third_party/WebKit/Source/platform/image-decoders/SegmentReader.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 SegmentReader_h
#define SegmentReader_h

#include "platform/SharedBuffer.h"
#include "platform/wtf/Noncopyable.h"
#include "platform/wtf/PassRefPtr.h"
#include "platform/wtf/ThreadSafeRefCounted.h"

class SkData;
class SkROBuffer;

namespace blink {

// Interface that looks like SharedBuffer. Used by ImageDecoders to use various
// sources of input including:
// - SharedBuffer
//   - for when the caller already has a SharedBuffer
// - SkData
//   - for when the caller already has an SkData
// - SkROBuffer
//   - for when the caller wants to read/write in different threads
//
// Unlike SharedBuffer, this is a read-only interface. There is no way to
// modify the underlying data source.
class PLATFORM_EXPORT SegmentReader
    : public ThreadSafeRefCounted<SegmentReader> {
  WTF_MAKE_NONCOPYABLE(SegmentReader);

 public:
  // This version is thread-safe so long as no thread is modifying the
  // underlying SharedBuffer. This class does not modify it, so that would
  // mean modifying it in another way.
  static PassRefPtr<SegmentReader> CreateFromSharedBuffer(
      PassRefPtr<SharedBuffer>);

  // These versions use thread-safe input, so they are always thread-safe.
  static PassRefPtr<SegmentReader> CreateFromSkData(sk_sp<SkData>);
  static PassRefPtr<SegmentReader> CreateFromSkROBuffer(sk_sp<SkROBuffer>);

  SegmentReader() {}
  virtual ~SegmentReader() {}
  virtual size_t size() const = 0;
  virtual size_t GetSomeData(const char*& data, size_t position) const = 0;
  virtual sk_sp<SkData> GetAsSkData() const = 0;
};

}  // namespace blink
#endif  // SegmentReader_h