.h"
+#else
+#import <libkern/OSAtomic.h>
+#endif
+
+#ifdef YYDispatchQueuePool_h
+static inline dispatch_queue_t YYMemoryCacheGetReleaseQueue() {
+    return YYDispatchQueueGetForQOS(NSQualityOfServiceUtility);
+}
+#else
+static inline dispatch_queue_t YYMemoryCacheGetReleaseQueue() {
+    return dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0);
+}
+#endif
+
+/**
+ A node in linked map.
+ Typically, you should not use this class directly.
+ */
+@interface _YYLinkedMapNode : NSObject {
+    @package
+    __unsafe_unretained _YYLinkedMapNode *_prev; // retained by dic
+    __unsafe_unretained _YYLinkedMapNode *_next; // retained by dic
+    id _key;
+    id _value;
+    NSUInteger _cost;
+    NSTimeInterval _time;
+}
+@end
+
+@implementation _YYLinkedMapNode
+@end
+
+
+/**
+ A linkd map used by YYMemoryCache.
+ It's not thread-safe and does not validate the parameters.
+ 
+ Typically, you should not use this class directly.
+ */
+@interface _YYLinkedMap : NSObject {
+    @package
+    CFMutableDictionaryRef _dic; // do not set object directly
+    NSUInteger _totalCost;
+    NSUInteger _totalCount;
+    _YYLinkedMapNode *_head; // MRU, do not change it directly
+    _YYLinkedMapNode *_tail; // LRU, do not change it directly
+    BOOL _releaseOnMainThread;
+}
+
+/// Insert a node at head and update the total cost.
+/// Node and node.key should not be nil.
+- (void)insertNodeAtHead:(_YYLinkedMapNode *)node;
+
+/// Bring a inner node to header.
+/// Node should already inside the dic.
+- (void)bringNodeToHead:(_YYLinkedMapNode *)node;
+
+/// Remove a inner node and update the total cost.
+/// Node should already inside the dic.
+- (void)removeNode:(_YYLinkedMapNode *)node;
+
+/// Remove tail node if exist.
+- (_YYLinkedMapNode *)removeTailNode;
+
+/// Remove all node in background queue.
+- (void)removeAll;
+
+@end
+
+@implementation _YYLinkedMap
+
+- (instancetype) init{
+    self = [super init];
+    _dic = CFDictionaryCreateMutable(CFAllocatorGetDefault(), 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
+    return self;
+}
+
+- (void)dealloc {
+    CFRelease(_dic);
+}
+
+- (void)insertNodeAtHead:(_YYLinkedMapNode *)node {
+    CFDictionarySetValue(_dic, (__bridge const void *)(node->_key), (__bridge const void *)(node));
+    _totalCost += node->_cost;
+    _totalCount++;
+    if (_head) {
+        node->_next = _head;
+        _head->_prev = node;
+        _head = node;
+    } else {
+        _head = _tail = node;
+    }
+}
+
+- (void)bringNodeToHead:(_YYLinkedMapNode *)node {
+    if (_head == node) return;
+    
+    if (_tail == node) {
+        _tail = node->_prev;
+        _tail->_next = nil;
+    } else {
+        node->_next->_prev = node->_prev;
+        node->_prev->_next = node->_next;
+    }
+    node->_next = _head;
+    node->_prev = nil;
+    _head->_prev = node;
+    _head = node;
+}
+
+- (void)removeNode:(_YYLinkedMapNode *)node {
+    CFDictionaryRemoveValue(_dic, (__bridge const void *)(node->_key));
+    _totalCost -= node->_cost;
+    _totalCount--;
+    if (node->_next) node->_next->_prev = node->_prev;
+    if (node->_prev) node->_prev->_next = node->_next;
+    if (_head == node) _head = node->_next;
+    if (_tail == node) _tail = node->_prev;
+}
+
+- (_YYLinkedMapNode *)removeTailNode {
+    if (!_tail) return nil;
+    _YYLinkedMapNode *tail = _tail;
+    CFDictionaryRemoveValue(_dic, (__bridge const void *)(_tail->_key));
+    _totalCost -= _tail->_cost;
+    _totalCount--;
+    if (_head == _tail) {
+        _head = _tail = nil;
+    } else {
+        _tail = _tail->_prev;
+        _tail->_next = nil;
+    }
+    return tail;
+}
+
+- (void)removeAll {
+    _totalCost = 0;
+    _totalCount = 0;
+    _head = nil;
+    _tail = nil;
+    if (CFDictionaryGetCount(_dic) > 0) {
+        CFMutableDictionaryRef holder = _dic;
+        _dic = CFDictionaryCreateMutable(CFAllocatorGetDefault(), 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
+        dispatch_queue_t queue = _releaseOnMainThread ? dispatch_get_main_queue() : YYMemoryCacheGetReleaseQueue();
+        dispatch_async(queue, ^{
+            CFRelease(holder); // hold and release in specified queue
+        });
+    }
+}
+
+@end
+
+
+
+@implementation YYMemoryCache {
+    OSSpinLock _lock;
+    _YYLinkedMap *_lru;
+    dispatch_queue_t _queue;
+}
+
+- (void)_trimRecursively {
+    __weak typeof(self) _self = self;
+    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(_autoTrimInterval * NSEC_PER_SEC)), dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
+        __strong typeof(_self) self = _self;
+        if (!self) return;
+        [self _trimInBackground];
+        [self _trimRecursively];
+    });
+}
+
+- (void)_trimInBackground {
+    dispatch_async(_queue, ^{
+        [self _trimToCost:self->_countLimit];
+        [self _trimToCount:self->_countLimit];
+        [self _trimToAge:self->_ageLimit];
+    });
+}
+
+- (void)_trimToCost:(NSUInteger)costLimit {
+    BOOL finish = NO;
+    OSSpinLockLock(&_lock);
+    if (costLimit == 0) {
+        [_lru removeAll];
+        finish = YES;
+    } else if (_lru->_totalCost <= costLimit) {
+        finish = YES;
+    }
+    OSSpinLockUnlock(&_lock);
+    if (finish) return;
+    
+    NSMutableArray *holder = [NSMutableArray new];
+    while (!finish) {
+        if (OSSpinLockTry(&_lock)) {
+            if (_lru->_totalCost > costLimit) {
+                _YYLinkedMapNode *node = [_lru removeTailNode];
+                if (node) [holder addObject:node];
+            } else {
+                finish = YES;
+            }
+            OSSpinLockUnlock(&_lock);
+        } else {
+            usleep(10 * 1000); //10 ms
+        }
+    }
+    if (holder.count) {
+        dispatch_queue_t queue = _lru->_releaseOnMainThread ? dispatch_get_main_queue() : YYMemoryCacheGetReleaseQueue();
+        dispatch_async(queue, ^{
+            [holder count]; // release in queue
+        });
+    }
+}
+
+- (void)_trimToCount:(NSUInteger)countLimit {
+    BOOL finish = NO;
+    OSSpinLockLock(&_lock);
+    if (countLimit == 0) {
+        [_lru removeAll];
+        finish = YES;
+    } else if (_lru->_totalCount <= countLimit) {
+        finish = YES;
+    }
+    OSSpinLockUnlock(&_lock);
+    if (finish) return;
+    
+    NSMutableArray *holder = [NSMutableArray new];
+    while (!finish) {
+        if (OSSpinLockTry(&_lock)) {
+            if (_lru->_totalCount > countLimit) {
+                _YYLinkedMapNode *node = [_lru removeTailNode];
+                if (node) [holder addObject:node];
+            } else {
+                finish = YES;
+            }
+            OSSpinLockUnlock(&_lock);
+        } else {
+            usleep(10 * 1000); //10 ms
+        }
+    }
+    if (holder.count) {
+        dispatch_queue_t queue = _lru->_releaseOnMainThread ? dispatch_get_main_queue() : YYMemoryCacheGetReleaseQueue();
+        dispatch_async(queue, ^{
+            [holder count]; // release in queue
+        });
+    }
+}
+
+- (void)_trimToAge:(NSTimeInterval)ageLimit {
+    BOOL finish = NO;
+    NSTimeInterval now = CACurrentMediaTime();
+    OSSpinLockLock(&_lock);
+    if (ageLimit <= 0) {
+        [_lru removeAll];
+        finish = YES;
+    } else if (!_lru->_tail || (now - _lru->_tail->_time) <= ageLimit) {
+        finish = YES;
+    }
+    OSSpinLockUnlock(&_lock);
+    if (finish) return;
+    
+    NSMutableArray *holder = [NSMutableArray new];
+    while (!finish) {
+        if (OSSpinLockTry(&_lock)) {
+            if (_lru->_tail && (now - _lru->_tail->_time) > ageLimit) {
+                _YYLinkedMapNode *node = [_lru removeTailNode];
+                if (node) [holder addObject:node];
+            } else {
+                finish = YES;
+            }
+            OSSpinLockUnlock(&_lock);
+        } else {
+            usleep(10 * 1000); //10 ms
+        }
+    }
+    if (holder.count) {
+        dispatch_queue_t queue = _lru->_releaseOnMainThread ? dispatch_get_main_queue() : YYMemoryCacheGetReleaseQueue();
+        dispatch_async(queue, ^{
+            [holder count]; // release in queue
+        });
+    }
+}
+
+- (void)_appDidReceiveMemoryWarningNotification {
+    if (self.didReceiveMemoryWarningBlock) {
+        self.didReceiveMemoryWarningBlock(self);
+    }
+    if (self.shouldRemoveAllObjectsOnMemoryWarning) {
+        [self removeAllObjects];
+    }
+}
+
+- (void)_appDidEnterBackgroundNotification {
+    if (self.didEnterBackgroundBlock) {
+        self.didEnterBackgroundBlock(self);
+    }
+    if (self.shouldRemoveAllObjectsWhenEnteringBackground) {
+        [self removeAllObjects];
+    }
+}
+
+#pragma mark - public
+
+- (instancetype)init {
+    self = super.init;
+    _lock = OS_SPINLOCK_INIT;
+    _lru = [_YYLinkedMap new];
+    _queue = dispatch_queue_create("com.ibireme.yykit.cache.memory", DISPATCH_QUEUE_SERIAL);
+    
+    _countLimit = NSUIntegerMax;
+    _costLimit = NSUIntegerMax;
+    _ageLimit = DBL_MAX;
+    _autoTrimInterval = 5.0;
+    _shouldRemoveAllObjectsOnMemoryWarning = YES;
+    _shouldRemoveAllObjectsWhenEnteringBackground = YES;
+    
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_appDidReceiveMemoryWarningNotification) name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_appDidEnterBackgroundNotification) name:UIApplicationDidEnterBackgroundNotification object:nil];
+    
+    [self _trimRecursively];
+    return self;
+}
+
+- (void)dealloc {
+    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
+    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
+    [_lru removeAll];
+}
+
+- (NSUInteger)totalCount {
+    OSSpinLockLock(&_lock);
+    NSUInteger count = _lru->_totalCount;
+    OSSpinLockUnlock(&_lock);
+    return count;
+}
+
+- (NSUInteger)totalCost {
+    OSSpinLockLock(&_lock);
+    NSUInteger totalCost = _lru->_totalCost;
+    OSSpinLockUnlock(&_lock);
+    return totalCost;
+}
+
+- (BOOL)releaseInMainThread {
+    OSSpinLockLock(&_lock);
+    BOOL releaseInMainThread = _lru->_releaseOnMainThread;
+    OSSpinLockUnlock(&_lock);
+    return releaseInMainThread;
+}
+
+- (void)setReleaseInMainThread:(BOOL)releaseInMainThread {
+    OSSpinLockLock(&_lock);
+    _lru->_releaseOnMainThread = releaseInMainThread;
+    OSSpinLockUnlock(&_lock);
+}
+
+- (BOOL)containsObjectForKey:(id)key {
+    if (!key) return NO;
+    OSSpinLockLock(&_lock);
+    BOOL contains = CFDictionaryContainsKey(_lru->_dic, (__bridge const void *)(key));
+    OSSpinLockUnlock(&_lock);
+    return contains;
+}
+
+- (id)objectForKey:(id)key {
+    if (!key) return nil;
+    OSSpinLockLock(&_lock);
+    _YYLinkedMapNode *node = CFDictionaryGetValue(_lru->_dic, (__bridge const void *)(key));
+    if (node) {
+        node->_time = CACurrentMediaTime();
+        [_lru bringNodeToHead:node];
+    }
+    OSSpinLockUnlock(&_lock);
+    return node ? node->_value : nil;
+}
+
+- (void)setObject:(id)object forKey:(id)key {
+    [self setObject:object forKey:key withCost:0];
+}
+
+- (void)setObject:(id)object forKey:(id)key withCost:(NSUInteger)cost {
+    if (!key) return;
+    if (!object) {
+        [self removeObjectForKey:key];
+        return;
+    }
+    OSSpinLockLock(&_lock);
+    _YYLinkedMapNode *node = CFDictionaryGetValue(_lru->_dic, (__bridge const void *)(key));
+    NSTimeInterval now = CACurrentMediaTime();
+    if (node) {
+        _lru->_totalCost -= node->_cost;
+        _lru->_totalCost += cost;
+        node->_cost = cost;
+        node->_time = now;
+        node->_value = object;
+        [_lru bringNodeToHead:node];
+    } else {
+        node = [_YYLinkedMapNode new];
+        node->_cost = cost;
+        node->_time = now;
+        node->_key = key;
+        node->_value = object;
+        [_lru insertNodeAtHead:node];
+    }
+    if (_lru->_totalCost > _costLimit) {
+        dispatch_async(_queue, ^{
+            [self trimToCost:_costLimit];
+        });
+    }
+    if (_lru->_totalCount > _countLimit) {
+        _YYLinkedMapNode *node = [_lru removeTailNode];
+        dispatch_queue_t queue = _lru->_releaseOnMainThread ? dispatch_get_main_queue() : YYMemoryCacheGetReleaseQueue();
+        dispatch_async(queue, ^{
+            [node class]; //hold and release in queue
+        });
+    }
+    OSSpinLockUnlock(&_lock);
+}
+
+- (void)removeObjectForKey:(id)key {
+    if (!key) return;
+    OSSpinLockLock(&_lock);
+    _YYLinkedMapNode *node = CFDictionaryGetValue(_lru->_dic, (__bridge const void *)(key));
+    if (node) {
+        [_lru removeNode:node];
+        _YYLinkedMapNode *node = [_lru removeTailNode];
+        dispatch_queue_t queue = _lru->_releaseOnMainThread ? dispatch_get_main_queue() : YYMemoryCacheGetReleaseQueue();
+        dispatch_async(queue, ^{
+            [node class]; //release in queue
+        });
+    }
+    OSSpinLockUnlock(&_lock);
+}
+
+- (void)removeAllObjects {
+    OSSpinLockLock(&_lock);
+    [_lru removeAll];
+    OSSpinLockUnlock(&_lock);
+}
+
+- (void)trimToCount:(NSUInteger)count {
+    if (count == 0) {
+        [self removeAllObjects];
+        return;
+    }
+    [self _trimToCount:count];
+}
+
+- (void)trimToCost:(NSUInteger)cost {
+    [self _trimToCost:cost];
+}
+
+- (void)trimToAge:(NSTimeInterval)age {
+    [self _trimToAge:age];
+}
+
+- (NSString *)description {
+    if (_name) return [NSString stringWithFormat:@"<%@: %p> (%@)", self.class, self, _name];
+    else return [NSString stringWithFormat:@"<%@: %p>", self.class, self];
+}
+
+@end

YYWebImage/Categories/CALayer+YYWebImage.h

@@ -0,0 +1,110 @@
+//
+//  CALayer+YYWebImage.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/23.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+#import <QuartzCore/QuartzCore.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYWebImageManager.h>
+#else
+#import "YYWebImageManager.h"
+#endif
+
+
+/**
+ Web image methods for CALayer.
+ It will set image to layer.contents.
+ */
+@interface CALayer (YYWebImage)
+
+
+#pragma mark - image
+
+/**
+ Current image URL.
+ 
+ @discussion Set a new value to this property will cancel the previous request
+ operation and create a new request operation to fetch image. Set nil to clear
+ the image and image URL.
+ */
+@property (nonatomic, strong) NSURL *yy_imageURL;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL placeholder:(UIImage *)placeholder;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL The image url (remote or local file path).
+ @param options  The options to use when request the image.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL options:(YYWebImageOptions)options;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder he image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param manager     The manager to create image request operation.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                   manager:(YYWebImageManager *)manager
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Cancel the current image request.
+ */
+- (void)yy_cancelCurrentImageRequest;
+
+@end

YYWebImage/Categories/CALayer+YYWebImage.m

@@ -0,0 +1,179 @@
+//
+//  CALayer+YYWebImage.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/23.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "CALayer+YYWebImage.h"
+#import "YYWebImageOperation.h"
+#import "_YYWebImageSetter.h"
+#import <objc/runtime.h>
+
+// Dummy class for category
+@interface CALayer_YYWebImage : NSObject @end
+@implementation CALayer_YYWebImage @end
+
+
+static int _YYWebImageSetterKey;
+
+@implementation CALayer (YYWebImage)
+
+- (NSURL *)yy_imageURL {
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    return setter.imageURL;
+}
+
+- (void)setYy_imageURL:(NSURL *)imageURL {
+    [self yy_setImageWithURL:imageURL
+              placeholder:nil
+                  options:kNilOptions
+                  manager:nil
+                 progress:nil
+                transform:nil
+               completion:nil];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL placeholder:(UIImage *)placeholder {
+    [self yy_setImageWithURL:imageURL
+                 placeholder:placeholder
+                     options:kNilOptions
+                     manager:nil
+                    progress:nil
+                   transform:nil
+                  completion:nil];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL options:(YYWebImageOptions)options {
+    [self yy_setImageWithURL:imageURL
+                 placeholder:nil
+                     options:options
+                     manager:nil
+                    progress:nil
+                   transform:nil
+                  completion:nil];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setImageWithURL:imageURL
+                 placeholder:placeholder
+                     options:options
+                     manager:nil
+                    progress:nil
+                   transform:nil
+                  completion:completion];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setImageWithURL:imageURL
+                 placeholder:placeholder
+                     options:options
+                     manager:nil
+                    progress:progress
+                   transform:transform
+                  completion:completion];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                   manager:(YYWebImageManager *)manager
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion {
+    if ([imageURL isKindOfClass:[NSString class]]) imageURL = [NSURL URLWithString:(id)imageURL];
+    manager = manager ? manager : [YYWebImageManager sharedManager];
+    
+    
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    if (!setter) {
+        setter = [_YYWebImageSetter new];
+        objc_setAssociatedObject(self, &_YYWebImageSetterKey, setter, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+    }
+    int32_t sentinel = [setter cancelWithNewURL:imageURL];
+    
+    _yy_dispatch_sync_on_main_queue(^{
+        if ((options & YYWebImageOptionSetImageWithFadeAnimation) &&
+            !(options & YYWebImageOptionAvoidSetImage)) {
+            [self removeAnimationForKey:_YYWebImageFadeAnimationKey];
+        }
+        
+        if (!imageURL) {
+            if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+                self.contents = (id)placeholder.CGImage;
+            }
+            return;
+        }
+        
+        // get the image from memory as quickly as possible
+        UIImage *imageFromMemory = nil;
+        if (manager.cache &&
+            !(options & YYWebImageOptionUseNSURLCache) &&
+            !(options & YYWebImageOptionRefreshImageCache)) {
+            imageFromMemory = [manager.cache getImageForKey:[manager cacheKeyForURL:imageURL] withType:YYImageCacheTypeMemory];
+        }
+        if (imageFromMemory) {
+            if (!(options & YYWebImageOptionAvoidSetImage)) {
+                self.contents = (id)imageFromMemory.CGImage;
+            }
+            if(completion) completion(imageFromMemory, imageURL, YYWebImageFromMemoryCacheFast, YYWebImageStageFinished, nil);
+            return;
+        }
+        
+        if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+            self.contents = (id)placeholder.CGImage;
+        }
+        
+        __weak typeof(self) _self = self;
+        dispatch_async([_YYWebImageSetter setterQueue], ^{
+            YYWebImageProgressBlock _progress = nil;
+            if (progress) _progress = ^(NSInteger receivedSize, NSInteger expectedSize) {
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    progress(receivedSize, expectedSize);
+                });
+            };
+            
+            YYWebImageCompletionBlock _completion = ^(UIImage *image, NSURL *url, YYWebImageFromType from, YYWebImageStage stage, NSError *error) {
+                __strong typeof(_self) self = _self;
+                BOOL setImage = (stage == YYWebImageStageFinished || stage == YYWebImageStageProgress) && image && !(options & YYWebImageOptionAvoidSetImage);
+                BOOL showFade = (options & YYWebImageOptionSetImageWithFadeAnimation);
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    if (setImage && self) {
+                        if (showFade) {
+                            CATransition *transition = [CATransition animation];
+                            transition.duration = stage == YYWebImageStageFinished ? _YYWebImageFadeTime : _YYWebImageProgressiveFadeTime;
+                            transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
+                            transition.type = kCATransitionFade;
+                            [self addAnimation:transition forKey:_YYWebImageFadeAnimationKey];
+                        }
+                        self.contents = (id)image.CGImage;
+                    }
+                    if (completion) completion(image, url, from, stage, error);
+                });
+            };
+            
+            [setter setOperationWithSentinel:sentinel url:imageURL options:options manager:manager progress:_progress transform:transform completion:_completion];
+        });
+        
+        
+    });
+}
+
+- (void)yy_cancelCurrentImageRequest {
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    if (setter) [setter cancel];
+}
+
+@end

YYWebImage/Categories/MKAnnotationView+YYWebImage.h

@@ -0,0 +1,106 @@
+//
+//  MKAnnotationView+YYWebImage.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/23.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+#import <MapKit/MapKit.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYWebImageManager.h>
+#else
+#import "YYWebImageManager.h"
+#endif
+
+
+/**
+ Web image methods for MKAnnotationView.
+ */
+@interface MKAnnotationView (YYWebImage)
+
+/**
+ Current image URL.
+ 
+ @discussion Set a new value to this property will cancel the previous request
+ operation and create a new request operation to fetch image. Set nil to clear
+ the image and image URL.
+ */
+@property (nonatomic, strong) NSURL *imageURL;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ */
+- (void)setImageWithURL:(NSURL *)imageURL placeholder:(UIImage *)placeholder;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL The image url (remote or local file path).
+ @param options  The options to use when request the image.
+ */
+- (void)setImageWithURL:(NSURL *)imageURL options:(YYWebImageOptions)options;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)setImageWithURL:(NSURL *)imageURL
+            placeholder:(UIImage *)placeholder
+                options:(YYWebImageOptions)options
+             completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)setImageWithURL:(NSURL *)imageURL
+            placeholder:(UIImage *)placeholder
+                options:(YYWebImageOptions)options
+               progress:(YYWebImageProgressBlock)progress
+              transform:(YYWebImageTransformBlock)transform
+             completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder he image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param manager     The manager to create image request operation.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)setImageWithURL:(NSURL *)imageURL
+            placeholder:(UIImage *)placeholder
+                options:(YYWebImageOptions)options
+                manager:(YYWebImageManager *)manager
+               progress:(YYWebImageProgressBlock)progress
+              transform:(YYWebImageTransformBlock)transform
+             completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Cancel the current image request.
+ */
+- (void)cancelCurrentImageRequest;
+
+@end

YYWebImage/Categories/MKAnnotationView+YYWebImage.m

@@ -0,0 +1,177 @@
+//
+//  MKAnnotationView+YYWebImage.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/23.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "MKAnnotationView+YYWebImage.h"
+#import "YYWebImageOperation.h"
+#import "_YYWebImageSetter.h"
+#import <objc/runtime.h>
+
+// Dummy class for category
+@interface MKAnnotationView_YYWebImage : NSObject @end
+@implementation MKAnnotationView_YYWebImage @end
+
+
+static int _YYWebImageSetterKey;
+
+@implementation MKAnnotationView (YYWebImage)
+
+- (NSURL *)imageURL {
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    return setter.imageURL;
+}
+
+- (void)setImageURL:(NSURL *)imageURL {
+    [self setImageWithURL:imageURL
+              placeholder:nil
+                  options:kNilOptions
+                  manager:nil
+                 progress:nil
+                transform:nil
+               completion:nil];
+}
+
+- (void)setImageWithURL:(NSURL *)imageURL placeholder:(UIImage *)placeholder {
+    [self setImageWithURL:imageURL
+              placeholder:placeholder
+                  options:kNilOptions
+                  manager:nil
+                 progress:nil
+                transform:nil
+               completion:nil];
+}
+
+- (void)setImageWithURL:(NSURL *)imageURL options:(YYWebImageOptions)options {
+    [self setImageWithURL:imageURL
+              placeholder:nil
+                  options:options
+                  manager:nil
+                 progress:nil
+                transform:nil
+               completion:nil];
+}
+
+- (void)setImageWithURL:(NSURL *)imageURL
+            placeholder:(UIImage *)placeholder
+                options:(YYWebImageOptions)options
+             completion:(YYWebImageCompletionBlock)completion {
+    [self setImageWithURL:imageURL
+              placeholder:placeholder
+                  options:options
+                  manager:nil
+                 progress:nil
+                transform:nil
+               completion:completion];
+}
+
+- (void)setImageWithURL:(NSURL *)imageURL
+            placeholder:(UIImage *)placeholder
+                options:(YYWebImageOptions)options
+               progress:(YYWebImageProgressBlock)progress
+              transform:(YYWebImageTransformBlock)transform
+             completion:(YYWebImageCompletionBlock)completion {
+    [self setImageWithURL:imageURL
+              placeholder:placeholder
+                  options:options
+                  manager:nil
+                 progress:progress
+                transform:transform
+               completion:completion];
+}
+
+- (void)setImageWithURL:(NSURL *)imageURL
+            placeholder:(UIImage *)placeholder
+                options:(YYWebImageOptions)options
+                manager:(YYWebImageManager *)manager
+               progress:(YYWebImageProgressBlock)progress
+              transform:(YYWebImageTransformBlock)transform
+             completion:(YYWebImageCompletionBlock)completion {
+    if ([imageURL isKindOfClass:[NSString class]]) imageURL = [NSURL URLWithString:(id)imageURL];
+    manager = manager ? manager : [YYWebImageManager sharedManager];
+    
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    if (!setter) {
+        setter = [_YYWebImageSetter new];
+        objc_setAssociatedObject(self, &_YYWebImageSetterKey, setter, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+    }
+    int32_t sentinel = [setter cancelWithNewURL:imageURL];
+    
+    _yy_dispatch_sync_on_main_queue(^{
+        if ((options & YYWebImageOptionSetImageWithFadeAnimation) &&
+            !(options & YYWebImageOptionAvoidSetImage)) {
+            if (!self.highlighted) {
+                [self.layer removeAnimationForKey:_YYWebImageFadeAnimationKey];
+            }
+        }
+        if (!imageURL) {
+            if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+                self.image = placeholder;
+            }
+            return;
+        }
+        
+        // get the image from memory as quickly as possible
+        UIImage *imageFromMemory = nil;
+        if (manager.cache &&
+            !(options & YYWebImageOptionUseNSURLCache) &&
+            !(options & YYWebImageOptionRefreshImageCache)) {
+            imageFromMemory = [manager.cache getImageForKey:[manager cacheKeyForURL:imageURL] withType:YYImageCacheTypeMemory];
+        }
+        if (imageFromMemory) {
+            if (!(options & YYWebImageOptionAvoidSetImage)) {
+                self.image = imageFromMemory;
+            }
+            if(completion) completion(imageFromMemory, imageURL, YYWebImageFromMemoryCacheFast, YYWebImageStageFinished, nil);
+            return;
+        }
+        
+        if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+            self.image = placeholder;
+        }
+        
+        __weak typeof(self) _self = self;
+        dispatch_async([_YYWebImageSetter setterQueue], ^{
+            YYWebImageProgressBlock _progress = nil;
+            if (progress) _progress = ^(NSInteger receivedSize, NSInteger expectedSize) {
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    progress(receivedSize, expectedSize);
+                });
+            };
+            
+            YYWebImageCompletionBlock _completion = ^(UIImage *image, NSURL *url, YYWebImageFromType from, YYWebImageStage stage, NSError *error) {
+                __strong typeof(_self) self = _self;
+                BOOL setImage = (stage == YYWebImageStageFinished || stage == YYWebImageStageProgress) && image && !(options & YYWebImageOptionAvoidSetImage);
+                BOOL showFade = ((options & YYWebImageOptionSetImageWithFadeAnimation) && !self.highlighted);
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    if (setImage && self) {
+                        if (showFade) {
+                            CATransition *transition = [CATransition animation];
+                            transition.duration = stage == YYWebImageStageFinished ? _YYWebImageFadeTime : _YYWebImageProgressiveFadeTime;
+                            transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
+                            transition.type = kCATransitionFade;
+                            [self.layer addAnimation:transition forKey:_YYWebImageFadeAnimationKey];
+                        }
+                        self.image = image;
+                    }
+                    if (completion) completion(image, url, from, stage, error);
+                });
+            };
+            
+            [setter setOperationWithSentinel:sentinel url:imageURL options:options manager:manager progress:_progress transform:transform completion:_completion];
+        });
+    });
+}
+
+- (void)cancelCurrentImageRequest {
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    if (setter) [setter cancel];
+}
+
+@end

YYWebImage/Categories/UIButton+YYWebImage.h

@@ -0,0 +1,210 @@
+//
+//  UIButton+YYWebImage.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/23.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYWebImageManager.h>
+#else
+#import "YYWebImageManager.h"
+#endif
+
+
+/**
+ Web image methods for UIButton.
+ */
+@interface UIButton (YYWebImage)
+
+#pragma mark - image
+
+/**
+ Current image URL for the specified state.
+ @return The image URL, or nil.
+ */
+- (NSURL *)yy_imageURLForState:(UIControlState)state;
+
+/**
+ Set the button's image with a specified URL for the specified state.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param state       The state that uses the specified image.
+ @param placeholder The image to be set initially, until the image request finishes.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+               placeholder:(UIImage *)placeholder;
+
+/**
+ Set the button's image with a specified URL for the specified state.
+ 
+ @param imageURL The image url (remote or local file path).
+ @param state    The state that uses the specified image.
+ @param options  The options to use when request the image.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+                   options:(YYWebImageOptions)options;
+
+/**
+ Set the button's image with a specified URL for the specified state.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param state       The state that uses the specified image.
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the button's image with a specified URL for the specified state.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param state       The state that uses the specified image.
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the button's image with a specified URL for the specified state.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param state       The state that uses the specified image.
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param manager     The manager to create image request operation.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                   manager:(YYWebImageManager *)manager
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Cancel the current image request for a specified state.
+ @param state The state that uses the specified image.
+ */
+- (void)yy_cancelImageRequestForState:(UIControlState)state;
+
+
+
+#pragma mark - background image
+
+/**
+ Current backgroundImage URL for the specified state.
+ @return The image URL, or nil.
+ */
+- (NSURL *)yy_backgroundImageURLForState:(UIControlState)state;
+
+/**
+ Set the button's backgroundImage with a specified URL for the specified state.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param state       The state that uses the specified image.
+ @param placeholder The image to be set initially, until the image request finishes.
+ */
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                         placeholder:(UIImage *)placeholder;
+
+/**
+ Set the button's backgroundImage with a specified URL for the specified state.
+ 
+ @param imageURL The image url (remote or local file path).
+ @param state    The state that uses the specified image.
+ @param options  The options to use when request the image.
+ */
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                             options:(YYWebImageOptions)options;
+
+/**
+ Set the button's backgroundImage with a specified URL for the specified state.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param state       The state that uses the specified image.
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                         placeholder:(UIImage *)placeholder
+                             options:(YYWebImageOptions)options
+                          completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the button's backgroundImage with a specified URL for the specified state.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param state       The state that uses the specified image.
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                         placeholder:(UIImage *)placeholder
+                             options:(YYWebImageOptions)options
+                            progress:(YYWebImageProgressBlock)progress
+                           transform:(YYWebImageTransformBlock)transform
+                          completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the button's backgroundImage with a specified URL for the specified state.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param state       The state that uses the specified image.
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param manager     The manager to create image request operation.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                         placeholder:(UIImage *)placeholder
+                             options:(YYWebImageOptions)options
+                             manager:(YYWebImageManager *)manager
+                            progress:(YYWebImageProgressBlock)progress
+                           transform:(YYWebImageTransformBlock)transform
+                          completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Cancel the current backgroundImage request for a specified state.
+ @param state The state that uses the specified image.
+ */
+- (void)yy_cancelBackgroundImageRequestForState:(UIControlState)state;
+
+@end

YYWebImage/Categories/UIButton+YYWebImage.m

@@ -0,0 +1,420 @@
+//
+//  UIButton+YYWebImage.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/23.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "UIButton+YYWebImage.h"
+#import "YYWebImageOperation.h"
+#import "_YYWebImageSetter.h"
+#import <libkern/OSAtomic.h>
+#import <objc/runtime.h>
+
+// Dummy class for category
+@interface UIButton_YYWebImage : NSObject @end
+@implementation UIButton_YYWebImage @end
+
+static inline NSNumber *UIControlStateSingle(UIControlState state) {
+    if (state & UIControlStateHighlighted) return @(UIControlStateHighlighted);
+    if (state & UIControlStateDisabled) return @(UIControlStateDisabled);
+    if (state & UIControlStateSelected) return @(UIControlStateSelected);
+    return @(UIControlStateNormal);
+}
+
+static inline NSArray *UIControlStateMulti(UIControlState state) {
+    NSMutableArray *array = [NSMutableArray new];
+    if (state & UIControlStateHighlighted) [array addObject:@(UIControlStateHighlighted)];
+    if (state & UIControlStateDisabled) [array addObject:@(UIControlStateDisabled)];
+    if (state & UIControlStateSelected) [array addObject:@(UIControlStateSelected)];
+    if ((state & 0xFF) == 0) [array addObject:@(UIControlStateNormal)];
+    return array;
+}
+
+static int _YYWebImageSetterKey;
+static int _YYWebImageBackgroundSetterKey;
+
+
+@interface _YYWebImageSetterDicForButton : NSObject
+- (_YYWebImageSetter *)setterForState:(NSNumber *)state;
+- (_YYWebImageSetter *)lazySetterForState:(NSNumber *)state;
+@end
+
+@implementation _YYWebImageSetterDicForButton {
+    NSMutableDictionary *_dic;
+    OSSpinLock _lock;
+}
+- (instancetype)init {
+    self = [super init];
+    _lock = OS_SPINLOCK_INIT;
+    _dic = [NSMutableDictionary new];
+    return self;
+}
+- (_YYWebImageSetter *)setterForState:(NSNumber *)state {
+    OSSpinLockLock(&_lock);
+    _YYWebImageSetter *setter = _dic[state];
+    OSSpinLockUnlock(&_lock);
+    return setter;
+    
+}
+- (_YYWebImageSetter *)lazySetterForState:(NSNumber *)state {
+    OSSpinLockLock(&_lock);
+    _YYWebImageSetter *setter = _dic[state];
+    if (!setter) {
+        setter = [_YYWebImageSetter new];
+        _dic[state] = setter;
+    }
+    OSSpinLockUnlock(&_lock);
+    return setter;
+}
+@end
+
+
+@implementation UIButton (YYWebImage)
+
+#pragma mark - image
+
+- (void)_yy_setImageWithURL:(NSURL *)imageURL
+             forSingleState:(NSNumber *)state
+                placeholder:(UIImage *)placeholder
+                    options:(YYWebImageOptions)options
+                    manager:(YYWebImageManager *)manager
+                   progress:(YYWebImageProgressBlock)progress
+                  transform:(YYWebImageTransformBlock)transform
+                 completion:(YYWebImageCompletionBlock)completion {
+    if ([imageURL isKindOfClass:[NSString class]]) imageURL = [NSURL URLWithString:(id)imageURL];
+    manager = manager ? manager : [YYWebImageManager sharedManager];
+    
+    _YYWebImageSetterDicForButton *dic = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    if (!dic) {
+        dic = [_YYWebImageSetterDicForButton new];
+        objc_setAssociatedObject(self, &_YYWebImageSetterKey, dic, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+    }
+    _YYWebImageSetter *setter = [dic lazySetterForState:state];
+    int32_t sentinel = [setter cancelWithNewURL:imageURL];
+    
+    _yy_dispatch_sync_on_main_queue(^{
+        if (!imageURL) {
+            if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+                [self setImage:placeholder forState:state.integerValue];
+            }
+            return;
+        }
+        
+        // get the image from memory as quickly as possible
+        UIImage *imageFromMemory = nil;
+        if (manager.cache &&
+            !(options & YYWebImageOptionUseNSURLCache) &&
+            !(options & YYWebImageOptionRefreshImageCache)) {
+            imageFromMemory = [manager.cache getImageForKey:[manager cacheKeyForURL:imageURL] withType:YYImageCacheTypeMemory];
+        }
+        if (imageFromMemory) {
+            if (!(options & YYWebImageOptionAvoidSetImage)) {
+                [self setImage:imageFromMemory forState:state.integerValue];
+            }
+            if(completion) completion(imageFromMemory, imageURL, YYWebImageFromMemoryCacheFast, YYWebImageStageFinished, nil);
+            return;
+        }
+        
+        
+        if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+            [self setImage:placeholder forState:state.integerValue];
+        }
+        
+        __weak typeof(self) _self = self;
+        dispatch_async([_YYWebImageSetter setterQueue], ^{
+            YYWebImageProgressBlock _progress = nil;
+            if (progress) _progress = ^(NSInteger receivedSize, NSInteger expectedSize) {
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    progress(receivedSize, expectedSize);
+                });
+            };
+            
+            YYWebImageCompletionBlock _completion = ^(UIImage *image, NSURL *url, YYWebImageFromType from, YYWebImageStage stage, NSError *error) {
+                __strong typeof(_self) self = _self;
+                BOOL setImage = (stage == YYWebImageStageFinished || stage == YYWebImageStageProgress) && image && !(options & YYWebImageOptionAvoidSetImage);
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    if (setImage && self) {
+                        [self setImage:image forState:state.integerValue];
+                    }
+                    if (completion) completion(image, url, from, stage, error);
+                });
+            };
+            
+            [setter setOperationWithSentinel:sentinel url:imageURL options:options manager:manager progress:_progress transform:transform completion:_completion];
+        });
+    });
+}
+
+- (void)_yy_cancelImageRequestForSingleState:(NSNumber *)state {
+    _YYWebImageSetterDicForButton *dic = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    _YYWebImageSetter *setter = [dic setterForState:state];
+    if (setter) [setter cancel];
+}
+
+- (NSURL *)yy_imageURLForState:(UIControlState)state {
+    _YYWebImageSetterDicForButton *dic = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    _YYWebImageSetter *setter = [dic setterForState:UIControlStateSingle(state)];
+    return setter.imageURL;
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+               placeholder:(UIImage *)placeholder {
+    [self yy_setImageWithURL:imageURL
+                 forState:state
+              placeholder:placeholder
+                  options:kNilOptions
+                  manager:nil
+                 progress:nil
+                transform:nil
+               completion:nil];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+                   options:(YYWebImageOptions)options {
+    [self yy_setImageWithURL:imageURL
+                    forState:state
+                 placeholder:nil
+                     options:options
+                     manager:nil
+                    progress:nil
+                   transform:nil
+                  completion:nil];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setImageWithURL:imageURL
+                    forState:state
+                 placeholder:placeholder
+                     options:options
+                     manager:nil
+                    progress:nil
+                   transform:nil
+                  completion:completion];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setImageWithURL:imageURL
+                    forState:state
+                 placeholder:placeholder
+                     options:options
+                     manager:nil
+                    progress:progress
+                   transform:transform
+                  completion:completion];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+                  forState:(UIControlState)state
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                   manager:(YYWebImageManager *)manager
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion {
+    for (NSNumber *num in UIControlStateMulti(state)) {
+        [self _yy_setImageWithURL:imageURL
+                   forSingleState:num
+                      placeholder:placeholder
+                          options:options
+                          manager:manager
+                         progress:progress
+                        transform:transform
+                       completion:completion];
+    }
+}
+
+- (void)yy_cancelImageRequestForState:(UIControlState)state {
+    for (NSNumber *num in UIControlStateMulti(state)) {
+        [self _yy_cancelImageRequestForSingleState:num];
+    }
+}
+
+
+#pragma mark - background image
+
+- (void)_yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                       forSingleState:(NSNumber *)state
+                          placeholder:(UIImage *)placeholder
+                              options:(YYWebImageOptions)options
+                              manager:(YYWebImageManager *)manager
+                             progress:(YYWebImageProgressBlock)progress
+                            transform:(YYWebImageTransformBlock)transform
+                           completion:(YYWebImageCompletionBlock)completion {
+    if ([imageURL isKindOfClass:[NSString class]]) imageURL = [NSURL URLWithString:(id)imageURL];
+    manager = manager ? manager : [YYWebImageManager sharedManager];
+    
+    _YYWebImageSetterDicForButton *dic = objc_getAssociatedObject(self, &_YYWebImageBackgroundSetterKey);
+    if (!dic) {
+        dic = [_YYWebImageSetterDicForButton new];
+        objc_setAssociatedObject(self, &_YYWebImageBackgroundSetterKey, dic, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+    }
+    _YYWebImageSetter *setter = [dic lazySetterForState:state];
+    int32_t sentinel = [setter cancelWithNewURL:imageURL];
+    
+    _yy_dispatch_sync_on_main_queue(^{
+        if (!imageURL) {
+            if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+                [self setBackgroundImage:placeholder forState:state.integerValue];
+            }
+            return;
+        }
+        
+        // get the image from memory as quickly as possible
+        UIImage *imageFromMemory = nil;
+        if (manager.cache &&
+            !(options & YYWebImageOptionUseNSURLCache) &&
+            !(options & YYWebImageOptionRefreshImageCache)) {
+            imageFromMemory = [manager.cache getImageForKey:[manager cacheKeyForURL:imageURL] withType:YYImageCacheTypeMemory];
+        }
+        if (imageFromMemory) {
+            if (!(options & YYWebImageOptionAvoidSetImage)) {
+                [self setBackgroundImage:imageFromMemory forState:state.integerValue];
+            }
+            if(completion) completion(imageFromMemory, imageURL, YYWebImageFromMemoryCacheFast, YYWebImageStageFinished, nil);
+            return;
+        }
+        
+        
+        if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+            [self setBackgroundImage:placeholder forState:state.integerValue];
+        }
+        
+        __weak typeof(self) _self = self;
+        dispatch_async([_YYWebImageSetter setterQueue], ^{
+            YYWebImageProgressBlock _progress = nil;
+            if (progress) _progress = ^(NSInteger receivedSize, NSInteger expectedSize) {
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    progress(receivedSize, expectedSize);
+                });
+            };
+            
+            YYWebImageCompletionBlock _completion = ^(UIImage *image, NSURL *url, YYWebImageFromType from, YYWebImageStage stage, NSError *error) {
+                __strong typeof(_self) self = _self;
+                BOOL setImage = (stage == YYWebImageStageFinished || stage == YYWebImageStageProgress) && image && !(options & YYWebImageOptionAvoidSetImage);
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    if (setImage && self) {
+                        [self setBackgroundImage:image forState:state.integerValue];
+                    }
+                    if (completion) completion(image, url, from, stage, error);
+                });
+            };
+            
+            [setter setOperationWithSentinel:sentinel url:imageURL options:options manager:manager progress:_progress transform:transform completion:_completion];
+        });
+    });
+}
+
+- (void)_yy_cancelBackgroundImageRequestForSingleState:(NSNumber *)state {
+    _YYWebImageSetterDicForButton *dic = objc_getAssociatedObject(self, &_YYWebImageBackgroundSetterKey);
+    _YYWebImageSetter *setter = [dic setterForState:state];
+    if (setter) [setter cancel];
+}
+
+- (NSURL *)yy_backgroundImageURLForState:(UIControlState)state {
+    _YYWebImageSetterDicForButton *dic = objc_getAssociatedObject(self, &_YYWebImageBackgroundSetterKey);
+    _YYWebImageSetter *setter = [dic setterForState:UIControlStateSingle(state)];
+    return setter.imageURL;
+}
+
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                         placeholder:(UIImage *)placeholder {
+    [self yy_setBackgroundImageWithURL:imageURL
+                              forState:state
+                           placeholder:placeholder
+                               options:kNilOptions
+                               manager:nil
+                              progress:nil
+                             transform:nil
+                            completion:nil];
+}
+
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                             options:(YYWebImageOptions)options {
+    [self yy_setBackgroundImageWithURL:imageURL
+                              forState:state
+                           placeholder:nil
+                               options:options
+                               manager:nil
+                              progress:nil
+                             transform:nil
+                            completion:nil];
+}
+
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                         placeholder:(UIImage *)placeholder
+                             options:(YYWebImageOptions)options
+                          completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setBackgroundImageWithURL:imageURL
+                              forState:state
+                           placeholder:placeholder
+                               options:options
+                               manager:nil
+                              progress:nil
+                             transform:nil
+                            completion:completion];
+}
+
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                         placeholder:(UIImage *)placeholder
+                             options:(YYWebImageOptions)options
+                            progress:(YYWebImageProgressBlock)progress
+                           transform:(YYWebImageTransformBlock)transform
+                          completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setBackgroundImageWithURL:imageURL
+                              forState:state
+                           placeholder:placeholder
+                               options:options
+                               manager:nil
+                              progress:progress
+                             transform:transform
+                            completion:completion];
+}
+
+- (void)yy_setBackgroundImageWithURL:(NSURL *)imageURL
+                            forState:(UIControlState)state
+                         placeholder:(UIImage *)placeholder
+                             options:(YYWebImageOptions)options
+                             manager:(YYWebImageManager *)manager
+                            progress:(YYWebImageProgressBlock)progress
+                           transform:(YYWebImageTransformBlock)transform
+                          completion:(YYWebImageCompletionBlock)completion {
+    for (NSNumber *num in UIControlStateMulti(state)) {
+        [self _yy_setBackgroundImageWithURL:imageURL
+                             forSingleState:num
+                                placeholder:placeholder
+                                    options:options
+                                    manager:manager
+                                   progress:progress
+                                  transform:transform
+                                 completion:completion];
+    }
+}
+
+- (void)yy_cancelBackgroundImageRequestForState:(UIControlState)state {
+    for (NSNumber *num in UIControlStateMulti(state)) {
+        [self _yy_cancelBackgroundImageRequestForSingleState:num];
+    }
+}
+
+@end

