WIP: Implement APNG

third_party/WebKit/Source/platform/image-decoders/ImageFrame.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 200 matching lines @@
   }
 
   static inline void setRGBARaw(PixelData* dest,
                                 unsigned r,
                                 unsigned g,
                                 unsigned b,
                                 unsigned a) {
     *dest = SkPackARGB32NoCheck(a, r, g, b);
   }
 
+  // Blend the RGBA pixel provided by |r|, |g|, |b|, |a| over the pixel in
+  // |dest|, without premultiplication, and overwrite |dest| with the result.
+  static void blendRGBARaw(PixelData* dest,
+                           unsigned r,
+                           unsigned g,
+                           unsigned b,
+                           unsigned a);
+
+  // Blend the pixel, without premultiplication, in |src| over |dst| and
+  // overwrite |src| with the result.
+  static void blendSrcOverDstRaw(PixelData* src, PixelData dst);
+
+  // Blend the RGBA pixel provided by |r|, |g|, |b|, |a| over the pixel in
+  // |dest| and overwrite |dest| with the result. Premultiply the pixel values
+  // before blending.
+  static inline void blendRGBAPremultiply(PixelData* dest,
+                                          unsigned r,
+                                          unsigned g,
+                                          unsigned b,
+                                          unsigned a) {
+    // If the new pixel is completely transparent, no operation is necessary
+    // since |dest| contains the background pixel.
+    if (a == 0x0)
+      return;
+
+    // If the new pixel is opaque, no need for blending - just write the pixel.
+    if (a == 0xFF)
+      return setRGBAPremultiply(dest, r, g, b, a);
+
+    PixelData src;
+    setRGBAPremultiply(&src, r, g, b, a);
+    *dest = SkPMSrcOver(src, *dest);
+  }
+
+  // Blend the pixel in |src| over |dst| and overwrite |src| with the result.
+  // This assumes the pixel values in |src| are already premultiplied.
+  static inline void blendSrcOverDstPremultiplied(PixelData* src,
+                                                  PixelData dst) {
+    *src = SkPMSrcOver(*src, dst);
+  }
+
   // Notifies the SkBitmap if any pixels changed and resets the flag.
   inline void notifyBitmapIfPixelsChanged() {
     if (m_pixelsChanged)
       m_bitmap.notifyPixelsChanged();
     m_pixelsChanged = false;
   }
 
  private:
   int width() const { return m_bitmap.width(); }
 
@@ skipping 22 matching lines @@
   // The frame that must be decoded before this frame can be decoded.
   // WTF::kNotFound 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;
 };
 
 }  // namespace blink
 
 #endif