Remove full-size bitmap copy on SkImage::scalePixels->IFG::decodeAndScale

third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.cpp

 /*
  * Copyright (C) 2012 Google Inc. 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 82 matching lines @@
 
   PlatformInstrumentation::willDecodeLazyPixelRef(uniqueID());
   bool decoded = m_frameGenerator->decodeAndScale(
       m_data.get(), m_allDataReceived, m_frameIndex, getInfo(), pixels,
       rowBytes);
   PlatformInstrumentation::didDecodeLazyPixelRef();
 
   return decoded;
 }
 
+bool DecodingImageGenerator::onGenerateScaledPixels(
+    const SkISize& scaledSize,
+    const SkIPoint& subsetOrigin,
+    const SkPixmap& subsetPixels,
+    SkFilterQuality quality) {
+  TRACE_EVENT1("blink", "DecodingImageGenerator::onGenerateScaledPixels",
+               "frame index", static_cast<int>(m_frameIndex));
+  // TODO(aleksandar.stojiljkovic): sub-rect decoding, see crbug.com/671821.
+  if (!subsetOrigin.isZero() || subsetPixels.width() != scaledSize.width() ||
+      subsetPixels.height() != subsetPixels.height())
+    return false;
+  PlatformInstrumentation::willDecodeLazyPixelRef(uniqueID());
+  bool decoded = m_frameGenerator->decodeAndScale(
+      m_data.get(), m_allDataReceived, m_frameIndex,
+      getInfo().makeWH(scaledSize.width(), scaledSize.height()),
+      subsetPixels.writable_addr(), subsetPixels.rowBytes(), quality);
+  PlatformInstrumentation::didDecodeLazyPixelRef();
+  return decoded;
+}
+
 bool DecodingImageGenerator::onQueryYUV8(SkYUVSizeInfo* sizeInfo,
                                          SkYUVColorSpace* colorSpace) const {
   // YUV decoding does not currently support progressive decoding. See comment
   // in ImageFrameGenerator.h.
   if (!m_canYUVDecode || !m_allDataReceived)
     return false;
 
   TRACE_EVENT1("blink", "DecodingImageGenerator::queryYUV8", "sizes",
                static_cast<int>(m_frameIndex));
 
@@ skipping 42 matching lines @@
       ImageFrameGenerator::create(SkISize::Make(size.width(), size.height()),
                                   false, decoder->colorBehavior());
   if (!frame)
     return nullptr;
 
   return new DecodingImageGenerator(frame, info, segmentReader.release(), true,
                                     0);
 }
 
 }  // namespace blink