YYWebImage/Categories/UIImage+YYWebImage.h

@@ -0,0 +1,289 @@
+//
+//  UIImage+YYAdd.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 13/4/4.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+/**
+ Provide some commen method for `UIImage`.
+ Image process is based on CoreGraphic and vImage.
+ */
+@interface UIImage (YYWebImage)
+
+#pragma mark - Create image
+///=============================================================================
+/// @name Create image
+///=============================================================================
+
+/**
+ Create an animated image with GIF data. After created, you can access
+ the images via property '.images'. If the data is not animated gif, this
+ function is same as [UIImage imageWithData:data scale:scale];
+ 
+ @discussion     It has a better display performance, but costs more memory
+                 (width * height * frames Bytes). It only suited to display small 
+                 gif such as animated emoticon. If you want to display large gif,
+                 see `YYImage`.
+ 
+ @param data     GIF data.
+ 
+ @param scale    The scale factor
+ 
+ @return A new image created from GIF, or nil when an error occurs.
+ */
++ (UIImage *)yy_imageWithSmallGIFData:(NSData *)data scale:(CGFloat)scale;
+
+/**
+ Create and return a 1x1 point size image with the given color.
+ 
+ @param color  The color.
+ */
++ (UIImage *)yy_imageWithColor:(UIColor *)color;
+
+/**
+ Create and return a pure color image with the given color and size.
+ 
+ @param color  The color.
+ @param size   New image's type.
+ */
++ (UIImage *)yy_imageWithColor:(UIColor *)color size:(CGSize)size;
+
+/**
+ Create and return an image with custom draw code.
+ 
+ @param size      The image size.
+ @param drawBlock The draw block.
+ 
+ @return The new image.
+ */
++ (UIImage *)yy_imageWithSize:(CGSize)size drawBlock:(void (^)(CGContextRef context))drawBlock;
+
+#pragma mark - Image Info
+///=============================================================================
+/// @name Image Info
+///=============================================================================
+
+/**
+ Whether this image has alpha channel.
+ */
+- (BOOL)yy_hasAlphaChannel;
+
+
+#pragma mark - Modify Image
+///=============================================================================
+/// @name Modify Image
+///=============================================================================
+
+/**
+ Draws the entire image in the specified rectangle, content changed with
+ the contentMode.
+ 
+ @discussion This method draws the entire image in the current graphics context, 
+ respecting the image's orientation setting. In the default coordinate system, 
+ images are situated down and to the right of the origin of the specified 
+ rectangle. This method respects any transforms applied to the current graphics 
+ context, however.
+ 
+ @param rect        The rectangle in which to draw the image.
+ 
+ @param contentMode Draw content mode
+ 
+ @param clips       A Boolean value that determines whether content are confined to the rect.
+ */
+- (void)yy_drawInRect:(CGRect)rect withContentMode:(UIViewContentMode)contentMode clipsToBounds:(BOOL)clips;
+
+/**
+ Returns a new image which is scaled from this image.
+ The image will be stretched as needed.
+ 
+ @param size  The new size to be scaled, values should be positive.
+ 
+ @return      The new image with the given size.
+ */
+- (UIImage *)yy_imageByResizeToSize:(CGSize)size;
+
+/**
+ Returns a new image which is scaled from this image.
+ The image content will be changed with thencontentMode.
+ 
+ @param size        The new size to be scaled, values should be positive.
+ 
+ @param contentMode The content mode for image content.
+ 
+ @return The new image with the given size.
+ */
+- (UIImage *)yy_imageByResizeToSize:(CGSize)size contentMode:(UIViewContentMode)contentMode;
+
+/**
+ Returns a new image which is cropped from this image.
+ 
+ @param rect  Image's inner rect.
+ 
+ @return      The new image, or nil if an error occurs.
+ */
+- (UIImage *)yy_imageByCropToRect:(CGRect)rect;
+
+/**
+ Returns a new image which is edge inset from this image.
+ 
+ @param insets  Inset (positive) for each of the edges, values can be negative to 'outset'.
+ 
+ @param color   Extend edge's fill color, nil means clear color.
+ 
+ @return        The new image, or nil if an error occurs.
+ */
+- (UIImage *)yy_imageByInsetEdge:(UIEdgeInsets)insets withColor:(UIColor *)color;
+
+/**
+ Rounds a new image with a given corner size.
+ 
+ @param radius  The radius of each corner oval. Values larger than half the
+                rectangle's width or height are clamped appropriately to half
+                the width or height.
+ */
+- (UIImage *)yy_imageByRoundCornerRadius:(CGFloat)radius;
+
+/**
+ Rounds a new image with a given corner size.
+ 
+ @param radius       The radius of each corner oval. Values larger than half the
+                     rectangle's width or height are clamped appropriately to
+                     half the width or height.
+ 
+ @param corners      A bitmask value that identifies the corners that you want
+                     rounded. You can use this parameter to round only a subset
+                     of the corners of the rectangle.
+ 
+ @param borderWidth  The inset border with clear color. Values larger than half
+                     the rectangle's width or height are clamped appropriately
+                     to half the width or height.
+ */
+- (UIImage *)yy_imageByRoundCornerRadius:(CGFloat)radius
+                                 corners:(UIRectCorner)corners
+                             borderWidth:(CGFloat)borderWidth;
+
+/**
+ Returns a new rotated image (relative to the center).
+ 
+ @param radians   Rotated radians in counterclockwise.⟲
+ 
+ @param fitSize   YES: new image's size is extend to fit all content.
+                  NO: image's size will not change, content may be clipped.
+ */
+- (UIImage *)yy_imageByRotate:(CGFloat)radians fitSize:(BOOL)fitSize;
+
+/**
+ Returns a new image rotated counterclockwise by a quarter‑turn (90°). ⤺
+ The width and height will be exchanged.
+ */
+- (UIImage *)yy_imageByRotateLeft90;
+
+/**
+ Returns a new image rotated clockwise by a quarter‑turn (90°). ⤼
+ The width and height will be exchanged.
+ */
+- (UIImage *)yy_imageByRotateRight90;
+
+/**
+ Returns a new image rotated 180° . ↻
+ */
+- (UIImage *)yy_imageByRotate180;
+
+/**
+ Returns a vertically flipped image. ⥯
+ */
+- (UIImage *)yy_imageByFlipVertical;
+
+/**
+ Returns a horizontally flipped image. ⇋
+ */
+- (UIImage *)yy_imageByFlipHorizontal;
+
+
+#pragma mark - Image Effect
+///=============================================================================
+/// @name Image Effect
+///=============================================================================
+
+/**
+ Tint the image in alpha channel with the given color.
+ 
+ @param color  The color.
+ */
+- (UIImage *)yy_imageByTintColor:(UIColor *)color;
+
+/**
+ Returns a grayscaled image.
+ */
+- (UIImage *)yy_imageByGrayscale;
+
+/**
+ Applies a blur effect to this image. Suitable for blur any content.
+ */
+- (UIImage *)yy_imageByBlurSoft;
+
+/**
+ Applies a blur effect to this image. Suitable for blur any content except pure white.
+ (same as iOS Control Panel)
+ */
+- (UIImage *)yy_imageByBlurLight;
+
+/**
+ Applies a blur effect to this image. Suitable for displaying black text.
+ (same as iOS Navigation Bar White)
+ */
+- (UIImage *)yy_imageByBlurExtraLight;
+
+/**
+ Applies a blur effect to this image. Suitable for displaying white text.
+ (same as iOS Notification Center)
+ */
+- (UIImage *)yy_imageByBlurDark;
+
+/**
+ Applies a blur and tint color to this image.
+ 
+ @param tintColor  The tint color.
+ */
+- (UIImage *)yy_imageByBlurWithTint:(UIColor *)tintColor;
+
+/**
+ Applies a blur, tint color, and saturation adjustment to this image,
+ optionally within the area specified by @a maskImage.
+ 
+ @param blurRadius     The radius of the blur in points, 0 means no blur effect.
+ 
+ @param tintColor      An optional UIColor object that is uniformly blended with
+                       the result of the blur and saturation operations. The
+                       alpha channel of this color determines how strong the
+                       tint is. nil means no tint.
+ 
+ @param tintBlendMode  The @a tintColor blend mode. Default is kCGBlendModeNormal (0).
+ 
+ @param saturation     A value of 1.0 produces no change in the resulting image.
+                       Values less than 1.0 will desaturation the resulting image
+                       while values greater than 1.0 will have the opposite effect.
+                       0 means gray scale.
+ 
+ @param maskImage      If specified, @a inputImage is only modified in the area(s)
+                       defined by this mask.  This must be an image mask or it
+                       must meet the requirements of the mask parameter of
+                       CGContextClipToMask.
+ 
+ @return               image with effect, or nil if an error occurs (e.g. no
+                       enough memory).
+ */
+- (UIImage *)yy_imageByBlurRadius:(CGFloat)blurRadius
+                        tintColor:(UIColor *)tintColor
+                         tintMode:(CGBlendMode)tintBlendMode
+                       saturation:(CGFloat)saturation
+                        maskImage:(UIImage *)maskImage;
+
+@end

YYWebImage/Categories/UIImage+YYWebImage.m

@@ -0,0 +1,699 @@
+//
+//  UIImage+YYAdd.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 13/4/4.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "UIImage+YYWebImage.h"
+#import <ImageIO/ImageIO.h>
+#import <Accelerate/Accelerate.h>
+#import <objc/runtime.h>
+
+// Dummy class for category
+@interface UIImage_YYWebImage : NSObject @end
+@implementation UIImage_YYWebImage @end
+
+
+
+/// Convert degrees to radians.
+static inline CGFloat _DegreesToRadians(CGFloat degrees) {
+    return degrees * M_PI / 180;
+}
+
+
+/**
+ Resize rect to fit the size using a given contentMode.
+ 
+ @param rect The draw rect
+ @param size The content size
+ @param mode The content mode
+ @return A resized rect for the given content mode.
+ @discussion UIViewContentModeRedraw is same as UIViewContentModeScaleToFill.
+ */
+static CGRect _YYCGRectFitWithContentMode(CGRect rect, CGSize size, UIViewContentMode mode) {
+    rect = CGRectStandardize(rect);
+    size.width = size.width < 0 ? -size.width : size.width;
+    size.height = size.height < 0 ? -size.height : size.height;
+    CGPoint center = CGPointMake(CGRectGetMidX(rect), CGRectGetMidY(rect));
+    switch (mode) {
+        case UIViewContentModeScaleAspectFit:
+        case UIViewContentModeScaleAspectFill: {
+            if (rect.size.width < 0.01 || rect.size.height < 0.01 ||
+                size.width < 0.01 || size.height < 0.01) {
+                rect.origin = center;
+                rect.size = CGSizeZero;
+            } else {
+                CGFloat scale;
+                if (size.width / size.height < rect.size.width / rect.size.height &&
+                    mode == UIViewContentModeScaleAspectFit) {
+                    scale = rect.size.height / size.height;
+                } else {
+                    scale = rect.size.width / size.width;
+                }
+                size.width *= scale;
+                size.height *= scale;
+                rect.size = size;
+                rect.origin = CGPointMake(center.x - size.width * 0.5, center.y - size.height * 0.5);
+            }
+        } break;
+        case UIViewContentModeCenter: {
+            rect.size = size;
+            rect.origin = CGPointMake(center.x - size.width * 0.5, center.y - size.height * 0.5);
+        } break;
+        case UIViewContentModeTop: {
+            rect.origin.x = center.x - size.width * 0.5;
+            rect.size = size;
+        } break;
+        case UIViewContentModeBottom: {
+            rect.origin.x = center.x - size.width * 0.5;
+            rect.origin.y += rect.size.height - size.height;
+            rect.size = size;
+        } break;
+        case UIViewContentModeLeft: {
+            rect.origin.y = center.y - size.height * 0.5;
+            rect.size = size;
+        } break;
+        case UIViewContentModeRight: {
+            rect.origin.y = center.y - size.height * 0.5;
+            rect.origin.x += rect.size.width - size.width;
+            rect.size = size;
+        } break;
+        case UIViewContentModeTopLeft: {
+            rect.size = size;
+        } break;
+        case UIViewContentModeTopRight: {
+            rect.origin.x += rect.size.width - size.width;
+            rect.size = size;
+        } break;
+        case UIViewContentModeBottomLeft: {
+            rect.origin.y += rect.size.height - size.height;
+            rect.size = size;
+        } break;
+        case UIViewContentModeBottomRight: {
+            rect.origin.x += rect.size.width - size.width;
+            rect.origin.y += rect.size.height - size.height;
+            rect.size = size;
+        } break;
+        case UIViewContentModeScaleToFill:
+        case UIViewContentModeRedraw:
+        default: {
+            rect = rect;
+        }
+    }
+    return rect;
+}
+
+
+
+
+static NSTimeInterval _yy_CGImageSourceGetGIFFrameDelayAtIndex(CGImageSourceRef source, size_t index) {
+    NSTimeInterval delay = 0;
+    CFDictionaryRef dic = CGImageSourceCopyPropertiesAtIndex(source, index, NULL);
+    if (dic) {
+        CFDictionaryRef dicGIF = CFDictionaryGetValue(dic, kCGImagePropertyGIFDictionary);
+        if (dicGIF) {
+            NSNumber *num = CFDictionaryGetValue(dicGIF, kCGImagePropertyGIFUnclampedDelayTime);
+            if (num.doubleValue <= __FLT_EPSILON__) {
+                num = CFDictionaryGetValue(dicGIF, kCGImagePropertyGIFDelayTime);
+            }
+            delay = num.doubleValue;
+        }
+        CFRelease(dic);
+    }
+    
+    // http://nullsleep.tumblr.com/post/16524517190/animated-gif-minimum-frame-delay-browser-compatibility
+    if (delay < 0.02) delay = 0.1;
+    return delay;
+}
+
+
+
+@implementation UIImage (YYWebImage)
+
++ (UIImage *)yy_imageWithSmallGIFData:(NSData *)data scale:(CGFloat)scale {
+    CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFTypeRef)(data), NULL);
+    if (!source) return nil;
+    
+    size_t count = CGImageSourceGetCount(source);
+    if (count <= 1) {
+        CFRelease(source);
+        return [self.class imageWithData:data scale:scale];
+    }
+    
+    NSUInteger frames[count];
+    double oneFrameTime = 1 / 50.0; // 50 fps
+    NSTimeInterval totalTime = 0;
+    NSUInteger totalFrame = 0;
+    NSUInteger gcdFrame = 0;
+    for (size_t i = 0; i < count; i++) {
+        NSTimeInterval delay = _yy_CGImageSourceGetGIFFrameDelayAtIndex(source, i);
+        totalTime += delay;
+        NSInteger frame = lrint(delay / oneFrameTime);
+        if (frame < 1) frame = 1;
+        frames[i] = frame;
+        totalFrame += frames[i];
+        if (i == 0) gcdFrame = frames[i];
+        else {
+            NSUInteger frame = frames[i], tmp;
+            if (frame < gcdFrame) {
+                tmp = frame; frame = gcdFrame; gcdFrame = tmp;
+            }
+            while (true) {
+                tmp = frame % gcdFrame;
+                if (tmp == 0) break;
+                frame = gcdFrame;
+                gcdFrame = tmp;
+            }
+        }
+    }
+    NSMutableArray *array = [NSMutableArray new];
+    for (size_t i = 0; i < count; i++) {
+        CGImageRef imageRef = CGImageSourceCreateImageAtIndex(source, i, NULL);
+        if (!imageRef) {
+            CFRelease(source);
+            return nil;
+        }
+        size_t width = CGImageGetWidth(imageRef);
+        size_t height = CGImageGetHeight(imageRef);
+        if (width == 0 || height == 0) {
+            CFRelease(source);
+            CFRelease(imageRef);
+            return nil;
+        }
+        
+        CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef) & kCGBitmapAlphaInfoMask;
+        BOOL hasAlpha = NO;
+        if (alphaInfo == kCGImageAlphaPremultipliedLast ||
+            alphaInfo == kCGImageAlphaPremultipliedFirst ||
+            alphaInfo == kCGImageAlphaLast ||
+            alphaInfo == kCGImageAlphaFirst) {
+            hasAlpha = YES;
+        }
+        // BGRA8888 (premultiplied) or BGRX8888
+        // same as UIGraphicsBeginImageContext() and -[UIView drawRect:]
+        CGBitmapInfo bitmapInfo = kCGBitmapByteOrder32Host;
+        bitmapInfo |= hasAlpha ? kCGImageAlphaPremultipliedFirst : kCGImageAlphaNoneSkipFirst;
+        CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
+        CGContextRef context = CGBitmapContextCreate(NULL, width, height, 8, 0, space, bitmapInfo);
+        CGColorSpaceRelease(space);
+        if (!context) {
+            CFRelease(source);
+            CFRelease(imageRef);
+            return nil;
+        }
+        CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef); // decode
+        CGImageRef decoded = CGBitmapContextCreateImage(context);
+        CFRelease(context);
+        if (!decoded) {
+            CFRelease(source);
+            CFRelease(imageRef);
+            return nil;
+        }
+        UIImage *image = image = [UIImage imageWithCGImage:decoded scale:scale orientation:UIImageOrientationUp];
+        CGImageRelease(imageRef);
+        CGImageRelease(decoded);
+        if (!image) {
+            CFRelease(source);
+            return nil;
+        }
+        for (size_t j = 0, max = frames[i] / gcdFrame; j < max; j++) {
+            [array addObject:image];
+        }
+    }
+    CFRelease(source);
+    UIImage *image = [self.class animatedImageWithImages:array duration:totalTime];
+    return image;
+}
+
++ (UIImage *)yy_imageWithColor:(UIColor *)color {
+    return [self yy_imageWithColor:color size:CGSizeMake(1, 1)];
+}
+
++ (UIImage *)yy_imageWithColor:(UIColor *)color size:(CGSize)size {
+    if (!color || size.width <= 0 || size.height <= 0) return nil;
+    CGRect rect = CGRectMake(0.0f, 0.0f, size.width, size.height);
+    UIGraphicsBeginImageContextWithOptions(rect.size, NO, 0);
+    CGContextRef context = UIGraphicsGetCurrentContext();
+    CGContextSetFillColorWithColor(context, color.CGColor);
+    CGContextFillRect(context, rect);
+    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+    return image;
+}
+
++ (UIImage *)yy_imageWithSize:(CGSize)size drawBlock:(void (^)(CGContextRef context))drawBlock {
+    if (!drawBlock) return nil;
+    UIGraphicsBeginImageContextWithOptions(size, NO, 0);
+    CGContextRef context = UIGraphicsGetCurrentContext();
+    if (!context) return nil;
+    drawBlock(context);
+    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+    return image;
+}
+
+- (BOOL)yy_hasAlphaChannel {
+    if (self.CGImage == NULL) return NO;
+    CGImageAlphaInfo alpha = CGImageGetAlphaInfo(self.CGImage) & kCGBitmapAlphaInfoMask;
+    return (alpha == kCGImageAlphaFirst ||
+            alpha == kCGImageAlphaLast ||
+            alpha == kCGImageAlphaPremultipliedFirst ||
+            alpha == kCGImageAlphaPremultipliedLast);
+}
+
+- (void)yy_drawInRect:(CGRect)rect withContentMode:(UIViewContentMode)contentMode clipsToBounds:(BOOL)clips{
+    CGRect drawRect = _YYCGRectFitWithContentMode(rect, self.size, contentMode);
+    if (drawRect.size.width == 0 || drawRect.size.height == 0) return;
+    if (clips) {
+        CGContextRef context = UIGraphicsGetCurrentContext();
+        if (context) {
+            CGContextSaveGState(context);
+            CGContextAddRect(context, rect);
+            CGContextClip(context);
+            [self drawInRect:drawRect];
+            CGContextRestoreGState(context);
+        }
+    } else {
+        [self drawInRect:drawRect];
+    }
+}
+
+- (UIImage *)yy_imageByResizeToSize:(CGSize)size {
+    if (size.width <= 0 || size.height <= 0) return nil;
+    UIGraphicsBeginImageContextWithOptions(size, NO, self.scale);
+    [self drawInRect:CGRectMake(0, 0, size.width, size.height)];
+    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+    return image;
+}
+
+- (UIImage *)yy_imageByResizeToSize:(CGSize)size contentMode:(UIViewContentMode)contentMode {
+    if (size.width <= 0 || size.height <= 0) return nil;
+    UIGraphicsBeginImageContextWithOptions(size, NO, self.scale);
+    [self yy_drawInRect:CGRectMake(0, 0, size.width, size.height) withContentMode:contentMode clipsToBounds:NO];
+    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+    return image;
+}
+
+- (UIImage *)yy_imageByCropToRect:(CGRect)rect {
+    rect.origin.x *= self.scale;
+    rect.origin.y *= self.scale;
+    rect.size.width *= self.scale;
+    rect.size.height *= self.scale;
+    if (rect.size.width <= 0 || rect.size.height <= 0) return nil;
+    CGImageRef imageRef = CGImageCreateWithImageInRect(self.CGImage, rect);
+    UIImage *image = [UIImage imageWithCGImage:imageRef scale:self.scale orientation:self.imageOrientation];
+    CGImageRelease(imageRef);
+    return image;
+}
+
+- (UIImage *)yy_imageByInsetEdge:(UIEdgeInsets)insets withColor:(UIColor *)color {
+    CGSize size = self.size;
+    size.width -= insets.left + insets.right;
+    size.height -= insets.top + insets.bottom;
+    if (size.width <= 0 || size.height <= 0) return nil;
+    CGRect rect = CGRectMake(-insets.left, -insets.top, self.size.width, self.size.height);
+    UIGraphicsBeginImageContextWithOptions(size, NO, self.scale);
+    CGContextRef context = UIGraphicsGetCurrentContext();
+    if (color) {
+        CGContextSetFillColorWithColor(context, color.CGColor);
+        CGMutablePathRef path = CGPathCreateMutable();
+        CGPathAddRect(path, NULL, CGRectMake(0, 0, size.width, size.height));
+        CGPathAddRect(path, NULL, rect);
+        CGContextAddPath(context, path);
+        CGContextEOFillPath(context);
+        CGPathRelease(path);
+    }
+    [self drawInRect:rect];
+    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+    return image;
+}
+
+- (UIImage *)yy_imageByRoundCornerRadius:(CGFloat)radius {
+    return [self yy_imageByRoundCornerRadius:radius corners:UIRectCornerAllCorners borderWidth:0];
+}
+
+- (UIImage *)yy_imageByRoundCornerRadius:(CGFloat)radius corners:(UIRectCorner)corners borderWidth:(CGFloat)borderWidth {
+    UIGraphicsBeginImageContextWithOptions(self.size, NO, self.scale);
+    CGContextRef context = UIGraphicsGetCurrentContext();
+    CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
+    CGContextScaleCTM(context, 1, -1);
+    CGContextTranslateCTM(context, 0, -rect.size.height);
+    
+    CGFloat minSize = MIN(self.size.width, self.size.height);
+    if (borderWidth < minSize / 2) {
+        [[UIBezierPath bezierPathWithRoundedRect:CGRectInset(rect, borderWidth, borderWidth) byRoundingCorners:corners cornerRadii:CGSizeMake(radius, borderWidth)] addClip];
+        CGContextDrawImage(context, rect, self.CGImage);
+    }
+    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+    return image;
+}
+
+- (UIImage *)yy_imageByRotate:(CGFloat)radians fitSize:(BOOL)fitSize {
+    size_t width = (size_t)CGImageGetWidth(self.CGImage);
+    size_t height = (size_t)CGImageGetHeight(self.CGImage);
+    CGRect newRect = CGRectApplyAffineTransform(CGRectMake(0., 0., width, height),
+                                                fitSize ? CGAffineTransformMakeRotation(radians) : CGAffineTransformIdentity);
+    
+    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
+    CGContextRef context = CGBitmapContextCreate(NULL,
+                                                 (size_t)newRect.size.width,
+                                                 (size_t)newRect.size.height,
+                                                 8,
+                                                 (size_t)newRect.size.width * 4,
+                                                 colorSpace,
+                                                 kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedFirst);
+    CGColorSpaceRelease(colorSpace);
+    if (!context) return nil;
+    
+    CGContextSetShouldAntialias(context, true);
+    CGContextSetAllowsAntialiasing(context, true);
+    CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
+    
+    CGContextTranslateCTM(context, +(newRect.size.width * 0.5), +(newRect.size.height * 0.5));
+    CGContextRotateCTM(context, radians);
+    
+    CGContextDrawImage(context, CGRectMake(-(width * 0.5), -(height * 0.5), width, height), self.CGImage);
+    CGImageRef imgRef = CGBitmapContextCreateImage(context);
+    UIImage *img = [UIImage imageWithCGImage:imgRef scale:self.scale orientation:self.imageOrientation];
+    CGImageRelease(imgRef);
+    CGContextRelease(context);
+    return img;
+}
+
+- (UIImage *)_yy_flipHorizontal:(BOOL)horizontal vertical:(BOOL)vertical {
+    if (!self.CGImage) return nil;
+    size_t width = (size_t)CGImageGetWidth(self.CGImage);
+    size_t height = (size_t)CGImageGetHeight(self.CGImage);
+    size_t bytesPerRow = width * 4;
+    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
+    CGContextRef context = CGBitmapContextCreate(NULL, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrderDefault | kCGImageAlphaPremultipliedFirst);
+    CGColorSpaceRelease(colorSpace);
+    if (!context) return nil;
+    
+    CGContextDrawImage(context, CGRectMake(0, 0, width, height), self.CGImage);
+    UInt8 *data = (UInt8 *)CGBitmapContextGetData(context);
+    if (!data) {
+        CGContextRelease(context);
+        return nil;
+    }
+    vImage_Buffer src = { data, height, width, bytesPerRow };
+    vImage_Buffer dest = { data, height, width, bytesPerRow };
+    if (vertical) {
+        vImageVerticalReflect_ARGB8888(&src, &dest, kvImageBackgroundColorFill);
+    }
+    if (horizontal) {
+        vImageHorizontalReflect_ARGB8888(&src, &dest, kvImageBackgroundColorFill);
+    }
+    CGImageRef imgRef = CGBitmapContextCreateImage(context);
+    CGContextRelease(context);
+    UIImage *img = [UIImage imageWithCGImage:imgRef scale:self.scale orientation:self.imageOrientation];
+    CGImageRelease(imgRef);
+    return img;
+}
+
+- (UIImage *)yy_imageByRotateLeft90 {
+    return [self yy_imageByRotate:_DegreesToRadians(90) fitSize:YES];
+}
+
+- (UIImage *)yy_imageByRotateRight90 {
+    return [self yy_imageByRotate:_DegreesToRadians(-90) fitSize:YES];
+}
+
+- (UIImage *)yy_imageByRotate180 {
+    return [self _yy_flipHorizontal:YES vertical:YES];
+}
+
+- (UIImage *)yy_imageByFlipVertical {
+    return [self _yy_flipHorizontal:NO vertical:YES];
+}
+
+- (UIImage *)yy_imageByFlipHorizontal {
+    return [self _yy_flipHorizontal:YES vertical:NO];
+}
+
+- (UIImage *)yy_imageByTintColor:(UIColor *)color {
+    UIGraphicsBeginImageContextWithOptions(self.size, NO, self.scale);
+    CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
+    [color set];
+    UIRectFill(rect);
+    [self drawAtPoint:CGPointMake(0, 0) blendMode:kCGBlendModeDestinationIn alpha:1];
+    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+    return newImage;
+}
+
+- (UIImage *)yy_imageByGrayscale {
+    return [self yy_imageByBlurRadius:0 tintColor:nil tintMode:0 saturation:0 maskImage:nil];
+}
+
+- (UIImage *)yy_imageByBlurSoft {
+    return [self yy_imageByBlurRadius:60 tintColor:[UIColor colorWithWhite:0.84 alpha:0.36] tintMode:kCGBlendModeNormal saturation:1.8 maskImage:nil];
+}
+
+- (UIImage *)yy_imageByBlurLight {
+    return [self yy_imageByBlurRadius:60 tintColor:[UIColor colorWithWhite:1.0 alpha:0.3] tintMode:kCGBlendModeNormal saturation:1.8 maskImage:nil];
+}
+
+- (UIImage *)yy_imageByBlurExtraLight {
+    return [self yy_imageByBlurRadius:40 tintColor:[UIColor colorWithWhite:0.97 alpha:0.82] tintMode:kCGBlendModeNormal saturation:1.8 maskImage:nil];
+}
+
+- (UIImage *)yy_imageByBlurDark {
+    return [self yy_imageByBlurRadius:40 tintColor:[UIColor colorWithWhite:0.11 alpha:0.73] tintMode:kCGBlendModeNormal saturation:1.8 maskImage:nil];
+}
+
+- (UIImage *)yy_imageByBlurWithTint:(UIColor *)tintColor {
+    const CGFloat EffectColorAlpha = 0.6;
+    UIColor *effectColor = tintColor;
+    size_t componentCount = CGColorGetNumberOfComponents(tintColor.CGColor);
+    if (componentCount == 2) {
+        CGFloat b;
+        if ([tintColor getWhite:&b alpha:NULL]) {
+            effectColor = [UIColor colorWithWhite:b alpha:EffectColorAlpha];
+        }
+    } else {
+        CGFloat r, g, b;
+        if ([tintColor getRed:&r green:&g blue:&b alpha:NULL]) {
+            effectColor = [UIColor colorWithRed:r green:g blue:b alpha:EffectColorAlpha];
+        }
+    }
+    return [self yy_imageByBlurRadius:20 tintColor:effectColor tintMode:kCGBlendModeNormal saturation:-1.0 maskImage:nil];
+}
+
+- (UIImage *)yy_imageByBlurRadius:(CGFloat)blurRadius
+                        tintColor:(UIColor *)tintColor
+                         tintMode:(CGBlendMode)tintBlendMode
+                       saturation:(CGFloat)saturation
+                        maskImage:(UIImage *)maskImage {
+    if (self.size.width < 1 || self.size.height < 1) {
+        NSLog(@"UIImage+YYAdd error: invalid size: (%.2f x %.2f). Both dimensions must be >= 1: %@", self.size.width, self.size.height, self);
+        return nil;
+    }
+    if (!self.CGImage) {
+        NSLog(@"UIImage+YYAdd error: inputImage must be backed by a CGImage: %@", self);
+        return nil;
+    }
+    if (maskImage && !maskImage.CGImage) {
+        NSLog(@"UIImage+YYAdd error: effectMaskImage must be backed by a CGImage: %@", maskImage);
+        return nil;
+    }
+    
+    // iOS7 and above can use new func.
+    BOOL hasNewFunc = (long)vImageBuffer_InitWithCGImage != 0 && (long)vImageCreateCGImageFromBuffer != 0;
+    BOOL hasBlur = blurRadius > __FLT_EPSILON__;
+    BOOL hasSaturation = fabs(saturation - 1.0) > __FLT_EPSILON__;
+    
+    CGSize size = self.size;
+    CGRect rect = { CGPointZero, size };
+    CGFloat scale = self.scale;
+    CGImageRef imageRef = self.CGImage;
+    BOOL opaque = NO;
+    
+    if (!hasBlur && !hasSaturation) {
+        return [self _yy_mergeImageRef:imageRef tintColor:tintColor tintBlendMode:tintBlendMode maskImage:maskImage opaque:opaque];
+    }
+    
+    vImage_Buffer effect = { 0 }, scratch = { 0 };
+    vImage_Buffer *input = NULL, *output = NULL;
+    
+    vImage_CGImageFormat format = {
+        .bitsPerComponent = 8,
+        .bitsPerPixel = 32,
+        .colorSpace = NULL,
+        .bitmapInfo = kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Little, //requests a BGRA buffer.
+        .version = 0,
+        .decode = NULL,
+        .renderingIntent = kCGRenderingIntentDefault
+    };
+    
+    if (hasNewFunc) {
+        vImage_Error err;
+        err = vImageBuffer_InitWithCGImage(&effect, &format, NULL, imageRef, kvImagePrintDiagnosticsToConsole);
+        if (err != kvImageNoError) {
+            NSLog(@"UIImage+YYAdd error: vImageBuffer_InitWithCGImage returned error code %zi for inputImage: %@", err, self);
+            return nil;
+        }
+        err = vImageBuffer_Init(&scratch, effect.height, effect.width, format.bitsPerPixel, kvImageNoFlags);
+        if (err != kvImageNoError) {
+            NSLog(@"UIImage+YYAdd error: vImageBuffer_Init returned error code %zi for inputImage: %@", err, self);
+            return nil;
+        }
+    } else {
+        UIGraphicsBeginImageContextWithOptions(size, opaque, scale);
+        CGContextRef effectCtx = UIGraphicsGetCurrentContext();
+        CGContextScaleCTM(effectCtx, 1.0, -1.0);
+        CGContextTranslateCTM(effectCtx, 0, -size.height);
+        CGContextDrawImage(effectCtx, rect, imageRef);
+        effect.data     = CGBitmapContextGetData(effectCtx);
+        effect.width    = CGBitmapContextGetWidth(effectCtx);
+        effect.height   = CGBitmapContextGetHeight(effectCtx);
+        effect.rowBytes = CGBitmapContextGetBytesPerRow(effectCtx);
+        
+        UIGraphicsBeginImageContextWithOptions(size, opaque, scale);
+        CGContextRef scratchCtx = UIGraphicsGetCurrentContext();
+        scratch.data     = CGBitmapContextGetData(scratchCtx);
+        scratch.width    = CGBitmapContextGetWidth(scratchCtx);
+        scratch.height   = CGBitmapContextGetHeight(scratchCtx);
+        scratch.rowBytes = CGBitmapContextGetBytesPerRow(scratchCtx);
+    }
+    
+    input = &effect;
+    output = &scratch;
+    
+    if (hasBlur) {
+        // A description of how to compute the box kernel width from the Gaussian
+        // radius (aka standard deviation) appears in the SVG spec:
+        // http://www.w3.org/TR/SVG/filters.html#feGaussianBlurElement
+        //
+        // For larger values of 's' (s >= 2.0), an approximation can be used: Three
+        // successive box-blurs build a piece-wise quadratic convolution kernel, which
+        // approximates the Gaussian kernel to within roughly 3%.
+        //
+        // let d = floor(s * 3*sqrt(2*pi)/4 + 0.5)
+        //
+        // ... if d is odd, use three box-blurs of size 'd', centered on the output pixel.
+        //
+        CGFloat inputRadius = blurRadius * scale;
+        if (inputRadius - 2.0 < __FLT_EPSILON__) inputRadius = 2.0;
+        uint32_t radius = floor((inputRadius * 3.0 * sqrt(2 * M_PI) / 4 + 0.5) / 2);
+        radius |= 1; // force radius to be odd so that the three box-blur methodology works.
+        int iterations;
+        if (blurRadius * scale < 0.5) iterations = 1;
+        else if (blurRadius * scale < 1.5) iterations = 2;
+        else iterations = 3;
+        NSInteger tempSize = vImageBoxConvolve_ARGB8888(input, output, NULL, 0, 0, radius, radius, NULL, kvImageGetTempBufferSize | kvImageEdgeExtend);
+        void *temp = malloc(tempSize);
+        for (int i = 0; i < iterations; i++) {
+            vImageBoxConvolve_ARGB8888(input, output, temp, 0, 0, radius, radius, NULL, kvImageEdgeExtend);
+            // swap
+            vImage_Buffer *swap_tmp = input;
+            input = output;
+            output = swap_tmp;
+        }
+        free(temp);
+    }
+    
+    
+    if (hasSaturation) {
+        // These values appear in the W3C Filter Effects spec:
+        // https://dvcs.w3.org/hg/FXTF/raw-file/default/filters/Publish.html#grayscaleEquivalent
+        CGFloat s = saturation;
+        CGFloat matrixFloat[] = {
+            0.0722 + 0.9278 * s,  0.0722 - 0.0722 * s,  0.0722 - 0.0722 * s,  0,
+            0.7152 - 0.7152 * s,  0.7152 + 0.2848 * s,  0.7152 - 0.7152 * s,  0,
+            0.2126 - 0.2126 * s,  0.2126 - 0.2126 * s,  0.2126 + 0.7873 * s,  0,
+            0,                    0,                    0,                    1,
+        };
+        const int32_t divisor = 256;
+        NSUInteger matrixSize = sizeof(matrixFloat) / sizeof(matrixFloat[0]);
+        int16_t matrix[matrixSize];
+        for (NSUInteger i = 0; i < matrixSize; ++i) {
+            matrix[i] = (int16_t)roundf(matrixFloat[i] * divisor);
+        }
+        vImageMatrixMultiply_ARGB8888(input, output, matrix, divisor, NULL, NULL, kvImageNoFlags);
+        // swap
+        vImage_Buffer *swap_tmp = input;
+        input = output;
+        output = swap_tmp;
+    }
+    
+    UIImage *outputImage = nil;
+    if (hasNewFunc) {
+        CGImageRef effectCGImage = NULL;
+        effectCGImage = vImageCreateCGImageFromBuffer(input, &format, &_yy_cleanupBuffer, NULL, kvImageNoAllocate, NULL);
+        if (effectCGImage == NULL) {
+            effectCGImage = vImageCreateCGImageFromBuffer(input, &format, NULL, NULL, kvImageNoFlags, NULL);
+            free(input->data);
+        }
+        free(output->data);
+        outputImage = [self _yy_mergeImageRef:effectCGImage tintColor:tintColor tintBlendMode:tintBlendMode maskImage:maskImage opaque:opaque];
+        CGImageRelease(effectCGImage);
+    } else {
+        CGImageRef effectCGImage;
+        UIImage *effectImage;
+        if (input != &effect) effectImage = UIGraphicsGetImageFromCurrentImageContext();
+        UIGraphicsEndImageContext();
+        if (input == &effect) effectImage = UIGraphicsGetImageFromCurrentImageContext();
+        UIGraphicsEndImageContext();
+        effectCGImage = effectImage.CGImage;
+        outputImage = [self _yy_mergeImageRef:effectCGImage tintColor:tintColor tintBlendMode:tintBlendMode maskImage:maskImage opaque:opaque];
+    }
+    return outputImage;
+}
+
+// Helper function to handle deferred cleanup of a buffer.
+static void _yy_cleanupBuffer(void *userData, void *buf_data) {
+    free(buf_data);
+}
+
+// Helper function to add tint and mask.
+- (UIImage *)_yy_mergeImageRef:(CGImageRef)effectCGImage
+                     tintColor:(UIColor *)tintColor
+                 tintBlendMode:(CGBlendMode)tintBlendMode
+                     maskImage:(UIImage *)maskImage
+                        opaque:(BOOL)opaque {
+    BOOL hasTint = tintColor != nil && CGColorGetAlpha(tintColor.CGColor) > __FLT_EPSILON__;
+    BOOL hasMask = maskImage != nil;
+    CGSize size = self.size;
+    CGRect rect = { CGPointZero, size };
+    CGFloat scale = self.scale;
+    
+    if (!hasTint && !hasMask) {
+        return [UIImage imageWithCGImage:effectCGImage];
+    }
+    
+    UIGraphicsBeginImageContextWithOptions(size, opaque, scale);
+    CGContextRef context = UIGraphicsGetCurrentContext();
+    CGContextScaleCTM(context, 1.0, -1.0);
+    CGContextTranslateCTM(context, 0, -size.height);
+    if (hasMask) {
+        CGContextDrawImage(context, rect, self.CGImage);
+        CGContextSaveGState(context);
+        CGContextClipToMask(context, rect, maskImage.CGImage);
+    }
+    CGContextDrawImage(context, rect, effectCGImage);
+    if (hasTint) {
+        CGContextSaveGState(context);
+        CGContextSetBlendMode(context, tintBlendMode);
+        CGContextSetFillColorWithColor(context, tintColor.CGColor);
+        CGContextFillRect(context, rect);
+        CGContextRestoreGState(context);
+    }
+    if (hasMask) {
+        CGContextRestoreGState(context);
+    }
+    UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+    return outputImage;
+}
+
+@end

YYWebImage/Categories/UIImageView+YYWebImage.h

@@ -0,0 +1,190 @@
+//
+//  UIImageView+YYWebImage.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/23.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYWebImageManager.h>
+#else
+#import "YYWebImageManager.h"
+#endif
+
+
+/**
+ Web image methods for UIImageView.
+ */
+@interface UIImageView (YYWebImage)
+
+#pragma mark - image
+
+/**
+ Current image URL.
+ 
+ @discussion Set a new value to this property will cancel the previous request 
+ operation and create a new request operation to fetch image. Set nil to clear 
+ the image and image URL.
+ */
+@property (nonatomic, strong) NSURL *yy_imageURL;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL placeholder:(UIImage *)placeholder;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL The image url (remote or local file path).
+ @param options  The options to use when request the image.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL options:(YYWebImageOptions)options;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the view's `image` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder he image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param manager     The manager to create image request operation.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                   manager:(YYWebImageManager *)manager
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Cancel the current image request.
+ */
+- (void)yy_cancelCurrentImageRequest;
+
+
+
+#pragma mark - highlight image
+
+/**
+ Current highlighted image URL.
+ 
+ @discussion Set a new value to this property will cancel the previous request
+ operation and create a new request operation to fetch image. Set nil to clear
+ the highlighted image and image URL.
+ */
+@property (nonatomic, strong) NSURL *yy_highlightedImageURL;
+
+/**
+ Set the view's `highlightedImage` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ */
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL placeholder:(UIImage *)placeholder;
+
+/**
+ Set the view's `highlightedImage` with a specified URL.
+ 
+ @param imageURL The image url (remote or local file path).
+ @param options  The options to use when request the image.
+ */
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL options:(YYWebImageOptions)options;
+
+/**
+ Set the view's `highlightedImage` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL
+                          placeholder:(UIImage *)placeholder
+                              options:(YYWebImageOptions)options
+                           completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the view's `highlightedImage` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder The image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL
+                          placeholder:(UIImage *)placeholder
+                              options:(YYWebImageOptions)options
+                             progress:(YYWebImageProgressBlock)progress
+                            transform:(YYWebImageTransformBlock)transform
+                           completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Set the view's `highlightedImage` with a specified URL.
+ 
+ @param imageURL    The image url (remote or local file path).
+ @param placeholder he image to be set initially, until the image request finishes.
+ @param options     The options to use when request the image.
+ @param manager     The manager to create image request operation.
+ @param progress    The block invoked (on main thread) during image request.
+ @param transform   The block invoked (on background thread) to do additional image process.
+ @param completion  The block invoked (on main thread) when image request completed.
+ */
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL
+                          placeholder:(UIImage *)placeholder
+                              options:(YYWebImageOptions)options
+                              manager:(YYWebImageManager *)manager
+                             progress:(YYWebImageProgressBlock)progress
+                            transform:(YYWebImageTransformBlock)transform
+                           completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ Cancel the current highlighed image request.
+ */
+- (void)yy_cancelCurrentHighlightedImageRequest;
+
+@end

