| /* |
| * Copyright 2015 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #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::NewFromStream |
| * 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 |
| * @param RLEBytes indicates the amount of data left in the stream |
| * after decoding the headers |
| */ |
| SkBmpRLECodec(int width, int height, const SkEncodedInfo& info, SkStream* stream, |
| uint16_t bitsPerPixel, uint32_t numColors, uint32_t bytesPerColor, |
| uint32_t offset, SkCodec::SkScanlineOrder rowOrder, |
| size_t RLEBytes); |
| |
| int setSampleX(int); |
| |
| protected: |
| |
| Result onGetPixels(const SkImageInfo& dstInfo, void* dst, |
| size_t dstRowBytes, const Options&, SkPMColor*, |
| int*, int*) override; |
| |
| SkCodec::Result prepareToDecode(const SkImageInfo& dstInfo, |
| const SkCodec::Options& options, SkPMColor inputColorPtr[], |
| int* inputColorCount) override; |
| |
| private: |
| |
| /* |
| * Creates the color table |
| * Sets colorCount to the new color count if it is non-nullptr |
| */ |
| bool createColorTable(SkColorType dstColorType, int* colorCount); |
| |
| 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; |
| |
| bool skipRows(int count) override; |
| |
| SkSampler* getSampler(bool createIfNecessary) override; |
| |
| SkAutoTUnref<SkColorTable> fColorTable; // owned |
| // 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; |
| std::unique_ptr<uint8_t[]> fStreamBuffer; |
| size_t fRLEBytes; |
| const size_t fOrigRLEBytes; |
| 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; |
| }; |