#include <SkJpegCodec.h>

Inheritance diagram for SkJpegCodec:

Public Member Functions
	~SkJpegCodec () override

Public Member Functions inherited from SkCodec
virtual	~SkCodec ()

SkImageInfo	getInfo () const

SkISize	dimensions () const

SkIRect	bounds () const

const skcms_ICCProfile *	getICCProfile () const

SkEncodedOrigin	getOrigin () const

SkISize	getScaledDimensions (float desiredScale) const

bool	getValidSubset (SkIRect *desiredSubset) const

SkEncodedImageFormat	getEncodedFormat () const

virtual std::unique_ptr< SkStream >	getEncodedData () const

Result	getPixels (const SkImageInfo &info, void pixels, size_t rowBytes, const Options )

Result	getPixels (const SkImageInfo &info, void *pixels, size_t rowBytes)

Result	getPixels (const SkPixmap &pm, const Options *opts=nullptr)

std::tuple< sk_sp< SkImage >, SkCodec::Result >	getImage (const SkImageInfo &info, const Options *opts=nullptr)

std::tuple< sk_sp< SkImage >, SkCodec::Result >	getImage ()

bool	queryYUVAInfo (const SkYUVAPixmapInfo::SupportedDataTypes &supportedDataTypes, SkYUVAPixmapInfo *yuvaPixmapInfo) const

Result	getYUVAPlanes (const SkYUVAPixmaps &yuvaPixmaps)

Result	startIncrementalDecode (const SkImageInfo &dstInfo, void dst, size_t rowBytes, const Options )

Result	startIncrementalDecode (const SkImageInfo &dstInfo, void *dst, size_t rowBytes)

Result	incrementalDecode (int *rowsDecoded=nullptr)

Result	startScanlineDecode (const SkImageInfo &dstInfo, const Options *options)

Result	startScanlineDecode (const SkImageInfo &dstInfo)

int	getScanlines (void *dst, int countLines, size_t rowBytes)

bool	skipScanlines (int countLines)

SkScanlineOrder	getScanlineOrder () const

int	nextScanline () const

int	outputScanline (int inputScanline) const

int	getFrameCount ()

bool	getFrameInfo (int index, FrameInfo *info) const

std::vector< FrameInfo >	getFrameInfo ()

int	getRepetitionCount ()

Static Public Member Functions
static bool	IsJpeg (const void *, size_t)

static std::unique_ptr< SkCodec >	MakeFromStream (std::unique_ptr< SkStream >, Result *)

Static Public Member Functions inherited from SkCodec
static constexpr size_t	MinBufferedBytesNeeded ()

static const char *	ResultToString (Result)

static std::unique_ptr< SkCodec >	MakeFromStream (std::unique_ptr< SkStream >, SkSpan< const SkCodecs::Decoder > decoders, Result =nullptr, SkPngChunkReader =nullptr, SelectionPolicy selectionPolicy=SelectionPolicy::kPreferStillImage)

static std::unique_ptr< SkCodec >	MakeFromStream (std::unique_ptr< SkStream >, Result =nullptr, SkPngChunkReader =nullptr, SelectionPolicy selectionPolicy=SelectionPolicy::kPreferStillImage)

static std::unique_ptr< SkCodec >	MakeFromData (sk_sp< SkData >, SkSpan< const SkCodecs::Decoder > decoders, SkPngChunkReader *=nullptr)

static std::unique_ptr< SkCodec >	MakeFromData (sk_sp< SkData >, SkPngChunkReader *=nullptr)

static void	Register (bool(peek)(const void , size_t), std::unique_ptr< SkCodec >(make)(std::unique_ptr< SkStream >, SkCodec::Result ))

Protected Member Functions
SkISize	onGetScaledDimensions (float desiredScale) const override

Result	onGetPixels (const SkImageInfo &dstInfo, void dst, size_t dstRowBytes, const Options &, int ) override

bool	onQueryYUVAInfo (const SkYUVAPixmapInfo::SupportedDataTypes &, SkYUVAPixmapInfo *) const override