YYWebImage/Categories/UIImageView+YYWebImage.m

@@ -0,0 +1,335 @@
+//
+//  UIImageView+YYWebImage.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/23.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "UIImageView+YYWebImage.h"
+#import "YYWebImageOperation.h"
+#import "_YYWebImageSetter.h"
+#import <objc/runtime.h>
+
+// Dummy class for category
+@interface UIImageView_YYWebImage : NSObject @end
+@implementation UIImageView_YYWebImage @end
+
+static int _YYWebImageSetterKey;
+static int _YYWebImageHighlightedSetterKey;
+
+
+@implementation UIImageView (YYWebImage)
+
+#pragma mark - image
+
+- (NSURL *)yy_imageURL {
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    return setter.imageURL;
+}
+
+- (void)setYy_imageURL:(NSURL *)imageURL {
+    [self yy_setImageWithURL:imageURL
+                 placeholder:nil
+                     options:kNilOptions
+                     manager:nil
+                    progress:nil
+                   transform:nil
+                  completion:nil];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL placeholder:(UIImage *)placeholder {
+    [self yy_setImageWithURL:imageURL
+                 placeholder:placeholder
+                     options:kNilOptions
+                     manager:nil
+                    progress:nil
+                   transform:nil
+                  completion:nil];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL options:(YYWebImageOptions)options {
+    [self yy_setImageWithURL:imageURL
+                 placeholder:nil
+                     options:options
+                     manager:nil
+                    progress:nil
+                   transform:nil
+                  completion:nil];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setImageWithURL:imageURL
+                 placeholder:placeholder
+                     options:options
+                     manager:nil
+                    progress:nil
+                   transform:nil
+                  completion:completion];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setImageWithURL:imageURL
+                 placeholder:placeholder
+                     options:options
+                     manager:nil
+                    progress:progress
+                   transform:transform
+                  completion:completion];
+}
+
+- (void)yy_setImageWithURL:(NSURL *)imageURL
+               placeholder:(UIImage *)placeholder
+                   options:(YYWebImageOptions)options
+                   manager:(YYWebImageManager *)manager
+                  progress:(YYWebImageProgressBlock)progress
+                 transform:(YYWebImageTransformBlock)transform
+                completion:(YYWebImageCompletionBlock)completion {
+    if ([imageURL isKindOfClass:[NSString class]]) imageURL = [NSURL URLWithString:(id)imageURL];
+    manager = manager ? manager : [YYWebImageManager sharedManager];
+    
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    if (!setter) {
+        setter = [_YYWebImageSetter new];
+        objc_setAssociatedObject(self, &_YYWebImageSetterKey, setter, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+    }
+    int32_t sentinel = [setter cancelWithNewURL:imageURL];
+    
+    _yy_dispatch_sync_on_main_queue(^{
+        if ((options & YYWebImageOptionSetImageWithFadeAnimation) &&
+            !(options & YYWebImageOptionAvoidSetImage)) {
+            if (!self.highlighted) {
+                [self.layer removeAnimationForKey:_YYWebImageFadeAnimationKey];
+            }
+        }
+        
+        if (!imageURL) {
+            if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+                self.image = placeholder;
+            }
+            return;
+        }
+        
+        // get the image from memory as quickly as possible
+        UIImage *imageFromMemory = nil;
+        if (manager.cache &&
+            !(options & YYWebImageOptionUseNSURLCache) &&
+            !(options & YYWebImageOptionRefreshImageCache)) {
+            imageFromMemory = [manager.cache getImageForKey:[manager cacheKeyForURL:imageURL] withType:YYImageCacheTypeMemory];
+        }
+        if (imageFromMemory) {
+            if (!(options & YYWebImageOptionAvoidSetImage)) {
+                self.image = imageFromMemory;
+            }
+            if(completion) completion(imageFromMemory, imageURL, YYWebImageFromMemoryCacheFast, YYWebImageStageFinished, nil);
+            return;
+        }
+        
+        if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+            self.image = placeholder;
+        }
+        
+        __weak typeof(self) _self = self;
+        dispatch_async([_YYWebImageSetter setterQueue], ^{
+            YYWebImageProgressBlock _progress = nil;
+            if (progress) _progress = ^(NSInteger receivedSize, NSInteger expectedSize) {
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    progress(receivedSize, expectedSize);
+                });
+            };
+            
+            YYWebImageCompletionBlock _completion = ^(UIImage *image, NSURL *url, YYWebImageFromType from, YYWebImageStage stage, NSError *error) {
+                __strong typeof(_self) self = _self;
+                BOOL setImage = (stage == YYWebImageStageFinished || stage == YYWebImageStageProgress) && image && !(options & YYWebImageOptionAvoidSetImage);
+                BOOL showFade = ((options & YYWebImageOptionSetImageWithFadeAnimation) && !self.highlighted);
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    if (setImage && self) {
+                        if (showFade) {
+                            CATransition *transition = [CATransition animation];
+                            transition.duration = stage == YYWebImageStageFinished ? _YYWebImageFadeTime : _YYWebImageProgressiveFadeTime;
+                            transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
+                            transition.type = kCATransitionFade;
+                            [self.layer addAnimation:transition forKey:_YYWebImageFadeAnimationKey];
+                        }
+                        self.image = image;
+                    }
+                    if (completion) completion(image, url, from, stage, error);
+                });
+            };
+            
+            [setter setOperationWithSentinel:sentinel url:imageURL options:options manager:manager progress:_progress transform:transform completion:_completion];
+        });
+    });
+}
+
+- (void)yy_cancelCurrentImageRequest {
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageSetterKey);
+    if (setter) [setter cancel];
+}
+
+
+#pragma mark - highlighted image
+
+- (NSURL *)yy_highlightedImageURL {
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageHighlightedSetterKey);
+    return setter.imageURL;
+}
+
+- (void)setYy_highlightedImageURL:(NSURL *)imageURL {
+    [self yy_setHighlightedImageWithURL:imageURL
+                            placeholder:nil
+                                options:kNilOptions
+                                manager:nil
+                               progress:nil
+                              transform:nil
+                             completion:nil];
+}
+
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL placeholder:(UIImage *)placeholder {
+    [self yy_setHighlightedImageWithURL:imageURL
+                            placeholder:placeholder
+                                options:kNilOptions
+                                manager:nil
+                               progress:nil
+                              transform:nil
+                             completion:nil];
+}
+
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL options:(YYWebImageOptions)options {
+    [self yy_setHighlightedImageWithURL:imageURL
+                            placeholder:nil
+                                options:options
+                                manager:nil
+                               progress:nil
+                              transform:nil
+                             completion:nil];
+}
+
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL
+                          placeholder:(UIImage *)placeholder
+                              options:(YYWebImageOptions)options
+                           completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setHighlightedImageWithURL:imageURL
+                            placeholder:placeholder
+                                options:options
+                                manager:nil
+                               progress:nil
+                              transform:nil
+                             completion:completion];
+}
+
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL
+                          placeholder:(UIImage *)placeholder
+                              options:(YYWebImageOptions)options
+                             progress:(YYWebImageProgressBlock)progress
+                            transform:(YYWebImageTransformBlock)transform
+                           completion:(YYWebImageCompletionBlock)completion {
+    [self yy_setHighlightedImageWithURL:imageURL
+                            placeholder:placeholder
+                                options:options
+                                manager:nil
+                               progress:progress
+                              transform:nil
+                             completion:completion];
+}
+
+- (void)yy_setHighlightedImageWithURL:(NSURL *)imageURL
+                          placeholder:(UIImage *)placeholder
+                              options:(YYWebImageOptions)options
+                              manager:(YYWebImageManager *)manager
+                             progress:(YYWebImageProgressBlock)progress
+                            transform:(YYWebImageTransformBlock)transform
+                           completion:(YYWebImageCompletionBlock)completion {
+    if ([imageURL isKindOfClass:[NSString class]]) imageURL = [NSURL URLWithString:(id)imageURL];
+    manager = manager ? manager : [YYWebImageManager sharedManager];
+    
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageHighlightedSetterKey);
+    if (!setter) {
+        setter = [_YYWebImageSetter new];
+        objc_setAssociatedObject(self, &_YYWebImageHighlightedSetterKey, setter, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+    }
+    int32_t sentinel = [setter cancelWithNewURL:imageURL];
+    
+    _yy_dispatch_sync_on_main_queue(^{
+        if ((options & YYWebImageOptionSetImageWithFadeAnimation) &&
+            !(options & YYWebImageOptionAvoidSetImage)) {
+            if (self.highlighted) {
+                [self.layer removeAnimationForKey:_YYWebImageFadeAnimationKey];
+            }
+        }
+        if (!imageURL) {
+            if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+                self.highlightedImage = placeholder;
+            }
+            return;
+        }
+        
+        // get the image from memory as quickly as possible
+        UIImage *imageFromMemory = nil;
+        if (manager.cache &&
+            !(options & YYWebImageOptionUseNSURLCache) &&
+            !(options & YYWebImageOptionRefreshImageCache)) {
+            imageFromMemory = [manager.cache getImageForKey:[manager cacheKeyForURL:imageURL] withType:YYImageCacheTypeMemory];
+        }
+        if (imageFromMemory) {
+            if (!(options & YYWebImageOptionAvoidSetImage)) {
+                self.highlightedImage = imageFromMemory;
+            }
+            if(completion) completion(imageFromMemory, imageURL, YYWebImageFromMemoryCacheFast, YYWebImageStageFinished, nil);
+            return;
+        }
+        
+        if (!(options & YYWebImageOptionIgnorePlaceHolder)) {
+            self.highlightedImage = placeholder;
+        }
+        
+        __weak typeof(self) _self = self;
+        dispatch_async([_YYWebImageSetter setterQueue], ^{
+            YYWebImageProgressBlock _progress = nil;
+            if (progress) _progress = ^(NSInteger receivedSize, NSInteger expectedSize) {
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    progress(receivedSize, expectedSize);
+                });
+            };
+            
+            YYWebImageCompletionBlock _completion = ^(UIImage *image, NSURL *url, YYWebImageFromType from, YYWebImageStage stage, NSError *error) {
+                __strong typeof(_self) self = _self;
+                BOOL setImage = (stage == YYWebImageStageFinished || stage == YYWebImageStageProgress) && image && !(options & YYWebImageOptionAvoidSetImage);
+                BOOL showFade = ((options & YYWebImageOptionSetImageWithFadeAnimation) && self.highlighted);
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    if (setImage && self) {
+                        if (showFade) {
+                            CATransition *transition = [CATransition animation];
+                            transition.duration = stage == YYWebImageStageFinished ? _YYWebImageFadeTime : _YYWebImageProgressiveFadeTime;
+                            transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
+                            transition.type = kCATransitionFade;
+                            [self.layer addAnimation:transition forKey:_YYWebImageFadeAnimationKey];
+                        }
+                        self.highlightedImage = image;
+                    }
+                    if (completion) completion(image, url, from, stage, error);
+                });
+            };
+            
+            [setter setOperationWithSentinel:sentinel url:imageURL options:options manager:manager progress:_progress transform:transform completion:_completion];
+        });
+    });
+}
+
+- (void)yy_cancelCurrentHighlightedImageRequest {
+    _YYWebImageSetter *setter = objc_getAssociatedObject(self, &_YYWebImageHighlightedSetterKey);
+    if (setter) [setter cancel];
+}
+
+@end

YYWebImage/Categories/_YYWebImageSetter.h

@@ -0,0 +1,62 @@
+//
+//  _YYWebImageSetter.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/7/15.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+#import <UIKit/UIKit.h>
+#import <pthread.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYWebImageManager.h>
+#else
+#import "YYWebImageManager.h"
+#endif
+
+
+/**
+ Submits a block for execution on a main queue and waits until the block completes.
+ */
+static inline void _yy_dispatch_sync_on_main_queue(void (^block)()) {
+    if (pthread_main_np()) {
+        block();
+    } else {
+        dispatch_sync(dispatch_get_main_queue(), block);
+    }
+}
+
+extern NSString *const _YYWebImageFadeAnimationKey;
+extern const NSTimeInterval _YYWebImageFadeTime;
+extern const NSTimeInterval _YYWebImageProgressiveFadeTime;
+
+/**
+ Private class used by web image categories.
+ Typically, you should not use this class directly.
+ */
+@interface _YYWebImageSetter : NSObject
+/// Current image url.
+@property (nonatomic, readonly) NSURL *imageURL;
+
+/// Create new operation for web image.
+- (void)setOperationWithSentinel:(int32_t)sentinel
+                             url:(NSURL *)imageURL
+                         options:(YYWebImageOptions)options
+                         manager:(YYWebImageManager *)manager
+                        progress:(YYWebImageProgressBlock)progress
+                       transform:(YYWebImageTransformBlock)transform
+                      completion:(YYWebImageCompletionBlock)completion;
+
+/// Cancel and return a sentinel value. The imageURL will be set to nil.
+- (int32_t)cancel;
+
+/// Cancel and return a sentinel value. The imageURL will be set to new value.
+- (int32_t)cancelWithNewURL:(NSURL *)imageURL;
+
+/// A queue to set operation.
++ (dispatch_queue_t)setterQueue;
+
+@end

YYWebImage/Categories/_YYWebImageSetter.m

@@ -0,0 +1,102 @@
+//
+//  _YYWebImageSetter.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/7/15.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "_YYWebImageSetter.h"
+#import "YYWebImageOperation.h"
+#import <libkern/OSAtomic.h>
+
+NSString *const _YYWebImageFadeAnimationKey = @"YYWebImageFade";
+const NSTimeInterval _YYWebImageFadeTime = 0.2;
+const NSTimeInterval _YYWebImageProgressiveFadeTime = 0.4;
+
+
+@implementation _YYWebImageSetter {
+    OSSpinLock _lock;
+    NSURL *_imageURL;
+    NSOperation *_operation;
+    int32_t _sentinel;
+}
+
+- (instancetype)init {
+    self = [super init];
+    _lock = OS_SPINLOCK_INIT;
+    return self;
+}
+
+- (NSURL *)imageURL {
+    OSSpinLockLock(&_lock);
+    NSURL *imageURL = _imageURL;
+    OSSpinLockUnlock(&_lock);
+    return imageURL;
+}
+
+- (void)dealloc {
+    OSAtomicIncrement32(&_sentinel);
+    [_operation cancel];
+}
+
+- (void)setOperationWithSentinel:(int32_t)sentinel
+                             url:(NSURL *)imageURL
+                         options:(YYWebImageOptions)options
+                         manager:(YYWebImageManager *)manager
+                        progress:(YYWebImageProgressBlock)progress
+                       transform:(YYWebImageTransformBlock)transform
+                      completion:(YYWebImageCompletionBlock)completion {
+    if (sentinel != _sentinel) {
+        if (completion) completion(nil, imageURL, YYWebImageFromNone, YYWebImageStageCancelled, nil);
+        return;
+    }
+    
+    NSOperation *operation = [manager requestImageWithURL:imageURL options:options progress:progress transform:transform completion:completion];
+    if (!operation && completion) {
+        NSDictionary *userInfo = @{ NSLocalizedDescriptionKey : @"YYWebImageOperation create failed." };
+        completion(nil, imageURL, YYWebImageFromNone, YYWebImageStageFinished, [NSError errorWithDomain:@"com.ibireme.yykit.webimage" code:-1 userInfo:userInfo]);
+    }
+    
+    OSSpinLockLock(&_lock);
+    if (sentinel == _sentinel) {
+        if (_operation) [_operation cancel];
+        _operation = operation;
+        OSAtomicIncrement32(&_sentinel);
+    } else {
+        [operation cancel];
+    }
+    OSSpinLockUnlock(&_lock);
+}
+
+- (int32_t)cancel {
+    return [self cancelWithNewURL:nil];
+}
+
+- (int32_t)cancelWithNewURL:(NSURL *)imageURL {
+    int32_t sentinel;
+    OSSpinLockLock(&_lock);
+    if (_operation) {
+        [_operation cancel];
+        _operation = nil;
+    }
+    _imageURL = imageURL;
+    sentinel = OSAtomicIncrement32(&_sentinel);
+    OSSpinLockUnlock(&_lock);
+    return sentinel;
+}
+
++ (dispatch_queue_t)setterQueue {
+    static dispatch_queue_t queue;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        queue = dispatch_queue_create("com.ibireme.yykit.webimage.setter", DISPATCH_QUEUE_SERIAL);
+        dispatch_set_target_queue(queue, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0));
+    });
+    return queue;
+}
+
+@end

YYWebImage/Image/YYAnimatedImageView.h

@@ -0,0 +1,121 @@
+//
+//  YYAnimatedImageView.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 14/10/19.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+/**
+ An image view for displaying animated image.
+ 
+ @discussion It is a fully compatible `UIImageView` subclass.
+ If the `image` or `highlightedImage` property adopt to the `YYAnimatedImage` protocol,
+ then it can be used to play the multi-frame animation. The animation can also be 
+ controlled with the UIImageView methods `-startAnimating`, `-stopAnimating` and `-isAnimating`.
+ 
+ This view request the frame data just in time. When the device has enough free memory, 
+ this view may cache some or all future frames in an inner buffer for lower CPU cost.
+ Buffer size is dynamically adjusted based on the current state of the device memory.
+ 
+ Sample Code:
+ 
+     // ani@3x.gif
+     YYImage *image = [YYImage imageNamed:@"ani"];
+     YYAnimatedImageView *imageView = [YYAnimatedImageView alloc] initWithImage:image];
+     [view addSubView:imageView];
+ */
+@interface YYAnimatedImageView : UIImageView
+
+/**
+ If the image has more than one frame, set this value to `YES` will automatically 
+ play/stop the animation when the view become visible/invisible.
+ 
+ The default value is `YES`.
+ */
+@property (nonatomic, assign) BOOL autoPlayAnimatedImage;
+
+/**
+ Index of the currently displayed frame (index from 0).
+ 
+ Set a new value to this property will cause to display the new frame immediately.
+ If the new value is invalid, this method has no effect.
+ 
+ You can add an observer to this property to observe the playing status.
+ */
+@property (nonatomic, assign) NSUInteger currentAnimatedImageIndex;
+
+/**
+ Whether the image view is playing animation currently.
+ 
+ You can add an observer to this property to observe the playing status.
+ */
+@property (nonatomic, readonly) BOOL currentIsPlayingAnimation;
+
+/**
+ The animation timer's runloop mode, default is `NSRunLoopCommonModes`.
+ 
+ Set this property to `NSDefaultRunLoopMode` will make the animation pause during
+ UIScrollView scrolling.
+ */
+@property (nonatomic, copy) NSString *runloopMode;
+
+/**
+ The max size (in bytes) for inner frame buffer size, default is 0 (dynamically).
+ 
+ When the device has enough free memory, this view will request and decode some or 
+ all future frame image into an inner buffer. If this property's value is 0, then 
+ the max buffer size will be dynamically adjusted based on the current state of 
+ the device free memory. Otherwise, the buffer size will be limited by this value.
+ 
+ When receive memory warning or app enter background, the buffer will be released 
+ immediately, and may grow back at the right time.
+ */
+@property (nonatomic, assign) NSUInteger maxBufferSize;
+
+@end
+
+
+
+/**
+ The YYAnimatedImage protocol declares the required methods for animated image
+ display with YYAnimatedImageView.
+ 
+ Subclass a UIImage and implement this protocol, so that instances of that class 
+ can be set to YYAnimatedImageView.image or YYAnimatedImageView.highlightedImage
+ to display animation.
+ 
+ See `YYImage` and `YYFrameImage` for example.
+ */
+@protocol YYAnimatedImage <NSObject>
+@required
+/// Total animated frame count.
+/// It the frame count is less than 1, then the methods below will be ignored.
+- (NSUInteger)animatedImageFrameCount;
+
+/// Animation loop count, 0 means infinite looping.
+- (NSUInteger)animatedImageLoopCount;
+
+/// Bytes per frame (in memory). It may used to optimize memory buffer size.
+- (NSUInteger)animatedImageBytesPerFrame;
+
+/// Returns the frame image from a specified index.
+/// This method may be called on background thread.
+/// @param index  Frame index (zero based).
+- (UIImage *)animatedImageFrameAtIndex:(NSUInteger)index;
+
+/// Returns the frames's duration from a specified index.
+/// @param index  Frame index (zero based).
+- (NSTimeInterval)animatedImageDurationAtIndex:(NSUInteger)index;
+
+@optional
+/// A rectangle in image coordinates defining the subrectangle of the image that
+/// will be displayed. The rectangle should not outside the image's bounds.
+/// It may used to display sprite animation with a single image (sprite sheet).
+- (CGRect)animatedImageContentsRectAtIndex:(NSUInteger)index;
+@end

YYWebImage/Image/YYAnimatedImageView.m

@@ -0,0 +1,653 @@
+//
+//  YYAnimatedImageView.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 14/10/19.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYAnimatedImageView.h"
+#import "YYImageCoder.h"
+#import <pthread.h>
+#import <libkern/OSAtomic.h>
+#import <mach/mach.h>
+
+
+#define BUFFER_SIZE (10 * 1024 * 1024) // 10MB (minimum memory buffer size)
+
+#define LOCK(...) OSSpinLockLock(&self->_lock); \
+__VA_ARGS__; \
+OSSpinLockUnlock(&self->_lock);
+
+#define LOCK_VIEW(...) OSSpinLockLock(&view->_lock); \
+__VA_ARGS__; \
+OSSpinLockUnlock(&view->_lock);
+
+
+static int64_t _YYDeviceMemoryTotal() {
+    int64_t mem = [[NSProcessInfo processInfo] physicalMemory];
+    if (mem < -1) mem = -1;
+        return mem;
+}
+
+static int64_t _YYDeviceMemoryFree() {
+    mach_port_t host_port = mach_host_self();
+    mach_msg_type_number_t host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
+    vm_size_t page_size;
+    vm_statistics_data_t vm_stat;
+    kern_return_t kern;
+    
+    kern = host_page_size(host_port, &page_size);
+    if (kern != KERN_SUCCESS) return -1;
+    kern = host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size);
+    if (kern != KERN_SUCCESS) return -1;
+    return vm_stat.free_count * page_size;
+}
+
+/**
+ A proxy used to hold a weak object.
+ It can be used to avoid retain cycles, such as the target in NSTimer or CADisplayLink.
+ */
+@interface _YYImageWeakProxy : NSProxy
+@property (nonatomic, weak, readonly) id target;
+- (instancetype)initWithTarget:(id)target;
++ (instancetype)proxyWithTarget:(id)target;
+@end
+
+@implementation _YYImageWeakProxy
+- (instancetype)initWithTarget:(id)target {
+    _target = target;
+    return self;
+}
++ (instancetype)proxyWithTarget:(id)target {
+    return [[_YYImageWeakProxy alloc] initWithTarget:target];
+}
+- (id)forwardingTargetForSelector:(SEL)selector {
+    return _target;
+}
+- (void)forwardInvocation:(NSInvocation *)invocation {
+    void *null = NULL;
+    [invocation setReturnValue:&null];
+}
+- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector {
+    return [NSObject instanceMethodSignatureForSelector:@selector(init)];
+}
+- (BOOL)respondsToSelector:(SEL)aSelector {
+    return [_target respondsToSelector:aSelector];
+}
+- (BOOL)isEqual:(id)object {
+    return [_target isEqual:object];
+}
+- (NSUInteger)hash {
+    return [_target hash];
+}
+- (Class)superclass {
+    return [_target superclass];
+}
+- (Class)class {
+    return [_target class];
+}
+- (BOOL)isKindOfClass:(Class)aClass {
+    return [_target isKindOfClass:aClass];
+}
+- (BOOL)isMemberOfClass:(Class)aClass {
+    return [_target isMemberOfClass:aClass];
+}
+- (BOOL)conformsToProtocol:(Protocol *)aProtocol {
+    return [_target conformsToProtocol:aProtocol];
+}
+- (BOOL)isProxy {
+    return YES;
+}
+- (NSString *)description {
+    return [_target description];
+}
+- (NSString *)debugDescription {
+    return [_target debugDescription];
+}
+@end
+
+
+
+
+typedef NS_ENUM(NSUInteger, YYAnimagedImageType) {
+    YYAnimagedImageTypeNone = 0,
+    YYAnimagedImageTypeImage,
+    YYAnimagedImageTypeHighlightedImage,
+    YYAnimagedImageTypeImages,
+    YYAnimagedImageTypeHighlightedImages,
+};
+
+@interface YYAnimatedImageView() {
+    @package
+    UIImage <YYAnimatedImage> *_curAnimatedImage;
+    
+    dispatch_once_t _onceToken;
+    OSSpinLock _lock; ///< lock for _buffer
+    NSOperationQueue *_requestQueue; ///< image request queue, serial
+    
+    CADisplayLink *_link; ///< ticker for change frame
+    NSTimeInterval _time; ///< time after last frame
+    
+    UIImage *_curFrame; ///< current frame to display
+    NSUInteger _curIndex; ///< current frame index (from 0)
+    NSUInteger _totalFrameCount; ///< total frame count
+    
+    BOOL _loopEnd; ///< weather the loop is end.
+    NSUInteger _curLoop; ///< current loop count (from 0)
+    NSUInteger _totalLoop; ///< total loop count, 0 means infinity
+    
+    NSMutableDictionary *_buffer; ///< frame buffer
+    BOOL _bufferMiss; ///< whether miss frame on last opportunity
+    NSUInteger _maxBufferCount; ///< maximum buffer count
+    NSInteger _incrBufferCount; ///< current allowed buffer count (will increase by step)
+    
+    CGRect _curContentsRect;
+    BOOL _curImageHasContentsRect; ///< image has implementated "animatedImageContentsRectAtIndex:"
+}
+@property (nonatomic, readwrite) BOOL currentIsPlayingAnimation;
+- (void)calcMaxBufferCount;
+@end
+
+/// An operation for image fetch
+@interface _YYAnimatedImageViewFetchOperation : NSOperation
+@property (nonatomic, weak) YYAnimatedImageView *view;
+@property (nonatomic, assign) NSUInteger nextIndex;
+@property (nonatomic, strong) UIImage <YYAnimatedImage> *curImage;
+@end
+
+@implementation _YYAnimatedImageViewFetchOperation
+- (void)main {
+    __strong YYAnimatedImageView *view = _view;
+    if (!view) return;
+    if ([self isCancelled]) return;
+    view->_incrBufferCount++;
+    if (view->_incrBufferCount == 0) [view calcMaxBufferCount];
+    if ((int)view->_incrBufferCount > (int)view->_maxBufferCount) {
+        view->_incrBufferCount = view->_maxBufferCount;
+    }
+    NSUInteger idx = _nextIndex;
+    NSUInteger max = view->_incrBufferCount < 1 ? 1 : view->_incrBufferCount;
+    NSUInteger total = view->_totalFrameCount;
+    for (int i = 0; i < max; i++, idx++) {
+        @autoreleasepool {
+            if (idx >= total) idx = 0;
+            if ([self isCancelled]) break;
+            LOCK_VIEW(BOOL miss = (view->_buffer[@(idx)] == nil));
+            if (miss) {
+                UIImage *img = [_curImage animatedImageFrameAtIndex:idx];
+                img = [img yy_imageByDecoded];
+                if ([self isCancelled]) break;
+                LOCK_VIEW(view->_buffer[@(idx)] = img ? img : [NSNull null]);
+            }
+        }
+    }
+}
+@end
+
+@implementation YYAnimatedImageView
+
+- (instancetype)init {
+    self = [super init];
+    _runloopMode = NSRunLoopCommonModes;
+    _autoPlayAnimatedImage = YES;
+    return self;
+}
+
+- (instancetype)initWithImage:(UIImage *)image {
+    self = [super init];
+    _runloopMode = NSRunLoopCommonModes;
+    _autoPlayAnimatedImage = YES;
+    self.frame = (CGRect) {CGPointZero, image.size };
+    self.image = image;
+    return self;
+}
+
+- (instancetype)initWithImage:(UIImage *)image highlightedImage:(UIImage *)highlightedImage {
+    self = [super init];
+    _runloopMode = NSRunLoopCommonModes;
+    _autoPlayAnimatedImage = YES;
+    CGSize size = image ? image.size : highlightedImage.size;
+    self.frame = (CGRect) {CGPointZero, size };
+    self.image = image;
+    self.highlightedImage = highlightedImage;
+    return self;
+}
+
+// init the animated params.
+- (void)resetAnimated {
+    dispatch_once(&_onceToken, ^{
+        _lock = OS_SPINLOCK_INIT;
+        _buffer = [NSMutableDictionary new];
+        _requestQueue = [[NSOperationQueue alloc] init];
+        _requestQueue.maxConcurrentOperationCount = 1;
+        _link = [CADisplayLink displayLinkWithTarget:[_YYImageWeakProxy proxyWithTarget:self] selector:@selector(step:)];
+        if (_runloopMode) {
+            [_link addToRunLoop:[NSRunLoop mainRunLoop] forMode:_runloopMode];
+        }
+        _link.paused = YES;
+        
+        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didReceiveMemoryWarning:) name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
+        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
+    });
+    
+    [_requestQueue cancelAllOperations];
+    LOCK(
+         if (_buffer.count) {
+             NSMutableDictionary *holder = _buffer;
+             _buffer = [NSMutableDictionary new];
+             dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0), ^{
+                 // Capture the dictionary to global queue,
+                 // release these images in background to avoid blocking UI thread.
+                 [holder class];
+             });
+         }
+    );
+    _link.paused = YES;
+    _time = 0;
+    if (_curIndex != 0) {
+        [self willChangeValueForKey:@"currentAnimatedImageIndex"];
+        _curIndex = 0;
+        [self didChangeValueForKey:@"currentAnimatedImageIndex"];
+    }
+    _curAnimatedImage = nil;
+    _curFrame = nil;
+    _curLoop = 0;
+    _totalLoop = 0;
+    _totalFrameCount = 1;
+    _loopEnd = NO;
+    _bufferMiss = NO;
+    _incrBufferCount = 0;
+}
+
+- (void)setImage:(UIImage *)image {
+    if (self.image == image) return;
+    [self setImage:image withType:YYAnimagedImageTypeImage];
+}
+
+- (void)setHighlightedImage:(UIImage *)highlightedImage {
+    if (self.highlightedImage == highlightedImage) return;
+    [self setImage:highlightedImage withType:YYAnimagedImageTypeHighlightedImage];
+}
+
+- (void)setAnimationImages:(NSArray *)animationImages {
+    if (self.animationImages == animationImages) return;
+    [self setImage:animationImages withType:YYAnimagedImageTypeImages];
+}
+
+- (void)setHighlightedAnimationImages:(NSArray *)highlightedAnimationImages {
+    if (self.highlightedAnimationImages == highlightedAnimationImages) return;
+    [self setImage:highlightedAnimationImages withType:YYAnimagedImageTypeHighlightedImages];
+}
+
+- (void)setHighlighted:(BOOL)highlighted {
+    [super setHighlighted:highlighted];
+    if (_link) [self resetAnimated];
+    [self imageChanged];
+}
+
+- (id)imageForType:(YYAnimagedImageType)type {
+    switch (type) {
+        case YYAnimagedImageTypeNone: return nil;
+        case YYAnimagedImageTypeImage: return self.image;
+        case YYAnimagedImageTypeHighlightedImage: return self.highlightedImage;
+        case YYAnimagedImageTypeImages: return self.animationImages;
+        case YYAnimagedImageTypeHighlightedImages: return self.highlightedAnimationImages;
+    }
+    return nil;
+}
+
+- (YYAnimagedImageType)currentImageType {
+    YYAnimagedImageType curType = YYAnimagedImageTypeNone;
+    if (self.highlighted) {
+        if (self.highlightedAnimationImages.count) curType = YYAnimagedImageTypeHighlightedImages;
+        else if (self.highlightedImage) curType = YYAnimagedImageTypeHighlightedImage;
+    }
+    if (curType == YYAnimagedImageTypeNone) {
+        if (self.animationImages.count) curType = YYAnimagedImageTypeImages;
+        else if (self.image) curType = YYAnimagedImageTypeImage;
+    }
+    return curType;
+}
+
+- (void)setImage:(id)image withType:(YYAnimagedImageType)type {
+    [self stopAnimating];
+    if (_link) [self resetAnimated];
+    _curFrame = nil;
+    switch (type) {
+        case YYAnimagedImageTypeNone: break;
+        case YYAnimagedImageTypeImage: super.image = image; break;
+        case YYAnimagedImageTypeHighlightedImage: super.highlightedImage = image; break;
+        case YYAnimagedImageTypeImages: super.animationImages = image; break;
+        case YYAnimagedImageTypeHighlightedImages: super.highlightedAnimationImages = image; break;
+    }
+    [self imageChanged];
+}
+
+- (void)imageChanged {
+    YYAnimagedImageType newType = [self currentImageType];
+    id newVisibleImage = [self imageForType:newType];
+    NSUInteger newImageFrameCount = 0;
+    BOOL hasContentsRect = NO;
+    if ([newVisibleImage isKindOfClass:[UIImage class]] &&
+        [newVisibleImage conformsToProtocol:@protocol(YYAnimatedImage)]) {
+        newImageFrameCount = ((UIImage<YYAnimatedImage> *) newVisibleImage).animatedImageFrameCount;
+        if (newImageFrameCount > 1) {
+            hasContentsRect = [((UIImage<YYAnimatedImage> *) newVisibleImage) respondsToSelector:@selector(animatedImageContentsRectAtIndex:)];
+        }
+    }
+    if (!hasContentsRect && _curImageHasContentsRect) {
+        if (!CGRectEqualToRect(self.layer.contentsRect, CGRectMake(0, 0, 1, 1)) ) {
+            [CATransaction begin];
+            [CATransaction setDisableActions:YES];
+            self.layer.contentsRect = CGRectMake(0, 0, 1, 1);
+            [CATransaction commit];
+        }
+    }
+    _curImageHasContentsRect = hasContentsRect;
+    if (hasContentsRect) {
+        CGRect rect = [((UIImage<YYAnimatedImage> *) newVisibleImage) animatedImageContentsRectAtIndex:0];
+        [self setContentsRect:rect forImage:newVisibleImage];
+    }
+    
+    if (newImageFrameCount > 1) {
+        [self resetAnimated];
+        _curAnimatedImage = newVisibleImage;
+        _curFrame = newVisibleImage;
+        _totalLoop = _curAnimatedImage.animatedImageLoopCount;
+        _totalFrameCount = _curAnimatedImage.animatedImageFrameCount;
+        [self calcMaxBufferCount];
+    }
+    [self setNeedsDisplay];
+    [self didMoved];
+}
+
+// dynamically adjust buffer size for current memory.
+- (void)calcMaxBufferCount {
+    NSUInteger bytes = _curAnimatedImage.animatedImageBytesPerFrame;
+    if (bytes == 0) bytes = 1;
+    
+    int64_t total = _YYDeviceMemoryTotal();
+    int64_t free = _YYDeviceMemoryFree();
+    int64_t max = MIN(total * 0.2, free * 0.6);
+    max = MAX(max, BUFFER_SIZE);
+    if (_maxBufferSize) max = max > _maxBufferSize ? _maxBufferSize : max;
+    _maxBufferCount = (float)max / (float)bytes;
+    if (_maxBufferCount == 0) _maxBufferCount = 1;
+}
+
+- (void)dealloc {
+    [_requestQueue cancelAllOperations];
+    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
+    [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
+    [_link invalidate];
+}
+
+- (BOOL)isAnimating {
+    return self.currentIsPlayingAnimation;
+}
+
+- (void)stopAnimating {
+    [super stopAnimating];
+    _link.paused = YES;
+    self.currentIsPlayingAnimation = NO;
+}
+
+- (void)startAnimating {
+    YYAnimagedImageType type = [self currentImageType];
+    if (type == YYAnimagedImageTypeImages || type == YYAnimagedImageTypeHighlightedImages) {
+        NSArray *images = [self imageForType:type];
+        if (images.count > 0) {
+            [super startAnimating];
+            self.currentIsPlayingAnimation = YES;
+        }
+    } else {
+        if (_curAnimatedImage && _link.paused) {
+            _curLoop = 0;
+            _loopEnd = NO;
+            _link.paused = NO;
+            self.currentIsPlayingAnimation = YES;
+        }
+    }
+}
+
+- (void)didReceiveMemoryWarning:(NSNotification *)notification {
+    [_requestQueue cancelAllOperations];
+    [_requestQueue addOperationWithBlock: ^{
+        _incrBufferCount = -60 - (int)(arc4random() % 120); // about 1~3 seconds to grow back..
+        NSNumber *next = @((_curIndex + 1) % _totalFrameCount);
+        LOCK(
+             NSArray * keys = _buffer.allKeys;
+             for (NSNumber * key in keys) {
+                 if (![key isEqualToNumber:next]) { // keep the next frame for smoothly animation
+                     [_buffer removeObjectForKey:key];
+                 }
+             }
+        )//LOCK
+    }];
+}
+
+- (void)didEnterBackground:(NSNotification *)notification {
+    [_requestQueue cancelAllOperations];
+    NSNumber *next = @((_curIndex + 1) % _totalFrameCount);
+    LOCK(
+         NSArray * keys = _buffer.allKeys;
+         for (NSNumber * key in keys) {
+             if (![key isEqualToNumber:next]) { // keep the next frame for smoothly animation
+                 [_buffer removeObjectForKey:key];
+             }
+         }
+     )//LOCK
+}
+
+- (void)step:(CADisplayLink *)link {
+    UIImage <YYAnimatedImage> *image = _curAnimatedImage;
+    NSMutableDictionary *buffer = _buffer;
+    UIImage *bufferedImage = nil;
+    NSUInteger nextIndex = (_curIndex + 1) % _totalFrameCount;
+    BOOL bufferIsFull = NO;
+    
+    if (!image) return;
+    if (_loopEnd) { // view will keep in last frame
+        [self stopAnimating];
+        return;
+    }
+    
+    NSTimeInterval delay = 0;
+    if (!_bufferMiss) {
+        _time += link.duration;
+        delay = [image animatedImageDurationAtIndex:_curIndex];
+        if (_time < delay) return;
+        _time -= delay;
+        if (nextIndex == 0) {
+            _curLoop++;
+            if (_curLoop >= _totalLoop && _totalLoop != 0) {
+                _loopEnd = YES;
+                [self stopAnimating];
+                [self.layer setNeedsDisplay]; // let system call `displayLayer:` before runloop sleep
+                return; // stop at last frame
+            }
+        }
+        delay = [image animatedImageDurationAtIndex:nextIndex];
+        if (_time > delay) _time = delay; // do not jump over frame
+    }
+    LOCK(
+         bufferedImage = buffer[@(nextIndex)];
+         if (bufferedImage) {
+             if ((int)_incrBufferCount < _totalFrameCount) {
+                 [buffer removeObjectForKey:@(nextIndex)];
+             }
+             [self willChangeValueForKey:@"currentAnimatedImageIndex"];
+             _curIndex = nextIndex;
+             [self didChangeValueForKey:@"currentAnimatedImageIndex"];
+             _curFrame = bufferedImage == (id)[NSNull null] ? nil : bufferedImage;
+             if (_curImageHasContentsRect) {
+                 _curContentsRect = [image animatedImageContentsRectAtIndex:_curIndex];
+                 [self setContentsRect:_curContentsRect forImage:_curFrame];
+             }
+             nextIndex = (_curIndex + 1) % _totalFrameCount;
+             _bufferMiss = NO;
+             if (buffer.count == _totalFrameCount) {
+                 bufferIsFull = YES;
+             }
+         } else {
+             _bufferMiss = YES;
+         }
+    )//LOCK
+    
+    if (!_bufferMiss) {
+        [self.layer setNeedsDisplay]; // let system call `displayLayer:` before runloop sleep
+    }
+    
+    if (!bufferIsFull && _requestQueue.operationCount == 0) { // if some work not finished, wait for next opportunity
+        _YYAnimatedImageViewFetchOperation *operation = [_YYAnimatedImageViewFetchOperation new];
+        operation.view = self;
+        operation.nextIndex = nextIndex;
+        operation.curImage = image;
+        [_requestQueue addOperation:operation];
+    }
+}
+
+- (void)displayLayer:(CALayer *)layer {
+    if (_curFrame) {
+        layer.contents = (__bridge id)_curFrame.CGImage;
+    }
+}
+
+- (void)setContentsRect:(CGRect)rect forImage:(UIImage *)image{
+    CGRect layerRect = CGRectMake(0, 0, 1, 1);
+    if (image) {
+        CGSize imageSize = image.size;
+        if (imageSize.width > 0.01 && imageSize.height > 0.01) {
+            layerRect.origin.x = rect.origin.x / imageSize.width;
+            layerRect.origin.y = rect.origin.y / imageSize.height;
+            layerRect.size.width = rect.size.width / imageSize.width;
+            layerRect.size.height = rect.size.height / imageSize.height;
+            layerRect = CGRectIntersection(layerRect, CGRectMake(0, 0, 1, 1));
+            if (CGRectIsNull(layerRect) || CGRectIsEmpty(layerRect)) {
+                layerRect = CGRectMake(0, 0, 1, 1);
+            }
+        }
+    }
+    [CATransaction begin];
+    [CATransaction setDisableActions:YES];
+    self.layer.contentsRect = layerRect;
+    [CATransaction commit];
+}
+
+- (void)didMoved {
+    if (self.autoPlayAnimatedImage) {
+        if(self.superview && self.window) {
+            [self startAnimating];
+        } else {
+            [self stopAnimating];
+        }
+    }
+}
+
+- (void)didMoveToWindow {
+    [super didMoveToWindow];
+    [self didMoved];
+}
+
+- (void)didMoveToSuperview {
+    [super didMoveToSuperview];
+    [self didMoved];
+}
+
+- (void)setCurrentAnimatedImageIndex:(NSUInteger)currentAnimatedImageIndex {
+    if (!_curAnimatedImage) return;
+    if (currentAnimatedImageIndex >= _curAnimatedImage.animatedImageFrameCount) return;
+    if (_curIndex == currentAnimatedImageIndex) return;
+    
+    void (^block)() = ^{
+        LOCK(
+             [_requestQueue cancelAllOperations];
+             [_buffer removeAllObjects];
+             [self willChangeValueForKey:@"currentAnimatedImageIndex"];
+             _curIndex = currentAnimatedImageIndex;
+             [self didChangeValueForKey:@"currentAnimatedImageIndex"];
+             _curFrame = [_curAnimatedImage animatedImageFrameAtIndex:_curIndex];
+             if (_curImageHasContentsRect) {
+                 _curContentsRect = [_curAnimatedImage animatedImageContentsRectAtIndex:_curIndex];
+             }
+             _time = 0;
+             _loopEnd = NO;
+             _bufferMiss = NO;
+             [self.layer setNeedsDisplay];
+        )//LOCK
+    };
+    
+    if (pthread_main_np()) {
+        block();
+    } else {
+        dispatch_async(dispatch_get_main_queue(), block);
+    }
+}
+
+- (NSUInteger)currentAnimatedImageIndex {
+    return _curIndex;
+}
+
+- (void)setRunloopMode:(NSString *)runloopMode {
+    if ([_runloopMode isEqual:runloopMode]) return;
+    if (_link) {
+        if (_runloopMode) {
+            [_link removeFromRunLoop:[NSRunLoop mainRunLoop] forMode:_runloopMode];
+        }
+        if (runloopMode.length) {
+            [_link addToRunLoop:[NSRunLoop mainRunLoop] forMode:runloopMode];
+        }
+    }
+    _runloopMode = runloopMode.copy;
+}
+
+#pragma mark - Overrice NSObject(NSKeyValueObservingCustomization)
+
++ (BOOL)automaticallyNotifiesObserversForKey:(NSString *)key {
+    if ([key isEqualToString:@"currentAnimatedImageIndex"]) {
+        return NO;
+    }
+    return [super automaticallyNotifiesObserversForKey:key];
+}
+
+#pragma mark - NSCoding
+
+- (instancetype)initWithCoder:(NSCoder *)aDecoder {
+    self = [super initWithCoder:aDecoder];
+    _runloopMode = [aDecoder decodeObjectForKey:@"runloopMode"];
+    if (_runloopMode.length == 0) _runloopMode = NSRunLoopCommonModes;
+    _autoPlayAnimatedImage = [aDecoder decodeBoolForKey:@"autoPlayAnimatedImage"];
+    
+    UIImage *image = [aDecoder decodeObjectForKey:@"YYAnimatedImage"];
+    UIImage *highlightedImage = [aDecoder decodeObjectForKey:@"YYHighlightedAnimatedImage"];
+    if (image) {
+        self.image = image;
+        [self setImage:image withType:YYAnimagedImageTypeImage];
+    }
+    if (highlightedImage) {
+        self.highlightedImage = highlightedImage;
+        [self setImage:highlightedImage withType:YYAnimagedImageTypeHighlightedImage];
+    }
+    return self;
+}
+
+- (void)encodeWithCoder:(NSCoder *)aCoder {
+    [super encodeWithCoder:aCoder];
+    [aCoder encodeObject:_runloopMode forKey:@"runloopMode"];
+    [aCoder encodeBool:_autoPlayAnimatedImage forKey:@"autoPlayAnimatedImage"];
+    
+    BOOL ani, multi;
+    ani = [self.image conformsToProtocol:@protocol(YYAnimatedImage)];
+    multi = (ani && ((UIImage <YYAnimatedImage> *)self.image).animatedImageFrameCount > 1);
+    if (multi) [aCoder encodeObject:self.image forKey:@"YYAnimatedImage"];
+    
+    ani = [self.highlightedImage conformsToProtocol:@protocol(YYAnimatedImage)];
+    multi = (ani && ((UIImage <YYAnimatedImage> *)self.highlightedImage).animatedImageFrameCount > 1);
+    if (multi) [aCoder encodeObject:self.highlightedImage forKey:@"YYHighlightedAnimatedImage"];
+}
+
+@end

YYWebImage/Image/YYFrameImage.h

@@ -0,0 +1,95 @@
+//
+//  YYFrameImage.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 14/12/9.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYAnimatedImageView.h>
+#else
+#import "YYAnimatedImageView.h"
+#endif
+
+/**
+ An image to display frame-based animation.
+ 
+ @discussion It is a fully compatible `UIImage` subclass.
+ It only support system image format such as png and jpeg.
+ The animation can be played by YYAnimatedImageView.
+ 
+ Sample Code:
+     
+     NSArray *paths = @[@"/ani/frame1.png", @"/ani/frame2.png", @"/ani/frame3.png"];
+     NSArray *times = @[@0.1, @0.2, @0.1];
+     YYFrameImage *image = [YYFrameImage alloc] initWithImagePaths:paths frameDurations:times repeats:YES];
+     YYAnimatedImageView *imageView = [YYAnimatedImageView alloc] initWithImage:image];
+     [view addSubView:imageView];
+ */
+@interface YYFrameImage : UIImage <YYAnimatedImage>
+
+/**
+ Create a frame animated image from files.
+ 
+ @param paths            An array of NSString objects, contains the full or 
+                         partial path to each image file.
+                         e.g. @[@"/ani/1.png",@"/ani/2.png",@"/ani/3.png"]
+ 
+ @param oneFrameDuration The duration (in seconds) per frame.
+ 
+ @param loopCount        The animation loop count, 0 means infinite.
+ 
+ @return An initialized YYFrameImage object, or nil when an error occurs.
+ */
+- (instancetype)initWithImagePaths:(NSArray *)paths oneFrameDuration:(NSTimeInterval)oneFrameDuration loopCount:(NSUInteger)loopCount;
+
+/**
+ Create a frame animated image from files.
+ 
+ @param paths          An array of NSString objects, contains the full or
+                       partial path to each image file.
+                       e.g. @[@"/ani/frame1.png",@"/ani/frame2.png",@"/ani/frame3.png"]
+ 
+ @param frameDurations An array of NSNumber objects, contains the duration (in seconds) per frame.
+                       e.g. @[@0.1, @0.2, @0.3];
+ 
+ @param loopCount      The animation loop count, 0 means infinite.
+ 
+ @return An initialized YYFrameImage object, or nil when an error occurs.
+ */
+- (instancetype)initWithImagePaths:(NSArray *)paths frameDurations:(NSArray *)frameDurations loopCount:(NSUInteger)loopCount;
+
+/**
+ Create a frame animated image from an array of data.
+ 
+ @param dataArray        An array of NSData objects.
+ 
+ @param oneFrameDuration The duration (in seconds) per frame.
+ 
+ @param loopCount        The animation loop count, 0 means infinite.
+ 
+ @return An initialized YYFrameImage object, or nil when an error occurs.
+ */
+- (instancetype)initWithImageDataArray:(NSArray *)dataArray oneFrameDuration:(NSTimeInterval)oneFrameDuration loopCount:(NSUInteger)loopCount;
+
+/**
+ Create a frame animated image from an array of data.
+ 
+ @param dataArray      An array of NSData objects.
+ 
+ @param frameDurations An array of NSNumber objects, contains the duration (in seconds) per frame.
+                       e.g. @[@0.1, @0.2, @0.3];
+ 
+ @param loopCount      The animation loop count, 0 means infinite.
+ 
+ @return An initialized YYFrameImage object, or nil when an error occurs.
+ */
+- (instancetype)initWithImageDataArray:(NSArray *)dataArray frameDurations:(NSArray *)frameDurations loopCount:(NSUInteger)loopCount;
+
+@end

