Animated PNG implementation

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);
   }
 
+  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);
+  }
+
   // Blend the RGBA pixel provided by |r|, |g|, |b|, |a| over the pixel in
   // |dest|, without premultiplication, and overwrite |dest| with the result.
   static inline void blendRGBARaw(PixelData* dest,
                                   unsigned r,
                                   unsigned g,
                                   unsigned b,
                                   unsigned a) {
     blendSrcOverDstRaw(dest, SkPackARGB32NoCheck(a, r, g, b));
   }
 
@@ skipping 52 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