Eliminate copies of encoded image data

third_party/WebKit/Source/platform/image-decoders/ROBufferSegmentReader.h

+// 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.
+
+#ifndef ROBufferSegmentReader_h
+#define ROBufferSegmentReader_h
+
+#include "platform/image-decoders/SegmentReader.h"
+#include "third_party/skia/src/core/SkRWBuffer.h"
+#include "wtf/Noncopyable.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefPtr.h"
+
+namespace blink {
+
+class ROBufferSegmentReader final : public SegmentReader {
+    WTF_MAKE_NONCOPYABLE(ROBufferSegmentReader);
+public:
+    ROBufferSegmentReader(PassRefPtr<SkROBuffer>);
+
+    size_t getSomeData(const char*& data, size_t position) const override;
+    size_t size() const override { return m_roBuffer ? m_roBuffer->size() : 0; }
+    PassRefPtr<SkData> getAsSkData() const override;
+
+private:
+    RefPtr<SkROBuffer> m_roBuffer;
+    // Position of the first char in the current block of m_iter.
+    mutable size_t m_positionOfBlock;
+    mutable SkROBuffer::Iter m_iter;
+};
+
+} // namespace blink
+
+#endif // ROBufferSegmentReader_h