YYWebImage/Image/YYFrameImage.m

@@ -0,0 +1,150 @@
+//
+//  YYFrameImage.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 14/12/9.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYFrameImage.h"
+#import "YYImageCoder.h"
+
+
+/**
+ Return the path scale.
+ 
+ e.g.
+ <table>
+ <tr><th>Path            </th><th>Scale </th></tr>
+ <tr><td>"icon.png"      </td><td>1     </td></tr>
+ <tr><td>"icon@2x.png"   </td><td>2     </td></tr>
+ <tr><td>"icon@2.5x.png" </td><td>2.5   </td></tr>
+ <tr><td>"icon@2x"       </td><td>1     </td></tr>
+ <tr><td>"icon@2x..png"  </td><td>1     </td></tr>
+ <tr><td>"icon@2x.png/"  </td><td>1     </td></tr>
+ </table>
+ */
+static CGFloat _NSStringPathScale(NSString *string) {
+    if (string.length == 0 || [string hasSuffix:@"/"]) return 1;
+    NSString *name = string.stringByDeletingPathExtension;
+    __block CGFloat scale = 1;
+    
+    NSRegularExpression *pattern = [NSRegularExpression regularExpressionWithPattern:@"@[0-9]+\\.?[0-9]*x$" options:NSRegularExpressionAnchorsMatchLines error:nil];
+    [pattern enumerateMatchesInString:name options:kNilOptions range:NSMakeRange(0, name.length) usingBlock:^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop) {
+        if (result.range.location >= 3) {
+            scale = [string substringWithRange:NSMakeRange(result.range.location + 1, result.range.length - 2)].doubleValue;
+        }
+    }];
+    
+    return scale;
+}
+
+
+
+@implementation YYFrameImage {
+    NSUInteger _loopCount;
+    NSUInteger _oneFrameBytes;
+    NSArray *_imagePaths;
+    NSArray *_imageDatas;
+    NSArray *_frameDurations;
+}
+
+- (instancetype)initWithImagePaths:(NSArray *)paths oneFrameDuration:(NSTimeInterval)oneFrameDuration loopCount:(NSUInteger)loopCount {
+    NSMutableArray *durations = [NSMutableArray new];
+    for (int i = 0, max = (int)paths.count; i < max; i++) {
+        [durations addObject:@(oneFrameDuration)];
+    }
+    return [self initWithImagePaths:paths frameDurations:durations loopCount:loopCount];
+}
+
+- (instancetype)initWithImagePaths:(NSArray *)paths frameDurations:(NSArray *)frameDurations loopCount:(NSUInteger)loopCount {
+    if (paths.count == 0) return nil;
+    if (paths.count != frameDurations.count) return nil;
+    
+    NSString *firstPath = paths[0];
+    NSData *firstData = [NSData dataWithContentsOfFile:firstPath];
+    CGFloat scale = _NSStringPathScale(firstPath);
+    UIImage *firstCG = [[[UIImage alloc] initWithData:firstData] yy_imageByDecoded];
+    self = [self initWithCGImage:firstCG.CGImage scale:scale orientation:UIImageOrientationUp];
+    if (!self) return nil;
+    long frameByte = CGImageGetBytesPerRow(firstCG.CGImage) * CGImageGetHeight(firstCG.CGImage);
+    _oneFrameBytes = (NSUInteger)frameByte;
+    _imagePaths = paths.copy;
+    _frameDurations = frameDurations.copy;
+    _loopCount = loopCount;
+    
+    return self;
+}
+
+- (instancetype)initWithImageDataArray:(NSArray *)dataArray oneFrameDuration:(NSTimeInterval)oneFrameDuration loopCount:(NSUInteger)loopCount {
+    NSMutableArray *durations = [NSMutableArray new];
+    for (int i = 0, max = (int)dataArray.count; i < max; i++) {
+        [durations addObject:@(oneFrameDuration)];
+    }
+    return [self initWithImageDataArray:dataArray frameDurations:durations loopCount:loopCount];
+}
+
+- (instancetype)initWithImageDataArray:(NSArray *)dataArray frameDurations:(NSArray *)frameDurations loopCount:(NSUInteger)loopCount {
+    if (dataArray.count == 0) return nil;
+    if (dataArray.count != frameDurations.count) return nil;
+    
+    NSData *firstData = dataArray[0];
+    CGFloat scale = [UIScreen mainScreen].scale;
+    UIImage *firstCG = [[[UIImage alloc] initWithData:firstData] yy_imageByDecoded];
+    self = [self initWithCGImage:firstCG.CGImage scale:scale orientation:UIImageOrientationUp];
+    if (!self) return nil;
+    long frameByte = CGImageGetBytesPerRow(firstCG.CGImage) * CGImageGetHeight(firstCG.CGImage);
+    _oneFrameBytes = (NSUInteger)frameByte;
+    _imageDatas = dataArray.copy;
+    _frameDurations = frameDurations.copy;
+    _loopCount = loopCount;
+    
+    return self;
+}
+
+#pragma mark - YYAnimtedImage
+
+- (NSUInteger)animatedImageFrameCount {
+    if (_imagePaths) {
+        return _imagePaths.count;
+    } else if (_imageDatas) {
+        return _imageDatas.count;
+    } else {
+        return 1;
+    }
+}
+
+- (NSUInteger)animatedImageLoopCount {
+    return _loopCount;
+}
+
+- (NSUInteger)animatedImageBytesPerFrame {
+    return _oneFrameBytes;
+}
+
+- (UIImage *)animatedImageFrameAtIndex:(NSUInteger)index {
+    if (_imagePaths) {
+        if (index >= _imagePaths.count) return nil;
+        NSString *path = _imagePaths[index];
+        CGFloat scale = _NSStringPathScale(path);
+        NSData *data = [NSData dataWithContentsOfFile:path];
+        return [[UIImage imageWithData:data scale:scale] yy_imageByDecoded];
+    } else if (_imageDatas) {
+        if (index >= _imageDatas.count) return nil;
+        NSData *data = _imageDatas[index];
+        return [[UIImage imageWithData:data scale:[UIScreen mainScreen].scale] yy_imageByDecoded];
+    } else {
+        return index == 0 ? self : nil;
+    }
+}
+
+- (NSTimeInterval)animatedImageDurationAtIndex:(NSUInteger)index {
+    if (index >= _frameDurations.count) return 0;
+    NSNumber *num = _frameDurations[index];
+    return [num doubleValue];
+}
+
+@end

YYWebImage/Image/YYImage.h

@@ -0,0 +1,81 @@
+//
+//  YYImage.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 14/10/20.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYFrameImage.h>
+#import <YYWebImage/YYSpriteSheetImage.h>
+#import <YYWebImage/YYImageCoder.h>
+#import <YYWebImage/YYAnimatedImageView.h>
+#else
+#import "YYFrameImage.h"
+#import "YYSpriteSheetImage.h"
+#import "YYImageCoder.h"
+#import "YYAnimatedImageView.h"
+#endif
+
+
+/**
+ A YYImage object is a high-level way to display animated image data.
+ 
+ @discussion It is a fully compatible `UIImage` subclass. It extends the UIImage
+ to support animated WebP, APNG and GIF format image data decoding. It also 
+ support NSCoding protocol to archive and unarchive multi-frame image data.
+ 
+ If the image is created from multi-frame image data, and you want to play the 
+ animation, try replace UIImageView with `YYAnimatedImageView`.
+ 
+ Sample Code:
+ 
+     // animation@3x.webp
+     YYImage *image = [YYImage imageNamed:@"animation.webp"];
+     YYAnimatedImageView *imageView = [YYAnimatedImageView alloc] initWithImage:image];
+     [view addSubView:imageView];
+    
+ */
+@interface YYImage : UIImage <YYAnimatedImage>
+
++ (YYImage *)imageNamed:(NSString *)name; // no cache!
++ (YYImage *)imageWithContentsOfFile:(NSString *)path;
++ (YYImage *)imageWithData:(NSData *)data;
++ (YYImage *)imageWithData:(NSData *)data scale:(CGFloat)scale;
+
+/**
+ If the image is created from data or file, then the value indicates the data type.
+ */
+@property (nonatomic, readonly) YYImageType animatedImageType;
+
+/**
+ If the image is created from animated image data (multi-frame GIF/APNG/WebP),
+ this property stores the original image data.
+ */
+@property (nonatomic, readonly) NSData *animatedImageData;
+
+/**
+ The total memory usage (in bytes) if all frame images was loaded into memory.
+ The value is 0 if the image is not created from a multi-frame image data.
+ */
+@property (nonatomic, readonly) NSUInteger animatedImageMemorySize;
+
+/**
+ Preload all frame image to memory.
+ 
+ @discussion Set this property to `YES` will block the calling thread to decode 
+ all animation frame image to memory, set to `NO` will release the preloaded frames.
+ If the image is shared by lots of image views (such as emoticon), preload all
+ frames will reduce the CPU cost.
+ 
+ See `animatedImageMemorySize` for memory cost.
+ */
+@property (nonatomic, assign) BOOL preloadAllAnimatedImageFrames;
+
+@end

YYWebImage/Image/YYImage.m

@@ -0,0 +1,255 @@
+//
+//  YYImage.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 14/10/20.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYImage.h"
+#import <libkern/OSAtomic.h>
+
+/**
+ An array of NSNumber objects, shows the best order for path scale search.
+ e.g. iPhone3GS:@[@1,@2,@3] iPhone5:@[@2,@3,@1]  iPhone6 Plus:@[@3,@2,@1]
+ */
+static NSArray *_NSBundlePreferredScales() {
+    static NSArray *scales;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        CGFloat screenScale = [UIScreen mainScreen].scale;
+        if (screenScale <= 1) {
+            scales = @[@1,@2,@3];
+        } else if (screenScale <= 2) {
+            scales = @[@2,@3,@1];
+        } else {
+            scales = @[@3,@2,@1];
+        }
+    });
+    return scales;
+}
+
+/**
+ Add scale modifier to the file name (without path extension),
+ From @"name" to @"name@2x".
+ 
+ e.g.
+ <table>
+ <tr><th>Before     </th><th>After(scale:2)</th></tr>
+ <tr><td>"icon"     </td><td>"icon@2x"     </td></tr>
+ <tr><td>"icon "    </td><td>"icon @2x"    </td></tr>
+ <tr><td>"icon.top" </td><td>"icon.top@2x" </td></tr>
+ <tr><td>"/p/name"  </td><td>"/p/name@2x"  </td></tr>
+ <tr><td>"/path/"   </td><td>"/path/"      </td></tr>
+ </table>
+ 
+ @param scale Resource scale.
+ @return String by add scale modifier, or just return if it's not end with file name.
+ */
+static NSString *_NSStringByAppendingNameScale(NSString *string, CGFloat scale) {
+    if (!string) return nil;
+    if (fabs(scale - 1) <= __FLT_EPSILON__ || string.length == 0 || [string hasSuffix:@"/"]) return string.copy;
+    return [string stringByAppendingFormat:@"@%@x", @(scale)];
+}
+
+/**
+ Return the path scale.
+ 
+ e.g.
+ <table>
+ <tr><th>Path            </th><th>Scale </th></tr>
+ <tr><td>"icon.png"      </td><td>1     </td></tr>
+ <tr><td>"icon@2x.png"   </td><td>2     </td></tr>
+ <tr><td>"icon@2.5x.png" </td><td>2.5   </td></tr>
+ <tr><td>"icon@2x"       </td><td>1     </td></tr>
+ <tr><td>"icon@2x..png"  </td><td>1     </td></tr>
+ <tr><td>"icon@2x.png/"  </td><td>1     </td></tr>
+ </table>
+ */
+static CGFloat _NSStringPathScale(NSString *string) {
+    if (string.length == 0 || [string hasSuffix:@"/"]) return 1;
+    NSString *name = string.stringByDeletingPathExtension;
+    __block CGFloat scale = 1;
+    
+    NSRegularExpression *pattern = [NSRegularExpression regularExpressionWithPattern:@"@[0-9]+\\.?[0-9]*x$" options:NSRegularExpressionAnchorsMatchLines error:nil];
+    [pattern enumerateMatchesInString:name options:kNilOptions range:NSMakeRange(0, name.length) usingBlock:^(NSTextCheckingResult *result, NSMatchingFlags flags, BOOL *stop) {
+        if (result.range.location >= 3) {
+            scale = [string substringWithRange:NSMakeRange(result.range.location + 1, result.range.length - 2)].doubleValue;
+        }
+    }];
+    
+    return scale;
+}
+
+
+@implementation YYImage {
+    YYImageDecoder *_decoder;
+    NSArray *_preloadedFrames;
+    OSSpinLock _preloadedLock;
+    NSUInteger _bytesPerFrame;
+}
+
++ (YYImage *)imageNamed:(NSString *)name {
+    if (name.length == 0) return nil;
+    if ([name hasSuffix:@"/"]) return nil;
+    
+    NSString *res = name.stringByDeletingPathExtension;
+    NSString *ext = name.pathExtension;
+    NSString *path = nil;
+    CGFloat scale = 1;
+    
+    NSArray *scales = _NSBundlePreferredScales();
+    for (int s = 0; s < scales.count; s++) {
+        scale = ((NSNumber *)scales[s]).floatValue;
+        NSString *scaledName = _NSStringByAppendingNameScale(res, scale);
+        // If no extension, guess by system supported (same as UIImage).
+        NSArray *exts = ext.length > 0 ? @[ext] : @[@"", @"png", @"jpeg", @"jpg", @"gif", @"webp"];
+        for (NSString *e in exts) {
+            path = [[NSBundle mainBundle] pathForResource:scaledName ofType:e];
+            if (path) break;
+        }
+        if (path) break;
+    }
+    if (path.length == 0) return nil;
+    
+    NSData *data = [NSData dataWithContentsOfFile:path];
+    if (data.length == 0) return nil;
+    
+    return [[self alloc] initWithData:data scale:scale];
+}
+
++ (YYImage *)imageWithContentsOfFile:(NSString *)path {
+    return [[self alloc] initWithContentsOfFile:path];
+}
+
++ (YYImage *)imageWithData:(NSData *)data {
+    return [[self alloc] initWithData:data];
+}
+
++ (YYImage *)imageWithData:(NSData *)data scale:(CGFloat)scale {
+    return [[self alloc] initWithData:data scale:scale];
+}
+
+- (instancetype)initWithContentsOfFile:(NSString *)path {
+    NSData *data = [NSData dataWithContentsOfFile:path];
+    return [self initWithData:data scale:_NSStringPathScale(path)];
+}
+
+- (instancetype)initWithData:(NSData *)data {
+    return [self initWithData:data scale:1];
+}
+
+- (instancetype)initWithData:(NSData *)data scale:(CGFloat)scale {
+    if (data.length == 0) return nil;
+    if (scale <= 0) scale = 1;
+    _preloadedLock = OS_SPINLOCK_INIT;
+    @autoreleasepool {
+        YYImageDecoder *decoder = [YYImageDecoder decoderWithData:data scale:scale];
+        YYImageFrame *frame = [decoder frameAtIndex:0 decodeForDisplay:YES];
+        UIImage *image = frame.image;
+        if (!image) return nil;
+        self = [self initWithCGImage:image.CGImage scale:decoder.scale orientation:image.imageOrientation];
+        if (!self) return nil;
+        _animatedImageType = decoder.type;
+        if (decoder.frameCount > 1) {
+            _decoder = decoder;
+            _bytesPerFrame = CGImageGetBytesPerRow(image.CGImage) * CGImageGetHeight(image.CGImage);
+            _animatedImageMemorySize = _bytesPerFrame * decoder.frameCount;
+        }
+        self.yy_isDecodedForDisplay = YES;
+    }
+    return self;
+}
+
+- (NSData *)animatedImageData {
+    return _decoder.data;
+}
+
+- (void)setPreloadAllAnimatedImageFrames:(BOOL)preloadAllAnimatedImageFrames {
+    if (_preloadAllAnimatedImageFrames != preloadAllAnimatedImageFrames) {
+        if (preloadAllAnimatedImageFrames && _decoder.frameCount > 0) {
+            NSMutableArray *frames = [NSMutableArray new];
+            for (NSUInteger i = 0, max = _decoder.frameCount; i < max; i++) {
+                UIImage *img = [self animatedImageFrameAtIndex:i];
+                if (img) {
+                    [frames addObject:img];
+                } else {
+                    [frames addObject:[NSNull null]];
+                }
+            }
+            OSSpinLockLock(&_preloadedLock);
+            _preloadedFrames = frames;
+            OSSpinLockUnlock(&_preloadedLock);
+        } else {
+            OSSpinLockLock(&_preloadedLock);
+            _preloadedFrames = nil;
+            OSSpinLockUnlock(&_preloadedLock);
+        }
+    }
+}
+
+#pragma mark - protocol NSCoding
+
+- (instancetype)initWithCoder:(NSCoder *)aDecoder {
+    NSNumber *scale = [aDecoder decodeObjectForKey:@"YYImageScale"];
+    NSData *data = [aDecoder decodeObjectForKey:@"YYImageData"];
+    if (data.length) {
+        self = [self initWithData:data scale:scale.doubleValue];
+    } else {
+        self = [super initWithCoder:aDecoder];
+    }
+    return self;
+}
+
+- (void)encodeWithCoder:(NSCoder *)aCoder {
+    if (_decoder.data.length) {
+        [aCoder encodeObject:@(self.scale) forKey:@"YYImageScale"];
+        [aCoder encodeObject:_decoder.data forKey:@"YYImageData"];
+    } else {
+        [super encodeWithCoder:aCoder]; // Apple use UIImagePNGRepresentation() to encode UIImage.
+    }
+}
+
+#pragma mark - protocol YYAnimatedImage
+
+- (NSUInteger)animatedImageFrameCount {
+    return _decoder.frameCount;
+}
+
+- (NSUInteger)animatedImageLoopCount {
+    return _decoder.loopCount;
+}
+
+- (NSUInteger)animatedImageBytesPerFrame {
+    return _bytesPerFrame;
+}
+
+- (UIImage *)animatedImageFrameAtIndex:(NSUInteger)index {
+    if (index >= _decoder.frameCount) return nil;
+    OSSpinLockLock(&_preloadedLock);
+    UIImage *image = _preloadedFrames[index];
+    OSSpinLockUnlock(&_preloadedLock);
+    if (image) return image == (id)[NSNull null] ? nil : image;
+    return [_decoder frameAtIndex:index decodeForDisplay:YES].image;
+}
+
+- (NSTimeInterval)animatedImageDurationAtIndex:(NSUInteger)index {
+    NSTimeInterval duration = [_decoder frameDurationAtIndex:index];
+    
+    /*
+     http://opensource.apple.com/source/WebCore/WebCore-7600.1.25/platform/graphics/cg/ImageSourceCG.cpp
+     Many annoying ads specify a 0 duration to make an image flash as quickly as 
+     possible. We follow Safari and Firefox's behavior and use a duration of 100 ms 
+     for any frames that specify a duration of <= 10 ms.
+     See <rdar://problem/7689300> and <http://webkit.org/b/36082> for more information.
+     
+     See also: http://nullsleep.tumblr.com/post/16524517190/animated-gif-minimum-frame-delay-browser.
+     */
+    if (duration < 0.011f) return 0.100f;
+    return duration;
+}
+
+@end

YYWebImage/Image/YYImageCoder.h

@@ -0,0 +1,502 @@
+//
+//  YYImageCoder.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/5/13.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+/**
+ Image file type.
+ */
+typedef NS_ENUM(NSUInteger, YYImageType) {
+    YYImageTypeUnknown = 0, ///< unknown
+    YYImageTypeJPEG,        ///< jpeg, jpg
+    YYImageTypeJPEG2000,    ///< jp2
+    YYImageTypeTIFF,        ///< tiff, tif
+    YYImageTypeBMP,         ///< bmp
+    YYImageTypeICO,         ///< ico
+    YYImageTypeICNS,        ///< icns
+    YYImageTypeGIF,         ///< gif
+    YYImageTypePNG,         ///< png
+    YYImageTypeWebP,        ///< webp
+    YYImageTypeOther,       ///< other image format
+};
+
+
+/**
+ Dispose method specifies how the area used by the current frame is to be treated
+ before rendering the next frame on the canvas.
+ */
+typedef NS_ENUM(NSUInteger, YYImageDisposeMethod) {
+    
+    /**
+     No disposal is done on this frame before rendering the next; the contents
+     of the canvas are left as is.
+     */
+    YYImageDisposeNone = 0,
+    
+    /**
+     The frame's region of the canvas is to be cleared to fully transparent black
+     before rendering the next frame.
+     */
+    YYImageDisposeBackground,
+    
+    /**
+     The frame's region of the canvas is to be reverted to the previous contents
+     before rendering the next frame.
+     */
+    YYImageDisposePrevious,
+};
+
+/**
+ Blend operation specifies how transparent pixels of the current frame are
+ blended with those of the previous canvas.
+ */
+typedef NS_ENUM(NSUInteger, YYImageBlendOperation) {
+    
+    /**
+     All color components of the frame, including alpha, overwrite the current
+     contents of the frame's canvas region.
+     */
+    YYImageBlendNone = 0,
+    
+    /**
+     The frame should be composited onto the output buffer based on its alpha.
+     */
+    YYImageBlendOver,
+};
+
+/**
+ An image frame object.
+ */
+@interface YYImageFrame : NSObject <NSCopying>
+@property (nonatomic, assign) NSUInteger index;    ///< Frame index (zero based)
+@property (nonatomic, assign) NSUInteger width;    ///< Frame width
+@property (nonatomic, assign) NSUInteger height;   ///< Frame height
+@property (nonatomic, assign) NSUInteger offsetX;  ///< Frame origin.x in canvas (left-bottom based)
+@property (nonatomic, assign) NSUInteger offsetY;  ///< Frame origin.y in canvas (left-bottom based)
+@property (nonatomic, assign) NSTimeInterval duration;      ///< Frame duration in seconds
+@property (nonatomic, assign) YYImageDisposeMethod dispose; ///< Frame dispose method.
+@property (nonatomic, assign) YYImageBlendOperation blend;  ///< Frame blend operation.
+@property (nonatomic, strong) UIImage *image; ///< The image.
++ (instancetype)frameWithImage:(UIImage *)image;
+@end
+
+
+#pragma mark - Decoder
+
+/**
+ An image decoder to decode image data.
+ 
+ @discussion This class supports decoding animated WebP, APNG, GIF and system
+ image format such as PNG, JPG, JP2, BMP, TIFF, PIC, ICNS and ICO. It can be used 
+ to decode complete image data, or to decode incremental image data during image 
+ download. This class is thread-safe.
+ 
+ Example:
+ 
+    // Decode single image:
+    NSData *data = [NSData dataWithContentOfFile:@"/tmp/image.webp"];
+    YYImageDecoder *decoder = [YYImageDecoder decoderWithData:data scale:2.0];
+    UIImage image = [decoder frameAtIndex:0 decodeForDisplay:YES].image;
+ 
+    // Decode image during download:
+    NSMutableData *data = [NSMutableData new];
+    YYImageDecoder *decoder = [[YYImageDecoder alloc] initWithScale:2.0];
+    while(newDataArrived) {
+        [data appendData:newData];
+        [decoder updateData:data final:NO];
+        if (decoder.frameCount > 0) {
+            UIImage image = [decoder frameAtIndex:0 decodeForDisplay:YES].image;
+            // progressive display...
+        }
+    }
+    [decoder updateData:data final:YES];
+    UIImage image = [decoder frameAtIndex:0 decodeForDisplay:YES].image;
+    // final display...
+ 
+ */
+@interface YYImageDecoder : NSObject
+
+@property (nonatomic, readonly) NSData *data;       ///< Image data.
+@property (nonatomic, readonly) YYImageType type;   ///< Image data type.
+@property (nonatomic, readonly) CGFloat scale;      ///< Image scale.
+@property (nonatomic, readonly) NSUInteger frameCount;     ///< Image frame count.
+@property (nonatomic, readonly) NSUInteger loopCount;      ///< Image loop count, 0 means infinite.
+@property (nonatomic, readonly) NSUInteger width;          ///< Image canvas width.
+@property (nonatomic, readonly) NSUInteger height;         ///< Image canvas height.
+@property (nonatomic, readonly, getter=isFinalized) BOOL finalized;
+
+/**
+ Creates an image decoder.
+ 
+ @param scale  Image's scale.
+ @return An image decoder.
+ */
+- (instancetype)initWithScale:(CGFloat)scale NS_DESIGNATED_INITIALIZER;
+
+/**
+ Updates the incremental image with new data.
+ 
+ @discussion You can use this method to decode progressive/interlaced/baseline
+ image when you do not have the complete image data. The `data` was retained by
+ decoder, you should not modify the data in other thread during decoding.
+ 
+ @param data  The data to add to the image decoder. Each time you call this 
+ function, the 'data' parameter must contain all of the image file data 
+ accumulated so far.
+ 
+ @param final  A value that specifies whether the data is the final set. 
+ Pass YES if it is, NO otherwise. When the data is already finalized, you can
+ not update the data anymore.
+ 
+ @return Whether succeed.
+ */
+- (BOOL)updateData:(NSData *)data final:(BOOL)final;
+
+/**
+ Convenience method to create a decoder with specified data.
+ @param data  Image data.
+ @param scale Image's scale.
+ @return A new decoder, or nil if an error occurs.
+ */
++ (instancetype)decoderWithData:(NSData *)data scale:(CGFloat)scale;
+
+/**
+ Decodes and returns a frame from a specified index.
+ @param index  Frame image index (zero-based).
+ @param decodeForDisplay Whether decode the image to memory bitmap for display.
+    If NO, it will try to returns the original frame data without blend.
+ @return A new frame with image, or nil if an error occurs.
+ */
+- (YYImageFrame *)frameAtIndex:(NSUInteger)index decodeForDisplay:(BOOL)decodeForDisplay;
+
+/**
+ Returns the frame duration from a specified index.
+ @param index  Frame image (zero-based).
+ @return Duration in seconds.
+ */
+- (NSTimeInterval)frameDurationAtIndex:(NSUInteger)index;
+
+/**
+ Returns the frame's properties. See "CGImageProperties.h" in ImageIO.framework
+ for more information.
+ 
+ @param index  Frame image index (zero-based).
+ @return The ImageIO frame property.
+ */
+- (NSDictionary *)framePropertiesAtIndex:(NSUInteger)index;
+
+/**
+ Returns the image's properties. See "CGImageProperties.h" in ImageIO.framework
+ for more information.
+ */
+- (NSDictionary *)imageProperties;
+
+@end
+
+
+
+#pragma mark - Encoder
+
+/**
+ An image encoder to encode image to data.
+ 
+ @discussion It supports encoding single frame image with the type defined in YYImageType.
+ It also supports encoding multi-frame image with GIF, APNG and WebP.
+ 
+ Example:
+    
+    YYImageEncoder *jpegEncoder = [[YYImageEncoder alloc] initWithType:YYImageTypeJPEG];
+    jpegEncoder.quality = 0.9;
+    [jpegEncoder addImage:image duration:0];
+    NSData jpegData = [jpegEncoder encode];
+ 
+    YYImageEncoder *gifEncoder = [[YYImageEncoder alloc] initWithType:YYImageTypeGIF];
+    gifEncoder.loopCount = 5;
+    [gifEncoder addImage:image0 duration:0.1];
+    [gifEncoder addImage:image1 duration:0.15];
+    [gifEncoder addImage:image2 duration:0.2];
+    NSData gifData = [gifEncoder encode];
+ 
+ @warning It just pack the images together when encoding multi-frame image. If you
+ want to reduce the image file size, try imagemagick/ffmpeg for GIF and WebP,
+ and apngasm for APNG.
+ */
+@interface YYImageEncoder : NSObject
+
+@property (nonatomic, readonly) YYImageType type;   ///< Image type.
+@property (nonatomic, assign) NSUInteger loopCount; ///< Loop count, 0 means infinit, only available for GIF/APNG/WebP.
+@property (nonatomic, assign) BOOL lossless;        ///< Lossless, only available for WebP.
+@property (nonatomic, assign) CGFloat quality;      ///< Compress quality, 0.0~1.0, only available for JPG/JP2/WebP.
+
+- (instancetype)init UNAVAILABLE_ATTRIBUTE;
++ (instancetype)new UNAVAILABLE_ATTRIBUTE;
+
+/**
+ Create an image encoder with a specified type.
+ @param type Image type.
+ @return A new encoder, or nil if an error occurs.
+ */
+- (instancetype)initWithType:(YYImageType)type NS_DESIGNATED_INITIALIZER;
+
+/**
+ Add an image to encoder.
+ @param image    Image.
+ @param duration Image duration for animation. Pass 0 to ignore this parameter.
+ */
+- (void)addImage:(UIImage *)image duration:(NSTimeInterval)duration;
+
+/**
+ Add an image with image data to encoder.
+ @param data    Image data.
+ @param duration Image duration for animation. Pass 0 to ignore this parameter.
+ */
+- (void)addImageWithData:(NSData *)data duration:(NSTimeInterval)duration;
+
+/**
+ Add an image from a file path to encoder.
+ @param image    Image file path.
+ @param duration Image duration for animation. Pass 0 to ignore this parameter.
+ */
+- (void)addImageWithFile:(NSString *)path duration:(NSTimeInterval)duration;
+
+/**
+ Encodes the image and returns the image data.
+ @return The image data, or nil if an error occurs.
+ */
+- (NSData *)encode;
+
+/**
+ Encodes the image to a file.
+ @param path The file path (overwrite if exist).
+ @return Whether succeed.
+ */
+- (BOOL)encodeToFile:(NSString *)path;
+
+/**
+ Convenience method to encode single frame image.
+ @param image   The image.
+ @param type    The destination image type.
+ @param quality Image quality, 0.0~1.0.
+ @return The image data, or nil if an error occurs.
+ */
++ (NSData *)encodeImage:(UIImage *)image type:(YYImageType)type quality:(CGFloat)quality;
+
+/**
+ Convenience method to encode image from a decoder.
+ @param decoder The image decoder.
+ @param type    The destination image type;
+ @param quality Image quality, 0.0~1.0.
+ @return The image data, or nil if an error occurs.
+ */
++ (NSData *)encodeImageWithDecoder:(YYImageDecoder *)decoder type:(YYImageType)type quality:(CGFloat)quality;
+
+@end
+
+
+#pragma mark - UIImage
+
+@interface UIImage (YYImageCoder)
+
+/**
+ Decompress this image to bitmap, so when the image is displayed on screen, 
+ the main thread won't be blocked by additional decode. If the image has already
+ been decoded or unable to decode, it just returns itself.
+ 
+ @return an image decoded, or just return itself if no needed.
+ @see yy_isDecodedForDisplay
+ */
+- (instancetype)yy_imageByDecoded;
+
+/**
+ Wherher the image can be display on screen without additional decoding.
+ @warning It just a hint for your code, change it has no other effect.
+ */
+@property (nonatomic, assign) BOOL yy_isDecodedForDisplay;
+
+/**
+ Saves this image to iOS Photos Album. 
+ 
+ @discussion  This method attempts to save the original data to album if the
+ image is created from an animated GIF/APNG, otherwise, it will save the image 
+ as JPEG or PNG (based on the alpha information).
+ 
+ @param completionBlock The block invoked (in main thread) after the save operation completes.
+    assetURL: An URL that identifies the saved image file. If the image is not saved, assetURL is nil.
+    error: If the image is not saved, an error object that describes the reason for failure, otherwise nil.
+ */
+- (void)yy_saveToAlbumWithCompletionBlock:(void(^)(NSURL *assetURL, NSError *error))completionBlock;
+
+/**
+ Return a 'best' data representation for this image.
+ 
+ @discussion The convertion based on these rule:
+ 1. If the image is created from an animated GIF/APNG/WebP, it returns the original data.
+ 2. It returns PNG or JPEG(0.9) representation based on the alpha information.
+ 
+ @return Image data, or nil if an error occurs.
+ */
+- (NSData *)yy_imageDataRepresentation;
+
+@end
+
+
+
+#pragma mark - Helper
+
+/// Detect a data's image type by reading the data's header 16 bytes (very fast).
+CG_EXTERN YYImageType YYImageDetectType(CFDataRef data);
+
+/// Convert YYImageType to UTI (such as kUTTypeJPEG).
+CG_EXTERN CFStringRef YYImageTypeToUTType(YYImageType type);
+
+/// Convert UTI (such as kUTTypeJPEG) to YYImageType.
+CG_EXTERN YYImageType YYImageTypeFromUTType(CFStringRef uti);
+
+/// Get image type's file extension (such as @"jpg").
+CG_EXTERN NSString *YYImageTypeGetExtension(YYImageType type);
+
+
+
+/// Returns the shared DeviceRGB color space.
+CG_EXTERN CGColorSpaceRef YYCGColorSpaceGetDeviceRGB();
+
+/// Returns the shared DeviceGray color space.
+CG_EXTERN CGColorSpaceRef YYCGColorSpaceGetDeviceGray();
+
+/// Returns whether a color space is DeviceRGB.
+CG_EXTERN BOOL YYCGColorSpaceIsDeviceRGB(CGColorSpaceRef space);
+
+/// Returns whether a color space is DeviceGray.
+CG_EXTERN BOOL YYCGColorSpaceIsDeviceGray(CGColorSpaceRef space);
+
+
+
+/// Convert EXIF orientation value to UIImageOrientation.
+CG_EXTERN UIImageOrientation YYUIImageOrientationFromEXIFValue(NSInteger value);
+
+/// Convert UIImageOrientation to EXIF orientation value.
+CG_EXTERN NSInteger YYUIImageOrientationToEXIFValue(UIImageOrientation orientation);
+
+
+
+/**
+ Create a decoded image.
+ 
+ @discussion If the source image is created from a compressed image data (such as
+ PNG or JPEG), you can use this method to decode the image. After decoded, you can
+ access the decoded bytes with CGImageGetDataProvider() and CGDataProviderCopyData()
+ without additional decode process. If the image has already decoded, this method
+ just copy the decoded bytes to the new image.
+ 
+ @param imageRef          The source image.
+ @param decodeForDisplay  If YES, this method will decode the image and convert
+          it to BGRA8888 (premultiplied) or BGRX8888 format for CALayer display.
+ 
+ @return A decoded image, or NULL if an error occurs.
+ */
+CG_EXTERN CGImageRef YYCGImageCreateDecodedCopy(CGImageRef imageRef, BOOL decodeForDisplay);
+
+/**
+ Create an image copy with an orientation.
+ 
+ @param imageRef       Source image
+ @param orientation    Image orientation which will applied to the image.
+ @param destBitmapInfo Destimation image bitmap, only support 32bit format (such as ARGB8888).
+ @return A new image, or NULL if an error occurs.
+ */
+CG_EXTERN CGImageRef YYCGImageCreateCopyWithOrientation(CGImageRef imageRef,
+                                              UIImageOrientation orientation,
+                                              CGBitmapInfo destBitmapInfo);
+
+/**
+ Create an image copy with CGAffineTransform.
+ 
+ @param imageRef       Source image.
+ @param transform      Transform applied to image (left-bottom based coordinate system).
+ @param destSize       Destination image size
+ @param destBitmapInfo Destimation image bitmap, only support 32bit format (such as ARGB8888).
+ @return A new image, or NULL if an error occurs.
+ */
+CG_EXTERN CGImageRef YYCGImageCreateAffineTransformCopy(CGImageRef imageRef,
+                                              CGAffineTransform transform,
+                                              CGSize destSize,
+                                              CGBitmapInfo destBitmapInfo);
+
+/**
+ Encode an image to data with CGImageDestination.
+ 
+ @param imageRef  The image.
+ @param type      The image destination data type.
+ @param quality   The quality (0.0~1.0)
+ @return A new image data, or nil if an error occurs.
+ */
+CG_EXTERN CFDataRef YYCGImageCreateEncodedData(CGImageRef imageRef, YYImageType type, CGFloat quality);
+
+
+/**
+ Whether WebP is available in YYImage.
+ */
+CG_EXTERN BOOL YYImageWebPAvailable();
+
+/**
+ Get a webp image frame count;
+ 
+ @param webpData WebP data.
+ @return Image frame count, or 0 if an error occurs.
+ */
+CG_EXTERN NSUInteger YYImageGetWebPFrameCount(CFDataRef webpData);
+
+/**
+ Decode an image from WebP data, returns NULL if an error occurs.
+ 
+ @param webpData          The WebP data.
+ @param decodeForDisplay  If YES, this method will decode the image and convert it
+                            to BGRA8888 (premultiplied) format for CALayer display.
+ @param useThreads        YES to enable multi-thread decode.
+                            (speed up, but cost more CPU)
+ @param bypassFiltering   YES to skip the in-loop filtering.
+                            (speed up, but may lose some smooth)
+ @param noFancyUpsampling YES to use faster pointwise upsampler.
+                            (speed down, and may lose some details).
+ @return The decoded image, or NULL if an error occurs.
+ */
+CG_EXTERN CGImageRef YYCGImageCreateWithWebPData(CFDataRef webpData,
+                                       BOOL decodeForDisplay,
+                                       BOOL useThreads,
+                                       BOOL bypassFiltering,
+                                       BOOL noFancyUpsampling);
+
+
+typedef NS_ENUM(NSUInteger, YYImagePreset) {
+    YYImagePresetDefault = 0,  ///< default preset.
+    YYImagePresetPicture,      ///< digital picture, like portrait, inner shot
+    YYImagePresetPhoto,        ///< outdoor photograph, with natural lighting
+    YYImagePresetDrawing,      ///< hand or line drawing, with high-contrast details
+    YYImagePresetIcon,         ///< small-sized colorful images
+    YYImagePresetText          ///< text-like
+};
+
+/**
+ Encode a CGImage to WebP data
+ 
+ @param imageRef      image
+ @param lossless      YES=lossless (similar to PNG), NO=lossy (similar to JPEG)
+ @param quality       0.0~1.0 (0=smallest file, 1.0=biggest file)
+                      For lossless image, try the value near 1.0; for lossy, try the value near 0.8.
+ @param compressLevel 0~6 (0=fast, 6=slower-better). Default is 4.
+ @param preset        Preset for different image type, default is YYImagePresetDefault.
+ @return WebP data, or nil if an error occurs.
+ */
+CG_EXTERN CFDataRef YYCGImageCreateEncodedWebPData(CGImageRef imageRef,
+                                         BOOL lossless,
+                                         CGFloat quality,
+                                         int compressLevel,
+                                         YYImagePreset preset);

