Make image decoders faster by refactoring hot loops that fills the lines of ImageFrame.

Source/core/platform/image-decoders/png/PNGImageDecoder.cpp

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  * Portions are Copyright (C) 2001 mozilla.org
  *
  * Other contributors:
  *   Stuart Parmenter <stuart@mozilla.com>
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 470 matching lines @@
     }
 
 #if USE(QCMSLIB)
     if (qcms_transform* transform = m_reader->colorTransform()) {
         qcms_transform_data(transform, row, m_reader->rowBuffer(), size().width());
         row = m_reader->rowBuffer();
     }
 #endif
 
     // Write the decoded row pixels to the frame buffer.
-    ImageFrame::PixelData* address = buffer.getAddr(0, y);
     bool nonTrivialAlpha = false;
-    int width = size().width();
-
-    png_bytep pixel = row;
-    for (int x = 0; x < width; ++x, pixel += colorChannels) {
-        unsigned alpha = hasAlpha ? pixel[3] : 255;
-        buffer.setRGBA(address++, pixel[0], pixel[1], pixel[2], alpha);
-        nonTrivialAlpha |= alpha < 255;
-    }
+    if (hasAlpha)
+        buffer.fillRowFromRGBASourceWithNonTrivialAlphaDetection(y, row, nonTrivialAlpha);
+    else
+        buffer.fillRowFromRGBSource(y, row);
 
     if (nonTrivialAlpha && !buffer.hasAlpha())
         buffer.setHasAlpha(nonTrivialAlpha);
 }
 
 void PNGImageDecoder::pngComplete()
 {
     if (!m_frameBufferCache.isEmpty())
         m_frameBufferCache.first().setStatus(ImageFrame::FrameComplete);
 }
@@ skipping 10 matching lines @@
     // has failed.
     if (!m_reader->decode(*m_data, onlySize) && isAllDataReceived())
         setFailed();
     // If we're done decoding the image, we don't need the PNGImageReader
     // anymore.  (If we failed, |m_reader| has already been cleared.)
     else if (isComplete())
         m_reader.clear();
 }
 
 } // namespace WebCore