Result	onGetYUVAPlanes (const SkYUVAPixmaps &yuvaPixmaps) override

SkEncodedImageFormat	onGetEncodedFormat () const override

bool	onRewind () override

bool	onDimensionsSupported (const SkISize &) override

bool	conversionSupported (const SkImageInfo &, bool, bool) override

bool	onGetGainmapInfo (SkGainmapInfo info, std::unique_ptr< SkStream > gainmapImageStream) override

Protected Member Functions inherited from SkCodec
const SkEncodedInfo &	getEncodedInfo () const

	SkCodec (SkEncodedInfo &&, XformFormat srcFormat, std::unique_ptr< SkStream >, SkEncodedOrigin=kTopLeft_SkEncodedOrigin)

void	setSrcXformFormat (XformFormat pixelFormat)

XformFormat	getSrcXformFormat () const

virtual bool	onGetValidSubset (SkIRect *) const

bool	rewindIfNeeded ()

SkStream *	stream ()

virtual SkScanlineOrder	onGetScanlineOrder () const

const SkImageInfo &	dstInfo () const

const Options &	options () const

int	currScanline () const

virtual int	onOutputScanline (int inputScanline) const

virtual bool	usesColorXform () const

void	applyColorXform (void dst, const void src, int count) const

bool	colorXform () const

bool	xformOnDecode () const

virtual int	onGetFrameCount ()

virtual bool	onGetFrameInfo (int, FrameInfo *) const

virtual int	onGetRepetitionCount ()

Private Member Functions
SkSampler *	getSampler (bool createIfNecessary) override

Result	onStartScanlineDecode (const SkImageInfo &dstInfo, const Options &options) override

int	onGetScanlines (void *dst, int count, size_t rowBytes) override

bool	onSkipScanlines (int count) override

Friends
class	SkRawCodec

Additional Inherited Members
Public Types inherited from SkCodec
enum	Result { kSuccess , kIncompleteInput , kErrorInInput , kInvalidConversion , kInvalidScale , kInvalidParameters , kInvalidInput , kCouldNotRewind , kInternalError , kUnimplemented }

enum class	SelectionPolicy { kPreferStillImage , kPreferAnimation }

enum	ZeroInitialized { kYes_ZeroInitialized , kNo_ZeroInitialized }

enum	SkScanlineOrder { kTopDown_SkScanlineOrder , kBottomUp_SkScanlineOrder }

Static Public Attributes inherited from SkCodec
static constexpr int	kNoFrame = -1

static constexpr int	kRepetitionCountInfinite = -1

Protected Types inherited from SkCodec
using	XformFormat = skcms_PixelFormat

Detailed Description

Definition at line 37 of file SkJpegCodec.h.

Constructor & Destructor Documentation

◆ ~SkJpegCodec()

SkJpegCodec::~SkJpegCodec ( )

overridedefault

Member Function Documentation

◆ conversionSupported()

bool SkJpegCodec::conversionSupported	(	const SkImageInfo &	dst,
		bool	srcIsOpaque,
		bool	needsColorXform
	)

overrideprotectedvirtual

Return whether we can convert to dst.

Will be called for the appropriate frame, prior to initializing the colorXform.

Reimplemented from SkCodec.

Definition at line 458 of file SkJpegCodec.cpp.

                                                            {
    SkASSERT(srcIsOpaque);
 
    if (kUnknown_SkAlphaType == dstInfo.alphaType()) {
        return false;
    }
 
    if (kOpaque_SkAlphaType != dstInfo.alphaType()) {
        SkCodecPrintf("Warning: an opaque image should be decoded as opaque "
                      "- it is being decoded as non-opaque, which will draw slower\n");
    }
 
    J_COLOR_SPACE encodedColorType = fDecoderMgr->dinfo()->jpeg_color_space;
 
