Animated PNG implementation

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 160 matching lines @@
         }
 
         *dest = SkPackARGB32NoCheck(a, r, g, b);
     }
 
     static inline void setRGBARaw(PixelData* dest, unsigned r, unsigned g, unsigned b, unsigned a)
     {
         *dest = SkPackARGB32NoCheck(a, r, g, b);
     }
 
+    inline void overRGBAPremultiply(PixelData* dest, unsigned r, unsigned g, unsigned b, unsigned a)
+    {
+        enum FractionControl { RoundFractionControl = 257 * 128 };
+
+        if (!a)
+            return;
+
+        if (a < 255) {
+            unsigned alpha = a * 257;
+            r = (r * alpha + RoundFractionControl) >> 16;
+            g = (g * alpha + RoundFractionControl) >> 16;
+            b = (b * alpha + RoundFractionControl) >> 16;
+            *dest = SkPMSrcOver(SkPackARGB32NoCheck(a, r, g, b), *dest);
+        } else {
+            *dest = SkPackARGB32NoCheck(a, r, g, b);
+        }
+    }
+
+    inline void overRGBARaw(PixelData* dest, unsigned r, unsigned g, unsigned b, unsigned a)
+    {
+        if (!a)
+            return;
+
+        unsigned aDest = SkGetPackedA32(*dest);
+        if (aDest && a < 255) {
+            unsigned u = a * 255;
+            unsigned v = (255 - a) * aDest;
+            unsigned alpha = u + v;
+            unsigned rDest = SkGetPackedR32(*dest);
+            unsigned gDest = SkGetPackedG32(*dest);
+            unsigned bDest = SkGetPackedB32(*dest);
+            a = (alpha + (alpha >> 8) + 1) >> 8;
+            r = (r * u + rDest * v) / alpha;
+            g = (g * u + gDest * v) / alpha;
+            b = (b * u + bDest * v) / alpha;
+        }
+        *dest = SkPackARGB32NoCheck(a, r, g, b);
+    }
+
     // 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
@@ skipping 23 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