Remove duplication of encoded image data

third_party/WebKit/Source/platform/graphics/DeferredImageDecoder.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 99 matching lines @@
     if (!m_actualDecoder || m_actualDecoder->failed())
         return nullptr;
 
     ImageFrame* frame = m_actualDecoder->frameBufferAtIndex(index);
     if (!frame || frame->getStatus() == ImageFrame::FrameEmpty)
         return nullptr;
 
     return adoptRef(SkImage::NewFromBitmap(frame->bitmap()));
 }
 
+bool DeferredImageDecoder::hasData() const
+{
+    return static_cast<bool>(m_rwBuffer);
+}
+
+PassRefPtr<SharedBuffer> DeferredImageDecoder::data()

[scroggo_chromium, 2016/06/20 19:00:43]

This method can be slow, especially if it's called regularly. Who calls it?

It looks like the stack trace would be:

ImageResource::resourceBuffer()
BitmapImage::data() (overriding Image::data())
ImageSource::data()

Does this get called often?

[hajimehoshi, 2016/06/22 09:42:29]

IIUC this is not called often: Resource::resourceBuffer() is called from
FrameSerializer, the inspector, tests, etc. The situation is limited.

+{
+    if (!m_rwBuffer)
+        return nullptr;
+    RefPtr<SkROBuffer> roBuffer = adoptRef(m_rwBuffer->newRBufferSnapshot());
+    RefPtr<SharedBuffer> sharedBuffer = SharedBuffer::create(roBuffer->size());
+    SkROBuffer::Iter it(roBuffer.get());
+    do {
+        sharedBuffer->append(static_cast<const char*>(it.data()), it.size());
+    } while (it.next());
+    return sharedBuffer;
+}
+
 void DeferredImageDecoder::setData(SharedBuffer& data, bool allDataReceived)
 {
     if (m_actualDecoder) {
         m_allDataReceived = allDataReceived;
         m_actualDecoder->setData(&data, allDataReceived);
         prepareLazyDecodedFrames();
     }
 
     if (m_frameGenerator) {
         if (!m_rwBuffer)
             m_rwBuffer = adoptPtr(new SkRWBuffer(data.size()));
 
         const char* segment = 0;
         for (size_t length = data.getSomeData(segment, m_rwBuffer->size());
-            length; length = data.getSomeData(segment, m_rwBuffer->size()))
+            length; length = data.getSomeData(segment, m_rwBuffer->size())) {
             m_rwBuffer->append(segment, length);
+        }
     }
 }
 
 bool DeferredImageDecoder::isSizeAvailable()
 {
     // m_actualDecoder is 0 only if image decoding is deferred and that means
     // the image header decoded successfully and the size is available.
     return m_actualDecoder ? m_actualDecoder->isSizeAvailable() : true;
 }
 
@@ skipping 173 matching lines @@
 }
 
 } // namespace blink
 
 namespace WTF {
 template<> struct VectorTraits<blink::DeferredFrameData> : public SimpleClassVectorTraits<blink::DeferredFrameData> {
     STATIC_ONLY(VectorTraits);
     static const bool canInitializeWithMemset = false; // Not all DeferredFrameData members initialize to 0.
 };
 }