    // Check for valid color types and set the output color space
    switch (dstInfo.colorType()) {
        case kRGBA_8888_SkColorType:
            fDecoderMgr->dinfo()->out_color_space = JCS_EXT_RGBA;
            break;
        case kBGRA_8888_SkColorType:
            if (needsColorXform) {
                // Always using RGBA as the input format for color xforms makes the
                // implementation a little simpler.
                fDecoderMgr->dinfo()->out_color_space = JCS_EXT_RGBA;
            } else {
                fDecoderMgr->dinfo()->out_color_space = JCS_EXT_BGRA;
            }
            break;
        case kRGB_565_SkColorType:
            if (needsColorXform) {
                fDecoderMgr->dinfo()->out_color_space = JCS_EXT_RGBA;
            } else {
                fDecoderMgr->dinfo()->dither_mode = JDITHER_NONE;
                fDecoderMgr->dinfo()->out_color_space = JCS_RGB565;
            }
            break;
        case kGray_8_SkColorType:
            if (JCS_GRAYSCALE != encodedColorType) {
                return false;
            }
 
            if (needsColorXform) {
                fDecoderMgr->dinfo()->out_color_space = JCS_EXT_RGBA;
            } else {
                fDecoderMgr->dinfo()->out_color_space = JCS_GRAYSCALE;
            }
            break;
        case kBGRA_10101010_XR_SkColorType:
        case kBGR_101010x_XR_SkColorType:
        case kRGBA_F16_SkColorType:
            SkASSERT(needsColorXform);
            fDecoderMgr->dinfo()->out_color_space = JCS_EXT_RGBA;
            break;
        default:
            return false;
    }
 
    // Check if we will decode to CMYK.  libjpeg-turbo does not convert CMYK to RGBA, so
    // we must do it ourselves.
    if (JCS_CMYK == encodedColorType || JCS_YCCK == encodedColorType) {
        fDecoderMgr->dinfo()->out_color_space = JCS_CMYK;
    }
 
    return true;
}

◆ getSampler()

SkSampler * SkJpegCodec::getSampler ( bool )

overrideprivatevirtual

Return an object which will allow forcing scanline decodes to sample in X.

May create a sampler, if one is not currently being used. Otherwise, does not affect ownership.

Only valid during scanline decoding or incremental decoding.

Reimplemented from SkCodec.

Definition at line 766 of file SkJpegCodec.cpp.

                                                         {
    if (!createIfNecessary || fSwizzler) {
        SkASSERT(!fSwizzler || (fSwizzleSrcRow && fStorage.get() == fSwizzleSrcRow));
        return fSwizzler.get();
    }
 
    bool needsCMYKToRGB = needs_swizzler_to_convert_from_cmyk(
            fDecoderMgr->dinfo()->out_color_space, this->getEncodedInfo().profile(),
            this->colorXform());
    this->initializeSwizzler(this->dstInfo(), this->options(), needsCMYKToRGB);
    if (!this->allocateStorage(this->dstInfo())) {
        return nullptr;
    }
    return fSwizzler.get();
}

◆ IsJpeg()

bool SkJpegCodec::IsJpeg	(	const void *	buffer,
		size_t	bytesRead
	)

static

Definition at line 61 of file SkJpegCodec.cpp.

                                                             {
    return bytesRead >= sizeof(kJpegSig) && !memcmp(buffer, kJpegSig, sizeof(kJpegSig));
}

◆ MakeFromStream()

std::unique_ptr< SkCodec > SkJpegCodec::MakeFromStream	(	std::unique_ptr< SkStream >	stream,
		Result *	result
	)

static

Definition at line 349 of file SkJpegCodec.cpp.

                                                                     {
    return SkJpegCodec::MakeFromStream(std::move(stream), result, nullptr);
}

◆ onDimensionsSupported()

bool SkJpegCodec::onDimensionsSupported ( const SkISize & )

overrideprotectedvirtual

Subclasses should override if they support dimensions other than the srcInfo's.

Reimplemented from SkCodec.

Definition at line 529 of file SkJpegCodec.cpp.

