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

third_party/WebKit/Source/platform/graphics/ImageFrameGenerator.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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 104 matching lines @@
 
 ImageFrameGenerator::~ImageFrameGenerator() {
   ImageDecodingStore::instance().removeCacheIndexedByGenerator(this);
 }
 
 bool ImageFrameGenerator::decodeAndScale(SegmentReader* data,
                                          bool allDataReceived,
                                          size_t index,
                                          const SkImageInfo& info,
                                          void* pixels,
-                                         size_t rowBytes) {
+                                         size_t rowBytes,
+                                         SkFilterQuality quality) {
   if (m_decodeFailed)
     return false;
 
   TRACE_EVENT1("blink", "ImageFrameGenerator::decodeAndScale", "frame index",
                static_cast<int>(index));
 
-  // This implementation does not support scaling so check the requested size.
   SkISize scaledSize = SkISize::Make(info.width(), info.height());
-  ASSERT(m_fullSize == scaledSize);
+  const bool doScaleAfterDecoding = m_fullSize != scaledSize;
 
   // It is okay to allocate ref-counted ExternalMemoryAllocator on the stack,
   // because 1) it contains references to memory that will be invalid after
   // returning (i.e. a pointer to |pixels|) and therefore 2) should not live
   // longer than the call to the current method.
   ExternalMemoryAllocator externalAllocator(info, pixels, rowBytes);
-  SkBitmap bitmap = tryToResumeDecode(data, allDataReceived, index, scaledSize,
-                                      &externalAllocator);
+  SkBitmap bitmap =
+      tryToResumeDecode(data, allDataReceived, index, m_fullSize,
+                        doScaleAfterDecoding ? nullptr : &externalAllocator);
   DCHECK(externalAllocator.unique());  // Verify we have the only ref-count.
 
   if (bitmap.isNull())
     return false;
 
   // Check to see if the decoder has written directly to the pixel memory
   // provided. If not, make a copy.
-  ASSERT(bitmap.width() == scaledSize.width());
-  ASSERT(bitmap.height() == scaledSize.height());
+  DCHECK_NE(bitmap.width(), m_fullSize.width());
+  DCHECK_NE(bitmap.height(), m_fullSize.height());
   SkAutoLockPixels bitmapLock(bitmap);
-  if (bitmap.getPixels() != pixels)
-    return bitmap.copyPixelsTo(pixels, rowBytes * info.height(), rowBytes);
+  if (bitmap.getPixels() != pixels) {
+    if (!doScaleAfterDecoding)
+      return bitmap.copyPixelsTo(pixels, rowBytes * info.height(), rowBytes);
+    SkPixmap pixmap;
+    SkPixmap scaled(info, pixels, rowBytes);
+    return bitmap.peekPixels(&pixmap) && pixmap.scalePixels(scaled, quality);
+  }
+  DCHECK(!doScaleAfterDecoding);
   return true;
 }
 
 bool ImageFrameGenerator::decodeToYUV(SegmentReader* data,
                                       size_t index,
                                       const SkISize componentSizes[3],
                                       void* planes[3],
                                       const size_t rowBytes[3]) {
   // TODO (scroggo): The only interesting thing this uses from the
   // ImageFrameGenerator is m_decodeFailed. Move this into
@@ skipping 209 matching lines @@
   // do YUV decoding.
   std::unique_ptr<ImagePlanes> dummyImagePlanes =
       WTF::wrapUnique(new ImagePlanes);
   decoder->setImagePlanes(std::move(dummyImagePlanes));
 
   return updateYUVComponentSizes(decoder.get(), sizeInfo->fSizes,
                                  sizeInfo->fWidthBytes);
 }
 
 }  // namespace blink