YYWebImage/Image/YYImageCoder.m

@@ -0,0 +1,2841 @@
+//
+//  YYImageCoder.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/5/13.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYImageCoder.h"
+#import "YYImage.h"
+#import <CoreFoundation/CoreFoundation.h>
+#import <ImageIO/ImageIO.h>
+#import <Accelerate/Accelerate.h>
+#import <QuartzCore/QuartzCore.h>
+#import <MobileCoreServices/MobileCoreServices.h>
+#import <AssetsLibrary/AssetsLibrary.h>
+#import <objc/runtime.h>
+#import <pthread.h>
+#import <libkern/OSAtomic.h>
+#import <zlib.h>
+
+
+
+#ifndef YYIMAGE_WEBP_ENABLED
+#if __has_include(<webp/decode.h>) && __has_include(<webp/encode.h>) && \
+    __has_include(<webp/demux.h>)  && __has_include(<webp/mux.h>)
+#define YYIMAGE_WEBP_ENABLED 1
+#import <webp/decode.h>
+#import <webp/encode.h>
+#import <webp/demux.h>
+#import <webp/mux.h>
+#elif __has_include("webp/decode.h") && __has_include("webp/encode.h") && \
+      __has_include("webp/demux.h")  && __has_include("webp/mux.h")
+#define YYIMAGE_WEBP_ENABLED 1
+#import "webp/decode.h"
+#import "webp/encode.h"
+#import "webp/demux.h"
+#import "webp/mux.h"
+#else
+#define YYIMAGE_WEBP_ENABLED 0
+#endif
+#endif
+
+
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+#pragma mark - Utility (for little endian platform)
+
+#define YY_FOUR_CC(c1,c2,c3,c4) ((uint32_t)(((c4) << 24) | ((c3) << 16) | ((c2) << 8) | (c1)))
+#define YY_TWO_CC(c1,c2) ((uint16_t)(((c2) << 8) | (c1)))
+
+static inline uint16_t yy_swap_endian_uint16(uint16_t value) {
+    return
+    (uint16_t) ((value & 0x00FF) << 8) |
+    (uint16_t) ((value & 0xFF00) >> 8) ;
+}
+
+static inline uint32_t yy_swap_endian_uint32(uint32_t value) {
+    return
+    (uint32_t)((value & 0x000000FFU) << 24) |
+    (uint32_t)((value & 0x0000FF00U) <<  8) |
+    (uint32_t)((value & 0x00FF0000U) >>  8) |
+    (uint32_t)((value & 0xFF000000U) >> 24) ;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+#pragma mark - APNG
+
+/*
+ PNG  spec: http://www.libpng.org/pub/png/spec/1.2/PNG-Structure.html
+ APNG spec: https://wiki.mozilla.org/APNG_Specification
+ 
+ ===============================================================================
+ PNG format:
+ header (8): 89 50 4e 47 0d 0a 1a 0a
+ chunk, chunk, chunk, ...
+ 
+ ===============================================================================
+ chunk format:
+ length (4): uint32_t big endian
+ fourcc (4): chunk type code
+ data   (length): data
+ crc32  (4): uint32_t big endian crc32(fourcc + data)
+ 
+ ===============================================================================
+ PNG chunk define:
+ 
+ IHDR (Image Header) required, must appear first, 13 bytes
+ width              (4) pixel count, should not be zero
+ height             (4) pixel count, should not be zero
+ bit depth          (1) expected: 1, 2, 4, 8, 16
+ color type         (1) 1<<0 (palette used), 1<<1 (color used), 1<<2 (alpha channel used)
+ compression method (1) 0 (deflate/inflate)
+ filter method      (1) 0 (adaptive filtering with five basic filter types)
+ interlace method   (1) 0 (no interlace) or 1 (Adam7 interlace)
+ 
+ IDAT (Image Data) required, must appear consecutively if there's multiple 'IDAT' chunk
+ 
+ IEND (End) required, must appear last, 0 bytes
+ 
+ ===============================================================================
+ APNG chunk define:
+ 
+ acTL (Animation Control) required, must appear before 'IDAT', 8 bytes
+ num frames     (4) number of frames
+ num plays      (4) number of times to loop, 0 indicates infinite looping
+ 
+ fcTL (Frame Control) required, must appear before the 'IDAT' or 'fdAT' chunks of the frame to which it applies, 26 bytes
+ sequence number   (4) sequence number of the animation chunk, starting from 0
+ width             (4) width of the following frame
+ height            (4) height of the following frame
+ x offset          (4) x position at which to render the following frame
+ y offset          (4) y position at which to render the following frame
+ delay num         (2) frame delay fraction numerator
+ delay den         (2) frame delay fraction denominator
+ dispose op        (1) type of frame area disposal to be done after rendering this frame (0:none, 1:background 2:previous)
+ blend op          (1) type of frame area rendering for this frame (0:source, 1:over)
+ 
+ fdAT (Frame Data) required
+ sequence number   (4) sequence number of the animation chunk
+ frame data        (x) frame data for this frame (same as 'IDAT')
+ 
+ ===============================================================================
+ `dispose_op` specifies how the output buffer should be changed at the end of the delay 
+ (before rendering the next frame).
+ 
+ * NONE: no disposal is done on this frame before rendering the next; the contents
+    of the output buffer are left as is.
+ * BACKGROUND: the frame's region of the output buffer is to be cleared to fully
+    transparent black before rendering the next frame.
+ * PREVIOUS: the frame's region of the output buffer is to be reverted to the previous
+    contents before rendering the next frame.
+
+ `blend_op` specifies whether the frame is to be alpha blended into the current output buffer
+ content, or whether it should completely replace its region in the output buffer.
+ 
+ * SOURCE: all color components of the frame, including alpha, overwrite the current contents
+    of the frame's output buffer region. 
+ * OVER: the frame should be composited onto the output buffer based on its alpha,
+    using a simple OVER operation as described in the "Alpha Channel Processing" section
+    of the PNG specification
+ */
+
+typedef enum {
+    YY_PNG_ALPHA_TYPE_PALEETE = 1 << 0,
+    YY_PNG_ALPHA_TYPE_COLOR = 1 << 1,
+    YY_PNG_ALPHA_TYPE_ALPHA = 1 << 2,
+} yy_png_alpha_type;
+
+typedef enum {
+    YY_PNG_DISPOSE_OP_NONE = 0,
+    YY_PNG_DISPOSE_OP_BACKGROUND = 1,
+    YY_PNG_DISPOSE_OP_PREVIOUS = 2,
+} yy_png_dispose_op;
+
+typedef enum {
+    YY_PNG_BLEND_OP_SOURCE = 0,
+    YY_PNG_BLEND_OP_OVER = 1,
+} yy_png_blend_op;
+
+typedef struct {
+    uint32_t width;             ///< pixel count, should not be zero
+    uint32_t height;            ///< pixel count, should not be zero
+    uint8_t bit_depth;          ///< expected: 1, 2, 4, 8, 16
+    uint8_t color_type;         ///< see yy_png_alpha_type
+    uint8_t compression_method; ///< 0 (deflate/inflate)
+    uint8_t filter_method;      ///< 0 (adaptive filtering with five basic filter types)
+    uint8_t interlace_method;   ///< 0 (no interlace) or 1 (Adam7 interlace)
+} yy_png_chunk_IHDR;
+
+typedef struct {
+    uint32_t sequence_number;  ///< sequence number of the animation chunk, starting from 0
+    uint32_t width;            ///< width of the following frame
+    uint32_t height;           ///< height of the following frame
+    uint32_t x_offset;         ///< x position at which to render the following frame
+    uint32_t y_offset;         ///< y position at which to render the following frame
+    uint16_t delay_num;        ///< frame delay fraction numerator
+    uint16_t delay_den;        ///< frame delay fraction denominator
+    uint8_t dispose_op;        ///< see yy_png_dispose_op
+    uint8_t blend_op;          ///< see yy_png_blend_op
+} yy_png_chunk_fcTL;
+
+typedef struct {
+    uint32_t offset; ///< chunk offset in PNG data
+    uint32_t fourcc; ///< chunk fourcc
+    uint32_t length; ///< chunk data length
+    uint32_t crc32;  ///< chunk crc32
+} yy_png_chunk_info;
+
+typedef struct {
+    uint32_t chunk_index; ///< the first `fdAT`/`IDAT` chunk index
+    uint32_t chunk_num;   ///< the `fdAT`/`IDAT` chunk count
+    uint32_t chunk_size;  ///< the `fdAT`/`IDAT` chunk bytes
+    yy_png_chunk_fcTL frame_control;
+} yy_png_frame_info;
+
+typedef struct {
+    yy_png_chunk_IHDR header;   ///< png header
+    yy_png_chunk_info *chunks;      ///< chunks
+    uint32_t chunk_num;          ///< count of chunks
+    
+    yy_png_frame_info *apng_frames; ///< frame info, NULL if not apng
+    uint32_t apng_frame_num;     ///< 0 if not apng
+    uint32_t apng_loop_num;      ///< 0 indicates infinite looping
+    
+    uint32_t *apng_shared_chunk_indexs; ///< shared chunk index
+    uint32_t apng_shared_chunk_num;     ///< shared chunk count
+    uint32_t apng_shared_chunk_size;    ///< shared chunk bytes
+    uint32_t apng_shared_insert_index;  ///< shared chunk insert index
+    bool apng_first_frame_is_cover;     ///< the first frame is same as png (cover)
+} yy_png_info;
+
+static void yy_png_chunk_IHDR_read(yy_png_chunk_IHDR *IHDR, const uint8_t *data) {
+    IHDR->width = yy_swap_endian_uint32(*((uint32_t *)(data)));
+    IHDR->height = yy_swap_endian_uint32(*((uint32_t *)(data + 4)));
+    IHDR->bit_depth = data[8];
+    IHDR->color_type = data[9];
+    IHDR->compression_method = data[10];
+    IHDR->filter_method = data[11];
+    IHDR->interlace_method = data[12];
+}
+
+static void yy_png_chunk_IHDR_write(yy_png_chunk_IHDR *IHDR, uint8_t *data) {
+    *((uint32_t *)(data)) = yy_swap_endian_uint32(IHDR->width);
+    *((uint32_t *)(data + 4)) = yy_swap_endian_uint32(IHDR->height);
+    data[8] = IHDR->bit_depth;
+    data[9] = IHDR->color_type;
+    data[10] = IHDR->compression_method;
+    data[11] = IHDR->filter_method;
+    data[12] = IHDR->interlace_method;
+}
+
+static void yy_png_chunk_fcTL_read(yy_png_chunk_fcTL *fcTL, const uint8_t *data) {
+    fcTL->sequence_number = yy_swap_endian_uint32(*((uint32_t *)(data)));
+    fcTL->width = yy_swap_endian_uint32(*((uint32_t *)(data + 4)));
+    fcTL->height = yy_swap_endian_uint32(*((uint32_t *)(data + 8)));
+    fcTL->x_offset = yy_swap_endian_uint32(*((uint32_t *)(data + 12)));
+    fcTL->y_offset = yy_swap_endian_uint32(*((uint32_t *)(data + 16)));
+    fcTL->delay_num = yy_swap_endian_uint16(*((uint16_t *)(data + 20)));
+    fcTL->delay_den = yy_swap_endian_uint16(*((uint16_t *)(data + 22)));
+    fcTL->dispose_op = data[24];
+    fcTL->blend_op = data[25];
+}
+
+static void yy_png_chunk_fcTL_write(yy_png_chunk_fcTL *fcTL, uint8_t *data) {
+    *((uint32_t *)(data)) = yy_swap_endian_uint32(fcTL->sequence_number);
+    *((uint32_t *)(data + 4)) = yy_swap_endian_uint32(fcTL->width);
+    *((uint32_t *)(data + 8)) = yy_swap_endian_uint32(fcTL->height);
+    *((uint32_t *)(data + 12)) = yy_swap_endian_uint32(fcTL->x_offset);
+    *((uint32_t *)(data + 16)) = yy_swap_endian_uint32(fcTL->y_offset);
+    *((uint16_t *)(data + 20)) = yy_swap_endian_uint16(fcTL->delay_num);
+    *((uint16_t *)(data + 22)) = yy_swap_endian_uint16(fcTL->delay_den);
+    data[24] = fcTL->dispose_op;
+    data[25] = fcTL->blend_op;
+}
+
+// convert double value to fraction
+static void yy_png_delay_to_fraction(double duration, uint16_t *num, uint16_t *den) {
+    if (duration >= 0xFF) {
+        *num = 0xFF;
+        *den = 1;
+    } else if (duration <= 1.0 / (double)0xFF) {
+        *num = 1;
+        *den = 0xFF;
+    } else {
+        // Use continued fraction to calculate the num and den.
+        long MAX = 10;
+        double eps = (0.5 / (double)0xFF);
+        long p[MAX], q[MAX], a[MAX], i, numl = 0, denl = 0;
+        // The first two convergents are 0/1 and 1/0
+        p[0] = 0; q[0] = 1;
+        p[1] = 1; q[1] = 0;
+        // The rest of the convergents (and continued fraction)
+        for (i = 2; i < MAX; i++) {
+            a[i] = lrint(floor(duration));
+            p[i] = a[i] * p[i - 1] + p[i - 2];
+            q[i] = a[i] * q[i - 1] + q[i - 2];
+            if (p[i] <= 0xFF && q[i] <= 0xFF) { // uint16_t
+                numl = p[i];
+                denl = q[i];
+            } else break;
+            if (fabs(duration - a[i]) < eps) break;
+            duration = 1.0 / (duration - a[i]);
+        }
+        
+        if (numl != 0 && denl != 0) {
+            *num = numl;
+            *den = denl;
+        } else {
+            *num = 1;
+            *den = 100;
+        }
+    }
+}
+
+// convert fraction to double value
+static double yy_png_delay_to_seconds(uint16_t num, uint16_t den) {
+    if (den == 0) {
+        return num / 100.0;
+    } else {
+        return (double)num / (double)den;
+    }
+}
+
+static bool yy_png_validate_animation_chunk_order(yy_png_chunk_info *chunks,  /* input */
+                                                  uint32_t chunk_num,         /* input */
+                                                  uint32_t *first_idat_index, /* output */
+                                                  bool *first_frame_is_cover  /* output */) {
+    /*
+     PNG at least contains 3 chunks: IHDR, IDAT, IEND.
+     `IHDR` must appear first.
+     `IDAT` must appear consecutively.
+     `IEND` must appear end.
+     
+     APNG must contains one `acTL` and at least one 'fcTL' and `fdAT`.
+     `fdAT` must appear consecutively.
+     `fcTL` must appear before `IDAT` or `fdAT`.
+     */
+    if (chunk_num <= 2) return false;
+    if (chunks->fourcc != YY_FOUR_CC('I', 'H', 'D', 'R')) return false;
+    if ((chunks + chunk_num - 1)->fourcc != YY_FOUR_CC('I', 'E', 'N', 'D')) return false;
+    
+    uint32_t prev_fourcc = 0;
+    uint32_t IHDR_num = 0;
+    uint32_t IDAT_num = 0;
+    uint32_t acTL_num = 0;
+    uint32_t fcTL_num = 0;
+    uint32_t first_IDAT = 0;
+    bool first_frame_cover = false;
+    for (uint32_t i = 0; i < chunk_num; i++) {
+        yy_png_chunk_info *chunk = chunks + i;
+        switch (chunk->fourcc) {
+            case YY_FOUR_CC('I', 'H', 'D', 'R'): {  // png header
+                if (i != 0) return false;
+                if (IHDR_num > 0) return false;
+                IHDR_num++;
+            } break;
+            case YY_FOUR_CC('I', 'D', 'A', 'T'): {  // png data
+                if (prev_fourcc != YY_FOUR_CC('I', 'D', 'A', 'T')) {
+                    if (IDAT_num == 0)
+                        first_IDAT = i;
+                    else
+                        return false;
+                }
+                IDAT_num++;
+            } break;
+            case YY_FOUR_CC('a', 'c', 'T', 'L'): {  // apng control
+                if (acTL_num > 0) return false;
+                acTL_num++;
+            } break;
+            case YY_FOUR_CC('f', 'c', 'T', 'L'): {  // apng frame control
+                if (i + 1 == chunk_num) return false;
+                if ((chunk + 1)->fourcc != YY_FOUR_CC('f', 'd', 'A', 'T') &&
+                    (chunk + 1)->fourcc != YY_FOUR_CC('I', 'D', 'A', 'T')) {
+                    return false;
+                }
+                if (fcTL_num == 0) {
+                    if ((chunk + 1)->fourcc == YY_FOUR_CC('I', 'D', 'A', 'T')) {
+                        first_frame_cover = true;
+                    }
+                }
+                fcTL_num++;
+            } break;
+            case YY_FOUR_CC('f', 'd', 'A', 'T'): {  // apng data
+                if (prev_fourcc != YY_FOUR_CC('f', 'd', 'A', 'T') && prev_fourcc != YY_FOUR_CC('f', 'c', 'T', 'L')) {
+                    return false;
+                }
+            } break;
+        }
+        prev_fourcc = chunk->fourcc;
+    }
+    if (IHDR_num != 1) return false;
+    if (IDAT_num == 0) return false;
+    if (acTL_num != 1) return false;
+    if (fcTL_num < acTL_num) return false;
+    *first_idat_index = first_IDAT;
+    *first_frame_is_cover = first_frame_cover;
+    return true;
+}
+
+static void yy_png_info_release(yy_png_info *info) {
+    if (info) {
+        if (info->chunks) free(info->chunks);
+        if (info->apng_frames) free(info->apng_frames);
+        if (info->apng_shared_chunk_indexs) free(info->apng_shared_chunk_indexs);
+        free(info);
+    }
+}
+
+/**
+ Create a png info from a png file. See struct png_info for more information.
+ 
+ @param data   png/apng file data.
+ @param length the data's length in bytes.
+ @return A png info object, you may call yy_png_info_release() to release it.
+ Returns NULL if an error occurs.
+ */
+static yy_png_info *yy_png_info_create(const uint8_t *data, uint32_t length) {
+    if (length < 32) return NULL;
+    if (*((uint32_t *)data) != YY_FOUR_CC(0x89, 0x50, 0x4E, 0x47)) return NULL;
+    if (*((uint32_t *)(data + 4)) != YY_FOUR_CC(0x0D, 0x0A, 0x1A, 0x0A)) return NULL;
+    
+    uint32_t chunk_realloc_num = 16;
+    yy_png_chunk_info *chunks = malloc(sizeof(yy_png_chunk_info) * chunk_realloc_num);
+    if (!chunks) return NULL;
+    
+    // parse png chunks
+    uint32_t offset = 8;
+    uint32_t chunk_num = 0;
+    uint32_t chunk_capacity = chunk_realloc_num;
+    uint32_t apng_loop_num = 0;
+    int32_t apng_sequence_index = -1;
+    int32_t apng_frame_index = 0;
+    int32_t apng_frame_number = -1;
+    bool apng_chunk_error = false;
+    do {
+        if (chunk_num >= chunk_capacity) {
+            yy_png_chunk_info *new_chunks = realloc(chunks, sizeof(yy_png_chunk_info) * (chunk_capacity + chunk_realloc_num));
+            if (!new_chunks) {
+                free(chunks);
+                return NULL;
+            }
+            chunks = new_chunks;
+            chunk_capacity += chunk_realloc_num;
+        }
+        yy_png_chunk_info *chunk = chunks + chunk_num;
+        const uint8_t *chunk_data = data + offset;
+        chunk->offset = offset;
+        chunk->length = yy_swap_endian_uint32(*((uint32_t *)chunk_data));
+        if ((uint64_t)chunk->offset + (uint64_t)chunk->length + 12 > length) {
+            free(chunks);
+            return NULL;
+        }
+        
+        chunk->fourcc = *((uint32_t *)(chunk_data + 4));
+        if ((uint64_t)chunk->offset + 4 + chunk->length + 4 > (uint64_t)length) break;
+        chunk->crc32 = yy_swap_endian_uint32(*((uint32_t *)(chunk_data + 8 + chunk->length)));
+        chunk_num++;
+        offset += 12 + chunk->length;
+        
+        switch (chunk->fourcc) {
+            case YY_FOUR_CC('a', 'c', 'T', 'L') : {
+                if (chunk->length == 8) {
+                    apng_frame_number = yy_swap_endian_uint32(*((uint32_t *)(chunk_data + 8)));
+                    apng_loop_num = yy_swap_endian_uint32(*((uint32_t *)(chunk_data + 12)));
+                } else {
+                    apng_chunk_error = true;
+                }
+            } break;
+            case YY_FOUR_CC('f', 'c', 'T', 'L') :
+            case YY_FOUR_CC('f', 'd', 'A', 'T') : {
+                if (chunk->fourcc == YY_FOUR_CC('f', 'c', 'T', 'L')) {
+                    if (chunk->length != 26) {
+                        apng_chunk_error = true;
+                    } else {
+                        apng_frame_index++;
+                    }
+                }
+                if (chunk->length > 4) {
+                    uint32_t sequence = yy_swap_endian_uint32(*((uint32_t *)(chunk_data + 8)));
+                    if (apng_sequence_index + 1 == sequence) {
+                        apng_sequence_index++;
+                    } else {
+                        apng_chunk_error = true;
+                    }
+                } else {
+                    apng_chunk_error = true;
+                }
+            } break;
+            case YY_FOUR_CC('I', 'E', 'N', 'D') : {
+                offset = length; // end, break do-while loop
+            } break;
+        }
+    } while (offset + 12 <= length);
+    
+    if (chunk_num < 3 ||
+        chunks->fourcc != YY_FOUR_CC('I', 'H', 'D', 'R') ||
+        chunks->length != 13) {
+        free(chunks);
+        return NULL;
+    }
+    
+    // png info
+    yy_png_info *info = calloc(1, sizeof(yy_png_info));
+    if (!info) {
+        free(chunks);
+        return NULL;
+    }
+    info->chunks = chunks;
+    info->chunk_num = chunk_num;
+    yy_png_chunk_IHDR_read(&info->header, data + chunks->offset + 8);
+    
+    // apng info
+    if (!apng_chunk_error && apng_frame_number == apng_frame_index && apng_frame_number >= 1) {
+        bool first_frame_is_cover = false;
+        uint32_t first_IDAT_index = 0;
+        if (!yy_png_validate_animation_chunk_order(info->chunks, info->chunk_num, &first_IDAT_index, &first_frame_is_cover)) {
+            return info; // ignore apng chunk
+        }
+        
+        info->apng_loop_num = apng_loop_num;
+        info->apng_frame_num = apng_frame_number;
+        info->apng_first_frame_is_cover = first_frame_is_cover;
+        info->apng_shared_insert_index = first_IDAT_index;
+        info->apng_frames = calloc(apng_frame_number, sizeof(yy_png_frame_info));
+        if (!info->apng_frames) {
+            yy_png_info_release(info);
+            return NULL;
+        }
+        info->apng_shared_chunk_indexs = calloc(info->chunk_num, sizeof(uint32_t));
+        if (!info->apng_shared_chunk_indexs) {
+            yy_png_info_release(info);
+            return NULL;
+        }
+        
+        int32_t frame_index = -1;
+        uint32_t *shared_chunk_index = info->apng_shared_chunk_indexs;
+        for (int32_t i = 0; i < info->chunk_num; i++) {
+            yy_png_chunk_info *chunk = info->chunks + i;
+            switch (chunk->fourcc) {
+                case YY_FOUR_CC('I', 'D', 'A', 'T'): {
+                    if (info->apng_shared_insert_index == 0) {
+                        info->apng_shared_insert_index = i;
+                    }
+                    if (first_frame_is_cover) {
+                        yy_png_frame_info *frame = info->apng_frames + frame_index;
+                        frame->chunk_num++;
+                        frame->chunk_size += chunk->length + 12;
+                    }
+                } break;
+                case YY_FOUR_CC('a', 'c', 'T', 'L'): {
+                } break;
+                case YY_FOUR_CC('f', 'c', 'T', 'L'): {
+                    frame_index++;
+                    yy_png_frame_info *frame = info->apng_frames + frame_index;
+                    frame->chunk_index = i + 1;
+                    yy_png_chunk_fcTL_read(&frame->frame_control, data + chunk->offset + 8);
+                } break;
+                case YY_FOUR_CC('f', 'd', 'A', 'T'): {
+                    yy_png_frame_info *frame = info->apng_frames + frame_index;
+                    frame->chunk_num++;
+                    frame->chunk_size += chunk->length + 12;
+                } break;
+                default: {
+                    *shared_chunk_index = i;
+                    shared_chunk_index++;
+                    info->apng_shared_chunk_size += chunk->length + 12;
+                    info->apng_shared_chunk_num++;
+                } break;
+            }
+        }
+    }
+    return info;
+}
+
+/**
+ Copy a png frame data from an apng file.
+ 
+ @param data  apng file data
+ @param info  png info
+ @param index frame index (zero-based)
+ @param size  output, the size of the frame data
+ @return A frame data (single-frame png file), call free() to release the data.
+ Returns NULL if an error occurs.
+ */
+static uint8_t *yy_png_copy_frame_data_at_index(const uint8_t *data,
+                                                const yy_png_info *info,
+                                                const uint32_t index,
+                                                uint32_t *size) {
+    if (index >= info->apng_frame_num) return NULL;
+    
+    yy_png_frame_info *frame_info = info->apng_frames + index;
+    uint32_t frame_remux_size = 8 /* PNG Header */ + info->apng_shared_chunk_size + frame_info->chunk_size;
+    if (!(info->apng_first_frame_is_cover && index == 0)) {
+        frame_remux_size -= frame_info->chunk_num * 4; // remove fdAT sequence number
+    }
+    uint8_t *frame_data = malloc(frame_remux_size);
+    if (!frame_data) return NULL;
+    *size = frame_remux_size;
+    
+    uint32_t data_offset = 0;
+    bool inserted = false;
+    memcpy(frame_data, data, 8); // PNG File Header
+    data_offset += 8;
+    for (uint32_t i = 0; i < info->apng_shared_chunk_num; i++) {
+        uint32_t shared_chunk_index = info->apng_shared_chunk_indexs[i];
+        yy_png_chunk_info *shared_chunk_info = info->chunks + shared_chunk_index;
+        
+        if (shared_chunk_index >= info->apng_shared_insert_index && !inserted) { // replace IDAT with fdAT
+            inserted = true;
+            for (uint32_t c = 0; c < frame_info->chunk_num; c++) {
+                yy_png_chunk_info *insert_chunk_info = info->chunks + frame_info->chunk_index + c;
+                if (insert_chunk_info->fourcc == YY_FOUR_CC('f', 'd', 'A', 'T')) {
+                    *((uint32_t *)(frame_data + data_offset)) = yy_swap_endian_uint32(insert_chunk_info->length - 4);
+                    *((uint32_t *)(frame_data + data_offset + 4)) = YY_FOUR_CC('I', 'D', 'A', 'T');
+                    memcpy(frame_data + data_offset + 8, data + insert_chunk_info->offset + 12, insert_chunk_info->length - 4);
+                    uint32_t crc = (uint32_t)crc32(0, frame_data + data_offset + 4, insert_chunk_info->length);
+                    *((uint32_t *)(frame_data + data_offset + insert_chunk_info->length + 4)) = yy_swap_endian_uint32(crc);
+                    data_offset += insert_chunk_info->length + 8;
+                } else { // IDAT
+                    memcpy(frame_data + data_offset, data + insert_chunk_info->offset, insert_chunk_info->length + 12);
+                    data_offset += insert_chunk_info->length + 12;
+                }
+            }
+        }
+        
+        if (shared_chunk_info->fourcc == YY_FOUR_CC('I', 'H', 'D', 'R')) {
+            uint8_t tmp[25] = {0};
+            memcpy(tmp, data + shared_chunk_info->offset, 25);
+            yy_png_chunk_IHDR IHDR = info->header;
+            IHDR.width = frame_info->frame_control.width;
+            IHDR.height = frame_info->frame_control.height;
+            yy_png_chunk_IHDR_write(&IHDR, tmp + 8);
+            *((uint32_t *)(tmp + 21)) = yy_swap_endian_uint32((uint32_t)crc32(0, tmp + 4, 17));
+            memcpy(frame_data + data_offset, tmp, 25);
+            data_offset += 25;
+        } else {
+            memcpy(frame_data + data_offset, data + shared_chunk_info->offset, shared_chunk_info->length + 12);
+            data_offset += shared_chunk_info->length + 12;
+        }
+    }
+    return frame_data;
+}
+
+
+
+////////////////////////////////////////////////////////////////////////////////
+#pragma mark - Helper
+
+/// Returns byte-aligned size.
+static inline size_t YYImageByteAlign(size_t size, size_t alignment) {
+    return ((size + (alignment - 1)) / alignment) * alignment;
+}
+
+/// Convert degree to radians
+static inline CGFloat YYImageDegreesToRadians(CGFloat degrees) {
+    return degrees * M_PI / 180;
+}
+
+CGColorSpaceRef YYCGColorSpaceGetDeviceRGB() {
+    static CGColorSpaceRef space;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        space = CGColorSpaceCreateDeviceRGB();
+    });
+    return space;
+}
+
+CGColorSpaceRef YYCGColorSpaceGetDeviceGray() {
+    static CGColorSpaceRef space;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        space = CGColorSpaceCreateDeviceGray();
+    });
+    return space;
+}
+
+BOOL YYCGColorSpaceIsDeviceRGB(CGColorSpaceRef space) {
+    return space && CFEqual(space, YYCGColorSpaceGetDeviceRGB());
+}
+
+BOOL YYCGColorSpaceIsDeviceGray(CGColorSpaceRef space) {
+    return space && CFEqual(space, YYCGColorSpaceGetDeviceGray());
+}
+
+/**
+ A callback used in CGDataProviderCreateWithData() to release data.
+ 
+ Example:
+ 
+ void *data = malloc(size);
+ CGDataProviderRef provider = CGDataProviderCreateWithData(data, data, size, YYCGDataProviderReleaseDataCallback);
+ */
+static void YYCGDataProviderReleaseDataCallback(void *info, const void *data, size_t size) {
+    if (info) free(info);
+}
+
+/**
+ Decode an image to bitmap buffer with the specified format.
+ 
+ @param srcImage   Source image.
+ @param dest       Destination buffer. It should be zero before call this method.
+                   If decode succeed, you should release the dest->data using free().
+ @param destFormat Destination bitmap format.
+ 
+ @return Whether succeed.
+ 
+ @warning This method support iOS7.0 and later. If call it on iOS6, it just returns NO.
+ CG_AVAILABLE_STARTING(__MAC_10_9, __IPHONE_7_0)
+ */
+static BOOL YYCGImageDecodeToBitmapBufferWithAnyFormat(CGImageRef srcImage, vImage_Buffer *dest, vImage_CGImageFormat *destFormat) {
+    if (!srcImage || (((long)vImageConvert_AnyToAny) + 1 == 1) || !destFormat || !dest) return NO;
+    size_t width = CGImageGetWidth(srcImage);
+    size_t height = CGImageGetHeight(srcImage);
+    if (width == 0 || height == 0) return NO;
+    dest->data = NULL;
+    
+    vImage_Error error = kvImageNoError;
+    CFDataRef srcData = NULL;
+    vImageConverterRef convertor = NULL;
+    vImage_CGImageFormat srcFormat = {0};
+    srcFormat.bitsPerComponent = (uint32_t)CGImageGetBitsPerComponent(srcImage);
+    srcFormat.bitsPerPixel = (uint32_t)CGImageGetBitsPerPixel(srcImage);
+    srcFormat.colorSpace = CGImageGetColorSpace(srcImage);
+    srcFormat.bitmapInfo = CGImageGetBitmapInfo(srcImage) | CGImageGetAlphaInfo(srcImage);
+    
+    convertor = vImageConverter_CreateWithCGImageFormat(&srcFormat, destFormat, NULL, kvImageNoFlags, NULL);
+    if (!convertor) goto fail;
+    
+    CGDataProviderRef srcProvider = CGImageGetDataProvider(srcImage);
+    srcData = srcProvider ? CGDataProviderCopyData(srcProvider) : NULL; // decode
+    size_t srcLength = srcData ? CFDataGetLength(srcData) : 0;
+    const void *srcBytes = srcData ? CFDataGetBytePtr(srcData) : NULL;
+    if (srcLength == 0 || !srcBytes) goto fail;
+    
+    vImage_Buffer src = {0};
+    src.data = (void *)srcBytes;
+    src.width = width;
+    src.height = height;
+    src.rowBytes = CGImageGetBytesPerRow(srcImage);
+    
+    error = vImageBuffer_Init(dest, height, width, 32, kvImageNoFlags);
+    if (error != kvImageNoError) goto fail;
+    
+    error = vImageConvert_AnyToAny(convertor, &src, dest, NULL, kvImageNoFlags); // convert
+    if (error != kvImageNoError) goto fail;
+    
+    CFRelease(convertor);
+    CFRelease(srcData);
+    return YES;
+    
+fail:
+    if (convertor) CFRelease(convertor);
+    if (srcData) CFRelease(srcData);
+    if (dest->data) free(dest->data);
+    dest->data = NULL;
+    return NO;
+}
+
+/**
+ Decode an image to bitmap buffer with the 32bit format (such as ARGB8888).
+ 
+ @param srcImage   Source image.
+ @param dest       Destination buffer. It should be zero before call this method.
+                   If decode succeed, you should release the dest->data using free().
+ @param bitmapInfo Destination bitmap format.
+ 
+ @return Whether succeed.
+ */
+static BOOL YYCGImageDecodeToBitmapBufferWith32BitFormat(CGImageRef srcImage, vImage_Buffer *dest, CGBitmapInfo bitmapInfo) {
+    if (!srcImage || !dest) return NO;
+    size_t width = CGImageGetWidth(srcImage);
+    size_t height = CGImageGetHeight(srcImage);
+    if (width == 0 || height == 0) return NO;
+    
+    BOOL hasAlpha = NO;
+    BOOL alphaFirst = NO;
+    BOOL alphaPremultiplied = NO;
+    BOOL byteOrderNormal = NO;
+    
+    switch (bitmapInfo & kCGBitmapAlphaInfoMask) {
+        case kCGImageAlphaPremultipliedLast: {
+            hasAlpha = YES;
+            alphaPremultiplied = YES;
+        } break;
+        case kCGImageAlphaPremultipliedFirst: {
+            hasAlpha = YES;
+            alphaPremultiplied = YES;
+            alphaFirst = YES;
+        } break;
+        case kCGImageAlphaLast: {
+            hasAlpha = YES;
+        } break;
+        case kCGImageAlphaFirst: {
+            hasAlpha = YES;
+            alphaFirst = YES;
+        } break;
+        case kCGImageAlphaNoneSkipLast: {
+        } break;
+        case kCGImageAlphaNoneSkipFirst: {
+            alphaFirst = YES;
+        } break;
+        default: {
+            return NO;
+        } break;
+    }
+    
+    switch (bitmapInfo & kCGBitmapByteOrderMask) {
+        case kCGBitmapByteOrderDefault: {
+            byteOrderNormal = YES;
+        } break;
+        case kCGBitmapByteOrder32Little: {
+        } break;
+        case kCGBitmapByteOrder32Big: {
+            byteOrderNormal = YES;
+        } break;
+        default: {
+            return NO;
+        } break;
+    }
+    
+    /*
+     Try convert with vImageConvert_AnyToAny() (avaliable since iOS 7.0).
+     If fail, try decode with CGContextDrawImage().
+     CGBitmapContext use a premultiplied alpha format, unpremultiply may lose precision.
+     */
+    vImage_CGImageFormat destFormat = {0};
+    destFormat.bitsPerComponent = 8;
+    destFormat.bitsPerPixel = 32;
+    destFormat.colorSpace = YYCGColorSpaceGetDeviceRGB();
+    destFormat.bitmapInfo = bitmapInfo;
+    dest->data = NULL;
+    if (YYCGImageDecodeToBitmapBufferWithAnyFormat(srcImage, dest, &destFormat)) return YES;
+    
+    CGBitmapInfo contextBitmapInfo = bitmapInfo & kCGBitmapByteOrderMask;
+    if (!hasAlpha || alphaPremultiplied) {
+        contextBitmapInfo |= (bitmapInfo & kCGBitmapAlphaInfoMask);
+    } else {
+        contextBitmapInfo |= alphaFirst ? kCGImageAlphaPremultipliedFirst : kCGImageAlphaPremultipliedLast;
+    }
+    CGContextRef context = CGBitmapContextCreate(NULL, width, height, 8, 32, YYCGColorSpaceGetDeviceRGB(), contextBitmapInfo);
+    if (!context) goto fail;
+    
+    CGContextDrawImage(context, CGRectMake(0, 0, width, height), srcImage); // decode and convert
+    size_t bytesPerRow = CGBitmapContextGetBytesPerRow(context);
+    size_t length = height * bytesPerRow;
+    void *data = CGBitmapContextGetData(context);
+    if (length == 0 || !data) goto fail;
+    
+    dest->data = malloc(length);
+    dest->width = width;
+    dest->height = height;
+    dest->rowBytes = bytesPerRow;
+    if (!dest->data) goto fail;
+    
+    if (hasAlpha && !alphaPremultiplied) {
+        vImage_Buffer tmpSrc = {0};
+        tmpSrc.data = data;
+        tmpSrc.width = width;
+        tmpSrc.height = height;
+        tmpSrc.rowBytes = bytesPerRow;
+        vImage_Error error;
+        if (alphaFirst && byteOrderNormal) {
+            error = vImageUnpremultiplyData_ARGB8888(&tmpSrc, dest, kvImageNoFlags);
+        } else {
+            error = vImageUnpremultiplyData_RGBA8888(&tmpSrc, dest, kvImageNoFlags);
+        }
+        if (error != kvImageNoError) goto fail;
+    } else {
+        memcpy(dest->data, data, length);
+    }
+    
+    CFRelease(context);
+    return YES;
+    
+fail:
+    if (context) CFRelease(context);
+    if (dest->data) free(dest->data);
+    dest->data = NULL;
+    return NO;
+    return NO;
+}
+
+CGImageRef YYCGImageCreateDecodedCopy(CGImageRef imageRef, BOOL decodeForDisplay) {
+    if (!imageRef) return NULL;
+    size_t width = CGImageGetWidth(imageRef);
+    size_t height = CGImageGetHeight(imageRef);
+    if (width == 0 || height == 0) return NULL;
+    
+    if (decodeForDisplay) { //decode with redraw (may lose some precision)
+        CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef) & kCGBitmapAlphaInfoMask;
+        BOOL hasAlpha = NO;
+        if (alphaInfo == kCGImageAlphaPremultipliedLast ||
+            alphaInfo == kCGImageAlphaPremultipliedFirst ||
+            alphaInfo == kCGImageAlphaLast ||
+            alphaInfo == kCGImageAlphaFirst) {
+            hasAlpha = YES;
+        }
+        // BGRA8888 (premultiplied) or BGRX8888
+        // same as UIGraphicsBeginImageContext() and -[UIView drawRect:]
+        CGBitmapInfo bitmapInfo = kCGBitmapByteOrder32Host;
+        bitmapInfo |= hasAlpha ? kCGImageAlphaPremultipliedFirst : kCGImageAlphaNoneSkipFirst;
+        CGContextRef context = CGBitmapContextCreate(NULL, width, height, 8, 0, YYCGColorSpaceGetDeviceRGB(), bitmapInfo);
+        if (!context) return NULL;
+        CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef); // decode
+        CGImageRef newImage = CGBitmapContextCreateImage(context);
+        CFRelease(context);
+        return newImage;
+        
+    } else {
+        CGColorSpaceRef space = CGImageGetColorSpace(imageRef);
+        size_t bitsPerComponent = CGImageGetBitsPerComponent(imageRef);
+        size_t bitsPerPixel = CGImageGetBitsPerPixel(imageRef);
+        size_t bytesPerRow = CGImageGetBytesPerRow(imageRef);
+        CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
+        if (bytesPerRow == 0 || width == 0 || height == 0) return NULL;
+        
+        CGDataProviderRef dataProvider = CGImageGetDataProvider(imageRef);
+        if (!dataProvider) return NULL;
+        CFDataRef data = CGDataProviderCopyData(dataProvider); // decode
+        if (!data) return NULL;
+        
+        CGDataProviderRef newProvider = CGDataProviderCreateWithCFData(data);
+        CFRelease(data);
+        if (!newProvider) return NULL;
+        
+        CGImageRef newImage = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, space, bitmapInfo, newProvider, NULL, false, kCGRenderingIntentDefault);
+        CFRelease(newProvider);
+        return newImage;
+    }
+}
+
+CGImageRef YYCGImageCreateAffineTransformCopy(CGImageRef imageRef, CGAffineTransform transform, CGSize destSize, CGBitmapInfo destBitmapInfo) {
+    if (!imageRef) return NULL;
+    size_t srcWidth = CGImageGetWidth(imageRef);
+    size_t srcHeight = CGImageGetHeight(imageRef);
+    size_t destWidth = round(destSize.width);
+    size_t destHeight = round(destSize.height);
+    if (srcWidth == 0 || srcHeight == 0 || destWidth == 0 || destHeight == 0) return NULL;
+    
+    CGDataProviderRef tmpProvider = NULL, destProvider = NULL;
+    CGImageRef tmpImage = NULL, destImage = NULL;;
+    vImage_Buffer src = {0}, tmp = {0}, dest = {0};
+    if(!YYCGImageDecodeToBitmapBufferWith32BitFormat(imageRef, &src, kCGImageAlphaFirst | kCGBitmapByteOrderDefault)) return NULL;
+    
+    size_t destBytesPerRow = YYImageByteAlign(destWidth * 4, 32);
+    tmp.data = malloc(destHeight * destBytesPerRow);
+    if (!tmp.data) goto fail;
+    
+    tmp.width = destWidth;
+    tmp.height = destHeight;
+    tmp.rowBytes = destBytesPerRow;
+    vImage_CGAffineTransform vTransform = *((vImage_CGAffineTransform *)&transform);
+    uint8_t backColor[4] = {0};
+    vImage_Error error = vImageAffineWarpCG_ARGB8888(&src, &tmp, NULL, &vTransform, backColor, kvImageBackgroundColorFill);
+    if (error != kvImageNoError) goto fail;
+    free(src.data);
+    src.data = NULL;
+    
+    tmpProvider = CGDataProviderCreateWithData(tmp.data, tmp.data, destHeight * destBytesPerRow, YYCGDataProviderReleaseDataCallback);
+    if (!tmpProvider) goto fail;
+    tmp.data = NULL; // hold by provider
+    tmpImage = CGImageCreate(destWidth, destHeight, 8, 32, destBytesPerRow, YYCGColorSpaceGetDeviceRGB(), kCGImageAlphaFirst | kCGBitmapByteOrderDefault, tmpProvider, NULL, false, kCGRenderingIntentDefault);
+    if (!tmpImage) goto fail;
+    CFRelease(tmpProvider);
+    tmpProvider = NULL;
+    
+    if ((destBitmapInfo & kCGBitmapAlphaInfoMask) == kCGImageAlphaFirst &&
+        (destBitmapInfo & kCGBitmapByteOrderMask) != kCGBitmapByteOrder32Little) {
+        return tmpImage;
+    }
+    
+    if (!YYCGImageDecodeToBitmapBufferWith32BitFormat(tmpImage, &dest, destBitmapInfo)) goto fail;
+    CFRelease(tmpImage);
+    tmpImage = NULL;
+    
+    destProvider = CGDataProviderCreateWithData(dest.data, dest.data, destHeight * destBytesPerRow, YYCGDataProviderReleaseDataCallback);
+    if (!destProvider) goto fail;
+    dest.data = NULL; // hold by provider
+    destImage = CGImageCreate(destWidth, destHeight, 8, 32, destBytesPerRow, YYCGColorSpaceGetDeviceRGB(), destBitmapInfo, destProvider, NULL, false, kCGRenderingIntentDefault);
+    if (!destImage) goto fail;
+    CFRelease(destProvider);
+    destProvider = NULL;
+    
+    return destImage;
+    
+fail:
+    if (src.data) free(src.data);
+    if (tmp.data) free(tmp.data);
+    if (dest.data) free(dest.data);
+    if (tmpProvider) CFRelease(tmpProvider);
+    if (tmpImage) CFRelease(tmpImage);
+    if (destProvider) CFRelease(destProvider);
+    return NULL;
+}
+
+UIImageOrientation YYUIImageOrientationFromEXIFValue(NSInteger value) {
+    switch (value) {
+        case kCGImagePropertyOrientationUp: return UIImageOrientationUp;
+        case kCGImagePropertyOrientationDown: return UIImageOrientationDown;
+        case kCGImagePropertyOrientationLeft: return UIImageOrientationLeft;
+        case kCGImagePropertyOrientationRight: return UIImageOrientationRight;
+        case kCGImagePropertyOrientationUpMirrored: return UIImageOrientationUpMirrored;
+        case kCGImagePropertyOrientationDownMirrored: return UIImageOrientationDownMirrored;
+        case kCGImagePropertyOrientationLeftMirrored: return UIImageOrientationLeftMirrored;
+        case kCGImagePropertyOrientationRightMirrored: return UIImageOrientationRightMirrored;
+        default: return UIImageOrientationUp;
+    }
+}
+
+NSInteger YYUIImageOrientationToEXIFValue(UIImageOrientation orientation) {
+    switch (orientation) {
+        case UIImageOrientationUp: return kCGImagePropertyOrientationUp;
+        case UIImageOrientationDown: return kCGImagePropertyOrientationDown;
+        case UIImageOrientationLeft: return kCGImagePropertyOrientationLeft;
+        case UIImageOrientationRight: return kCGImagePropertyOrientationRight;
+        case UIImageOrientationUpMirrored: return kCGImagePropertyOrientationUpMirrored;
+        case UIImageOrientationDownMirrored: return kCGImagePropertyOrientationDownMirrored;
+        case UIImageOrientationLeftMirrored: return kCGImagePropertyOrientationLeftMirrored;
+        case UIImageOrientationRightMirrored: return kCGImagePropertyOrientationRightMirrored;
+        default: return kCGImagePropertyOrientationUp;
+    }
+}
+
+CGImageRef YYCGImageCreateCopyWithOrientation(CGImageRef imageRef, UIImageOrientation orientation, CGBitmapInfo destBitmapInfo) {
+    if (!imageRef) return NULL;
+    if (orientation == UIImageOrientationUp) return (CGImageRef)CFRetain(imageRef);
+    
+    size_t width = CGImageGetWidth(imageRef);
+    size_t height = CGImageGetHeight(imageRef);
+    
+    CGAffineTransform transform = CGAffineTransformIdentity;
+    BOOL swapWidthAndHeight = NO;
+    switch (orientation) {
+        case UIImageOrientationDown: {
+            transform = CGAffineTransformMakeRotation(YYImageDegreesToRadians(180));
+            transform = CGAffineTransformTranslate(transform, -(CGFloat)width, -(CGFloat)height);
+        } break;
+        case UIImageOrientationLeft: {
+            transform = CGAffineTransformMakeRotation(YYImageDegreesToRadians(90));
+            transform = CGAffineTransformTranslate(transform, -(CGFloat)0, -(CGFloat)height);
+            swapWidthAndHeight = YES;
+        } break;
+        case UIImageOrientationRight: {
+            transform = CGAffineTransformMakeRotation(YYImageDegreesToRadians(-90));
+            transform = CGAffineTransformTranslate(transform, -(CGFloat)width, (CGFloat)0);
+            swapWidthAndHeight = YES;
+        } break;
+        case UIImageOrientationUpMirrored: {
+            transform = CGAffineTransformTranslate(transform, (CGFloat)width, 0);
+            transform = CGAffineTransformScale(transform, -1, 1);
+        } break;
+        case UIImageOrientationDownMirrored: {
+            transform = CGAffineTransformTranslate(transform, 0, (CGFloat)height);
+            transform = CGAffineTransformScale(transform, 1, -1);
+        } break;
+        case UIImageOrientationLeftMirrored: {
+            transform = CGAffineTransformMakeRotation(YYImageDegreesToRadians(-90));
+            transform = CGAffineTransformScale(transform, 1, -1);
+            transform = CGAffineTransformTranslate(transform, -(CGFloat)width, -(CGFloat)height);
+            swapWidthAndHeight = YES;
+        } break;
+        case UIImageOrientationRightMirrored: {
+            transform = CGAffineTransformMakeRotation(YYImageDegreesToRadians(90));
+            transform = CGAffineTransformScale(transform, 1, -1);
+            swapWidthAndHeight = YES;
+        } break;
+        default: break;
+    }
+    if (CGAffineTransformIsIdentity(transform)) return (CGImageRef)CFRetain(imageRef);
+    
+    CGSize destSize = {width, height};
+    if (swapWidthAndHeight) {
+        destSize.width = height;
+        destSize.height = width;
+    }
+    
+    return YYCGImageCreateAffineTransformCopy(imageRef, transform, destSize, destBitmapInfo);
+}
+
+YYImageType YYImageDetectType(CFDataRef data) {
+    if (!data) return YYImageTypeUnknown;
+    uint64_t length = CFDataGetLength(data);
+    if (length < 16) return YYImageTypeUnknown;
+    
+    const char *bytes = (char *)CFDataGetBytePtr(data);
+    
+    uint32_t magic4 = *((uint32_t *)bytes);
+    switch (magic4) {
+        case YY_FOUR_CC(0x4D, 0x4D, 0x00, 0x2A): { // big endian TIFF
+            return YYImageTypeTIFF;
+        } break;
+            
+        case YY_FOUR_CC(0x49, 0x49, 0x2A, 0x00): { // little endian TIFF
+            return YYImageTypeTIFF;
+        } break;
+            
+        case YY_FOUR_CC(0x00, 0x00, 0x01, 0x00): { // ICO
+            return YYImageTypeICO;
+        } break;
+            
+        case YY_FOUR_CC(0x00, 0x00, 0x02, 0x00): { // CUR
+            return YYImageTypeICO;
+        } break;
+            
+        case YY_FOUR_CC('i', 'c', 'n', 's'): { // ICNS
+            return YYImageTypeICNS;
+        } break;
+            
+        case YY_FOUR_CC('G', 'I', 'F', '8'): { // GIF
+            return YYImageTypeGIF;
+        } break;
+            
+        case YY_FOUR_CC(0x89, 'P', 'N', 'G'): {  // PNG
+            uint32_t tmp = *((uint32_t *)(bytes + 4));
+            if (tmp == YY_FOUR_CC('\r', '\n', 0x1A, '\n')) {
+                return YYImageTypePNG;
+            }
+        } break;
+            
+        case YY_FOUR_CC('R', 'I', 'F', 'F'): { // WebP
+            uint32_t tmp = *((uint32_t *)(bytes + 8));
+            if (tmp == YY_FOUR_CC('W', 'E', 'B', 'P')) {
+                return YYImageTypeWebP;
+            }
+        } break;
+        /*
+        case YY_FOUR_CC('B', 'P', 'G', 0xFB): { // BPG
+            return YYImageTypeBPG;
+        } break;
+        */
+    }
+    
+    uint16_t magic2 = *((uint16_t *)bytes);
+    switch (magic2) {
+        case YY_TWO_CC('B', 'A'):
+        case YY_TWO_CC('B', 'M'):
+        case YY_TWO_CC('I', 'C'):
+        case YY_TWO_CC('P', 'I'):
+        case YY_TWO_CC('C', 'I'):
+        case YY_TWO_CC('C', 'P'): { // BMP
+            return YYImageTypeBMP;
+        }
+        case YY_TWO_CC(0xFF, 0x4F): { // JPEG2000
+            return YYImageTypeJPEG2000;
+        }
+    }
+    
+    // JPG             FF D8 FF
+    if (memcmp(bytes,"\377\330\377",3) == 0) return YYImageTypeJPEG;
+    
+    // JP2
+    if (memcmp(bytes + 4, "\152\120\040\040\015", 5) == 0) return YYImageTypeJPEG2000;
+    
+    return YYImageTypeUnknown;
+}
+
+CFStringRef YYImageTypeToUTType(YYImageType type) {
+    switch (type) {
+        case YYImageTypeJPEG: return kUTTypeJPEG;
+        case YYImageTypeJPEG2000: return kUTTypeJPEG2000;
+        case YYImageTypeTIFF: return kUTTypeTIFF;
+        case YYImageTypeBMP: return kUTTypeBMP;
+        case YYImageTypeICO: return kUTTypeICO;
+        case YYImageTypeICNS: return kUTTypeAppleICNS;
+        case YYImageTypeGIF: return kUTTypeGIF;
+        case YYImageTypePNG: return kUTTypePNG;
+        default: return NULL;
+    }
+}
+
+YYImageType YYImageTypeFromUTType(CFStringRef uti) {
+    static NSDictionary *dic;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        dic = @{(id)kUTTypeJPEG : @(YYImageTypeJPEG),
+                (id)kUTTypeJPEG2000 : @(YYImageTypeJPEG2000),
+                (id)kUTTypeTIFF : @(YYImageTypeTIFF),
+                (id)kUTTypeBMP : @(YYImageTypeBMP),
+                (id)kUTTypeICO : @(YYImageTypeICO),
+                (id)kUTTypeAppleICNS : @(YYImageTypeICNS),
+                (id)kUTTypeGIF : @(YYImageTypeGIF),
+                (id)kUTTypePNG : @(YYImageTypePNG)};
+    });
+    if (!uti) return YYImageTypeUnknown;
+    NSNumber *num = dic[(__bridge __strong id)(uti)];
+    return num.unsignedIntegerValue;
+}
+
+NSString *YYImageTypeGetExtension(YYImageType type) {
+    switch (type) {
+        case YYImageTypeJPEG: return @"jpg";
+        case YYImageTypeJPEG2000: return @"jp2";
+        case YYImageTypeTIFF: return @"tiff";
+        case YYImageTypeBMP: return @"bmp";
+        case YYImageTypeICO: return @"ico";
+        case YYImageTypeICNS: return @"icns";
+        case YYImageTypeGIF: return @"gif";
+        case YYImageTypePNG: return @"png";
+        case YYImageTypeWebP: return @"webp";
+        default: return nil;
+    }
+}
+
+CFDataRef YYCGImageCreateEncodedData(CGImageRef imageRef, YYImageType type, CGFloat quality) {
+    if (!imageRef) return nil;
+    quality = quality < 0 ? 0 : quality > 1 ? 1 : quality;
+    
+    if (type == YYImageTypeWebP) {
+#if YYIMAGE_WEBP_ENABLED
+        if (quality == 1) {
+            return YYCGImageCreateEncodedWebPData(imageRef, YES, quality, 4, YYImagePresetDefault);
+        } else {
+            return YYCGImageCreateEncodedWebPData(imageRef, NO, quality, 4, YYImagePresetDefault);
+        }
+#else
+        return NULL;
+#endif
+    }
+    
+    CFStringRef uti = YYImageTypeToUTType(type);
+    if (!uti) return nil;
+    
+    CFMutableDataRef data = CFDataCreateMutable(CFAllocatorGetDefault(), 0);
+    if (!data) return NULL;
+    CGImageDestinationRef dest = CGImageDestinationCreateWithData(data, uti, 1, NULL);
+    if (!dest) {
+        CFRelease(data);
+        return NULL;
+    }
+    NSDictionary *options = @{(id)kCGImageDestinationLossyCompressionQuality : @(quality) };
+    CGImageDestinationAddImage(dest, imageRef, (CFDictionaryRef)options);
+    if (!CGImageDestinationFinalize(dest)) {
+        CFRelease(data);
+        CFRelease(dest);
+        return nil;
+    }
+    CFRelease(dest);
+    
+    if (CFDataGetLength(data) == 0) {
+        CFRelease(data);
+        return NULL;
+    }
+    return data;
+}
+
+#if YYIMAGE_WEBP_ENABLED
+
+BOOL YYImageWebPAvailable() {
+    return YES;
+}
+
+CFDataRef YYCGImageCreateEncodedWebPData(CGImageRef imageRef, BOOL lossless, CGFloat quality, int compressLevel, YYImagePreset preset) {
+    if (!imageRef) return nil;
+    size_t width = CGImageGetWidth(imageRef);
+    size_t height = CGImageGetHeight(imageRef);
+    if (width == 0 || width > WEBP_MAX_DIMENSION) return nil;
+    if (height == 0 || height > WEBP_MAX_DIMENSION) return nil;
+    
+    vImage_Buffer buffer = {0};
+    if(!YYCGImageDecodeToBitmapBufferWith32BitFormat(imageRef, &buffer, kCGImageAlphaLast | kCGBitmapByteOrderDefault)) return nil;
+    
+    WebPConfig config = {0};
+    WebPPicture picture = {0};
+    WebPMemoryWriter writer = {0};
+    CFDataRef webpData = NULL;
+    BOOL pictureNeedFree = NO;
+    
+    quality = quality < 0 ? 0 : quality > 1 ? 1 : quality;
+    preset = preset > YYImagePresetText ? YYImagePresetDefault : preset;
+    compressLevel = compressLevel < 0 ? 0 : compressLevel > 6 ? 6 : compressLevel;
+    if (!WebPConfigPreset(&config, (WebPPreset)preset, quality)) goto fail;
+    
+    config.quality = round(quality * 100.0);
+    config.lossless = lossless;
+    config.method = compressLevel;
+    switch ((WebPPreset)preset) {
+        case WEBP_PRESET_DEFAULT: {
+            config.image_hint = WEBP_HINT_DEFAULT;
+        } break;
+        case WEBP_PRESET_PICTURE: {
+            config.image_hint = WEBP_HINT_PICTURE;
+        } break;
+        case WEBP_PRESET_PHOTO: {
+            config.image_hint = WEBP_HINT_PHOTO;
+        } break;
+        case WEBP_PRESET_DRAWING:
+        case WEBP_PRESET_ICON:
+        case WEBP_PRESET_TEXT: {
+            config.image_hint = WEBP_HINT_GRAPH;
+        } break;
+    }
+    if (!WebPValidateConfig(&config)) goto fail;
+    
+    if (!WebPPictureInit(&picture)) goto fail;
+    pictureNeedFree = YES;
+    picture.width = (int)buffer.width;
+    picture.height = (int)buffer.height;
+    picture.use_argb = lossless;
+    if(!WebPPictureImportRGBA(&picture, buffer.data, (int)buffer.rowBytes)) goto fail;
+    
+    WebPMemoryWriterInit(&writer);
+    picture.writer = WebPMemoryWrite;
+    picture.custom_ptr = &writer;
+    if(!WebPEncode(&config, &picture)) goto fail;
+    
+    webpData = CFDataCreate(CFAllocatorGetDefault(), writer.mem, writer.size);
+    free(writer.mem);
+    WebPPictureFree(&picture);
+    free(buffer.data);
+    return webpData;
+    
+fail:
+    if (buffer.data) free(buffer.data);
+    if (pictureNeedFree) WebPPictureFree(&picture);
+    return nil;
+}
+
+NSUInteger YYImageGetWebPFrameCount(CFDataRef webpData) {
+    if (!webpData || CFDataGetLength(webpData) == 0) return 0;
+    
+    WebPData data = {CFDataGetBytePtr(webpData), CFDataGetLength(webpData)};
+    WebPDemuxer *demuxer = WebPDemux(&data);
+    if (!demuxer) return 0;
+    NSUInteger webpFrameCount = WebPDemuxGetI(demuxer, WEBP_FF_FRAME_COUNT);
+    WebPDemuxDelete(demuxer);
+    return webpFrameCount;
+}
+
+CGImageRef YYCGImageCreateWithWebPData(CFDataRef webpData,
+                                       BOOL decodeForDisplay,
+                                       BOOL useThreads,
+                                       BOOL bypassFiltering,
+                                       BOOL noFancyUpsampling) {
+    /*
+     Call WebPDecode() on a multi-frame webp data will get an error (VP8_STATUS_UNSUPPORTED_FEATURE).
+     Use WebPDemuxer to unpack it first.
+     */
+    WebPData data = {0};
+    WebPDemuxer *demuxer = NULL;
+    
+    int frameCount = 0, canvasWidth = 0, canvasHeight = 0;
+    WebPIterator iter = {0};
+    BOOL iterInited = NO;
+    const uint8_t *payload = NULL;
+    size_t payloadSize = 0;
+    WebPDecoderConfig config = {0};
+    
+    BOOL hasAlpha = NO;
+    size_t bitsPerComponent = 0, bitsPerPixel = 0, bytesPerRow = 0, destLength = 0;
+    CGBitmapInfo bitmapInfo = 0;
+    WEBP_CSP_MODE colorspace = 0;
+    void *destBytes = NULL;
+    CGDataProviderRef provider = NULL;
+    CGImageRef imageRef = NULL;
+    
+    if (!webpData || CFDataGetLength(webpData) == 0) return NULL;
+    data.bytes = CFDataGetBytePtr(webpData);
+    data.size = CFDataGetLength(webpData);
+    demuxer = WebPDemux(&data);
+    if (!demuxer) goto fail;
+    
+    frameCount = WebPDemuxGetI(demuxer, WEBP_FF_FRAME_COUNT);
+    if (frameCount == 0) {
+        goto fail;
+        
+    } else if (frameCount == 1) { // single-frame
+        payload = data.bytes;
+        payloadSize = data.size;
+        if (!WebPInitDecoderConfig(&config)) goto fail;
+        if (WebPGetFeatures(payload , payloadSize, &config.input) != VP8_STATUS_OK) goto fail;
+        canvasWidth = config.input.width;
+        canvasHeight = config.input.height;
+        
+    } else { // multi-frame
+        canvasWidth = WebPDemuxGetI(demuxer, WEBP_FF_CANVAS_WIDTH);
+        canvasHeight = WebPDemuxGetI(demuxer, WEBP_FF_CANVAS_HEIGHT);
+        if (canvasWidth < 1 || canvasHeight < 1) goto fail;
+        
+        if (!WebPDemuxGetFrame(demuxer, 1, &iter)) goto fail;
+        iterInited = YES;
+        
+        if (iter.width > canvasWidth || iter.height > canvasHeight) goto fail;
+        payload = iter.fragment.bytes;
+        payloadSize = iter.fragment.size;
+        
+        if (!WebPInitDecoderConfig(&config)) goto fail;
+        if (WebPGetFeatures(payload , payloadSize, &config.input) != VP8_STATUS_OK) goto fail;
+    }
+    if (payload == NULL || payloadSize == 0) goto fail;
+    
+    hasAlpha = config.input.has_alpha;
+    bitsPerComponent = 8;
+    bitsPerPixel = 32;
+    bytesPerRow = YYImageByteAlign(bitsPerPixel / 8 * canvasWidth, 32);
+    destLength = bytesPerRow * canvasHeight;
+    if (decodeForDisplay) {
+        bitmapInfo = kCGBitmapByteOrder32Host;
+        bitmapInfo |= hasAlpha ? kCGImageAlphaPremultipliedFirst : kCGImageAlphaNoneSkipFirst;
+        colorspace = MODE_bgrA; // small endian
+    } else {
+        bitmapInfo = kCGBitmapByteOrderDefault;
+        bitmapInfo |= hasAlpha ? kCGImageAlphaLast : kCGImageAlphaNoneSkipLast;
+        colorspace = MODE_RGBA;
+    }
+    destBytes = calloc(1, destLength);
+    if (!destBytes) goto fail;
+    
+    config.options.use_threads = useThreads; //speed up 23%
+    config.options.bypass_filtering = bypassFiltering; //speed up 11%, cause some banding
+    config.options.no_fancy_upsampling = noFancyUpsampling; //speed down 16%, lose some details
+    config.output.colorspace = colorspace;
+    config.output.is_external_memory = 1;
+    config.output.u.RGBA.rgba = destBytes;
+    config.output.u.RGBA.stride = (int)bytesPerRow;
+    config.output.u.RGBA.size = destLength;
+    
+    if (WebPDecode(payload, payloadSize, &config) != VP8_STATUS_OK) goto fail;
+    
+    if (iter.x_offset != 0 || iter.y_offset != 0) {
+        void *tmp = calloc(1, destLength);
+        if (tmp) {
+            vImage_Buffer src = {destBytes, canvasHeight, canvasWidth, bytesPerRow};
+            vImage_Buffer dest = {destBytes, canvasHeight, canvasWidth, bytesPerRow};
+            vImage_CGAffineTransform transform = {1, 0, 0, 1, iter.x_offset, -iter.y_offset};
+            uint8_t backColor[4] = {0};
+            vImageAffineWarpCG_ARGB8888(&src, &dest, NULL, &transform, backColor, kvImageBackgroundColorFill);