                                                           {
    skjpeg_error_mgr::AutoPushJmpBuf jmp(fDecoderMgr->errorMgr());
    if (setjmp(jmp)) {
        return fDecoderMgr->returnFalse("onDimensionsSupported");
    }
 
    const unsigned int dstWidth = size.width();
    const unsigned int dstHeight = size.height();
 
    // Set up a fake decompress struct in order to use libjpeg to calculate output dimensions
    // FIXME: Why is this necessary?
    jpeg_decompress_struct dinfo;
    sk_bzero(&dinfo, sizeof(dinfo));
    dinfo.image_width = this->dimensions().width();
    dinfo.image_height = this->dimensions().height();
    dinfo.global_state = fReadyState;
 
    // libjpeg-turbo can scale to 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, and 1/1
    unsigned int num = 8;
    const unsigned int denom = 8;
    calc_output_dimensions(&dinfo, num, denom);
    while (dinfo.output_width != dstWidth || dinfo.output_height != dstHeight) {
 
        // Return a failure if we have tried all of the possible scales
        if (1 == num || dstWidth > dinfo.output_width || dstHeight > dinfo.output_height) {
            return false;
        }
 
        // Try the next scale
        num -= 1;
        calc_output_dimensions(&dinfo, num, denom);
    }
 
    fDecoderMgr->dinfo()->scale_num = num;
    fDecoderMgr->dinfo()->scale_denom = denom;
    return true;
}

◆ onGetEncodedFormat()

SkEncodedImageFormat SkJpegCodec::onGetEncodedFormat ( ) const

inlineoverrideprotectedvirtual

Implements SkCodec.

Definition at line 67 of file SkJpegCodec.h.

                                                             {
        return SkEncodedImageFormat::kJPEG;
    }

◆ onGetGainmapInfo()

bool SkJpegCodec::onGetGainmapInfo	(	SkGainmapInfo *	info,
		std::unique_ptr< SkStream > *	gainmapImageStream
	)

overrideprotectedvirtual

Reimplemented from SkCodec.

Definition at line 1312 of file SkJpegCodec.cpp.

                                                                                {
    return false;
}

◆ onGetPixels()

SkCodec::Result SkJpegCodec::onGetPixels	(	const SkImageInfo &	info,
		void *	pixels,
		size_t	rowBytes,
		const Options &	,
		int *	rowsDecoded
	)

overrideprotectedvirtual

Parameters

rowsDecoded When the encoded image stream is incomplete, this function will return kIncompleteInput and rowsDecoded will be set to the number of scanlines that were successfully decoded. This will allow getPixels() to fill the uninitialized memory.

Implements SkCodec.

Definition at line 647 of file SkJpegCodec.cpp.

                                                           {
    if (options.fSubset) {
        // Subsets are not supported.
        return kUnimplemented;
    }
 
    // Get a pointer to the decompress info since we will use it quite frequently
    jpeg_decompress_struct* dinfo = fDecoderMgr->dinfo();
 
    // Set the jump location for libjpeg errors
    skjpeg_error_mgr::AutoPushJmpBuf jmp(fDecoderMgr->errorMgr());
    if (setjmp(jmp)) {
        return fDecoderMgr->returnFailure("setjmp", kInvalidInput);
    }
 
    if (!jpeg_start_decompress(dinfo)) {
        return fDecoderMgr->returnFailure("startDecompress", kInvalidInput);
    }
 
    // The recommended output buffer height should always be 1 in high quality modes.
    // If it's not, we want to know because it means our strategy is not optimal.
    SkASSERT(1 == dinfo->rec_outbuf_height);
 
    if (needs_swizzler_to_convert_from_cmyk(dinfo->out_color_space,
                                            this->getEncodedInfo().profile(), this->colorXform())) {
        this->initializeSwizzler(dstInfo, options, true);
    }
 
    if (!this->allocateStorage(dstInfo)) {
        return kInternalError;
    }
 
    int rows = this->readRows(dstInfo, dst, dstRowBytes, dstInfo.height(), options);
    if (rows < dstInfo.height()) {
        *rowsDecoded = rows;
        return fDecoderMgr->returnFailure("Incomplete image data", kIncompleteInput);
    }
 
    return kSuccess;
}

◆ onGetScaledDimensions()

SkISize SkJpegCodec::onGetScaledDimensions ( float desiredScale ) const

overrideprotectedvirtual

Reimplemented from SkCodec.

