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// Copyright 2016 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_IMAGE_DECODERS_SEGMENT_READER_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_IMAGE_DECODERS_SEGMENT_READER_H_
#include <stdint.h>
#include "base/containers/span.h"
#include "base/memory/scoped_refptr.h"
#include "third_party/blink/renderer/platform/image-decoders/rw_buffer.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/wtf/shared_buffer.h"
#include "third_party/blink/renderer/platform/wtf/thread_safe_ref_counted.h"
class SkData;
template <typename T>
class sk_sp;
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
// - ROBuffer
// - 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> {
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 scoped_refptr<SegmentReader> CreateFromSharedBuffer(
scoped_refptr<const SharedBuffer>);
// These versions use thread-safe input, so they are always thread-safe.
static scoped_refptr<SegmentReader> CreateFromSkData(sk_sp<SkData>);
static scoped_refptr<SegmentReader> CreateFromROBuffer(
scoped_refptr<ROBuffer>);
SegmentReader() = default;
SegmentReader(const SegmentReader&) = delete;
SegmentReader& operator=(const SegmentReader&) = delete;
virtual size_t size() const = 0;
// Returns a span of however much data is left in the segment containing the
// `position`. If there's no data at the specified `position`, an empty span
// is returned.
virtual base::span<const uint8_t> GetSomeData(size_t position) const = 0;
virtual sk_sp<SkData> GetAsSkData() const = 0;
virtual void LockData() {}
virtual void UnlockData() {}
static sk_sp<SkData> RWBufferCopyAsSkData(RWBuffer::ROIter iter,
size_t available);
static base::span<const uint8_t> RWBufferGetSomeData(
RWBuffer::ROIter& iter,
size_t& position_of_block,
size_t position);
protected:
friend class ThreadSafeRefCounted<SegmentReader>;
virtual ~SegmentReader() = default;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_IMAGE_DECODERS_SEGMENT_READER_H_
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