Eliminate copies of encoded image data

third_party/WebKit/Source/platform/image-decoders/SharedBufferSegmentReader.cpp

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "platform/image-decoders/SegmentReader.h"
+
+#include "platform/SharedBuffer.h"
+#include "third_party/skia/include/core/SkData.h"
+#include "wtf/Noncopyable.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefPtr.h"
+
+namespace blink {
+
+// Interface for ImageDecoder to read a SharedBuffer.
+class SharedBufferSegmentReader final : public SegmentReader {
+    WTF_MAKE_NONCOPYABLE(SharedBufferSegmentReader);
+public:
+    SharedBufferSegmentReader(PassRefPtr<SharedBuffer>);
+    size_t size() const override;
+    size_t getSomeData(const char*& data, size_t position) const override;
+    PassRefPtr<SkData> getAsSkData() const override;
+private:
+    RefPtr<SharedBuffer> m_sharedBuffer;
+};
+
+PassRefPtr<SegmentReader> SegmentReader::createFromSharedBuffer(PassRefPtr<SharedBuffer> buffer)
+{
+    return adoptRef(new SharedBufferSegmentReader(buffer));
+}
+
+SharedBufferSegmentReader::SharedBufferSegmentReader(PassRefPtr<SharedBuffer> buffer)
+: m_sharedBuffer(buffer) {}
+
+size_t SharedBufferSegmentReader::size() const
+{
+    return m_sharedBuffer->size();
+}
+
+size_t SharedBufferSegmentReader::getSomeData(const char*& data, size_t position) const
+{
+    return m_sharedBuffer->getSomeData(data, position);
+}
+
+PassRefPtr<SkData> SharedBufferSegmentReader::getAsSkData() const
+{
+    return m_sharedBuffer->getAsSkData();
+}
+
+} // namespace blink
+