JPEGImageDecoder RGB565 and downsample support and related Skia imagegenerator changes

third_party/WebKit/Source/platform/graphics/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 67 matching lines @@
     // 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; }
 
     // FIXME: Return alpha state for each frame.
     bool hasAlpha(size_t);
 
+    // for single frame, if decoder can produce RGB_565 by decoding current image
+    bool canDecodeToRGB565();
+
     bool getYUVComponentSizes(SkISize componentSizes[3]);
 
 private:
     class ExternalMemoryAllocator;
     friend class ImageFrameGeneratorTest;
     friend class DeferredImageDecoderTest;
     // For testing. |factory| will overwrite the default ImageDecoder creation logic if |factory->create()| returns non-zero.
     void setImageDecoderFactory(PassOwnPtr<ImageDecoderFactory> factory) { m_imageDecoderFactory = factory; }
 
     void setHasAlpha(size_t index, bool hasAlpha);
 
     // These methods are called while m_decodeMutex is locked.
-    SkBitmap tryToResumeDecode(const SkISize& scaledSize, size_t index);
+    SkBitmap tryToResumeDecode(const SkISize& scaledSize, size_t index, SkColorType outType);

[scroggo_chromium, 2015/10/19 20:41:36]

Maybe this should use an SkImageInfo, and combine the color type and size? Or
would that be confusing since we ignore the other pieces (profile and alpha)?

[aleksandar.stojiljkovic, 2015/10/20 09:51:12]

This is private code for this class.
It comes back to proposal about SkImageGenerator::canDecodeAndScale API (to put
SkImageInfo there) and if Alpha should be part specified or implicitly covered
by RGB565.   

 
     // Use the given decoder to decode. If a decoder is not given then try to create one.
     // Returns true if decoding was complete.
-    bool decode(size_t index, ImageDecoder**, SkBitmap*);
+    bool decode(size_t index, ImageDecoder**, SkBitmap*, SkColorType outType);
 
     SkISize m_fullSize;
     ThreadSafeDataTransport m_data;
     bool m_isMultiFrame;
     bool m_decodeFailedAndEmpty;
     Vector<bool> m_hasAlpha;
     int m_decodeCount;
     Vector<bool> m_frameComplete;
     size_t m_frameCount;
     OwnPtr<ExternalMemoryAllocator> m_externalAllocator;
 
     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 blink
 
 #endif