Eliminate copies of encoded image data

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

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 18 matching lines @@
  */
 
 #include "platform/graphics/PictureSnapshot.h"
 
 #include "platform/geometry/IntSize.h"
 #include "platform/graphics/ImageBuffer.h"
 #include "platform/graphics/LoggingCanvas.h"
 #include "platform/graphics/ProfilingCanvas.h"
 #include "platform/graphics/ReplayingCanvas.h"
 #include "platform/graphics/skia/ImagePixelLocker.h"
+#include "platform/image-decoders/DataSegmentReader.h"
 #include "platform/image-decoders/ImageDecoder.h"
 #include "platform/image-decoders/ImageFrame.h"
 #include "platform/image-encoders/skia/PNGImageEncoder.h"
+#include "third_party/skia/include/core/SkData.h"
 #include "third_party/skia/include/core/SkImage.h"
 #include "third_party/skia/include/core/SkPictureRecorder.h"
 #include "third_party/skia/include/core/SkStream.h"
 #include "wtf/HexNumber.h"
 #include "wtf/text/Base64.h"
 #include "wtf/text/TextEncoding.h"
 
 namespace blink {
 
 PictureSnapshot::PictureSnapshot(PassRefPtr<const SkPicture> picture)
     : m_picture(picture)
 {
 }
 
 static bool decodeBitmap(const void* data, size_t length, SkBitmap* result)
 {
-    RefPtr<SharedBuffer> buffer = SharedBuffer::create(static_cast<const char*>(data), length);
-    OwnPtr<ImageDecoder> imageDecoder = ImageDecoder::create(*buffer, ImageDecoder::AlphaPremultiplied, ImageDecoder::GammaAndColorProfileIgnored);
+    OwnPtr<ImageDecoder> imageDecoder = ImageDecoder::create(static_cast<const char*>(data), length,
+        ImageDecoder::AlphaPremultiplied, ImageDecoder::GammaAndColorProfileIgnored);
     if (!imageDecoder)
         return false;
-    imageDecoder->setData(buffer.get(), true);
+
+    // No need to copy the data; this decodes immediately.
+    RefPtr<DataSegmentReader> segmentReader = new DataSegmentReader(adoptRef(SkData::NewWithoutCopy(data, length)));

[scroggo_chromium, 2016/03/24 13:59:46]

Oops, I think the DataSegmentReader needs to be adopted. Fixed in next patch
set.

+    imageDecoder->setData(segmentReader.release(), true);
     ImageFrame* frame = imageDecoder->frameBufferAtIndex(0);
     if (!frame)
         return true;
     *result = frame->getSkBitmap();
     return true;
 }
 
 PassRefPtr<PictureSnapshot> PictureSnapshot::load(const Vector<RefPtr<TilePictureStream>>& tiles)
 {
     ASSERT(!tiles.isEmpty());
@@ skipping 89 matching lines @@
 
 PassRefPtr<JSONArray> PictureSnapshot::snapshotCommandLog() const
 {
     const SkIRect bounds = m_picture->cullRect().roundOut();
     LoggingCanvas canvas(bounds.width(), bounds.height());
     m_picture->playback(&canvas);
     return canvas.log();
 }
 
 } // namespace blink