Add animation support for WebP images

Source/core/platform/image-decoders/ImageDecoder.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) Research In Motion Limited 2009-2010. 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
@@ skipping 197 matching lines @@
             *dest = SkPackARGB32NoCheck(a, r, g, b);
         }
 
         inline void setRGBARaw(PixelData* dest, unsigned r, unsigned g, unsigned b, unsigned a)
         {
             ASSERT(!m_premultiplyAlpha);
 
             *dest = SkPackARGB32NoCheck(a, r, g, b);
         }
 
+        void zeroFillFrameRect(const IntRect&);
+
     private:
         int width() const
         {
             return m_bitmap->bitmap().width();
         }
 
         int height() const
         {
             return m_bitmap->bitmap().height();
         }
 
         RefPtr<NativeImageSkia> m_bitmap;
         SkBitmap::Allocator* m_allocator;
         bool m_hasAlpha;
-        IntRect m_originalFrameRect; // This will always just be the entire
-                                     // buffer except for GIF frames whose
-                                     // original rect was smaller than the
-                                     // overall image size.
+        // This will always just be the entire buffer except for GIF or WebP
+        // frames whose original rect was smaller than the overall image size.
+        IntRect m_originalFrameRect;
         FrameStatus m_status;
         unsigned m_duration;
         FrameDisposalMethod m_disposalMethod;
         bool m_premultiplyAlpha;
 
         // The frame that must be decoded before this frame can be decoded.
         // WTF::notFound if this frame doesn't require any previous frame.
         // This is used by ImageDecoder::clearCacheExceptFrame(), and will never
         // be read for image formats that do not have multiple frames.
         size_t m_requiredPreviousFrameIndex;
@@ skipping 38 matching lines @@
         // decode call out and use it here.
         virtual bool isSizeAvailable()
         {
             return !m_failed && m_sizeAvailable;
         }
 
         virtual IntSize size() const { return m_size; }
 
         // This will only differ from size() for ICO (where each frame is a
         // different icon) or other formats where different frames are different
-        // sizes.  This does NOT differ from size() for GIF, since decoding GIFs
-        // composites any smaller frames against previous frames to create full-
-        // size frames.
+        // sizes. This does NOT differ from size() for GIF or WebP, since
+        // decoding GIF or WebP composites any smaller frames against previous
+        // frames to create full-size frames.
         virtual IntSize frameSizeAtIndex(size_t) const
         {
             return size();
         }
 
         // Returns whether the size is legal (i.e. not going to result in
         // overflow elsewhere).  If not, marks decoding as failed.
         virtual bool setSize(unsigned width, unsigned height)
         {
             if (isOverSize(width, height))
@@ skipping 90 matching lines @@
         // to enable easy tailcalling.  Subclasses may override this to also
         // clean up any local data.
         virtual bool setFailed()
         {
             m_failed = true;
             return false;
         }
 
         bool failed() const { return m_failed; }
 
-        // Clears decoded pixel data from all frames except the provided frame,
-        // unless that frame has status FrameEmpty, in which case we instead
-        // preserve the most recent frame whose data is required in order to
-        // decode this frame. Callers may pass WTF::notFound to clear all frames.
-        //
+        // Clears decoded pixel data from all frames except the provided frame.
+        // Callers may pass WTF::notFound to clear all frames.
+        // Note: If |m_frameBufferCache| contains only one frame, it won't be cleared.
         // Returns the number of bytes of frame data actually cleared.
-        size_t clearCacheExceptFrame(size_t);
+        virtual size_t clearCacheExceptFrame(size_t);
 
         // If the image has a cursor hot-spot, stores it in the argument
         // and returns true. Otherwise returns false.
         virtual bool hotSpot(IntPoint&) const { return false; }
 
         virtual void reportMemoryUsage(MemoryObjectInfo*) const;
 
         virtual void setMemoryAllocator(SkBitmap::Allocator* allocator)
         {
             // FIXME: this doesn't work for images with multiple frames.
@@ skipping 40 matching lines @@
 
         IntSize m_size;
         bool m_sizeAvailable;
         bool m_isAllDataReceived;
         bool m_failed;
     };
 
 } // namespace WebCore
 
 #endif