+            memcpy(destBytes, tmp, destLength);
+            free(tmp);
+        }
+    }
+    
+    provider = CGDataProviderCreateWithData(destBytes, destBytes, destLength, YYCGDataProviderReleaseDataCallback);
+    if (!provider) goto fail;
+    destBytes = NULL; // hold by provider
+    
+    imageRef = CGImageCreate(canvasWidth, canvasHeight, bitsPerComponent, bitsPerPixel, bytesPerRow, YYCGColorSpaceGetDeviceRGB(), bitmapInfo, provider, NULL, false, kCGRenderingIntentDefault);
+    
+    CFRelease(provider);
+    if (iterInited) WebPDemuxReleaseIterator(&iter);
+    WebPDemuxDelete(demuxer);
+    
+    return imageRef;
+    
+fail:
+    if (destBytes) free(destBytes);
+    if (provider) CFRelease(provider);
+    if (iterInited) WebPDemuxReleaseIterator(&iter);
+    if (demuxer) WebPDemuxDelete(demuxer);
+    return NULL;
+}
+
+#else
+
+BOOL YYImageWebPAvailable() {
+    return NO;
+}
+
+CFDataRef YYCGImageCreateEncodedWebPData(CGImageRef imageRef, BOOL lossless, CGFloat quality, int compressLevel, YYImagePreset preset) {
+    NSLog(@"WebP decoder is disabled");
+    return NULL;
+}
+
+NSUInteger YYImageGetWebPFrameCount(CFDataRef webpData) {
+    NSLog(@"WebP decoder is disabled");
+    return 0;
+}
+
+CGImageRef YYCGImageCreateWithWebPData(CFDataRef webpData,
+                                       BOOL decodeForDisplay,
+                                       BOOL useThreads,
+                                       BOOL bypassFiltering,
+                                       BOOL noFancyUpsampling) {
+    NSLog(@"WebP decoder is disabled");
+    return NULL;
+}
+
+#endif
+
+
+////////////////////////////////////////////////////////////////////////////////
+#pragma mark - Decoder
+
+@implementation YYImageFrame
++ (instancetype)frameWithImage:(UIImage *)image {
+    YYImageFrame *frame = [self new];
+    frame.image = image;
+    return frame;
+}
+- (id)copyWithZone:(NSZone *)zone {
+    YYImageFrame *frame = [self.class new];
+    frame.index = _index;
+    frame.width = _width;
+    frame.height = _height;
+    frame.offsetX = _offsetX;
+    frame.offsetY = _offsetY;
+    frame.duration = _duration;
+    frame.dispose = _dispose;
+    frame.blend = _blend;
+    frame.image = _image.copy;
+    return frame;
+}
+@end
+
+// Internal frame object.
+@interface _YYImageDecoderFrame : YYImageFrame
+@property (nonatomic, assign) BOOL hasAlpha;                ///< Whether frame has alpha.
+@property (nonatomic, assign) BOOL isFullSize;              ///< Whether frame fill the canvas.
+@property (nonatomic, assign) NSUInteger blendFromIndex;    ///< Blend from frame index to current frame.
+@end
+
+@implementation _YYImageDecoderFrame
+- (id)copyWithZone:(NSZone *)zone {
+    _YYImageDecoderFrame *frame = [super copyWithZone:zone];
+    frame.hasAlpha = _hasAlpha;
+    frame.isFullSize = _isFullSize;
+    frame.blendFromIndex = _blendFromIndex;
+    return frame;
+}
+@end
+
+
+@implementation YYImageDecoder {
+    pthread_mutex_t _lock;
+    
+    BOOL _sourceTypeDetected;
+    CGImageSourceRef _source;
+    yy_png_info *_apngSource;
+#if YYIMAGE_WEBP_ENABLED
+    WebPDemuxer *_webpSource;
+#endif
+    
+    UIImageOrientation _orientation;
+    OSSpinLock _framesLock;
+    NSArray *_frames; ///< Array<GGImageDecoderFrame>, without image
+    BOOL _needBlend;
+    NSUInteger _blendFrameIndex;
+    CGContextRef _blendCanvas;
+}
+
+- (void)dealloc {
+    if (_source) CFRelease(_source);
+    if (_apngSource) yy_png_info_release(_apngSource);
+#if YYIMAGE_WEBP_ENABLED
+    if (_webpSource) WebPDemuxDelete(_webpSource);
+#endif
+    if (_blendCanvas) CFRelease(_blendCanvas);
+}
+
++ (instancetype)decoderWithData:(NSData *)data scale:(CGFloat)scale {
+    if (!data) return nil;
+    YYImageDecoder *decoder = [[YYImageDecoder alloc] initWithScale:scale];
+    [decoder updateData:data final:YES];
+    if (decoder.frameCount == 0) return nil;
+    return decoder;
+}
+
+- (instancetype)init {
+    return [self initWithScale:[UIScreen mainScreen].scale];
+}
+
+- (instancetype)initWithScale:(CGFloat)scale {
+    self = [super init];
+    if (scale <= 0) scale = 1;
+    _scale = scale;
+    _framesLock = OS_SPINLOCK_INIT;
+    
+    pthread_mutexattr_t attr;
+    pthread_mutexattr_init (&attr);
+    pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_RECURSIVE);
+    pthread_mutex_init (&_lock, &attr);
+    pthread_mutexattr_destroy (&attr);
+    
+    return self;
+}
+
+- (BOOL)updateData:(NSData *)data final:(BOOL)final {
+    BOOL result = NO;
+    pthread_mutex_lock(&_lock);
+    result = [self _updateData:data final:final];
+    pthread_mutex_unlock(&_lock);
+    return result;
+}
+
+- (YYImageFrame *)frameAtIndex:(NSUInteger)index decodeForDisplay:(BOOL)decodeForDisplay {
+    YYImageFrame *result = nil;
+    pthread_mutex_lock(&_lock);
+    result = [self _frameAtIndex:index decodeForDisplay:decodeForDisplay];
+    pthread_mutex_unlock(&_lock);
+    return result;
+}
+
+- (NSTimeInterval)frameDurationAtIndex:(NSUInteger)index {
+    NSTimeInterval result = 0;
+    OSSpinLockLock(&_framesLock); // for better performance when play animation...
+    if (index < _frames.count) {
+        result = ((_YYImageDecoderFrame *)_frames[index]).duration;
+    }
+    OSSpinLockUnlock(&_framesLock);
+    return result;
+}
+
+- (NSDictionary *)framePropertiesAtIndex:(NSUInteger)index {
+    NSDictionary *result = nil;
+    pthread_mutex_lock(&_lock);
+    result = [self _framePropertiesAtIndex:index];
+    pthread_mutex_unlock(&_lock);
+    return result;
+}
+
+- (NSDictionary *)imageProperties {
+    NSDictionary *result = nil;
+    pthread_mutex_lock(&_lock);
+    result = [self _imageProperties];
+    pthread_mutex_unlock(&_lock);
+    return result;
+}
+
+#pragma private (wrap)
+
+- (BOOL)_updateData:(NSData *)data final:(BOOL)final {
+    if (_finalized) return NO;
+    if (data.length < _data.length) return NO;
+    _finalized = final;
+    _data = data;
+    
+    YYImageType type = YYImageDetectType((__bridge CFDataRef)data);
+    if (_sourceTypeDetected) {
+        if (_type != type) {
+            return NO;
+        } else {
+            [self _updateSource];
+        }
+    } else {
+        if (_data.length > 16) {
+            _type = type;
+            _sourceTypeDetected = YES;
+            [self _updateSource];
+        }
+    }
+    return YES;
+}
+
+- (YYImageFrame *)_frameAtIndex:(NSUInteger)index decodeForDisplay:(BOOL)decodeForDisplay {
+    if (index >= _frames.count) return 0;
+    _YYImageDecoderFrame *frame = [(_YYImageDecoderFrame *)_frames[index] copy];
+    BOOL decoded = NO;
+    BOOL extendToCanvas = NO;
+    if (_type != YYImageTypeICO && decodeForDisplay) { // ICO contains multi-size frame and should not extend to canvas.
+        extendToCanvas = YES;
+    }
+    
+    if (!_needBlend) {
+        CGImageRef imageRef = [self _newUnblendedImageAtIndex:index extendToCanvas:extendToCanvas decoded:&decoded];
+        if (!imageRef) return nil;
+        if (decodeForDisplay && !decoded) {
+            CGImageRef imageRefDecoded = YYCGImageCreateDecodedCopy(imageRef, YES);
+            if (imageRefDecoded) {
+                CFRelease(imageRef);
+                imageRef = imageRefDecoded;
+                decoded = YES;
+            }
+        }
+        UIImage *image = [UIImage imageWithCGImage:imageRef scale:_scale orientation:_orientation];
+        CFRelease(imageRef);
+        if (!image) return nil;
+        image.yy_isDecodedForDisplay = decoded;
+        frame.image = image;
+        return frame;
+    }
+    
+    // blend
+    if (![self _createBlendContextIfNeeded]) return nil;
+    CGImageRef imageRef = NULL;
+    
+    if (_blendFrameIndex + 1 == frame.index) {
+        imageRef = [self _newBlendedImageWithFrame:frame];
+        _blendFrameIndex = index;
+    } else { // should draw canvas from previous frame
+        _blendFrameIndex = NSNotFound;
+        CGContextClearRect(_blendCanvas, CGRectMake(0, 0, _width, _height));
+        
+        if (frame.blendFromIndex == frame.index) {
+            CGImageRef unblendedImage = [self _newUnblendedImageAtIndex:index extendToCanvas:NO decoded:NULL];
+            if (unblendedImage) {
+                CGContextDrawImage(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), unblendedImage);
+                CFRelease(unblendedImage);
+            }
+            imageRef = CGBitmapContextCreateImage(_blendCanvas);
+            if (frame.dispose == YYImageDisposeBackground) {
+                CGContextClearRect(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height));
+            }
+            _blendFrameIndex = index;
+        } else { // canvas is not ready
+            for (uint32_t i = (uint32_t)frame.blendFromIndex; i <= (uint32_t)frame.index; i++) {
+                if (i == frame.index) {
+                    if (!imageRef) imageRef = [self _newBlendedImageWithFrame:frame];
+                } else {
+                    [self _blendImageWithFrame:_frames[i]];
+                }
+            }
+            _blendFrameIndex = index;
+        }
+    }
+    
+    if (!imageRef) return nil;
+    UIImage *image = [UIImage imageWithCGImage:imageRef scale:_scale orientation:_orientation];
+    CFRelease(imageRef);
+    if (!image) return nil;
+    
+    image.yy_isDecodedForDisplay = YES;
+    frame.image = image;
+    if (extendToCanvas) {
+        frame.width = _width;
+        frame.height = _height;
+        frame.offsetX = 0;
+        frame.offsetY = 0;
+        frame.dispose = YYImageDisposeNone;
+        frame.blend = YYImageBlendNone;
+    }
+    return frame;
+}
+
+- (NSDictionary *)_framePropertiesAtIndex:(NSUInteger)index {
+    if (index >= _frames.count) return nil;
+    if (!_source) return nil;
+    CFDictionaryRef properties = CGImageSourceCopyPropertiesAtIndex(_source, index, NULL);
+    if (!properties) return nil;
+    return CFBridgingRelease(properties);
+}
+
+- (NSDictionary *)_imageProperties {
+    if (!_source) return nil;
+    CFDictionaryRef properties = CGImageSourceCopyProperties(_source, NULL);
+    if (!properties) return nil;
+    return CFBridgingRelease(properties);
+}
+
+#pragma private
+
+- (void)_updateSource {
+    switch (_type) {
+        case YYImageTypeWebP: {
+            [self _updateSourceWebP];
+        } break;
+            
+        case YYImageTypePNG: {
+            [self _updateSourceAPNG];
+        } break;
+            
+        default: {
+            [self _updateSourceImageIO];
+        } break;
+    }
+}
+
+- (void)_updateSourceWebP {
+#if YYIMAGE_WEBP_ENABLED
+    _width = 0;
+    _height = 0;
+    _loopCount = 0;
+    if (_webpSource) WebPDemuxDelete(_webpSource);
+    _webpSource = NULL;
+    OSSpinLockLock(&_framesLock);
+    _frames = nil;
+    OSSpinLockUnlock(&_framesLock);
+    
+    /*
+     https://developers.google.com/speed/webp/docs/api
+     The documentation said we can use WebPIDecoder to decode webp progressively, 
+     but currently it can only returns an empty image (not same as progressive jpegs),
+     so we don't use progressive decoding.
+     
+     When using WebPDecode() to decode multi-frame webp, we will get the error
+     "VP8_STATUS_UNSUPPORTED_FEATURE", so we first use WebPDemuxer to unpack it.
+     */
+    
+    WebPData webPData = {0};
+    webPData.bytes = _data.bytes;
+    webPData.size = _data.length;
+    WebPDemuxer *demuxer = WebPDemux(&webPData);
+    if (!demuxer) return;
+    
+    uint32_t webpFrameCount = WebPDemuxGetI(demuxer, WEBP_FF_FRAME_COUNT);
+    uint32_t webpLoopCount =  WebPDemuxGetI(demuxer, WEBP_FF_LOOP_COUNT);
+    uint32_t canvasWidth = WebPDemuxGetI(demuxer, WEBP_FF_CANVAS_WIDTH);
+    uint32_t canvasHeight = WebPDemuxGetI(demuxer, WEBP_FF_CANVAS_HEIGHT);
+    if (webpFrameCount == 0 || canvasWidth < 1 || canvasHeight < 1) {
+        WebPDemuxDelete(demuxer);
+        return;
+    }
+    
+    NSMutableArray *frames = [NSMutableArray new];
+    BOOL needBlend = NO;
+    uint32_t iterIndex = 0;
+    uint32_t lastBlendIndex = 0;
+    WebPIterator iter = {0};
+    if (WebPDemuxGetFrame(demuxer, 1, &iter)) { // one-based index...
+        do {
+            _YYImageDecoderFrame *frame = [_YYImageDecoderFrame new];
+            [frames addObject:frame];
+            if (iter.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) {
+                frame.dispose = YYImageDisposeBackground;
+            }
+            if (iter.blend_method == WEBP_MUX_BLEND) {
+                frame.blend = YYImageBlendOver;
+            }
+            
+            int canvasWidth = WebPDemuxGetI(demuxer, WEBP_FF_CANVAS_WIDTH);
+            int canvasHeight = WebPDemuxGetI(demuxer, WEBP_FF_CANVAS_HEIGHT);
+            frame.index = iterIndex;
+            frame.duration = iter.duration / 1000.0;
+            frame.width = iter.width;
+            frame.height = iter.height;
+            frame.hasAlpha = iter.has_alpha;
+            frame.blend = iter.blend_method == WEBP_MUX_BLEND;
+            frame.offsetX = iter.x_offset;
+            frame.offsetY = canvasHeight - iter.y_offset - iter.height;
+            
+            BOOL sizeEqualsToCanvas = (iter.width == canvasWidth && iter.height == canvasHeight);
+            BOOL offsetIsZero = (iter.x_offset == 0 && iter.y_offset == 0);
+            frame.isFullSize = (sizeEqualsToCanvas && offsetIsZero);
+            
+            if ((!frame.blend || !frame.hasAlpha) && frame.isFullSize) {
+                frame.blendFromIndex = lastBlendIndex = iterIndex;
+            } else {
+                if (frame.dispose && frame.isFullSize) {
+                    frame.blendFromIndex = lastBlendIndex;
+                    lastBlendIndex = iterIndex + 1;
+                } else {
+                    frame.blendFromIndex = lastBlendIndex;
+                }
+            }
+            if (frame.index != frame.blendFromIndex) needBlend = YES;
+            iterIndex++;
+        } while (WebPDemuxNextFrame(&iter));
+        WebPDemuxReleaseIterator(&iter);
+    }
+    if (frames.count != webpFrameCount) {
+        WebPDemuxDelete(demuxer);
+        return;
+    }
+    
+    _width = canvasWidth;
+    _height = canvasHeight;
+    _frameCount = frames.count;
+    _loopCount = webpLoopCount;
+    _needBlend = needBlend;
+    _webpSource = demuxer;
+    OSSpinLockLock(&_framesLock);
+    _frames = frames;
+    OSSpinLockUnlock(&_framesLock);
+#endif
+}
+
+- (void)_updateSourceAPNG {
+    /*
+     APNG extends PNG format to support animation, it was supported by ImageIO
+     since iOS 8.
+     
+     We use a custom APNG decoder to make APNG available in old system, so we
+     ignore the ImageIO's APNG frame info. Typically the custom decoder is a bit
+     faster than ImageIO.
+     */
+    
+    yy_png_info_release(_apngSource);
+    _apngSource = nil;
+    
+    [self _updateSourceImageIO]; // decode first frame
+    if (_frameCount == 0) return; // png decode failed
+    if (!_finalized) return; // ignore multi-frame before finalized
+    
+    yy_png_info *apng = yy_png_info_create(_data.bytes, (uint32_t)_data.length);
+    if (!apng) return; // apng decode failed
+    if (apng->apng_frame_num == 0 ||
+        (apng->apng_frame_num == 1 && apng->apng_first_frame_is_cover)) {
+        yy_png_info_release(apng);
+        return; // no animation
+    }
+    if (_source) { // apng decode succeed, no longer need image souce
+        CFRelease(_source);
+        _source = NULL;
+    }
+    
+    uint32_t canvasWidth = apng->header.width;
+    uint32_t canvasHeight = apng->header.height;
+    NSMutableArray *frames = [NSMutableArray new];
+    BOOL needBlend = NO;
+    uint32_t lastBlendIndex = 0;
+    for (uint32_t i = 0; i < apng->apng_frame_num; i++) {
+        _YYImageDecoderFrame *frame = [_YYImageDecoderFrame new];
+        [frames addObject:frame];
+        
+        yy_png_frame_info *fi = apng->apng_frames + i;
+        frame.index = i;
+        frame.duration = yy_png_delay_to_seconds(fi->frame_control.delay_num, fi->frame_control.delay_den);
+        frame.hasAlpha = YES;
+        frame.width = fi->frame_control.width;
+        frame.height = fi->frame_control.height;
+        frame.offsetX = fi->frame_control.x_offset;
+        frame.offsetY = canvasHeight - fi->frame_control.y_offset - fi->frame_control.height;
+        
+        BOOL sizeEqualsToCanvas = (frame.width == canvasWidth && frame.height == canvasHeight);
+        BOOL offsetIsZero = (fi->frame_control.x_offset == 0 && fi->frame_control.y_offset == 0);
+        frame.isFullSize = (sizeEqualsToCanvas && offsetIsZero);
+        
+        switch (fi->frame_control.dispose_op) {
+            case YY_PNG_DISPOSE_OP_BACKGROUND: {
+                frame.dispose = YYImageDisposeBackground;
+            } break;
+            case YY_PNG_DISPOSE_OP_PREVIOUS: {
+                frame.dispose = YYImageDisposePrevious;
+            } break;
+            default: {
+                frame.dispose = YYImageDisposeNone;
+            } break;
+        }
+        switch (fi->frame_control.blend_op) {
+            case YY_PNG_BLEND_OP_OVER: {
+                frame.blend = YYImageBlendOver;
+            } break;
+                
+            default: {
+                frame.blend = YYImageBlendNone;
+            } break;
+        }
+        
+        if (frame.blend == YYImageBlendNone && frame.isFullSize) {
+            frame.blendFromIndex  = i;
+            if (frame.dispose != YYImageDisposePrevious) lastBlendIndex = i;
+        } else {
+            if (frame.dispose == YYImageDisposeBackground && frame.isFullSize) {
+                frame.blendFromIndex = lastBlendIndex;
+                lastBlendIndex = i + 1;
+            } else {
+                frame.blendFromIndex = lastBlendIndex;
+            }
+        }
+        if (frame.index != frame.blendFromIndex) needBlend = YES;
+    }
+    
+    _width = canvasWidth;
+    _height = canvasHeight;
+    _frameCount = frames.count;
+    _loopCount = apng->apng_loop_num;
+    _needBlend = needBlend;
+    _apngSource = apng;
+    OSSpinLockLock(&_framesLock);
+    _frames = frames;
+    OSSpinLockUnlock(&_framesLock);
+}
+
+- (void)_updateSourceImageIO {
+    _width = 0;
+    _height = 0;
+    _orientation = UIImageOrientationUp;
+    _loopCount = 0;
+    OSSpinLockLock(&_framesLock);
+    _frames = nil;
+    OSSpinLockUnlock(&_framesLock);
+    
+    if (!_source) {
+        if (_finalized) {
+            _source = CGImageSourceCreateWithData((__bridge CFDataRef)_data, NULL);
+        } else {
+            _source = CGImageSourceCreateIncremental(NULL);
+            if (_source) CGImageSourceUpdateData(_source, (__bridge CFDataRef)_data, false);
+        }
+    } else {
+        CGImageSourceUpdateData(_source, (__bridge CFDataRef)_data, _finalized);
+    }
+    if (!_source) return;
+    
+    _frameCount = CGImageSourceGetCount(_source);
+    if (_frameCount == 0) return;
+    
+    if (!_finalized) { // ignore multi-frame before finalized
+        _frameCount = 1;
+    } else {
+        if (_type == YYImageTypePNG) { // use custom apng decoder and ignore multi-frame
+            _frameCount = 1;
+        }
+        if (_type == YYImageTypeGIF) { // get gif loop count
+            CFDictionaryRef properties = CGImageSourceCopyProperties(_source, NULL);
+            if (properties) {
+                CFTypeRef loop = CFDictionaryGetValue(properties, kCGImagePropertyGIFLoopCount);
+                if (loop) CFNumberGetValue(loop, kCFNumberNSIntegerType, &_loopCount);
+                CFRelease(properties);
+            }
+        }
+    }
+    
+    /*
+     ICO, GIF, APNG may contains multi-frame.
+     */
+    NSMutableArray *frames = [NSMutableArray new];
+    for (NSUInteger i = 0; i < _frameCount; i++) {
+        _YYImageDecoderFrame *frame = [_YYImageDecoderFrame new];
+        frame.index = i;
+        frame.blendFromIndex = i;
+        frame.hasAlpha = YES;
+        frame.isFullSize = YES;
+        [frames addObject:frame];
+        
+        CFDictionaryRef properties = CGImageSourceCopyPropertiesAtIndex(_source, i, NULL);
+        if (properties) {
+            NSTimeInterval duration = 0;
+            NSInteger orientationValue = 0, width = 0, height = 0;
+            CFTypeRef value = NULL;
+            
+            value = CFDictionaryGetValue(properties, kCGImagePropertyPixelWidth);
+            if (value) CFNumberGetValue(value, kCFNumberNSIntegerType, &width);
+            value = CFDictionaryGetValue(properties, kCGImagePropertyPixelHeight);
+            if (value) CFNumberGetValue(value, kCFNumberNSIntegerType, &height);
+            if (_type == YYImageTypeGIF) {
+                CFDictionaryRef gif = CFDictionaryGetValue(properties, kCGImagePropertyGIFDictionary);
+                if (gif) {
+                    // Use the unclamped frame delay if it exists.
+                    value = CFDictionaryGetValue(gif, kCGImagePropertyGIFUnclampedDelayTime);
+                    if (!value) {
+                        // Fall back to the clamped frame delay if the unclamped frame delay does not exist.
+                        value = CFDictionaryGetValue(gif, kCGImagePropertyGIFDelayTime);
+                    }
+                    if (value) CFNumberGetValue(value, kCFNumberDoubleType, &duration);
+                }
+            }
+            
+            frame.width = width;
+            frame.height = height;
+            frame.duration = duration;
+            
+            if (i == 0 && _width + _height == 0) { // init first frame
+                _width = width;
+                _height = height;
+                value = CFDictionaryGetValue(properties, kCGImagePropertyOrientation);
+                if (value) {
+                    CFNumberGetValue(value, kCFNumberNSIntegerType, &orientationValue);
+                    _orientation = YYUIImageOrientationFromEXIFValue(orientationValue);
+                }
+            }
+            CFRelease(properties);
+        }
+    }
+    OSSpinLockLock(&_framesLock);
+    _frames = frames;
+    OSSpinLockUnlock(&_framesLock);
+}
+
+- (CGImageRef)_newUnblendedImageAtIndex:(NSUInteger)index
+                         extendToCanvas:(BOOL)extendToCanvas
+                                decoded:(BOOL *)decoded CF_RETURNS_RETAINED {
+    
+    if (!_finalized && index > 0) return NULL;
+    if (_frames.count <= index) return NULL;
+    _YYImageDecoderFrame *frame = _frames[index];
+    
+    if (_source) {
+        CGImageRef imageRef = CGImageSourceCreateImageAtIndex(_source, index, (CFDictionaryRef)@{(id)kCGImageSourceShouldCache:@(YES)});
+        if (imageRef && extendToCanvas) {
+            size_t width = CGImageGetWidth(imageRef);
+            size_t height = CGImageGetHeight(imageRef);
+            if (width == _width && height == _height) {
+                CGImageRef imageRefExtended = YYCGImageCreateDecodedCopy(imageRef, YES);
+                if (imageRefExtended) {
+                    CFRelease(imageRef);
+                    imageRef = imageRefExtended;
+                    if (decoded) *decoded = YES;
+                }
+            } else {
+                CGContextRef context = CGBitmapContextCreate(NULL, _width, _height, 8, 0, YYCGColorSpaceGetDeviceRGB(), kCGBitmapByteOrder32Host | kCGImageAlphaPremultipliedFirst);
+                if (context) {
+                    CGContextDrawImage(context, CGRectMake(0, _height - height, width, height), imageRef);
+                    CGImageRef imageRefExtended = CGBitmapContextCreateImage(context);
+                    CFRelease(context);
+                    if (imageRefExtended) {
+                        CFRelease(imageRef);
+                        imageRef = imageRefExtended;
+                        if (decoded) *decoded = YES;
+                    }
+                }
+            }
+        }
+        return imageRef;
+    }
+    
+    if (_apngSource) {
+        uint32_t size = 0;
+        uint8_t *bytes = yy_png_copy_frame_data_at_index(_data.bytes, _apngSource, (uint32_t)index, &size);
+        if (!bytes) return NULL;
+        CGDataProviderRef provider = CGDataProviderCreateWithData(bytes, bytes, size, YYCGDataProviderReleaseDataCallback);
+        if (!provider) {
+            free(bytes);
+            return NULL;
+        }
+        bytes = NULL; // hold by provider
+        
+        CGImageSourceRef source = CGImageSourceCreateWithDataProvider(provider, NULL);
+        if (!source) {
+            CFRelease(provider);
+            return NULL;
+        }
+        CFRelease(provider);
+        
+        if(CGImageSourceGetCount(source) < 1) {
+            CFRelease(source);
+            return NULL;
+        }
+        
+        CGImageRef imageRef = CGImageSourceCreateImageAtIndex(source, 0, (CFDictionaryRef)@{(id)kCGImageSourceShouldCache:@(YES)});
+        CFRelease(source);
+        if (!imageRef) return NULL;
+        if (extendToCanvas) {
+            CGContextRef context = CGBitmapContextCreate(NULL, _width, _height, 8, 0, YYCGColorSpaceGetDeviceRGB(), kCGBitmapByteOrder32Host | kCGImageAlphaPremultipliedFirst); //bgrA
+            if (context) {
+                CGContextDrawImage(context, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), imageRef);
+                CFRelease(imageRef);
+                imageRef = CGBitmapContextCreateImage(context);
+                CFRelease(context);
+                if (decoded) *decoded = YES;
+            }
+        }
+        return imageRef;
+    }
+    
+#if YYIMAGE_WEBP_ENABLED
+    if (_webpSource) {
+        WebPIterator iter;
+        if (!WebPDemuxGetFrame(_webpSource, (int)(index + 1), &iter)) return NULL; // demux webp frame data
+        // frame numbers are one-based in webp -----------^
+        
+        int frameWidth = iter.width;
+        int frameHeight = iter.height;
+        if (frameWidth < 1 || frameHeight < 1) return NULL;
+        
+        int width = extendToCanvas ? (int)_width : frameWidth;
+        int height = extendToCanvas ? (int)_height : frameHeight;
+        if (width > _width || height > _height) return NULL;
+        
+        const uint8_t *payload = iter.fragment.bytes;
+        size_t payloadSize = iter.fragment.size;
+        
+        WebPDecoderConfig config;
+        if (!WebPInitDecoderConfig(&config)) {
+            WebPDemuxReleaseIterator(&iter);
+            return NULL;
+        }
+        if (WebPGetFeatures(payload , payloadSize, &config.input) != VP8_STATUS_OK) {
+            WebPDemuxReleaseIterator(&iter);
+            return NULL;
+        }
+        
+        size_t bitsPerComponent = 8;
+        size_t bitsPerPixel = 32;
+        size_t bytesPerRow = YYImageByteAlign(bitsPerPixel / 8 * width, 32);
+        size_t length = bytesPerRow * height;
+        CGBitmapInfo bitmapInfo = kCGBitmapByteOrder32Host | kCGImageAlphaPremultipliedFirst; //bgrA
+        
+        void *pixels = calloc(1, length);
+        if (!pixels) {
+            WebPDemuxReleaseIterator(&iter);
+            return NULL;
+        }
+        
+        config.output.colorspace = MODE_bgrA;
+        config.output.is_external_memory = 1;
+        config.output.u.RGBA.rgba = pixels;
+        config.output.u.RGBA.stride = (int)bytesPerRow;
+        config.output.u.RGBA.size = length;
+        if (WebPDecode(payload, payloadSize, &config) != VP8_STATUS_OK) { // decode
+            WebPDemuxReleaseIterator(&iter);
+            free(pixels);
+            return NULL;
+        }
+        WebPDemuxReleaseIterator(&iter);
+        
+        if (extendToCanvas && (iter.x_offset != 0 || iter.y_offset != 0)) {
+            void *tmp = calloc(1, length);
+            if (tmp) {
+                vImage_Buffer src = {pixels, height, width, bytesPerRow};
+                vImage_Buffer dest = {tmp, height, width, bytesPerRow};
+                vImage_CGAffineTransform transform = {1, 0, 0, 1, iter.x_offset, -iter.y_offset};
+                uint8_t backColor[4] = {0};
+                vImage_Error error = vImageAffineWarpCG_ARGB8888(&src, &dest, NULL, &transform, backColor, kvImageBackgroundColorFill);
+                if (error == kvImageNoError) {
+                    memcpy(pixels, tmp, length);
+                }
+                free(tmp);
+            }
+        }
+        
+        CGDataProviderRef provider = CGDataProviderCreateWithData(pixels, pixels, length, YYCGDataProviderReleaseDataCallback);
+        if (!provider) {
+            free(pixels);
+            return NULL;
+        }
+        pixels = NULL; // hold by provider
+        
+        CGImageRef image = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, YYCGColorSpaceGetDeviceRGB(), bitmapInfo, provider, NULL, false, kCGRenderingIntentDefault);
+        CFRelease(provider);
+        if (decoded) *decoded = YES;
+        return image;
+    }
+#endif
+    
+    return NULL;
+}
+
+- (BOOL)_createBlendContextIfNeeded {
+    if (!_blendCanvas) {
+        _blendFrameIndex = NSNotFound;
+        _blendCanvas = CGBitmapContextCreate(NULL, _width, _height, 8, 0, YYCGColorSpaceGetDeviceRGB(), kCGBitmapByteOrder32Host | kCGImageAlphaPremultipliedFirst);
+    }
+    BOOL suc = _blendCanvas != NULL;
+    return suc;
+}
+
+- (void)_blendImageWithFrame:(_YYImageDecoderFrame *)frame {
+    if (frame.dispose == YYImageDisposePrevious) {
+        // nothing
+    } else if (frame.dispose == YYImageDisposeBackground) {
+        CGContextClearRect(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height));
+    } else { // no dispose
+        if (frame.blend == YYImageBlendOver) {
+            CGImageRef unblendImage = [self _newUnblendedImageAtIndex:frame.index extendToCanvas:NO decoded:NULL];
+            if (unblendImage) {
+                CGContextDrawImage(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), unblendImage);
+                CFRelease(unblendImage);
+            }
+        } else {
+            CGContextClearRect(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height));
+            CGImageRef unblendImage = [self _newUnblendedImageAtIndex:frame.index extendToCanvas:NO decoded:NULL];
+            if (unblendImage) {
+                CGContextDrawImage(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), unblendImage);
+                CFRelease(unblendImage);
+            }
+        }
+    }
+}
+
+- (CGImageRef)_newBlendedImageWithFrame:(_YYImageDecoderFrame *)frame CF_RETURNS_RETAINED{
+    CGImageRef imageRef = NULL;
+    if (frame.dispose == YYImageDisposePrevious) {
+        if (frame.blend == YYImageBlendOver) {
+            CGImageRef previousImage = CGBitmapContextCreateImage(_blendCanvas);
+            CGImageRef unblendImage = [self _newUnblendedImageAtIndex:frame.index extendToCanvas:NO decoded:NULL];
+            if (unblendImage) {
+                CGContextDrawImage(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), unblendImage);
+                CFRelease(unblendImage);
+            }
+            imageRef = CGBitmapContextCreateImage(_blendCanvas);
+            CGContextClearRect(_blendCanvas, CGRectMake(0, 0, _width, _height));
+            if (previousImage) {
+                CGContextDrawImage(_blendCanvas, CGRectMake(0, 0, _width, _height), previousImage);
+                CFRelease(previousImage);
+            }
+        } else {
+            CGImageRef previousImage = CGBitmapContextCreateImage(_blendCanvas);
+            CGImageRef unblendImage = [self _newUnblendedImageAtIndex:frame.index extendToCanvas:NO decoded:NULL];
+            if (unblendImage) {
+                CGContextClearRect(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height));
+                CGContextDrawImage(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), unblendImage);
+                CFRelease(unblendImage);
+            }
+            imageRef = CGBitmapContextCreateImage(_blendCanvas);
+            CGContextClearRect(_blendCanvas, CGRectMake(0, 0, _width, _height));
+            if (previousImage) {
+                CGContextDrawImage(_blendCanvas, CGRectMake(0, 0, _width, _height), previousImage);
+                CFRelease(previousImage);
+            }
+        }
+    } else if (frame.dispose == YYImageDisposeBackground) {
+        if (frame.blend == YYImageBlendOver) {
+            CGImageRef unblendImage = [self _newUnblendedImageAtIndex:frame.index extendToCanvas:NO decoded:NULL];
+            if (unblendImage) {
+                CGContextDrawImage(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), unblendImage);
+                CFRelease(unblendImage);
+            }
+            imageRef = CGBitmapContextCreateImage(_blendCanvas);
+            CGContextClearRect(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height));
+        } else {
+            CGImageRef unblendImage = [self _newUnblendedImageAtIndex:frame.index extendToCanvas:NO decoded:NULL];
+            if (unblendImage) {
+                CGContextClearRect(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height));
+                CGContextDrawImage(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), unblendImage);
+                CFRelease(unblendImage);
+            }
+            imageRef = CGBitmapContextCreateImage(_blendCanvas);
+            CGContextClearRect(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height));
+        }
+    } else { // no dispose
+        if (frame.blend == YYImageBlendOver) {
+            CGImageRef unblendImage = [self _newUnblendedImageAtIndex:frame.index extendToCanvas:NO decoded:NULL];
+            if (unblendImage) {
+                CGContextDrawImage(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), unblendImage);
+                CFRelease(unblendImage);
+            }
+            imageRef = CGBitmapContextCreateImage(_blendCanvas);
+        } else {
+            CGImageRef unblendImage = [self _newUnblendedImageAtIndex:frame.index extendToCanvas:NO decoded:NULL];
+            if (unblendImage) {
+                CGContextClearRect(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height));
+                CGContextDrawImage(_blendCanvas, CGRectMake(frame.offsetX, frame.offsetY, frame.width, frame.height), unblendImage);
+                CFRelease(unblendImage);
+            }
+            imageRef = CGBitmapContextCreateImage(_blendCanvas);
+        }
+    }
+    return imageRef;
+}
+
+@end
+
+
+////////////////////////////////////////////////////////////////////////////////
+#pragma mark - Encoder
+
+@implementation YYImageEncoder {
+    NSMutableArray *_images;
+    NSMutableArray *_durations;
+}
+
+- (instancetype)init {
+    @throw [NSException exceptionWithName:@"YYImageEncoder init error" reason:@"YYImageEncoder must be initialized with a type. Use 'initWithType:' instead." userInfo:nil];
+    return [self initWithType:YYImageTypeUnknown];
+}
+
+- (instancetype)initWithType:(YYImageType)type {
+    if (type == YYImageTypeUnknown || type >= YYImageTypeOther) return nil;
+    
+#if !YYIMAGE_WEBP_ENABLED
+    if (type == YYImageTypeWebP) return nil;
+#endif
+    
+    self = [super init];
+    if (!self) return nil;
+    _type = type;
+    _images = [NSMutableArray new];
+    _durations = [NSMutableArray new];
+
+    switch (type) {
+        case YYImageTypeJPEG:
+        case YYImageTypeJPEG2000: {
+            _quality = 0.9;
+        } break;
+        case YYImageTypeTIFF:
+        case YYImageTypeBMP:
+        case YYImageTypeGIF:
+        case YYImageTypeICO:
+        case YYImageTypeICNS:
+        case YYImageTypePNG: {
+            _quality = 1;
+            _lossless = YES;
+        } break;
+        case YYImageTypeWebP: {
+            _quality = 0.8;
+        } break;
+        default:
+            break;
+    }
+    
+    return self;
+}
+
+- (void)setQuality:(CGFloat)quality {
+    _quality = quality < 0 ? 0 : quality > 1 ? 1 : quality;
+}
+
+- (void)addImage:(UIImage *)image duration:(NSTimeInterval)duration {
+    if (!image.CGImage) return;
+    duration = duration < 0 ? 0 : duration;
+    [_images addObject:image];
+    [_durations addObject:@(duration)];
+}
+
+- (void)addImageWithData:(NSData *)data duration:(NSTimeInterval)duration {
+    if (data.length == 0) return;
+    duration = duration < 0 ? 0 : duration;
+    [_images addObject:data];
+    [_durations addObject:@(duration)];
+}
+
+- (void)addImageWithFile:(NSString *)path duration:(NSTimeInterval)duration {
+    if (path.length == 0) return;
+    duration = duration < 0 ? 0 : duration;
+    NSURL *url = [NSURL URLWithString:path];
+    if (!url) return;
+    [_images addObject:url];
+    [_durations addObject:@(duration)];
+}
+
+- (BOOL)_imageIOAvaliable {
+    switch (_type) {
+        case YYImageTypeJPEG:
+        case YYImageTypeJPEG2000:
+        case YYImageTypeTIFF:
+        case YYImageTypeBMP:
+        case YYImageTypeICO:
+        case YYImageTypeICNS:
+        case YYImageTypeGIF: {
+            return _images.count > 0;
+        } break;
+        case YYImageTypePNG: {
+            return _images.count == 1;
+        } break;
+        case YYImageTypeWebP: {
+            return NO;
+        } break;
+        default: return NO;
+    }
+}
+
+- (CGImageDestinationRef)_newImageDestination:(id)dest imageCount:(NSUInteger)count CF_RETURNS_RETAINED {
+    if (!dest) return nil;
+    CGImageDestinationRef destination = NULL;
+    if ([dest isKindOfClass:[NSString class]]) {
+        NSURL *url = [[NSURL alloc] initFileURLWithPath:dest];
+        if (url) {
+            destination = CGImageDestinationCreateWithURL((CFURLRef)url, YYImageTypeToUTType(_type), count, NULL);
+        }
+    } else if ([dest isKindOfClass:[NSMutableData class]]) {
+        destination = CGImageDestinationCreateWithData((CFMutableDataRef)dest, YYImageTypeToUTType(_type), count, NULL);
+    }
+    return destination;
+}
+
+- (void)_encodeImageWithDestination:(CGImageDestinationRef)destination imageCount:(NSUInteger)count {
+    if (_type == YYImageTypeGIF) {
+        NSDictionary *gifProperty = @{(__bridge id)kCGImagePropertyGIFDictionary:
+                                        @{(__bridge id)kCGImagePropertyGIFLoopCount: @(_loopCount)}};
+        CGImageDestinationSetProperties(destination, (__bridge CFDictionaryRef)gifProperty);
+    }
+    
+    for (int i = 0; i < count; i++) {
+        id imageSrc = _images[i];
+        NSDictionary *frameProperty = NULL;
+        if (_type == YYImageTypeGIF && count > 1) {
+            frameProperty = @{(NSString *)kCGImagePropertyGIFDictionary : @{(NSString *) kCGImagePropertyGIFDelayTime:_durations[i]}};
+        } else {
+            frameProperty = @{(id)kCGImageDestinationLossyCompressionQuality : @(_quality)};
+        }
+        
+        if ([imageSrc isKindOfClass:[UIImage class]]) {
+            CGImageDestinationAddImage(destination, ((UIImage *)imageSrc).CGImage, (CFDictionaryRef)frameProperty);
+        } else if ([imageSrc isKindOfClass:[NSURL class]]) {
+            CGImageSourceRef source = CGImageSourceCreateWithURL((CFURLRef)imageSrc, NULL);
+            if (source) {
+                CGImageDestinationAddImageFromSource(destination, source, i, (CFDictionaryRef)frameProperty);
+                CFRelease(source);
+            }
+        } else if ([imageSrc isKindOfClass:[NSData class]]) {
+            CGImageSourceRef source = CGImageSourceCreateWithData((CFDataRef)imageSrc, NULL);
+            if (source) {
+                CGImageDestinationAddImageFromSource(destination, source, i, (CFDictionaryRef)frameProperty);
+                CFRelease(source);
+            }
+        }
+    }
+}
+
+- (CGImageRef)_newCGImageFromIndex:(NSUInteger)index decoded:(BOOL)decoded CF_RETURNS_RETAINED {
+    UIImage *image = nil;
+    id imageSrc= _images[index];
+    if ([imageSrc isKindOfClass:[UIImage class]]) {
+        image = imageSrc;
+    } else if ([imageSrc isKindOfClass:[NSURL class]]) {
+        image = [UIImage imageWithContentsOfFile:((NSURL *)imageSrc).absoluteString];
+    } else if ([imageSrc isKindOfClass:[NSData class]]) {
+        image = [UIImage imageWithData:imageSrc];
+    }
+    if (!image) return NULL;
+    CGImageRef imageRef = image.CGImage;
+    if (!imageRef) return NULL;
+    if (image.imageOrientation != UIImageOrientationUp) {
+        return YYCGImageCreateCopyWithOrientation(imageRef, image.imageOrientation, kCGBitmapByteOrder32Host | kCGImageAlphaPremultipliedFirst);
+    }
+    if (decoded) {
+        return YYCGImageCreateDecodedCopy(imageRef, YES);
+    }
+    return (CGImageRef)CFRetain(imageRef);
+}
+
+- (NSData *)_encodeWithImageIO {
+    NSMutableData *data = [NSMutableData new];
+    NSUInteger count = _type == YYImageTypeGIF ? _images.count : 1;
+    CGImageDestinationRef destination = [self _newImageDestination:data imageCount:count];
+    BOOL suc = NO;
+    if (destination) {
+        [self _encodeImageWithDestination:destination imageCount:count];
+        suc = CGImageDestinationFinalize(destination);
+        CFRelease(destination);
+    }
+    if (suc && data.length > 0) {
+        return data;
+    } else {
+        return nil;
+    }
+}
+
+- (BOOL)_encodeWithImageIO:(NSString *)path {
+    NSUInteger count = _type == YYImageTypeGIF ? _images.count : 1;
+    CGImageDestinationRef destination = [self _newImageDestination:path imageCount:count];
+    BOOL suc = NO;
+    if (destination) {
+        [self _encodeImageWithDestination:destination imageCount:count];
+        suc = CGImageDestinationFinalize(destination);
+        CFRelease(destination);
+    }
+    return suc;
+}
+
+- (NSData *)_encodeAPNG {
+    // encode APNG (ImageIO doesn't support APNG encoding, so we use a custom encoder)
+    NSMutableArray *pngDatas = [NSMutableArray new];
+    NSMutableArray *pngSizes = [NSMutableArray new];
+    NSUInteger canvasWidth = 0, canvasHeight = 0;
+    for (int i = 0; i < _images.count; i++) {
+        CGImageRef decoded = [self _newCGImageFromIndex:i decoded:YES];
+        if (!decoded) return nil;
+        CGSize size = CGSizeMake(CGImageGetWidth(decoded), CGImageGetHeight(decoded));
+        [pngSizes addObject:[NSValue valueWithCGSize:size]];
+        if (canvasWidth < size.width) canvasWidth = size.width;
+        if (canvasHeight < size.height) canvasHeight = size.height;
+        CFDataRef frameData = YYCGImageCreateEncodedData(decoded, YYImageTypePNG, 1);
+        CFRelease(decoded);
+        if (!frameData) return nil;
+        [pngDatas addObject:(__bridge id)(frameData)];
+        CFRelease(frameData);
+        if (size.width < 1 || size.height < 1) return nil;
+    }
+    CGSize firstFrameSize = [(NSValue *)[pngSizes firstObject] CGSizeValue];
+    if (firstFrameSize.width < canvasWidth || firstFrameSize.height < canvasHeight) {
+        CGImageRef decoded = [self _newCGImageFromIndex:0 decoded:YES];
+        if (!decoded) return nil;
+        CGContextRef context = CGBitmapContextCreate(NULL, canvasWidth, canvasHeight, 8,
+                                                     0, YYCGColorSpaceGetDeviceRGB(), kCGBitmapByteOrder32Host | kCGImageAlphaPremultipliedFirst);
+        if (!context) {
+            CFRelease(decoded);
+            return nil;
+        }
+        CGContextDrawImage(context, CGRectMake(0, canvasHeight - firstFrameSize.height, firstFrameSize.width, firstFrameSize.height), decoded);
+        CFRelease(decoded);
+        CGImageRef extendedImage = CGBitmapContextCreateImage(context);
+        CFRelease(context);
+        if (!extendedImage) return nil;
+        CFDataRef frameData = YYCGImageCreateEncodedData(extendedImage, YYImageTypePNG, 1);
+        if (!frameData) {
+            CFRelease(extendedImage);
+            return nil;
+        }
+        pngDatas[0] = (__bridge id)(frameData);
+        CFRelease(frameData);
+    }
+    
+    NSData *firstFrameData = pngDatas[0];
+    yy_png_info *info = yy_png_info_create(firstFrameData.bytes, (uint32_t)firstFrameData.length);
+    if (!info) return nil;
+    NSMutableData *result = [NSMutableData new];
+    BOOL insertBefore = NO, insertAfter = NO;
+    uint32_t apngSequenceIndex = 0;
+    
+    uint32_t png_header[2];
+    png_header[0] = YY_FOUR_CC(0x89, 0x50, 0x4E, 0x47);
+    png_header[1] = YY_FOUR_CC(0x0D, 0x0A, 0x1A, 0x0A);
+    
+    [result appendBytes:png_header length:8];
+    
+    for (int i = 0; i < info->chunk_num; i++) {
+        yy_png_chunk_info *chunk = info->chunks + i;
+        
+        if (!insertBefore && chunk->fourcc == YY_FOUR_CC('I', 'D', 'A', 'T')) {
+            insertBefore = YES;
+            // insert acTL (APNG Control)
+            uint32_t acTL[5] = {0};
+            acTL[0] = yy_swap_endian_uint32(8); //length
+            acTL[1] = YY_FOUR_CC('a', 'c', 'T', 'L'); // fourcc
+            acTL[2] = yy_swap_endian_uint32((uint32_t)pngDatas.count); // num frames
+            acTL[3] = yy_swap_endian_uint32((uint32_t)_loopCount); // num plays
+            acTL[4] = yy_swap_endian_uint32((uint32_t)crc32(0, (const Bytef *)(acTL + 1), 12)); //crc32
+            [result appendBytes:acTL length:20];
+            
+            // insert fcTL (first frame control)
+            yy_png_chunk_fcTL chunk_fcTL = {0};
+            chunk_fcTL.sequence_number = apngSequenceIndex;
+            chunk_fcTL.width = (uint32_t)firstFrameSize.width;
+            chunk_fcTL.height = (uint32_t)firstFrameSize.height;
+            yy_png_delay_to_fraction([(NSNumber *)_durations[0] doubleValue], &chunk_fcTL.delay_num, &chunk_fcTL.delay_den);
+            chunk_fcTL.delay_num = chunk_fcTL.delay_num;
+            chunk_fcTL.delay_den = chunk_fcTL.delay_den;
+            chunk_fcTL.dispose_op = YY_PNG_DISPOSE_OP_BACKGROUND;
+            chunk_fcTL.blend_op = YY_PNG_BLEND_OP_SOURCE;
+            
+            uint8_t fcTL[38] = {0};
+            *((uint32_t *)fcTL) = yy_swap_endian_uint32(26); //length
+            *((uint32_t *)(fcTL + 4)) = YY_FOUR_CC('f', 'c', 'T', 'L'); // fourcc
+            yy_png_chunk_fcTL_write(&chunk_fcTL, fcTL + 8);
+            *((uint32_t *)(fcTL + 34)) = yy_swap_endian_uint32((uint32_t)crc32(0, (const Bytef *)(fcTL + 4), 30));
+            [result appendBytes:fcTL length:38];
+            
+            apngSequenceIndex++;
+        }
+        
+        if (!insertAfter && insertBefore && chunk->fourcc != YY_FOUR_CC('I', 'D', 'A', 'T')) {
+            insertAfter = YES;
+            // insert fcTL and fdAT (APNG frame control and data)
+            
+            for (int i = 1; i < pngDatas.count; i++) {
+                NSData *frameData = pngDatas[i];
+                yy_png_info *frame = yy_png_info_create(frameData.bytes, (uint32_t)frameData.length);
+                if (!frame) {
+                    yy_png_info_release(info);
+                    return nil;
+                }
+                
+                // insert fcTL (first frame control)
+                yy_png_chunk_fcTL chunk_fcTL = {0};
+                chunk_fcTL.sequence_number = apngSequenceIndex;
+                chunk_fcTL.width = frame->header.width;
+                chunk_fcTL.height = frame->header.height;
+                yy_png_delay_to_fraction([(NSNumber *)_durations[0] doubleValue], &chunk_fcTL.delay_num, &chunk_fcTL.delay_den);
+                chunk_fcTL.delay_num = chunk_fcTL.delay_num;
+                chunk_fcTL.delay_den = chunk_fcTL.delay_den;
+                chunk_fcTL.dispose_op = YY_PNG_DISPOSE_OP_BACKGROUND;
+                chunk_fcTL.blend_op = YY_PNG_BLEND_OP_SOURCE;
+                
+                uint8_t fcTL[38] = {0};
+                *((uint32_t *)fcTL) = yy_swap_endian_uint32(26); //length
+                *((uint32_t *)(fcTL + 4)) = YY_FOUR_CC('f', 'c', 'T', 'L'); // fourcc
+                yy_png_chunk_fcTL_write(&chunk_fcTL, fcTL + 8);
+                *((uint32_t *)(fcTL + 34)) = yy_swap_endian_uint32((uint32_t)crc32(0, (const Bytef *)(fcTL + 4), 30));
+                [result appendBytes:fcTL length:38];
+                
+                apngSequenceIndex++;
+                
+                // insert fdAT (frame data)
+                for (int d = 0; d < frame->chunk_num; d++) {
+                    yy_png_chunk_info *dchunk = frame->chunks + d;
+                    if (dchunk->fourcc == YY_FOUR_CC('I', 'D', 'A', 'T')) {
+                        uint32_t length = yy_swap_endian_uint32(dchunk->length + 4);
+                        [result appendBytes:&length length:4]; //length
+                        uint32_t fourcc = YY_FOUR_CC('f', 'd', 'A', 'T');
+                        [result appendBytes:&fourcc length:4]; //fourcc
+                        uint32_t sq = yy_swap_endian_uint32(apngSequenceIndex);
+                        [result appendBytes:&sq length:4]; //data (sq)
+                        [result appendBytes:(((uint8_t *)frameData.bytes) + dchunk->offset + 8) length:dchunk->length]; //data
+                        uint8_t *bytes = ((uint8_t *)result.bytes) + result.length - dchunk->length - 8;
+                        uint32_t crc = yy_swap_endian_uint32((uint32_t)crc32(0, bytes, dchunk->length + 8));
+                        [result appendBytes:&crc length:4]; //crc
+                        
+                        apngSequenceIndex++;
+                    }
+                }
+                yy_png_info_release(frame);
+            }
+        }
+        
+        [result appendBytes:((uint8_t *)firstFrameData.bytes) + chunk->offset length:chunk->length + 12];
+    }
+    yy_png_info_release(info);
+    return result;
+}
+
+- (NSData *)_encodeWebP {
+#if YYIMAGE_WEBP_ENABLED
+    // encode webp
+    NSMutableArray *webpDatas = [NSMutableArray new];
+    for (NSUInteger i = 0; i < _images.count; i++) {
+        CGImageRef image = [self _newCGImageFromIndex:i decoded:NO];
+        if (!image) return nil;
+        CFDataRef frameData = YYCGImageCreateEncodedWebPData(image, _lossless, _quality, 4, YYImagePresetDefault);
+        CFRelease(image);
+        if (!frameData) return nil;
+        [webpDatas addObject:(__bridge id)frameData];
+        CFRelease(frameData);
+    }
+    if (webpDatas.count == 1) {
+        return webpDatas.firstObject;
+    } else {
+        // multi-frame webp
+        WebPMux *mux = WebPMuxNew();
+        if (!mux) return nil;
+        for (NSUInteger i = 0; i < _images.count; i++) {
+            NSData *data = webpDatas[i];
+            NSNumber *duration = _durations[i];
+            WebPMuxFrameInfo frame = {0};
+            frame.bitstream.bytes = data.bytes;
+            frame.bitstream.size = data.length;
+            frame.duration = (int)(duration.floatValue * 1000.0);
+            frame.id = WEBP_CHUNK_ANMF;
+            frame.dispose_method = WEBP_MUX_DISPOSE_BACKGROUND;
+            frame.blend_method = WEBP_MUX_NO_BLEND;
+            if (WebPMuxPushFrame(mux, &frame, 0) != WEBP_MUX_OK) {
+                WebPMuxDelete(mux);
+                return nil;
+            }
+        }
+        
+        WebPMuxAnimParams params = {(uint32_t)0, (int)_loopCount};
+        if (WebPMuxSetAnimationParams(mux, &params) != WEBP_MUX_OK) {
+            WebPMuxDelete(mux);
+            return nil;
+        }
+        
+        WebPData output_data;
+        WebPMuxError error = WebPMuxAssemble(mux, &output_data);
+        WebPMuxDelete(mux);
+        if (error != WEBP_MUX_OK) {
+            return nil;
+        }
+        NSData *result = [NSData dataWithBytes:output_data.bytes length:output_data.size];
+        WebPDataClear(&output_data);
+        return result.length ? result : nil;
+    }
+#else
+    return nil;
+#endif
+}
+- (NSData *)encode {
+    if (_images.count == 0) return nil;
+    
+    if ([self _imageIOAvaliable]) return [self _encodeWithImageIO];
+    if (_type == YYImageTypePNG) return [self _encodeAPNG];
+    if (_type == YYImageTypeWebP) return [self _encodeWebP];
+    return nil;
+}
+
+- (BOOL)encodeToFile:(NSString *)path {
+    if (_images.count == 0 || path.length == 0) return NO;
+    
+    if ([self _imageIOAvaliable]) return [self _encodeWithImageIO:path];
+    NSData *data = [self encode];
+    if (!data) return NO;
+    return [data writeToFile:path atomically:YES];
+}
+
++ (NSData *)encodeImage:(UIImage *)image type:(YYImageType)type quality:(CGFloat)quality {
+    YYImageEncoder *encoder = [[YYImageEncoder alloc] initWithType:type];
+    encoder.quality = quality;
+    [encoder addImage:image duration:0];
+    return [encoder encode];
+}
+
++ (NSData *)encodeImageWithDecoder:(YYImageDecoder *)decoder type:(YYImageType)type quality:(CGFloat)quality {
+    if (!decoder || !decoder.frameCount == 0) return nil;
+    YYImageEncoder *encoder = [[YYImageEncoder alloc] initWithType:type];
+    encoder.quality = quality;
+    for (int i = 0; i < decoder.frameCount; i++) {
+        UIImage *frame = [decoder frameAtIndex:i decodeForDisplay:YES].image;
+        [encoder addImageWithData:UIImagePNGRepresentation(frame) duration:[decoder frameDurationAtIndex:i]];
+    }
+    return encoder.encode;
+}
+
+@end
+
+
+@implementation UIImage (YYImageCoder)
+
+- (instancetype)yy_imageByDecoded {
+    if (self.yy_isDecodedForDisplay) return self;
+    CGImageRef imageRef = self.CGImage;
+    if (!imageRef) return self;
+    CGImageRef newImageRef = YYCGImageCreateDecodedCopy(imageRef, YES);
+    if (!newImageRef) return self;
+    UIImage *newImage = [[self.class alloc] initWithCGImage:newImageRef scale:self.scale orientation:self.imageOrientation];
+    CGImageRelease(newImageRef);
+    if (!newImage) newImage = self; // decode failed, return self.
+    newImage.yy_isDecodedForDisplay = YES;
+    return newImage;
+}
+
+- (BOOL)yy_isDecodedForDisplay {
+    if (self.images.count > 1) return YES;
+    NSNumber *num = objc_getAssociatedObject(self, @selector(yy_isDecodedForDisplay));
+    return [num boolValue];
+}
+
+- (void)setYy_isDecodedForDisplay:(BOOL)isDecodedForDisplay {
+    objc_setAssociatedObject(self, @selector(yy_isDecodedForDisplay), @(isDecodedForDisplay), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+}
+
+- (void)yy_saveToAlbumWithCompletionBlock:(void(^)(NSURL *assetURL, NSError *error))completionBlock {
+    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+        NSData *data = [self _yy_dataRepresentationForSystem:YES];
+        ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
+        [library writeImageDataToSavedPhotosAlbum:data metadata:nil completionBlock:^(NSURL *assetURL, NSError *error){
+            if (!completionBlock) return;
+            if (pthread_main_np()) {
+                completionBlock(assetURL, error);
+            } else {
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    completionBlock(assetURL, error);
+                });
+            }
+        }];
+    });
+}
+
+- (NSData *)yy_imageDataRepresentation {
+    return [self _yy_dataRepresentationForSystem:NO];
+}
+
+/// @param forSystem YES: used for system album (PNG/JPEG/GIF), NO: used for YYImage (PNG/JPEG/GIF/WebP)
+- (NSData *)_yy_dataRepresentationForSystem:(BOOL)forSystem {
+    NSData *data = nil;
+    if ([self isKindOfClass:[YYImage class]]) {
+        YYImage *image = (id)self;
+        if (image.animatedImageData) {
+            if (forSystem) { // system only support GIF and PNG
+                if (image.animatedImageType == YYImageTypeGIF ||
+                    image.animatedImageType == YYImageTypePNG) {
+                    data = image.animatedImageData;
+                }
+            } else {
+                data = image.animatedImageData;
+            }
+        }
+    }
+    if (!data) {
+        CGImageRef imageRef = self.CGImage ? (CGImageRef)CFRetain(self.CGImage) : nil;
+        if (imageRef) {
+            CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
+            CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef) & kCGBitmapAlphaInfoMask;
+            BOOL hasAlpha = NO;
+            if (alphaInfo == kCGImageAlphaPremultipliedLast ||
+                alphaInfo == kCGImageAlphaPremultipliedFirst ||
+                alphaInfo == kCGImageAlphaLast ||
+                alphaInfo == kCGImageAlphaFirst) {
+                hasAlpha = YES;
+            }
+            if (self.imageOrientation != UIImageOrientationUp) {
+                CGImageRef rotated = YYCGImageCreateCopyWithOrientation(imageRef, self.imageOrientation, bitmapInfo | alphaInfo);
+                if (rotated) {
+                    CFRelease(imageRef);
+                    imageRef = rotated;
+                }
+            }
+            @autoreleasepool {
+                UIImage *newImage = [UIImage imageWithCGImage:imageRef];
+                if (newImage) {
+                    if (hasAlpha) {
+                        data = UIImagePNGRepresentation([UIImage imageWithCGImage:imageRef]);
+                    } else {
+                        data = UIImageJPEGRepresentation([UIImage imageWithCGImage:imageRef], 0.9); // same as Apple's example
+                    }
+                }
+            }
+            CFRelease(imageRef);
+        }
+    }
+    if (!data) {
+        data = UIImagePNGRepresentation(self);
+    }
+    return data;
+}
+
+@end

