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/*
* Copyright 2015 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkBmpRLECodec_DEFINED
#define SkBmpRLECodec_DEFINED
#include "SkBmpCodec.h"
#include "SkColorTable.h"
#include "SkImageInfo.h"
#include "SkSampler.h"
#include "SkTypes.h"
/*
* This class implements the decoding for bmp images that use an RLE encoding
*/
class SkBmpRLECodec : public SkBmpCodec {
public:
/*
* Creates an instance of the decoder
*
* Called only by SkBmpCodec::MakeFromStream
* There should be no other callers despite this being public
*
* @param info contains properties of the encoded data
* @param stream the stream of encoded image data
* @param bitsPerPixel the number of bits used to store each pixel
* @param numColors the number of colors in the color table
* @param bytesPerColor the number of bytes in the stream used to represent
each color in the color table
* @param offset the offset of the image pixel data from the end of the
* headers
* @param rowOrder indicates whether rows are ordered top-down or bottom-up
*/
SkBmpRLECodec(int width, int height, const SkEncodedInfo& info, std::unique_ptr<SkStream>,
uint16_t bitsPerPixel, uint32_t numColors, uint32_t bytesPerColor,
uint32_t offset, SkCodec::SkScanlineOrder rowOrder);
int setSampleX(int);
protected:
Result onGetPixels(const SkImageInfo& dstInfo, void* dst,
size_t dstRowBytes, const Options&,
int*) override;
SkCodec::Result onPrepareToDecode(const SkImageInfo& dstInfo,
const SkCodec::Options& options) override;
private:
/*
* Creates the color table
* Sets colorCount to the new color count if it is non-nullptr
*/
bool createColorTable(SkColorType dstColorType);
bool initializeStreamBuffer();
/*
* Before signalling kIncompleteInput, we should attempt to load the
* stream buffer with additional data.
*
* @return the number of bytes remaining in the stream buffer after
* attempting to read more bytes from the stream
*/
size_t checkForMoreData();
/*
* Set an RLE pixel using the color table
*/
void setPixel(void* dst, size_t dstRowBytes,
const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
uint8_t index);
/*
* Set an RLE24 pixel from R, G, B values
*/
void setRGBPixel(void* dst, size_t dstRowBytes,
const SkImageInfo& dstInfo, uint32_t x, uint32_t y,
uint8_t red, uint8_t green, uint8_t blue);
/*
* If dst is NULL, this is a signal to skip the rows.
*/
int decodeRows(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes,
const Options& opts) override;
int decodeRLE(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes);
bool skipRows(int count) override;
SkSampler* getSampler(bool createIfNecessary) override;
sk_sp<SkColorTable> fColorTable;
// fNumColors is the number specified in the header, or 0 if not present in the header.
const uint32_t fNumColors;
const uint32_t fBytesPerColor;
const uint32_t fOffset;
static constexpr size_t kBufferSize = 4096;
uint8_t fStreamBuffer[kBufferSize];
size_t fBytesBuffered;
uint32_t fCurrRLEByte;
int fSampleX;
std::unique_ptr<SkSampler> fSampler;
// Scanline decodes allow the client to ask for a single scanline at a time.
// This can be tricky when the RLE encoding instructs the decoder to jump down
// multiple lines. This field keeps track of lines that need to be skipped
// on subsequent calls to decodeRows().
int fLinesToSkip;
typedef SkBmpCodec INHERITED;
};
#endif // SkBmpRLECodec_DEFINED
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