Deferred image decoding to support animated GIFs

Source/core/platform/graphics/chromium/ImageFrameGenerator.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 35 matching lines @@
 class SharedBuffer;
 
 class ImageDecoderFactory {
 public:
     virtual ~ImageDecoderFactory() { }
     virtual PassOwnPtr<ImageDecoder> create() = 0;
 };
 
 class ImageFrameGenerator : public ThreadSafeRefCounted<ImageFrameGenerator> {
 public:
-    static PassRefPtr<ImageFrameGenerator> create(const SkISize& fullSize, PassRefPtr<SharedBuffer> data, bool allDataReceived)
+    static PassRefPtr<ImageFrameGenerator> create(const SkISize& fullSize, PassRefPtr<SharedBuffer> data, bool allDataReceived, bool isMultiFrame = false)
     {
-        return adoptRef(new ImageFrameGenerator(fullSize, data, allDataReceived));
+        return adoptRef(new ImageFrameGenerator(fullSize, data, allDataReceived, isMultiFrame));
     }
 
-    ImageFrameGenerator(const SkISize& fullSize, PassRefPtr<SharedBuffer>, bool allDataReceived);
+    ImageFrameGenerator(const SkISize& fullSize, PassRefPtr<SharedBuffer>, bool allDataReceived, bool isMultiFrame);
     ~ImageFrameGenerator();
 
-    const ScaledImageFragment* decodeAndScale(const SkISize& scaledSize);
+    const ScaledImageFragment* decodeAndScale(const SkISize& scaledSize, size_t index = 0);
 
     void setData(PassRefPtr<SharedBuffer>, bool allDataReceived);
 
     // Creates a new SharedBuffer containing the data received so far.
     void copyData(RefPtr<SharedBuffer>*, bool* allDataReceived);
 
     SkISize getFullSize() const { return m_fullSize; }
 
+    bool isMultiFrame() const { return m_isMultiFrame; }
+
     void setImageDecoderFactoryForTesting(PassOwnPtr<ImageDecoderFactory> factory) { m_imageDecoderFactory = factory; }
 
+    // FIXME: Return alpha state for each frame.
     bool hasAlpha();
 
 private:
     // These methods are called while m_decodeMutex is locked.
-    const ScaledImageFragment* tryToLockCompleteCache(const SkISize& scaledSize);
-    const ScaledImageFragment* tryToScale(const ScaledImageFragment* fullSizeImage, const SkISize& scaledSize);
-    const ScaledImageFragment* tryToResumeDecodeAndScale(const SkISize& scaledSize);
-    const ScaledImageFragment* tryToDecodeAndScale(const SkISize& scaledSize);
+    const ScaledImageFragment* tryToLockCompleteCache(const SkISize& scaledSize, size_t index);
+    const ScaledImageFragment* tryToScale(const ScaledImageFragment* fullSizeImage, const SkISize& scaledSize, size_t index);
+    const ScaledImageFragment* tryToResumeDecodeAndScale(const SkISize& scaledSize, size_t index);
+    const ScaledImageFragment* tryToDecodeAndScale(const SkISize& scaledSize, size_t index);
 
     // Use the given decoder to decode. If a decoder is not given then try to create one.
-    PassOwnPtr<ScaledImageFragment> decode(ImageDecoder**);
+    PassOwnPtr<ScaledImageFragment> decode(size_t index, ImageDecoder**);
 
     // Return the next generation ID of a new image object. This is used
     // to identify images of the same frame from different stages of
     // progressive decode.
     size_t nextGenerationId() { return m_decodeCount++; }
 
     SkISize m_fullSize;
     ThreadSafeDataTransport m_data;
+    bool m_isMultiFrame;
     bool m_decodeFailedAndEmpty;
     bool m_hasAlpha;
     size_t m_decodeCount;
     DiscardablePixelRefAllocator m_allocator;
 
     OwnPtr<ImageDecoderFactory> m_imageDecoderFactory;
 
     // Prevents multiple decode operations on the same data.
     Mutex m_decodeMutex;
 
     // Protect concurrent access to m_hasAlpha.
     Mutex m_alphaMutex;
 };
 
 } // namespace WebCore
 
 #endif