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