YYWebImage/Image/YYSpriteSheetImage.h

@@ -0,0 +1,98 @@
+//
+//  YYSpriteImage.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/4/21.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYAnimatedImageView.h>
+#else
+#import "YYAnimatedImageView.h"
+#endif
+
+/**
+ An image to display sprite sheet animation.
+ 
+ @discussion It is a fully compatible `UIImage` subclass.
+ The animation can be played by YYAnimatedImageView.
+ 
+ Sample Code:
+  
+    // 8 * 12 sprites in a single sheet image
+    UIImage *spriteSheet = [UIImage imageNamed:@"sprite-sheet"];
+    NSMutableArray *contentRects = [NSMutableArray new];
+    NSMutableArray *durations = [NSMutableArray new];
+    for (int j = 0; j < 12; j++) {
+        for (int i = 0; i < 8; i++) {
+            CGRect rect;
+            rect.size = CGSizeMake(img.size.width / 8, img.size.height / 12);
+            rect.origin.x = img.size.width / 8 * i;
+            rect.origin.y = img.size.height / 12 * j;
+            [contentRects addObject:[NSValue valueWithCGRect:rect]];
+            [durations addObject:@(1 / 60.0)];
+        }
+    }
+    YYSpriteSheetImage *sprite;
+    sprite = [[YYSpriteSheetImage alloc] initWithSpriteSheetImage:img
+                                                     contentRects:contentRects
+                                                   frameDurations:durations
+                                                        loopCount:0];
+    YYAnimatedImageView *imgView = [YYAnimatedImageView new];
+    imgView.size = CGSizeMake(img.size.width / 8, img.size.height / 12);
+    imgView.image = sprite;
+ 
+ 
+ 
+ @discussion It can also be used to display single frame in sprite sheet image.
+ Sample Code:
+ 
+    YYSpriteSheetImage *sheet = ...;
+    UIImageView *imageView = ...;
+    imageView.image = sheet;
+    imageView.layer.contentsRect = [sheet contentsRectForCALayerAtIndex:6];
+ 
+ */
+@interface YYSpriteSheetImage : UIImage <YYAnimatedImage>
+
+/**
+ Creates and returns an image object.
+ 
+ @param image          The sprite sheet image (contains all frames).
+ 
+ @param contentRects   The sprite sheet image frame rects in the image coordinates.
+     The rectangle should not outside the image's bounds. The objects in this array
+     should be created with [NSValue valueWithCGRect:].
+ 
+ @param frameDurations The sprite sheet image frame's durations in seconds. 
+     The objects in this array should be NSNumber.
+ 
+ @param loopCount      Animation loop count, 0 means infinite looping.
+ 
+ @return An image object, or nil if an error occurs.
+ */
+- (instancetype)initWithSpriteSheetImage:(UIImage *)image
+                            contentRects:(NSArray *)contentRects
+                          frameDurations:(NSArray *)frameDurations
+                               loopCount:(NSUInteger)loopCount;
+
+@property (nonatomic, readonly) NSArray *contentRects;
+@property (nonatomic, readonly) NSArray *frameDurations;
+@property (nonatomic, readonly) NSUInteger loopCount;
+
+/**
+ Get the contents rect for CALayer.
+ See "contentsRect" property in CALayer for more information.
+ 
+ @param index Index of frame.
+ @return Contents Rect.
+ */
+- (CGRect)contentsRectForCALayerAtIndex:(NSUInteger)index;
+
+@end

YYWebImage/Image/YYSpriteSheetImage.m

@@ -0,0 +1,80 @@
+//
+//  YYSpriteImage.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/4/21.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYSpriteSheetImage.h"
+
+@implementation YYSpriteSheetImage
+
+- (instancetype)initWithSpriteSheetImage:(UIImage *)image
+                            contentRects:(NSArray *)contentRects
+                          frameDurations:(NSArray *)frameDurations
+                               loopCount:(NSUInteger)loopCount {
+    if (!image.CGImage) return nil;
+    if (contentRects.count < 1 || frameDurations.count < 1) return nil;
+    if (contentRects.count != frameDurations.count) return nil;
+    
+    self = [super initWithCGImage:image.CGImage scale:image.scale orientation:image.imageOrientation];
+    if (!self) return nil;
+    
+    _contentRects = contentRects.copy;
+    _frameDurations = frameDurations.copy;
+    _loopCount = loopCount;
+    return self;
+}
+
+- (CGRect)contentsRectForCALayerAtIndex:(NSUInteger)index {
+    CGRect layerRect = CGRectMake(0, 0, 1, 1);
+    if (index >= _contentRects.count) return layerRect;
+    
+    CGSize imageSize = self.size;
+    CGRect rect = [self animatedImageContentsRectAtIndex:index];
+    if (imageSize.width > 0.01 && imageSize.height > 0.01) {
+        layerRect.origin.x = rect.origin.x / imageSize.width;
+        layerRect.origin.y = rect.origin.y / imageSize.height;
+        layerRect.size.width = rect.size.width / imageSize.width;
+        layerRect.size.height = rect.size.height / imageSize.height;
+        layerRect = CGRectIntersection(layerRect, CGRectMake(0, 0, 1, 1));
+        if (CGRectIsNull(layerRect) || CGRectIsEmpty(layerRect)) {
+            layerRect = CGRectMake(0, 0, 1, 1);
+        }
+    }
+    return layerRect;
+}
+
+#pragma mark @protocol YYAnimatedImage
+
+- (NSUInteger)animatedImageFrameCount {
+    return _contentRects.count;
+}
+
+- (NSUInteger)animatedImageLoopCount {
+    return _loopCount;
+}
+
+- (NSUInteger)animatedImageBytesPerFrame {
+    return 0;
+}
+
+- (UIImage *)animatedImageFrameAtIndex:(NSUInteger)index {
+    return self;
+}
+
+- (NSTimeInterval)animatedImageDurationAtIndex:(NSUInteger)index {
+    if (index >= _frameDurations.count) return 0;
+    return ((NSNumber *)_frameDurations[index]).doubleValue;
+}
+
+- (CGRect)animatedImageContentsRectAtIndex:(NSUInteger)index {
+    if (index >= _contentRects.count) return CGRectZero;
+    return ((NSValue *)_contentRects[index]).CGRectValue;
+}
+
+@end

YYWebImage/YYImageCache.h

@@ -0,0 +1,218 @@
+//
+//  YYImageCache.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/15.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+@class YYMemoryCache, YYDiskCache;
+
+/// Image cache type
+typedef NS_OPTIONS(NSUInteger, YYImageCacheType) {
+    /// No value.
+    YYImageCacheTypeNone   = 0,
+    
+    /// Get/store image with memory cache.
+    YYImageCacheTypeMemory = 1 << 0,
+    
+    /// Get/store image with disk cache.
+    YYImageCacheTypeDisk   = 1 << 1,
+    
+    /// Get/store image with both memory cache and disk cache.
+    YYImageCacheTypeAll    = YYImageCacheTypeMemory | YYImageCacheTypeDisk,
+};
+
+
+/**
+ YYImageCache is a cache that stores UIImage and image data based on memory cache and disk cache.
+ 
+ @discussion The disk cache will try to protect the original image data:
+ 
+ * If the original image is still image, it will be saved as png/jpeg file based on alpha information.
+ * If the original image is animated gif, apng or webp, it will be saved as original format.
+ * If the original image's scale is not 1, the scale value will be saved as extended data.
+ 
+ Although UIImage can be serialized with NSCoding protocol, but it's not a good idea:
+ Apple actually use UIImagePNGRepresentation() to encode all kind of image, it may 
+ lose the original multi-frame data. The result is packed to plist file and cannot
+ view with photo viewer directly. If the image has no alpha channel, using JPEG 
+ instead of PNG can save more disk size and encoding/decoding time.
+ */
+@interface YYImageCache : NSObject
+
+#pragma mark - Attribute
+///=============================================================================
+/// @name Attribute
+///=============================================================================
+
+/** The name of the cache. Default is nil. */
+@property (copy) NSString *name;
+
+/** The underlying memory cache. see `YYMemoryCache` for more information.*/
+@property (strong, readonly) YYMemoryCache *memoryCache;
+
+/** The underlying disk cache. see `YYDiskCache` for more information.*/
+@property (strong, readonly) YYDiskCache *diskCache;
+
+/**
+ Whether decode animated image when fetch image from disk cache. Default is YES.
+ 
+ @discussion When fetch image from disk cache, it will use 'YYImage' to decode 
+ animated image such as WebP/APNG/GIF. Set to 'NO' to ignore animated image.
+ */
+@property (assign) BOOL allowAnimatedImage;
+
+/**
+ Whether decode the image to memory bitmap. Default is YES.
+ 
+ @discussion If the value is YES, then the image will be decoded to memory bitmap
+ for better display performance, but may cost more memory.
+ */
+@property (assign) BOOL decodeForDisplay;
+
+
+#pragma mark - Initializer
+///=============================================================================
+/// @name Initializer
+///=============================================================================
+- (instancetype)init UNAVAILABLE_ATTRIBUTE;
++ (instancetype)new UNAVAILABLE_ATTRIBUTE;
+
+/**
+ Returns global shared image cache instance.
+ @return  The singleton YYImageCache instance.
+ */
++ (instancetype)sharedCache;
+
+/**
+ The designated initializer. Multiple instances with the same path will make the
+ cache unstable.
+ 
+ @param path Full path of a directory in which the cache will write data.
+ Once initialized you should not read and write to this directory.
+ @result A new cache object, or nil if an error occurs.
+ */
+- (instancetype)initWithPath:(NSString *)path NS_DESIGNATED_INITIALIZER;
+
+
+#pragma mark - Access Methods
+///=============================================================================
+/// @name Access Methods
+///=============================================================================
+
+/**
+ Sets the image with the specified key in the cache (both memory and disk).
+ This method returns immediately and executes the store operation in background.
+ 
+ @param image The image to be stored in the cache. If nil, this method has no effect.
+ @param key   The key with which to associate the image. If nil, this method has no effect.
+ */
+- (void)setImage:(UIImage *)image forKey:(NSString *)key;
+
+/**
+ Sets the image with the specified key in the cache.
+ This method returns immediately and executes the store operation in background.
+ 
+ @discussion If the `type` contain `YYImageCacheTypeMemory`, then the `image` will 
+ be stored in the memory cache; `imageData` will be used instead if `image` is nil.
+ If the `type` contain `YYImageCacheTypeDisk`, then the `imageData` will
+ be stored in the disk cache; `image` will be used instead if `imageData` is nil.
+ 
+ @param image     The image to be stored in the cache.
+ @param imageData The image data to be stored in the cache.
+ @param key       The key with which to associate the image. If nil, this method has no effect.
+ @param type      The cache type to store image.
+ */
+- (void)setImage:(UIImage *)image imageData:(NSData *)imageData forKey:(NSString *)key withType:(YYImageCacheType)type;
+
+/**
+ Removes the image of the specified key in the cache (both memory and disk).
+ This method returns immediately and executes the remove operation in background.
+ 
+ @param key The key identifying the image to be removed. If nil, this method has no effect.
+ */
+- (void)removeImageForKey:(NSString *)key;
+
+/**
+ Removes the image of the specified key in the cache.
+ This method returns immediately and executes the remove operation in background.
+ 
+ @param key  The key identifying the image to be removed. If nil, this method has no effect.
+ @param type The cache type to remove image.
+ */
+- (void)removeImageForKey:(NSString *)key withType:(YYImageCacheType)type;
+
+/**
+ Returns a Boolean value that indicates whether a given key is in cache.
+ If the image is not in memory, this method may blocks the calling thread until 
+ file read finished.
+ 
+ @param key A string identifying the image. If nil, just return NO.
+ @return Whether the image is in cache.
+ */
+- (BOOL)containsImageForKey:(NSString *)key;
+
+/**
+ Returns a Boolean value that indicates whether a given key is in cache.
+ If the image is not in memory and the `type` contains `YYImageCacheTypeDisk`,
+ this method may blocks the calling thread until file read finished.
+ 
+ @param key  A string identifying the image. If nil, just return NO.
+ @param type The cache type.
+ @return Whether the image is in cache.
+ */
+- (BOOL)containsImageForKey:(NSString *)key withType:(YYImageCacheType)type;
+
+/**
+ Returns the image associated with a given key.
+ If the image is not in memory, this method may blocks the calling thread until
+ file read finished.
+ 
+ @param key A string identifying the image. If nil, just return nil.
+ @return The image associated with key, or nil if no image is associated with key.
+ */
+- (UIImage *)getImageForKey:(NSString *)key;
+
+/**
+ Returns the image associated with a given key.
+ If the image is not in memory and the `type` contains `YYImageCacheTypeDisk`,
+ this method may blocks the calling thread until file read finished.
+ 
+ @param key A string identifying the image. If nil, just return nil.
+ @return The image associated with key, or nil if no image is associated with key.
+ */
+- (UIImage *)getImageForKey:(NSString *)key withType:(YYImageCacheType)type;
+
+/**
+ Asynchronously get the image associated with a given key.
+ 
+ @param key   A string identifying the image. If nil, just return nil.
+ @param type  The cache type.
+ @param block A completion block which will be called on main thread.
+ */
+- (void)getImageForKey:(NSString *)key withType:(YYImageCacheType)type withBlock:(void(^)(UIImage *image, YYImageCacheType type))block;
+
+/**
+ Returns the image data associated with a given key.
+ This method may blocks the calling thread until file read finished.
+ 
+ @param key A string identifying the image. If nil, just return nil.
+ @return The image data associated with key, or nil if no image is associated with key.
+ */
+- (NSData *)getImageDataForKey:(NSString *)key;
+
+/**
+ Asynchronously get the image data associated with a given key.
+ 
+ @param key   A string identifying the image. If nil, just return nil.
+ @param block A completion block which will be called on main thread.
+ */
+- (void)getImageDataForKey:(NSString *)key withBlock:(void(^)(NSData *imageData))block;
+
+@end

YYWebImage/YYImageCache.m

@@ -0,0 +1,264 @@
+//
+//  YYImageCache.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/15.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYImageCache.h"
+#import "YYImage.h"
+#import "UIImage+YYWebImage.h"
+
+#if __has_include(<YYImage/YYImage.h>)
+#import <YYImage/YYImage.h>
+#else
+#import "YYImage.h"
+#endif
+
+#if __has_include(<YYCache/YYCache.h>)
+#import <YYCache/YYCache.h>
+#else
+#import "YYCache.h"
+#endif
+
+#if __has_include("YYDispatchQueuePool.h")
+#import "YYDispatchQueuePool.h"
+#endif
+
+
+static inline dispatch_queue_t YYImageCacheIOQueue() {
+#ifdef YYDispatchQueuePool_h
+    return YYDispatchQueueGetForQOS(NSQualityOfServiceDefault);
+#else
+    return dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
+#endif
+}
+
+static inline dispatch_queue_t YYImageCacheDecodeQueue() {
+#ifdef YYDispatchQueuePool_h
+    return YYDispatchQueueGetForQOS(NSQualityOfServiceUtility);
+#else
+    return dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0);
+#endif
+}
+
+
+@interface YYImageCache ()
+- (NSUInteger)imageCost:(UIImage *)image;
+- (UIImage *)imageFromData:(NSData *)data;
+@end
+
+
+@implementation YYImageCache
+
+- (NSUInteger)imageCost:(UIImage *)image {
+    CGImageRef cgImage = image.CGImage;
+    if (!cgImage) return 1;
+    CGFloat height = CGImageGetHeight(cgImage);
+    size_t bytesPerRow = CGImageGetBytesPerRow(cgImage);
+    NSUInteger cost = bytesPerRow * height;
+    if (cost == 0) cost = 1;
+    return cost;
+}
+
+- (UIImage *)imageFromData:(NSData *)data {
+    NSData *scaleData = [YYDiskCache getExtendedDataFromObject:data];
+    CGFloat scale = 0;
+    if (scaleData) {
+        scale = ((NSNumber *)[NSKeyedUnarchiver unarchiveObjectWithData:scaleData]).doubleValue;
+    }
+    if (scale <= 0) scale = [UIScreen mainScreen].scale;
+    UIImage *image;
+    if (_allowAnimatedImage) {
+        image = [[YYImage alloc] initWithData:data scale:scale];
+        if (_decodeForDisplay) image = [image yy_imageByDecoded];
+    } else {
+        YYImageDecoder *decoder = [YYImageDecoder decoderWithData:data scale:scale];
+        image = [decoder frameAtIndex:0 decodeForDisplay:_decodeForDisplay].image;
+    }
+    return image;
+}
+
+#pragma mark Public
+
++ (instancetype)sharedCache {
+    static YYImageCache *cache = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        NSString *cachePath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory,
+                                                                   NSUserDomainMask, YES) firstObject];
+        cachePath = [cachePath stringByAppendingPathComponent:@"com.ibireme.yykit"];
+        cachePath = [cachePath stringByAppendingPathComponent:@"images"];
+        cache = [[self alloc] initWithPath:cachePath];
+    });
+    return cache;
+}
+
+- (instancetype)init {
+    @throw [NSException exceptionWithName:@"YYImageCache init error" reason:@"YYImageCache must be initialized with a path. Use 'initWithPath:' instead." userInfo:nil];
+    return [self initWithPath:nil];
+}
+
+- (instancetype)initWithPath:(NSString *)path {
+    YYMemoryCache *memoryCache = [YYMemoryCache new];
+    memoryCache.shouldRemoveAllObjectsOnMemoryWarning = YES;
+    memoryCache.shouldRemoveAllObjectsWhenEnteringBackground = YES;
+    memoryCache.countLimit = NSUIntegerMax;
+    memoryCache.costLimit = NSUIntegerMax;
+    memoryCache.ageLimit = 12 * 60 * 60;
+    
+    YYDiskCache *diskCache = [[YYDiskCache alloc] initWithPath:path];
+    diskCache.customArchiveBlock = ^(id object) { return (NSData *)object; };
+    diskCache.customUnarchiveBlock = ^(NSData *data) { return (id)data; };
+    if (!memoryCache || !diskCache) return nil;
+    
+    self = [super init];
+    _memoryCache = memoryCache;
+    _diskCache = diskCache;
+    _allowAnimatedImage = YES;
+    _decodeForDisplay = YES;
+    return self;
+}
+
+- (void)setImage:(UIImage *)image forKey:(NSString *)key {
+    [self setImage:image imageData:nil forKey:key withType:YYImageCacheTypeAll];
+}
+
+- (void)setImage:(UIImage *)image imageData:(NSData *)imageData forKey:(NSString *)key withType:(YYImageCacheType)type {
+    if (!key || (image == nil && imageData.length == 0)) return;
+    
+    __weak typeof(self) _self = self;
+    if (type & YYImageCacheTypeMemory) { // add to memory cache
+        if (image) {
+            if (image.yy_isDecodedForDisplay) {
+                [_memoryCache setObject:image forKey:key withCost:[_self imageCost:image]];
+            } else {
+                dispatch_async(YYImageCacheDecodeQueue(), ^{
+                    __strong typeof(_self) self = _self;
+                    if (!self) return;
+                    [self.memoryCache setObject:[image yy_imageByDecoded] forKey:key withCost:[self imageCost:image]];
+                });
+            }
+        } else if (imageData) {
+            dispatch_async(YYImageCacheDecodeQueue(), ^{
+                __strong typeof(_self) self = _self;
+                if (!self) return;
+                UIImage *newImage = [self imageFromData:imageData];
+                [self.memoryCache setObject:[self imageFromData:imageData] forKey:key withCost:[self imageCost:newImage]];
+            });
+        }
+    }
+    if (type & YYImageCacheTypeDisk) { // add to disk cache
+        if (imageData) {
+            if (image) {
+                [YYDiskCache setExtendedData:[NSKeyedArchiver archivedDataWithRootObject:@(image.scale)] toObject:imageData];
+            }
+            [_diskCache setObject:imageData forKey:key];
+        } else if (image) {
+            dispatch_async(YYImageCacheIOQueue(), ^{
+                __strong typeof(_self) self = _self;
+                if (!self) return;
+                NSData *data = [image yy_imageDataRepresentation];
+                [YYDiskCache setExtendedData:[NSKeyedArchiver archivedDataWithRootObject:@(image.scale)] toObject:data];
+                [self.diskCache setObject:data forKey:key];
+            });
+        }
+    }
+}
+
+- (void)removeImageForKey:(NSString *)key {
+    [self removeImageForKey:key withType:YYImageCacheTypeAll];
+}
+
+- (void)removeImageForKey:(NSString *)key withType:(YYImageCacheType)type {
+    if (type & YYImageCacheTypeMemory) [_memoryCache removeObjectForKey:key];
+    if (type & YYImageCacheTypeDisk) [_diskCache removeObjectForKey:key];
+}
+
+- (BOOL)containsImageForKey:(NSString *)key {
+    return [self containsImageForKey:key withType:YYImageCacheTypeAll];
+}
+
+- (BOOL)containsImageForKey:(NSString *)key withType:(YYImageCacheType)type {
+    if (type & YYImageCacheTypeMemory) {
+        if ([_memoryCache containsObjectForKey:key]) return YES;
+    }
+    if (type & YYImageCacheTypeDisk) {
+        if ([_diskCache containsObjectForKey:key]) return YES;
+    }
+    return NO;
+}
+
+- (UIImage *)getImageForKey:(NSString *)key {
+    return [self getImageForKey:key withType:YYImageCacheTypeAll];
+}
+
+- (UIImage *)getImageForKey:(NSString *)key withType:(YYImageCacheType)type {
+    if (!key) return nil;
+    if (type & YYImageCacheTypeMemory) {
+        UIImage *image = [_memoryCache objectForKey:key];
+        if (image) return image;
+    }
+    if (type & YYImageCacheTypeDisk) {
+        NSData *data = (id)[_diskCache objectForKey:key];
+        UIImage *image = [self imageFromData:data];
+        if (image && (type & YYImageCacheTypeMemory)) {
+            [_memoryCache setObject:image forKey:key withCost:[self imageCost:image]];
+        }
+        return image;
+    }
+    return nil;
+}
+
+- (void)getImageForKey:(NSString *)key withType:(YYImageCacheType)type withBlock:(void (^)(UIImage *image, YYImageCacheType type))block {
+    if (!block) return;
+    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+        UIImage *image = nil;
+        
+        if (type & YYImageCacheTypeMemory) {
+            image = [_memoryCache objectForKey:key];
+            if (image) {
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    block(image, YYImageCacheTypeMemory);
+                });
+                return;
+            }
+        }
+        
+        if (type & YYImageCacheTypeDisk) {
+            NSData *data = (id)[_diskCache objectForKey:key];
+            image = [self imageFromData:data];
+            if (image) {
+                [_memoryCache setObject:image forKey:key];
+                dispatch_async(dispatch_get_main_queue(), ^{
+                    block(image, YYImageCacheTypeDisk);
+                });
+                return;
+            }
+        }
+        
+        dispatch_async(dispatch_get_main_queue(), ^{
+            block(nil, YYImageCacheTypeNone);
+        });
+    });
+}
+
+- (NSData *)getImageDataForKey:(NSString *)key {
+    return (id)[_diskCache objectForKey:key];
+}
+
+- (void)getImageDataForKey:(NSString *)key withBlock:(void (^)(NSData *imageData))block {
+    if (!block) return;
+    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+        NSData *data = (id)[_diskCache objectForKey:key];
+        dispatch_async(dispatch_get_main_queue(), ^{
+            block(data);
+        });
+    });
+}
+
+@end

YYWebImage/YYWebImage.h

@@ -0,0 +1,65 @@
+//
+//  YYWebImage.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/23.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+FOUNDATION_EXPORT double YYWebImageVersionNumber;
+FOUNDATION_EXPORT const unsigned char YYWebImageVersionString[];
+#import <YYWebImage/YYImageCache.h>
+#import <YYWebImage/YYWebImageOperation.h>
+#import <YYWebImage/YYWebImageManager.h>
+#import <YYWebImage/UIImage+YYWebImage.h>
+#import <YYWebImage/UIImageView+YYWebImage.h>
+#import <YYWebImage/UIButton+YYWebImage.h>
+#import <YYWebImage/CALayer+YYWebImage.h>
+#import <YYWebImage/MKAnnotationView+YYWebImage.h>
+#else
+#import "YYImageCache.h"
+#import "YYWebImageOperation.h"
+#import "YYWebImageManager.h"
+#import "UIImage+YYWebImage.h"
+#import "UIImageView+YYWebImage.h"
+#import "UIButton+YYWebImage.h"
+#import "CALayer+YYWebImage.h"
+#import "MKAnnotationView+YYWebImage.h"
+#endif
+
+#if __has_include(<YYImage/YYImage.h>)
+#import <YYImage/YYImage.h>
+#elif __has_include(YYWebImage/YYImage.h)
+#import <YYWebImage/YYImage.h>
+#import <YYWebImage/YYFrameImage.h>
+#import <YYWebImage/YYSpriteSheetImage.h>
+#import <YYWebImage/YYImageCocder.h>
+#import <YYWebImage/YYAnimatedImageView.h>
+#else
+#import "YYImage.h"
+#import "YYFrameImage.h"
+#import "YYSpriteSheetImage.h"
+#import "YYImageCocder.h"
+#import "YYAnimatedImageView.h"
+#endif
+
+#if __has_include(<YYCache/YYCache.h>)
+#import <YYCache/YYCache.h>
+#elif __has_include(YYWebImage/YYCache.h)
+#import <YYWebImage/YYCache.h>
+#import <YYWebImage/YYMemoryCache.h>
+#import <YYWebImage/YYDiskCache.h>
+#import <YYWebImage/YYKVStorage.h>
+#else
+#import "YYCache.h"
+#import "YYMemoryCache.h"
+#import "YYDiskCache.h"
+#import "YYKVStorage.h"
+#endif
+

