| /* |
| * 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 SkJpegCodec_DEFINED |
| #define SkJpegCodec_DEFINED |
| |
| #include "SkCodec.h" |
| #include "SkImageInfo.h" |
| #include "SkSwizzler.h" |
| #include "SkStream.h" |
| #include "SkTemplates.h" |
| |
| class JpegDecoderMgr; |
| |
| /* |
| * |
| * This class implements the decoding for jpeg images |
| * |
| */ |
| class SkJpegCodec : public SkCodec { |
| public: |
| static bool IsJpeg(const void*, size_t); |
| |
| /* |
| * Assumes IsJpeg was called and returned true |
| * Creates a jpeg decoder |
| * Takes ownership of the stream |
| */ |
| static SkCodec* NewFromStream(SkStream*); |
| |
| protected: |
| |
| /* |
| * Recommend a set of destination dimensions given a requested scale |
| */ |
| SkISize onGetScaledDimensions(float desiredScale) const override; |
| |
| /* |
| * Initiates the jpeg decode |
| */ |
| Result onGetPixels(const SkImageInfo& dstInfo, void* dst, size_t dstRowBytes, const Options&, |
| SkPMColor*, int*, int*) override; |
| |
| bool onQueryYUV8(YUVSizeInfo* sizeInfo, SkYUVColorSpace* colorSpace) const override; |
| |
| Result onGetYUV8Planes(const YUVSizeInfo& sizeInfo, void* pixels[3]) override; |
| |
| SkEncodedFormat onGetEncodedFormat() const override { |
| return kJPEG_SkEncodedFormat; |
| } |
| |
| bool onRewind() override; |
| |
| bool onDimensionsSupported(const SkISize&) override; |
| |
| private: |
| |
| /* |
| * Read enough of the stream to initialize the SkJpegCodec. |
| * Returns a bool representing success or failure. |
| * |
| * @param codecOut |
| * If this returns true, and codecOut was not nullptr, |
| * codecOut will be set to a new SkJpegCodec. |
| * |
| * @param decoderMgrOut |
| * If this returns true, and codecOut was nullptr, |
| * decoderMgrOut must be non-nullptr and decoderMgrOut will be set to a new |
| * JpegDecoderMgr pointer. |
| * |
| * @param stream |
| * Deleted on failure. |
| * codecOut will take ownership of it in the case where we created a codec. |
| * Ownership is unchanged when we set decoderMgrOut. |
| * |
| */ |
| static bool ReadHeader(SkStream* stream, SkCodec** codecOut, |
| JpegDecoderMgr** decoderMgrOut); |
| |
| /* |
| * Creates an instance of the decoder |
| * Called only by NewFromStream |
| * |
| * @param srcInfo contains the source width and height |
| * @param stream the encoded image data |
| * @param decoderMgr holds decompress struct, src manager, and error manager |
| * takes ownership |
| */ |
| SkJpegCodec(const SkImageInfo& srcInfo, SkStream* stream, JpegDecoderMgr* decoderMgr); |
| |
| /* |
| * Checks if the conversion between the input image and the requested output |
| * image has been implemented |
| * Sets the output color space |
| */ |
| bool setOutputColorSpace(const SkImageInfo& dst); |
| |
| // scanline decoding |
| void initializeSwizzler(const SkImageInfo& dstInfo, const Options& options); |
| SkSampler* getSampler(bool createIfNecessary) override; |
| Result onStartScanlineDecode(const SkImageInfo& dstInfo, const Options& options, |
| SkPMColor ctable[], int* ctableCount) override; |
| int onGetScanlines(void* dst, int count, size_t rowBytes) override; |
| bool onSkipScanlines(int count) override; |
| |
| SkAutoTDelete<JpegDecoderMgr> fDecoderMgr; |
| // We will save the state of the decompress struct after reading the header. |
| // This allows us to safely call onGetScaledDimensions() at any time. |
| const int fReadyState; |
| |
| // scanline decoding |
| SkAutoTMalloc<uint8_t> fStorage; // Only used if sampling is needed |
| uint8_t* fSrcRow; // Only used if sampling is needed |
| // libjpeg-turbo provides some subsetting. In the case that libjpeg-turbo |
| // cannot take the exact the subset that we need, we will use the swizzler |
| // to further subset the output from libjpeg-turbo. |
| SkIRect fSwizzlerSubset; |
| SkAutoTDelete<SkSwizzler> fSwizzler; |
| |
| typedef SkCodec INHERITED; |
| }; |
| |
| #endif |