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* Copyright 2023 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkJpegSourceMgr_codec_DEFINED
#define SkJpegSourceMgr_codec_DEFINED
#include "include/core/SkTypes.h"
#include "include/core/SkRefCnt.h"
#include <cstddef>
#include <cstdint>
#include <memory>
#include <vector>
class SkStream;
class SkData;
class SkJpegSegmentScanner;
struct SkJpegSegment;
* Interface to adapt an SkStream to the jpeg_source_mgr interface. This interface has different
* implementations for SkStreams with different capabilities.
class SkJpegSourceMgr {
// Create a source manager. If the source manager will buffer data, |bufferSize| specifies
// the size of that buffer.
static std::unique_ptr<SkJpegSourceMgr> Make(SkStream* stream, size_t bufferSize = 1024);
virtual ~SkJpegSourceMgr();
// Interface called by libjpeg via its jpeg_source_mgr interface.
virtual void initSource(const uint8_t*& nextInputByte, size_t& bytesInBuffer) = 0;
virtual bool fillInputBuffer(const uint8_t*& nextInputByte, size_t& bytesInBuffer) = 0;
virtual bool skipInputBytes(size_t bytes,
const uint8_t*& nextInputByte,
size_t& bytesInBuffer) = 0;
// Parse this stream all the way through its EndOfImage marker and return the list of segments.
// Return false if there is an error or if no EndOfImage marker is found.
virtual const std::vector<SkJpegSegment>& getAllSegments() = 0;
// Return an the data for a subset of this source's stream, with the specified offset and size.
// If the returned SkData is a copy (it does not refer directly to memory owned by |fStream|),
// then |wasCopied| is set to true.
virtual sk_sp<SkData> getSubsetData(size_t offset, size_t size, bool* wasCopied = nullptr) = 0;
// Segments start with a 2 byte marker, followed by a 2 byte parameter length (which includes
// those two bytes, followed by parameters. Return the parameters portion of the specified
// segment. If possible, the returned SkData will refer to memory owned by |fStream|.
virtual sk_sp<SkData> getSegmentParameters(const SkJpegSegment& segment) = 0;
SkJpegSourceMgr(SkStream* stream);
SkStream* const fStream; // unowned
// The segment scanner is lazily creatd only when needed.
std::unique_ptr<SkJpegSegmentScanner> fScanner;