YYWebImage/YYWebImageManager.h

@@ -0,0 +1,295 @@
+//
+//  YYWebImageManager.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/19.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYImageCache.h>
+#else
+#import "YYImageCache.h"
+#endif
+
+@class YYWebImageOperation;
+
+
+/// The options to control image operation.
+typedef NS_OPTIONS(NSUInteger, YYWebImageOptions) {
+    
+    /// Show network activity on status bar when download image.
+    YYWebImageOptionShowNetworkActivity = 1 << 0,
+    
+    /// Display progressive/interlaced/baseline image during download (same as web browser).
+    YYWebImageOptionProgressive = 1 << 1,
+    
+    /// Display blurred progressive JPEG or interlaced PNG image during download.
+    /// This will ignore baseline image for better user experience.
+    YYWebImageOptionProgressiveBlur = 1 << 2,
+    
+    /// Use NSURLCache instead of YYImageCache.
+    YYWebImageOptionUseNSURLCache = 1 << 3,
+    
+    /// Allows untrusted SSL ceriticates.
+    YYWebImageOptionAllowInvalidSSLCertificates = 1 << 4,
+    
+    /// Allows background task to download image when app is in background.
+    YYWebImageOptionAllowBackgroundTask = 1 << 5,
+    
+    /// Handles cookies stored in NSHTTPCookieStore.
+    YYWebImageOptionHandleCookies = 1 << 6,
+    
+    /// Load the image from remote and refresh the image cache.
+    YYWebImageOptionRefreshImageCache = 1 << 7,
+    
+    /// Do not load image from/to disk cache.
+    YYWebImageOptionIgnoreDiskCache = 1 << 8,
+    
+    /// Do not change the view's image before set a new URL to it.
+    YYWebImageOptionIgnorePlaceHolder = 1 << 9,
+    
+    /// Ignore image decoding.
+    /// This may used for image downloading without display.
+    YYWebImageOptionIgnoreImageDecoding = 1 << 10,
+    
+    /// Ignore multi-frame image decoding.
+    /// This will handle the GIF/APNG/WebP/ICO image as single frame image.
+    YYWebImageOptionIgnoreAnimatedImage = 1 << 11,
+    
+    /// Set the image to view with a fade animation.
+    /// This will add a "fade" animation on image view's layer for better user experience.
+    YYWebImageOptionSetImageWithFadeAnimation = 1 << 12,
+    
+    /// Do not set the image to the view when image fetch complete.
+    /// You may set the image manually.
+    YYWebImageOptionAvoidSetImage = 1 << 13,
+};
+
+/// Indicated where the image came from.
+typedef NS_ENUM(NSUInteger, YYWebImageFromType) {
+    
+    /// No value.
+    YYWebImageFromNone = 0,
+    
+    /// Fetched from memory cache immediately.
+    /// If you called "setImageWithURL:..." and the image is already in memory,
+    /// then you will get this value at the same call.
+    YYWebImageFromMemoryCacheFast,
+    
+    /// Fetched from memory cache.
+    YYWebImageFromMemoryCache,
+    
+    /// Fetched from disk cache.
+    YYWebImageFromDiskCache,
+    
+    /// Fetched from remote (web or file path).
+    YYWebImageFromRemote,
+};
+
+/// Indicated image fetch complete stage.
+typedef NS_ENUM(NSUInteger, YYWebImageStage) {
+    
+    /// Incomplete, progressive image.
+    YYWebImageStageProgress  = -1,
+    
+    /// Cancelled.
+    YYWebImageStageCancelled = 0,
+    
+    /// Finished (succeed or failed).
+    YYWebImageStageFinished  = 1,
+};
+
+
+/**
+ The block invoked in remote image fetch progress.
+ 
+ @param receivedSize Current received size in bytes.
+ @param expectedSize Expected total size in bytes (-1 means unknown).
+ */
+typedef void(^YYWebImageProgressBlock)(NSInteger receivedSize, NSInteger expectedSize);
+
+/**
+ The block invoked before remote image fetch finished to do additional image process.
+ 
+ @discussion This block will be invoked before `YYWebImageCompletionBlock` to give
+ you a chance to do additional image process (such as resize or crop). If there's
+ no need to transform the image, just return the `image` parameter.
+ 
+ @example You can clip the image, blur it and add rounded corners with these code:
+    ^(UIImage *image, NSURL *url) {
+        // Maybe you need to create an @autoreleasepool to limit memory cost.
+        image = [image yy_imageByResizeToSize:CGSizeMake(100, 100) contentMode:UIViewContentModeScaleAspectFill];
+        image = [image yy_imageByBlurRadius:20 tintColor:nil tintMode:kCGBlendModeNormal saturation:1.2 maskImage:nil];
+        image = [image yy_imageByRoundCornerRadius:5];
+        return image;
+    }
+ 
+ @param image The image fetched from url.
+ @param url   The image url (remote or local file path).
+ @return The transformed image.
+ */
+typedef UIImage *(^YYWebImageTransformBlock)(UIImage *image, NSURL *url);
+
+/**
+ The block invoked when image fetch finished or cancelled.
+ 
+ @param image       The image.
+ @param url         The image url (remote or local file path).
+ @param from        Where the image came from.
+ @param error       Error during image fetching.
+ @param finished    If the operation is cancelled, this value is NO, otherwise YES.
+ */
+typedef void (^YYWebImageCompletionBlock)(UIImage *image, NSURL *url, YYWebImageFromType from, YYWebImageStage stage, NSError *error);
+
+
+
+
+/**
+ A manager to create and manage web image operation.
+ */
+@interface YYWebImageManager : NSObject
+
+/**
+ Returns global YYWebImageManager instance.
+ 
+ @return YYWebImageManager shared instance.
+ */
++ (instancetype)sharedManager;
+
+/**
+ Creates a manager with an image cache and operation queue.
+ 
+ @param cache  Image cache used by manager (pass nil to avoid image cache).
+ @param queue  The operation queue on which image operations are scheduled and run
+                (pass nil to make the new operation start immediately without queue).
+ @return A new manager.
+ */
+- (instancetype)initWithCache:(YYImageCache *)cache queue:(NSOperationQueue *)queue NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init UNAVAILABLE_ATTRIBUTE;
++ (instancetype)new UNAVAILABLE_ATTRIBUTE;
+
+/**
+ Creates and returns a new image operation, the operation will start immediately.
+ 
+ @param url        The image url (remote or local file path).
+ @param options    The options to control image operation.
+ @param progress   Progress block which will be invoked on background thread (pass nil to avoid).
+ @param transform  Transform block which will be invoked on background thread  (pass nil to avoid).
+ @param completion Completion block which will be invoked on background thread  (pass nil to avoid).
+ @return A new image operation.
+ */
+- (YYWebImageOperation *)requestImageWithURL:(NSURL *)url
+                                     options:(YYWebImageOptions)options
+                                    progress:(YYWebImageProgressBlock)progress
+                                   transform:(YYWebImageTransformBlock)transform
+                                  completion:(YYWebImageCompletionBlock)completion;
+
+/**
+ The image cache used by image operation. 
+ You can set it to nil to avoid image cache.
+ */
+@property (nonatomic, strong) YYImageCache *cache;
+
+/**
+ The operation queue on which image operations are scheduled and run.
+ You can set it to nil to make the new operation start immediately without queue.
+ 
+ You can use this queue to control maximum number of concurrent operations, to obtain 
+ the status of the current operations, or to cancel all operations in this manager.
+ */
+@property (nonatomic, strong) NSOperationQueue *queue;
+
+/**
+ The shared transform block to process image. Default is nil.
+ 
+ When called `requestImageWithURL:options:progress:transform:completion` and
+ the `transform` is nil, this block will be used.
+ */
+@property (nonatomic, copy) YYWebImageTransformBlock sharedTransformBlock;
+
+/**
+ The image request timeout interval in seconds. Default is 15.
+ */
+@property (nonatomic, assign) NSTimeInterval timeout;
+
+/**
+ The username used by NSURLCredential, default is nil.
+ */
+@property (nonatomic, strong) NSString *username;
+
+/**
+ The password used by NSURLCredential, default is nil.
+ */
+@property (nonatomic, strong) NSString *password;
+
+/**
+ The image HTTP request header. Default is "Accept:image/webp,image/\*;q=0.8".
+ */
+@property (nonatomic, copy) NSDictionary *headers;
+
+/**
+ A block which will be invoked for each image HTTP request to do additional
+ HTTP header process. Default is nil.
+ 
+ Use this block to add or remove HTTP header field for a specified URL.
+ */
+@property (nonatomic, copy) NSDictionary *(^headersFilter)(NSURL *url, NSDictionary *header);
+
+/**
+ A block which will be invoked for each image operation. Default is nil.
+ 
+ Use this block to provide a custom image cache key for a specified URL.
+ */
+@property (nonatomic, copy) NSString *(^cacheKeyFilter)(NSURL *url);
+
+/**
+ Returns the HTTP headers for a specified URL.
+ 
+ @param url A specified URL.
+ @return HTTP headers.
+ */
+- (NSDictionary *)headersForURL:(NSURL *)url;
+
+/**
+ Returns the cache key for a specified URL.
+ 
+ @param url A specified URL
+ @return Cache key used in YYImageCache.
+ */
+- (NSString *)cacheKeyForURL:(NSURL *)url;
+
+
+
+/**
+ Increments the number of active network requests.
+ If this number was zero before incrementing, this will start animating the
+ status bar network activity indicator.
+ 
+ This method is thread safe.
+ */
++ (void)incrementNetworkActivityCount;
+
+/**
+ Decrements the number of active network requests.
+ If this number becomes zero after decrementing, this will stop animating the
+ status bar network activity indicator.
+ 
+ This method is thread safe.
+ */
++ (void)decrementNetworkActivityCount;
+
+/**
+ Get current number of active network requests.
+ 
+ This method is thread safe.
+ */
++ (NSInteger)currentNetworkActivityCount;
+
+@end

YYWebImage/YYWebImageManager.m

@@ -0,0 +1,156 @@
+//
+//  YYWebImageManager.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/19.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYWebImageManager.h"
+#import "YYImageCache.h"
+#import "YYWebImageOperation.h"
+#import <objc/runtime.h>
+
+#define kNetworkIndicatorDelay (1/30.0)
+@interface _YYUIApplicationNetworkIndicatorInfo : NSObject
+@property (nonatomic, assign) NSInteger count;
+@property (nonatomic, strong) NSTimer *timer;
+@end
+@implementation _YYUIApplicationNetworkIndicatorInfo
+@end
+
+@implementation YYWebImageManager
+
++ (instancetype)sharedManager {
+    static YYWebImageManager *manager;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        YYImageCache *cache = [YYImageCache sharedCache];
+        NSOperationQueue *queue = [NSOperationQueue new];
+        if ([queue respondsToSelector:@selector(setQualityOfService:)]) {
+            queue.qualityOfService = NSQualityOfServiceBackground;
+        }
+        manager = [[self alloc] initWithCache:cache queue:queue];
+    });
+    return manager;
+}
+
+- (instancetype)init {
+    @throw [NSException exceptionWithName:@"YYWebImageManager init error" reason:@"Use the designated initializer to init." userInfo:nil];
+    return [self initWithCache:nil queue:nil];
+}
+
+- (instancetype)initWithCache:(YYImageCache *)cache queue:(NSOperationQueue *)queue{
+    self = [super init];
+    if (!self) return nil;
+    _cache = cache;
+    _queue = queue;
+    _timeout = 15.0;
+    _headers = @{ @"Accept" : @"image/webp,image/*;q=0.8" };
+    return self;
+}
+
+- (YYWebImageOperation *)requestImageWithURL:(NSURL *)url
+                                     options:(YYWebImageOptions)options
+                                    progress:(YYWebImageProgressBlock)progress
+                                   transform:(YYWebImageTransformBlock)transform
+                                  completion:(YYWebImageCompletionBlock)completion {
+    
+    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
+    request.timeoutInterval = _timeout;
+    request.HTTPShouldHandleCookies = (options & YYWebImageOptionHandleCookies) != 0;
+    request.allHTTPHeaderFields = [self headersForURL:url];
+    request.HTTPShouldUsePipelining = YES;
+    request.cachePolicy = (options & YYWebImageOptionUseNSURLCache) ?
+        NSURLRequestUseProtocolCachePolicy : NSURLRequestReloadIgnoringLocalCacheData;
+    
+    YYWebImageOperation *operation = [[YYWebImageOperation alloc] initWithRequest:request
+                                                                          options:options
+                                                                            cache:_cache
+                                                                         cacheKey:[self cacheKeyForURL:url]
+                                                                         progress:progress
+                                                                        transform:transform ? transform : _sharedTransformBlock
+                                                                       completion:completion];
+
+    if (_username && _password) {
+        operation.credential = [NSURLCredential credentialWithUser:_username password:_password persistence:NSURLCredentialPersistenceForSession];
+    }
+    if (operation) {
+        NSOperationQueue *queue = _queue;
+        if (queue) {
+            [queue addOperation:operation];
+        } else {
+            [operation start];
+        }
+    }
+    return operation;
+}
+
+- (NSDictionary *)headersForURL:(NSURL *)url {
+    if (!url) return nil;
+    return _headersFilter ? _headersFilter(url, _headers) : _headers;
+}
+
+- (NSString *)cacheKeyForURL:(NSURL *)url {
+    if (!url) return nil;
+    return _cacheKeyFilter ? _cacheKeyFilter(url) : url.absoluteString;
+}
+
+
+
+#pragma mark Network Indicator
+
++ (_YYUIApplicationNetworkIndicatorInfo *)_networkIndicatorInfo {
+    return objc_getAssociatedObject(self, @selector(_networkIndicatorInfo));
+}
+
++ (void)_setNetworkIndicatorInfo:(_YYUIApplicationNetworkIndicatorInfo *)info {
+    objc_setAssociatedObject(self, @selector(_networkIndicatorInfo), info, OBJC_ASSOCIATION_RETAIN);
+}
+
++ (void)_delaySetActivity:(NSTimer *)timer {
+    NSNumber *visiable = timer.userInfo;
+    if ([UIApplication sharedApplication].networkActivityIndicatorVisible != visiable.boolValue) {
+        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:visiable.boolValue];
+    }
+    [timer invalidate];
+}
+
++ (void)_changeNetworkActivityCount:(NSInteger)delta {
+    void (^block)() = ^{
+        _YYUIApplicationNetworkIndicatorInfo *info = [self _networkIndicatorInfo];
+        if (!info) {
+            info = [_YYUIApplicationNetworkIndicatorInfo new];
+            [self _setNetworkIndicatorInfo:info];
+        }
+        NSInteger count = info.count;
+        count += delta;
+        info.count = count;
+        [info.timer invalidate];
+        info.timer = [NSTimer timerWithTimeInterval:kNetworkIndicatorDelay target:self selector:@selector(_delaySetActivity:) userInfo:@(info.count > 0) repeats:NO];
+        [[NSRunLoop mainRunLoop] addTimer:info.timer forMode:NSRunLoopCommonModes];
+    };
+    if ([NSThread isMainThread]) {
+        block();
+    } else {
+        dispatch_async(dispatch_get_main_queue(), block);
+    }
+}
+
++ (void)incrementNetworkActivityCount {
+    [self _changeNetworkActivityCount:1];
+}
+
++ (void)decrementNetworkActivityCount {
+    [self _changeNetworkActivityCount:-1];
+}
+
++ (NSInteger)currentNetworkActivityCount {
+    _YYUIApplicationNetworkIndicatorInfo *info = [self _networkIndicatorInfo];
+    return info.count;
+}
+
+@end

YYWebImage/YYWebImageOperation.h

@@ -0,0 +1,93 @@
+//
+//  YYWebImageOperation.h
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/15.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import <UIKit/UIKit.h>
+
+#if __has_include(<YYWebImage/YYWebImage.h>)
+#import <YYWebImage/YYImageCache.h>
+#import <YYWebImage/YYWebImageManager.h>
+#else
+#import "YYImageCache.h"
+#import "YYWebImageManager.h"
+#endif
+
+/**
+ The YYWebImageOperation class is an NSOperation subclass used to fetch image 
+ from URL request.
+ 
+ @discussion It's an asynchronous operation. You typically execute it by adding 
+ it to an operation queue, or calls 'start' to execute it manually. When the 
+ operation is started, it will:
+ 
+     1. Get the image from the cache, if exist, return it with `completion` block.
+     2. Start an URL connection to fetch image from the request, revoke the `progress`
+        to notify request progress (and revoke `completion` block to return the 
+        progressive image if enabled by progressive option).
+     3. Process the image by revoke the `transform` block.
+     4. Put the image to cache and return it with `completion` block.
+ 
+ */
+@interface YYWebImageOperation : NSOperation
+
+@property (nonatomic, strong, readonly) NSURLRequest *request;     ///< The image URL request.
+@property (nonatomic, strong, readonly) NSURLResponse *response;   ///< The response for request.
+@property (nonatomic, assign, readonly) YYWebImageOptions options; ///< The operation's option.
+@property (nonatomic, strong, readonly) YYImageCache *cache;       ///< The image cache.
+@property (nonatomic, strong, readonly) NSString *cacheKey;        ///< The image cache key.
+
+/**
+ Whether the URL connection should consult the credential storage for authenticating 
+ the connection. Default is YES.
+ 
+ @discussion This is the value that is returned in the `NSURLConnectionDelegate` 
+ method `-connectionShouldUseCredentialStorage:`.
+ */
+@property (nonatomic, assign) BOOL shouldUseCredentialStorage;
+
+/**
+ The credential used for authentication challenges in `-connection:didReceiveAuthenticationChallenge:`.
+ 
+ @discussion This will be overridden by any shared credentials that exist for the 
+ username or password of the request URL, if present.
+ */
+@property (nonatomic, strong) NSURLCredential *credential;
+
+/**
+ Creates and returns a new operation.
+ 
+ You should call `start` to execute this operation, or you can add the operation
+ to an operation queue.
+ 
+ @param request    The Image request. This value should not be nil.
+ @param options    A mask to specify options to use for this operation.
+ @param cache      An image cache. Pass nil to avoid image cache.
+ @param cacheKey   An image cache key. Pass nil to avoid image cache.
+ @param progress   A block invoked in image fetch progress.
+                     The block will be invoked in background thread. Pass nil to avoid it.
+ @param transform  A block invoked before image fetch finished to do additional image process.
+                     The block will be invoked in background thread. Pass nil to avoid it.
+ @param completion A block invoked when image fetch finished or cancelled.
+                     The block will be invoked in background thread. Pass nil to avoid it.
+ 
+ @return The image request opeartion, or nil if an error occurs.
+ */
+- (instancetype)initWithRequest:(NSURLRequest *)request
+                        options:(YYWebImageOptions)options
+                          cache:(YYImageCache *)cache
+                       cacheKey:(NSString *)cacheKey
+                       progress:(YYWebImageProgressBlock)progress
+                      transform:(YYWebImageTransformBlock)transform
+                     completion:(YYWebImageCompletionBlock)completion NS_DESIGNATED_INITIALIZER;
+
+- (instancetype)init UNAVAILABLE_ATTRIBUTE;
++ (instancetype)new UNAVAILABLE_ATTRIBUTE;
+
+@end

YYWebImage/YYWebImageOperation.m

@@ -0,0 +1,804 @@
+//
+//  YYWebImageOperation.m
+//  YYKit <https://github.com/ibireme/YYKit>
+//
+//  Created by ibireme on 15/2/15.
+//  Copyright (c) 2015 ibireme.
+//
+//  This source code is licensed under the MIT-style license found in the
+//  LICENSE file in the root directory of this source tree.
+//
+
+#import "YYWebImageOperation.h"
+#import "UIImage+YYWebImage.h"
+#import <ImageIO/ImageIO.h>
+
+#if __has_include(<YYImage/YYImage.h>)
+#import <YYImage/YYImage.h>
+#else
+#import "YYImage.h"
+#endif
+
+#if __has_include("YYDispatchQueuePool.h")
+#import "YYDispatchQueuePool.h"
+#else
+#import <libkern/OSAtomic.h>
+#endif
+
+#define MIN_PROGRESSIVE_TIME_INTERVAL 0.2
+#define MIN_PROGRESSIVE_BLUR_TIME_INTERVAL 0.4
+
+/// Returns YES if the right-bottom pixel is filled.
+static BOOL YYCGImageLastPixelFilled(CGImageRef image) {
+    if (!image) return NO;
+    size_t width = CGImageGetWidth(image);
+    size_t height = CGImageGetHeight(image);
+    if (width == 0 || height == 0) return NO;
+    CGContextRef ctx = CGBitmapContextCreate(NULL, 1, 1, 8, 0, YYCGColorSpaceGetDeviceRGB(), kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrderDefault);
+    if (!ctx) return NO;
+    CGContextDrawImage(ctx, CGRectMake( -(int)width + 1, 0, width, height), image);
+    uint8_t *bytes = CGBitmapContextGetData(ctx);
+    BOOL isAlpha = bytes && bytes[0] == 0;
+    CFRelease(ctx);
+    return !isAlpha;
+}
+
+/// Returns JPEG SOS (Start Of Scan) Marker
+static NSData *JPEGSOSMarker() {
+    // "Start Of Scan" Marker
+    static NSData *marker = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        uint8_t bytes[2] = {0xFF, 0xDA};
+        marker = [NSData dataWithBytes:bytes length:2];
+    });
+    return marker;
+}
+
+
+/// A proxy used to hold a weak object.
+@interface _YYWebImageWeakProxy : NSProxy
+@property (nonatomic, weak, readonly) id target;
+- (instancetype)initWithTarget:(id)target;
++ (instancetype)proxyWithTarget:(id)target;
+@end
+
+@implementation _YYWebImageWeakProxy
+- (instancetype)initWithTarget:(id)target {
+    _target = target;
+    return self;
+}
++ (instancetype)proxyWithTarget:(id)target {
+    return [[_YYWebImageWeakProxy alloc] initWithTarget:target];
+}
+- (id)forwardingTargetForSelector:(SEL)selector {
+    return _target;
+}
+- (void)forwardInvocation:(NSInvocation *)invocation {
+    void *null = NULL;
+    [invocation setReturnValue:&null];
+}
+- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector {
+    return [NSObject instanceMethodSignatureForSelector:@selector(init)];
+}
+- (BOOL)respondsToSelector:(SEL)aSelector {
+    return [_target respondsToSelector:aSelector];
+}
+- (BOOL)isEqual:(id)object {
+    return [_target isEqual:object];
+}
+- (NSUInteger)hash {
+    return [_target hash];
+}
+- (Class)superclass {
+    return [_target superclass];
+}
+- (Class)class {
+    return [_target class];
+}
+- (BOOL)isKindOfClass:(Class)aClass {
+    return [_target isKindOfClass:aClass];
+}
+- (BOOL)isMemberOfClass:(Class)aClass {
+    return [_target isMemberOfClass:aClass];
+}
+- (BOOL)conformsToProtocol:(Protocol *)aProtocol {
+    return [_target conformsToProtocol:aProtocol];
+}
+- (BOOL)isProxy {
+    return YES;
+}
+- (NSString *)description {
+    return [_target description];
+}
+- (NSString *)debugDescription {
+    return [_target debugDescription];
+}
+@end
+
+
+@interface YYWebImageOperation() <NSURLConnectionDelegate>
+@property (readwrite, getter=isExecuting) BOOL executing;
+@property (readwrite, getter=isFinished) BOOL finished;
+@property (readwrite, getter=isCancelled) BOOL cancelled;
+@property (readwrite, getter=isStarted) BOOL started;
+@property (nonatomic, strong) NSRecursiveLock *lock;
+@property (nonatomic, strong) NSURLConnection *connection;
+@property (nonatomic, strong) NSMutableData *data;
+@property (nonatomic, assign) NSInteger expectedSize;
+@property (nonatomic, assign) UIBackgroundTaskIdentifier taskID;
+
+@property (nonatomic, assign) NSTimeInterval lastProgressiveDecodeTimestamp;
+@property (nonatomic, strong) YYImageDecoder *progressiveDecoder;
+@property (nonatomic, assign) BOOL progressiveIgnored;
+@property (nonatomic, assign) BOOL progressiveDetected;
+@property (nonatomic, assign) NSUInteger progressiveScanedLength;
+@property (nonatomic, assign) NSUInteger progressiveDisplayCount;
+
+@property (nonatomic, copy) YYWebImageProgressBlock progress;
+@property (nonatomic, copy) YYWebImageTransformBlock transform;
+@property (nonatomic, copy) YYWebImageCompletionBlock completion;
+@end
+
+
+@implementation YYWebImageOperation
+@synthesize executing = _executing;
+@synthesize finished = _finished;
+@synthesize cancelled = _cancelled;
+
+/// Network thread entry point.
++ (void)_networkThreadMain:(id)object {
+    @autoreleasepool {
+        [[NSThread currentThread] setName:@"com.ibireme.yykit.webimage.request"];
+        NSRunLoop *runLoop = [NSRunLoop currentRunLoop];
+        [runLoop addPort:[NSMachPort port] forMode:NSDefaultRunLoopMode];
+        [runLoop run];
+    }
+}
+
+/// Global image request network thread, used by NSURLConnection delegate.
++ (NSThread *)_networkThread {
+    static NSThread *thread = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        thread = [[NSThread alloc] initWithTarget:self selector:@selector(_networkThreadMain:) object:nil];
+        if ([thread respondsToSelector:@selector(setQualityOfService:)]) {
+            thread.qualityOfService = NSQualityOfServiceBackground;
+        }
+        [thread start];
+    });
+    return thread;
+}
+
+/// Global image queue, used for image reading and decoding.
++ (dispatch_queue_t)_imageQueue {
+#ifdef YYDispatchQueuePool_h
+    return YYDispatchQueueGetForQOS(NSQualityOfServiceUtility);
+#else
+    #define MAX_QUEUE_COUNT 16
+    static int queueCount;
+    static dispatch_queue_t queues[MAX_QUEUE_COUNT];
+    static dispatch_once_t onceToken;
+    static int32_t counter = 0;
+    dispatch_once(&onceToken, ^{
+        queueCount = (int)[NSProcessInfo processInfo].activeProcessorCount;
+        queueCount = queueCount < 1 ? 1 : queueCount > MAX_QUEUE_COUNT ? MAX_QUEUE_COUNT : queueCount;
+        if ([UIDevice currentDevice].systemVersion.floatValue >= 8.0) {
+            for (NSUInteger i = 0; i < queueCount; i++) {
+                dispatch_queue_attr_t attr = dispatch_queue_attr_make_with_qos_class(DISPATCH_QUEUE_SERIAL, QOS_CLASS_UTILITY, 0);
+                queues[i] = dispatch_queue_create("com.ibireme.yykit.decode", attr);
+            }
+        } else {
+            for (NSUInteger i = 0; i < queueCount; i++) {
+                queues[i] = dispatch_queue_create("com.ibireme.yykit.decode", DISPATCH_QUEUE_SERIAL);
+                dispatch_set_target_queue(queues[i], dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0));
+            }
+        }
+    });
+    int32_t cur = OSAtomicIncrement32(&counter);
+    if (cur < 0) cur = -cur;
+    return queues[(cur) % queueCount];
+    #undef MAX_QUEUE_COUNT
+#endif
+}
+
+- (instancetype)init {
+    @throw [NSException exceptionWithName:@"YYWebImageOperation init error" reason:@"YYWebImageOperation must be initialized with a request. Use the designated initializer to init." userInfo:nil];
+    return [self initWithRequest:nil options:0 cache:nil cacheKey:nil progress:nil transform:nil completion:nil];
+}
+
+- (instancetype)initWithRequest:(NSURLRequest *)request
+                        options:(YYWebImageOptions)options
+                          cache:(YYImageCache *)cache
+                       cacheKey:(NSString *)cacheKey
+                       progress:(YYWebImageProgressBlock)progress
+                      transform:(YYWebImageTransformBlock)transform
+                     completion:(YYWebImageCompletionBlock)completion {
+    self = [super init];
+    if (!self) return nil;
+    if (!request) return nil;
+    _request = request;
+    _options = options;
+    _cache = cache;
+    _cacheKey = cacheKey ? cacheKey : request.URL.absoluteString;
+    _shouldUseCredentialStorage = YES;
+    _progress = progress;
+    _transform = transform;
+    _completion = completion;
+    _executing = NO;
+    _finished = NO;
+    _cancelled = NO;
+    _taskID = UIBackgroundTaskInvalid;
+    return self;
+}
+
+- (void)dealloc {
+    [_lock lock];
+    if (_taskID != UIBackgroundTaskInvalid) {
+        [[UIApplication sharedApplication] endBackgroundTask:_taskID];
+        _taskID = UIBackgroundTaskInvalid;
+    }
+    if ([self isExecuting]) {
+        self.cancelled = YES;
+        self.finished = YES;
+        if (_connection) {
+            [_connection cancel];
+            if (![_request.URL isFileURL] && (_options & YYWebImageOptionShowNetworkActivity)) {
+                [YYWebImageManager decrementNetworkActivityCount];
+            }
+        }
+        if (_completion) {
+            @autoreleasepool {
+                _completion(nil, _request.URL, YYWebImageFromNone, YYWebImageStageCancelled, nil);
+            }
+        }
+    }
+    [_lock unlock];
+}
+
+- (void)_endBackgroundTask {
+    [_lock lock];
+    if (_taskID != UIBackgroundTaskInvalid) {
+        [[UIApplication sharedApplication] endBackgroundTask:_taskID];
+        _taskID = UIBackgroundTaskInvalid;
+    }
+    [_lock unlock];
+}
+
+#pragma mark - Runs in operation thread
+
+- (void)_finish {
+    self.executing = NO;
+    self.finished = YES;
+    [self _endBackgroundTask];
+}
+
+// runs on network thread
+- (void)_startOperation {
+    if ([self isCancelled]) return;
+    @autoreleasepool {
+        // get image from cache
+        if (_cache &&
+            !(_options & YYWebImageOptionUseNSURLCache) &&
+            !(_options & YYWebImageOptionRefreshImageCache)) {
+            UIImage *image = [_cache getImageForKey:_cacheKey withType:YYImageCacheTypeMemory];
+            if (image) {
+                [_lock lock];
+                if (![self isCancelled]) {
+                    if (_completion) _completion(image, _request.URL, YYWebImageFromMemoryCache, YYWebImageStageCancelled, nil);
+                }
+                [self _finish];
+                [_lock unlock];
+                return;
+            }
+            if (!(_options & YYWebImageOptionIgnoreDiskCache)) {
+                __weak typeof(self) _self = self;
+                dispatch_async([self.class _imageQueue], ^{
+                    __strong typeof(_self) self = _self;
+                    if (!self || [self isCancelled]) return;
+                    UIImage *image = [self.cache getImageForKey:self.cacheKey withType:YYImageCacheTypeDisk];
+                    if (image) {
+                        [self.cache setImage:image imageData:nil forKey:self.cacheKey withType:YYImageCacheTypeMemory];
+                        [self performSelector:@selector(_didReceiveImageFromDiskCache:) onThread:[self.class _networkThread] withObject:image waitUntilDone:NO];
+                    } else {
+                        [self performSelector:@selector(_startRequest:) onThread:[self.class _networkThread] withObject:nil waitUntilDone:NO];
+                    }
+                });
+                return;
+            }
+        }
+    }
+    [self performSelector:@selector(_startRequest:) onThread:[self.class _networkThread] withObject:nil waitUntilDone:NO];
+}
+
+// runs on network thread
+- (void)_startRequest:(id)object {
+    if ([self isCancelled]) return;
+    @autoreleasepool {
+        if (_request.URL.isFileURL) {
+            NSArray *keys = @[NSURLFileSizeKey];
+            NSDictionary *attr = [_request.URL resourceValuesForKeys:keys error:nil];
+            NSNumber *fileSize = attr[NSURLFileSizeKey];
+            _expectedSize = fileSize ? fileSize.unsignedIntegerValue : -1;
+        }
+        
+        // request image from web
+        [_lock lock];
+        if (![self isCancelled]) {
+            _connection = [[NSURLConnection alloc] initWithRequest:_request delegate:[_YYWebImageWeakProxy proxyWithTarget:self]];
+            if (![_request.URL isFileURL] && (_options & YYWebImageOptionShowNetworkActivity)) {
+                [YYWebImageManager incrementNetworkActivityCount];
+            }
+        }
+        [_lock unlock];
+    }
+}
+
+// runs on network thread, called from outer "cancel"
+- (void)_cancelOperation {
+    @autoreleasepool {
+        if (_connection) {
+            if (![_request.URL isFileURL] && (_options & YYWebImageOptionShowNetworkActivity)) {
+                [YYWebImageManager decrementNetworkActivityCount];
+            }
+        }
+        [_connection cancel];
+        _connection = nil;
+        if (_completion) _completion(nil, _request.URL, YYWebImageFromNone, YYWebImageStageCancelled, nil);
+        [self _endBackgroundTask];
+    }
+}
+
+
+// runs on network thread
+- (void)_didReceiveImageFromDiskCache:(UIImage *)image {
+    @autoreleasepool {
+        [_lock lock];
+        if (![self isCancelled]) {
+            if (image) {
+                if (_completion) _completion(image, _request.URL, YYWebImageFromDiskCache, YYWebImageStageFinished, nil);
+                [self _finish];
+            } else {
+                [self _startRequest:nil];
+            }
+        }
+        [_lock unlock];
+    }
+}
+
+- (void)_didReceiveImageFromWeb:(UIImage *)image {
+    @autoreleasepool {
+        [_lock lock];
+        if (![self isCancelled]) {
+            if (_cache) {
+                if (image || (_options & YYWebImageOptionRefreshImageCache)) {
+                    NSData *data = _data;
+                    dispatch_async([YYWebImageOperation _imageQueue], ^{
+                        [_cache setImage:image imageData:data forKey:_cacheKey withType:YYImageCacheTypeAll];
+                    });
+                }
+            }
+            _data = nil;
+            NSError *error = nil;
+            if (!image) {
+                error = [NSError errorWithDomain:@"com.ibireme.yykit.image" code:-1 userInfo:@{ NSLocalizedDescriptionKey : @"Web image decode fail." }];
+            }
+            if (_completion) _completion(image, _request.URL, YYWebImageFromRemote, YYWebImageStageFinished, error);
+            [self _finish];
+        }
+        [_lock unlock];
+    }
+}
+
+#pragma mark - NSURLConnectionDelegate runs in operation thread
+
+- (BOOL)connectionShouldUseCredentialStorage:(NSURLConnection *)connection {
+    return _shouldUseCredentialStorage;
+}
+
+- (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
+    @autoreleasepool {
+        if ([challenge.protectionSpace.authenticationMethod isEqualToString:NSURLAuthenticationMethodServerTrust]) {
+            if (!(_options & YYWebImageOptionAllowInvalidSSLCertificates) &&
+                [challenge.sender respondsToSelector:@selector(performDefaultHandlingForAuthenticationChallenge:)]) {
+                [challenge.sender performDefaultHandlingForAuthenticationChallenge:challenge];
+            } else {
+                NSURLCredential *credential = [NSURLCredential credentialForTrust:challenge.protectionSpace.serverTrust];
+                [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
+            }
+        } else {
+            if ([challenge previousFailureCount] == 0) {
+                if (_credential) {
+                    [[challenge sender] useCredential:_credential forAuthenticationChallenge:challenge];
+                } else {
+                    [[challenge sender] continueWithoutCredentialForAuthenticationChallenge:challenge];
+                }
+            } else {
+                [[challenge sender] continueWithoutCredentialForAuthenticationChallenge:challenge];
+            }
+        }
+    }
+}
+
+- (nullable NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse {
+    if (!cachedResponse) return cachedResponse;
+    if (_options & YYWebImageOptionUseNSURLCache) {
+        return cachedResponse;
+    } else {
+        // ignore NSURLCache
+        NSCachedURLResponse *response = [[NSCachedURLResponse alloc] initWithResponse:cachedResponse.response data:cachedResponse.data userInfo:cachedResponse.userInfo ? cachedResponse.userInfo : @{} storagePolicy:NSURLCacheStorageNotAllowed];
+        return response;
+    }
+}
+
+- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
+    @autoreleasepool {
+        NSError *error = nil;
+        if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
+            NSHTTPURLResponse *httpResponse = (id) response;
+            NSInteger statusCode = httpResponse.statusCode;
+            if (statusCode >= 400 || statusCode == 304) {
+                error = [NSError errorWithDomain:NSURLErrorDomain code:statusCode userInfo:nil];
+            }
+        }
+        if (error) {
+            [_connection cancel];
+            [self connection:_connection didFailWithError:error];
+        } else {
+            if (response.expectedContentLength) {
+                _expectedSize = (NSInteger)response.expectedContentLength;
+                if (_expectedSize < 0) _expectedSize = -1;
+            }
+            _data = [NSMutableData dataWithCapacity:_expectedSize > 0 ? _expectedSize : 0];
+            if (_progress) {
+                [_lock lock];
+                if ([self isCancelled]) _progress(0, _expectedSize);
+                [_lock unlock];
+            }
+        }
+    }
+}
+
+- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
+    @autoreleasepool {
+        [_lock lock];
+        BOOL canceled = [self isCancelled];
+        [_lock unlock];
+        if (canceled) return;
+        
+        if (data) [_data appendData:data];
+        if (_progress) {
+            [_lock lock];
+            if (![self isCancelled]) {
+                _progress(_data.length, _expectedSize);
+            }
+            [_lock unlock];
+        }
+        
+        /*--------------------------- progressive ----------------------------*/
+        BOOL progressive = (_options & YYWebImageOptionProgressive) > 0;
+        BOOL progressiveBlur = (_options & YYWebImageOptionProgressiveBlur) > 0;
+        if (!_completion || !(progressive || progressiveBlur)) return;
+        if (data.length <= 16) return;
+        if (_expectedSize > 0 && data.length >= _expectedSize * 0.99) return;
+        if (_progressiveIgnored) return;
+        
+        NSTimeInterval min = progressiveBlur ? MIN_PROGRESSIVE_BLUR_TIME_INTERVAL : MIN_PROGRESSIVE_TIME_INTERVAL;
+        NSTimeInterval now = CACurrentMediaTime();
+        if (now - _lastProgressiveDecodeTimestamp < min) return;
+        
+        if (!_progressiveDecoder) {
+            _progressiveDecoder = [[YYImageDecoder alloc] initWithScale:[UIScreen mainScreen].scale];
+        }
+        [_progressiveDecoder updateData:_data final:NO];
+        if ([self isCancelled]) return;
+        
+        if (_progressiveDecoder.type == YYImageTypeUnknown ||
+            _progressiveDecoder.type == YYImageTypeWebP ||
+            _progressiveDecoder.type == YYImageTypeOther) {
+            _progressiveDecoder = nil;
+            _progressiveIgnored = YES;
+            return;
+        }
+        if (progressiveBlur) { // only support progressive JPEG and interlaced PNG
+            if (_progressiveDecoder.type != YYImageTypeJPEG &&
+                _progressiveDecoder.type != YYImageTypePNG) {
+                _progressiveDecoder = nil;
+                _progressiveIgnored = YES;
+                return;
+            }
+        }
+        if (_progressiveDecoder.frameCount == 0) return;
+        
+        if (!progressiveBlur) {
+            YYImageFrame *frame = [_progressiveDecoder frameAtIndex:0 decodeForDisplay:YES];
+            if (frame.image) {
+                [_lock lock];
+                if (![self isCancelled]) {
+                    _completion(frame.image, _request.URL, YYWebImageFromRemote, YYWebImageStageProgress, nil);
+                    _lastProgressiveDecodeTimestamp = now;
+                }
+                [_lock unlock];
+            }
+            return;
+        } else {
+            if (_progressiveDecoder.type == YYImageTypeJPEG) {
+                if (!_progressiveDetected) {
+                    NSDictionary *dic = [_progressiveDecoder framePropertiesAtIndex:0];
+                    NSDictionary *jpeg = dic[(id)kCGImagePropertyJFIFDictionary];
+                    NSNumber *isProg = jpeg[(id)kCGImagePropertyJFIFIsProgressive];
+                    if (!isProg.boolValue) {
+                        _progressiveIgnored = YES;
+                        _progressiveDecoder = nil;
+                        return;
+                    }
+                    _progressiveDetected = YES;
+                }
+                
+                NSInteger scanLength = (NSInteger)_data.length - (NSInteger)_progressiveScanedLength - 4;
+                if (scanLength <= 2) return;
+                NSRange scanRange = NSMakeRange(_progressiveScanedLength, scanLength);
+                NSRange markerRange = [_data rangeOfData:JPEGSOSMarker() options:kNilOptions range:scanRange];
+                _progressiveScanedLength = _data.length;
+                if (markerRange.location == NSNotFound) return;
+                if ([self isCancelled]) return;
+                
+            } else if (_progressiveDecoder.type == YYImageTypePNG) {
+                if (!_progressiveDetected) {
+                    NSDictionary *dic = [_progressiveDecoder framePropertiesAtIndex:0];
+                    NSDictionary *png = dic[(id)kCGImagePropertyPNGDictionary];
+                    NSNumber *isProg = png[(id)kCGImagePropertyPNGInterlaceType];
+                    if (!isProg.boolValue) {
+                        _progressiveIgnored = YES;
+                        _progressiveDecoder = nil;
+                        return;
+                    }
+                    _progressiveDetected = YES;
+                }
+            }
+            
+            YYImageFrame *frame = [_progressiveDecoder frameAtIndex:0 decodeForDisplay:YES];
+            UIImage *image = frame.image;
+            if (!image) return;
+            if ([self isCancelled]) return;
+            
+            if (!YYCGImageLastPixelFilled(image.CGImage)) return;
+            _progressiveDisplayCount++;
+            
+            CGFloat radius = 32;
+            if (_expectedSize > 0) {
+                radius *= 1.0 / (3 * _data.length / (CGFloat)_expectedSize + 0.6) - 0.25;
+            } else {
+                radius /= (_progressiveDisplayCount);
+            }
+            image = [image yy_imageByBlurRadius:radius tintColor:nil tintMode:0 saturation:1 maskImage:nil];
+            
+            if (image) {
+                [_lock lock];
+                if (![self isCancelled]) {
+                    _completion(image, _request.URL, YYWebImageFromRemote, YYWebImageStageProgress, nil);
+                    _lastProgressiveDecodeTimestamp = now;
+                }
+                [_lock unlock];
+            }
+        }
+    }
+}
+
+- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
+    @autoreleasepool {
+        [_lock lock];
+        _connection = nil;
+        if (![self isCancelled]) {
+            __weak typeof(self) _self = self;
+            dispatch_async([self.class _imageQueue], ^{
+                __strong typeof(_self) self = _self;
+                if (!self) return;
+                
+                BOOL shouldDecode = (self.options & YYWebImageOptionIgnoreImageDecoding) == 0;
+                BOOL allowAnimation = (self.options & YYWebImageOptionIgnoreAnimatedImage) == 0;
+                UIImage *image;
+                BOOL hasAnimation = NO;
+                if (allowAnimation) {
+                    image = [[YYImage alloc] initWithData:self.data scale:[UIScreen mainScreen].scale];
+                    if (shouldDecode) image = [image yy_imageByDecoded];
+                    if ([((YYImage *)image) animatedImageFrameCount] > 1) {
+                        hasAnimation = YES;
+                    }
+                } else {
+                    YYImageDecoder *decoder = [YYImageDecoder decoderWithData:self.data scale:[UIScreen mainScreen].scale];
+                    image = [decoder frameAtIndex:0 decodeForDisplay:shouldDecode].image;
+                }
+                
+                /*
+                 If the image has animation, save the original image data to disk cache.
+                 If the image is not PNG or JPEG, re-encode the image to PNG or JPEG for
+                 better decoding performance.
+                 */
+                YYImageType imageType = YYImageDetectType((__bridge CFDataRef)self.data);
+                switch (imageType) {
+                    case YYImageTypeJPEG:
+                    case YYImageTypeGIF:
+                    case YYImageTypePNG:
+                    case YYImageTypeWebP: { // save to disk cache
+                        if (!hasAnimation) {
+                            if (imageType == YYImageTypeGIF ||
+                                imageType == YYImageTypeWebP) {
+                                self.data = nil; // clear the data, re-encode for disk cache
+                            }
+                        }
+                    } break;
+                    default: {
+                        self.data = nil; // clear the data, re-encode for disk cache
+                    } break;
+                }
+                if ([self isCancelled]) return;
+                
+                if (self.transform && image) {
+                    UIImage *newImage = self.transform(image, self.request.URL);
+                    if (newImage != image) {
+                        self.data = nil;
+                    }
+                    image = newImage;
+                    if ([self isCancelled]) return;
+                }
+                
+                [self performSelector:@selector(_didReceiveImageFromWeb:) onThread:[self.class _networkThread] withObject:image waitUntilDone:NO];
+            });
+            if (![self.request.URL isFileURL] && (self.options & YYWebImageOptionShowNetworkActivity)) {
+                [YYWebImageManager decrementNetworkActivityCount];
+            }
+        }
+        [_lock unlock];
+    }
+}
+
+- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
+    @autoreleasepool {
+        [_lock lock];
+        if (![self isCancelled]) {
+            if (_completion) {
+                _completion(nil, _request.URL, YYWebImageFromNone, YYWebImageStageFinished, error);
+            }
+            _connection = nil;
+            _data = nil;
+            if (![_request.URL isFileURL] && (_options & YYWebImageOptionShowNetworkActivity)) {
+                [YYWebImageManager decrementNetworkActivityCount];
+            }
+            [self _finish];
+        }
+        [_lock unlock];
+    }
+}
+
+#pragma mark - Override NSOperation
+
+- (void)start {
+    @autoreleasepool {
+        [_lock lock];
+        self.started = YES;
+        if ([self isCancelled]) {
+            [self performSelector:@selector(_cancelOperation) onThread:[[self class] _networkThread] withObject:nil waitUntilDone:NO modes:@[NSDefaultRunLoopMode]];
+            self.finished = YES;
+        } else if ([self isReady] && ![self isFinished] && ![self isExecuting]) {
+            if (!_request) {
+                self.finished = YES;
+                if (_completion) {
+                    NSError *error = [NSError errorWithDomain:NSURLErrorDomain code:NSURLErrorFileDoesNotExist userInfo:@{NSLocalizedDescriptionKey:@"request in nil"}];
+                    _completion(nil, _request.URL, YYWebImageFromNone, YYWebImageStageFinished, error);
+                }
+            } else {
+                self.executing = YES;
+                [self performSelector:@selector(_startOperation) onThread:[[self class] _networkThread] withObject:nil waitUntilDone:NO modes:@[NSDefaultRunLoopMode]];
+                if (_options & YYWebImageOptionAllowBackgroundTask) {
+                    __weak __typeof__ (self) _self = self;
+                    if (_taskID == UIBackgroundTaskInvalid) {
+                        _taskID = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{
+                            __strong __typeof (_self) self = _self;
+                            if (self) {
+                                [self cancel];
+                                self.finished = YES;
+                            }
+                        }];
+                    }
+                }
+            }
+        }
+        [_lock unlock];
+    }
+}
+
+- (void)cancel {
+    [_lock lock];
+    if (![self isCancelled]) {
+        [super cancel];
+        self.cancelled = YES;
+        if ([self isExecuting]) {
+            self.executing = NO;
+            [self performSelector:@selector(_cancelOperation) onThread:[[self class] _networkThread] withObject:nil waitUntilDone:NO modes:@[NSDefaultRunLoopMode]];
+        }
+        if (self.started) {
+            self.finished = YES;
+        }
+    }
+    [_lock unlock];
+}
+
+- (void)setExecuting:(BOOL)executing {
+    [_lock lock];
+    if (_executing != executing) {
+        [self willChangeValueForKey:@"isExecuting"];
+        _executing = executing;
+        [self didChangeValueForKey:@"isExecuting"];
+    }
+    [_lock unlock];
+}
+
+- (BOOL)isExecuting {
+    [_lock lock];
+    BOOL executing = _executing;
+    [_lock unlock];
+    return executing;
+}
+
+- (void)setFinished:(BOOL)finished {
+    [_lock lock];
+    if (_finished != finished) {
+        [self willChangeValueForKey:@"isFinished"];
+        _finished = finished;
+        [self didChangeValueForKey:@"isFinished"];
+    }
+    [_lock unlock];
+}
+
+- (BOOL)isFinished {
+    [_lock lock];
+    BOOL finished = _finished;
+    [_lock unlock];
+    return finished;
+}
+
+- (void)setCancelled:(BOOL)cancelled {
+    [_lock lock];
+    if (_cancelled != cancelled) {
+        [self willChangeValueForKey:@"isCancelled"];
+        _cancelled = cancelled;
+        [self didChangeValueForKey:@"isCancelled"];
+    }
+    [_lock unlock];
+}
+
+- (BOOL)isCancelled {
+    [_lock lock];
+    BOOL cancelled = _cancelled;
+    [_lock unlock];
+    return cancelled;
+}
+
+- (BOOL)isConcurrent {
+    return YES;
+}
+
+- (BOOL)isAsynchronous {
+    return YES;
+}
+
++ (BOOL)automaticallyNotifiesObserversForKey:(NSString *)key {
+    if ([key isEqualToString:@"isExecuting"] ||
+        [key isEqualToString:@"isFinished"] ||
+        [key isEqualToString:@"isCancelled"]) {
+        return NO;
+    }
+    return [super automaticallyNotifiesObserversForKey:key];
+}
+
+- (NSString *)description {
+    NSMutableString *string = [NSMutableString stringWithFormat:@"<%@: %p ",self.class, self];
+    [string appendFormat:@" executing:%@", [self isExecuting] ? @"YES" : @"NO"];
+    [string appendFormat:@" finished:%@", [self isFinished] ? @"YES" : @"NO"];
+    [string appendFormat:@" cancelled:%@", [self isCancelled] ? @"YES" : @"NO"];
+    [string appendString:@">"];
+    return string;
+}
+
+@end