Definition at line 407 of file SkJpegCodec.cpp.

                                                                   {
    // libjpeg-turbo supports scaling by 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7/8, and 1/1, so we will
    // support these as well
    unsigned int num;
    unsigned int denom = 8;
    if (desiredScale >= 0.9375) {
        num = 8;
    } else if (desiredScale >= 0.8125) {
        num = 7;
    } else if (desiredScale >= 0.6875f) {
        num = 6;
    } else if (desiredScale >= 0.5625f) {
        num = 5;
    } else if (desiredScale >= 0.4375f) {
        num = 4;
    } else if (desiredScale >= 0.3125f) {
        num = 3;
    } else if (desiredScale >= 0.1875f) {
        num = 2;
    } else {
        num = 1;
    }
 
    // Set up a fake decompress struct in order to use libjpeg to calculate output dimensions
    jpeg_decompress_struct dinfo;
    sk_bzero(&dinfo, sizeof(dinfo));
    dinfo.image_width = this->dimensions().width();
    dinfo.image_height = this->dimensions().height();
    dinfo.global_state = fReadyState;
    calc_output_dimensions(&dinfo, num, denom);
 
    // Return the calculated output dimensions for the given scale
    return SkISize::Make(dinfo.output_width, dinfo.output_height);
}

◆ onGetScanlines()

int SkJpegCodec::onGetScanlines	(	void *	dst,
		int	count,
		size_t	rowBytes
	)

overrideprivatevirtual

Reimplemented from SkCodec.

Definition at line 848 of file SkJpegCodec.cpp.

                                                                        {
    int rows = this->readRows(this->dstInfo(), dst, dstRowBytes, count, this->options());
    if (rows < count) {
        // This allows us to skip calling jpeg_finish_decompress().
        fDecoderMgr->dinfo()->output_scanline = this->dstInfo().height();
    }
 
    return rows;
}

◆ onGetYUVAPlanes()

SkCodec::Result SkJpegCodec::onGetYUVAPlanes ( const SkYUVAPixmaps & yuvaPixmaps )

overrideprotectedvirtual

Reimplemented from SkCodec.

Definition at line 967 of file SkJpegCodec.cpp.

                                                                           {
    // Get a pointer to the decompress info since we will use it quite frequently
    jpeg_decompress_struct* dinfo = fDecoderMgr->dinfo();
    if (!is_yuv_supported(dinfo, *this, nullptr, nullptr)) {
        return fDecoderMgr->returnFailure("onGetYUVAPlanes", kInvalidInput);
    }
    // Set the jump location for libjpeg errors
    skjpeg_error_mgr::AutoPushJmpBuf jmp(fDecoderMgr->errorMgr());
    if (setjmp(jmp)) {
        return fDecoderMgr->returnFailure("setjmp", kInvalidInput);
    }
 
    dinfo->raw_data_out = TRUE;
    if (!jpeg_start_decompress(dinfo)) {
        return fDecoderMgr->returnFailure("startDecompress", kInvalidInput);
    }
 
    const std::array<SkPixmap, SkYUVAPixmaps::kMaxPlanes>& planes = yuvaPixmaps.planes();
 
#ifdef SK_DEBUG
    {
        // A previous implementation claims that the return value of is_yuv_supported()
        // may change after calling jpeg_start_decompress().  It looks to me like this
        // was caused by a bug in the old code, but we'll be safe and check here.
        // Also check that pixmap properties agree with expectations.
        SkYUVAPixmapInfo info;
        SkASSERT(is_yuv_supported(dinfo, *this, nullptr, &info));
        SkASSERT(info.yuvaInfo() == yuvaPixmaps.yuvaInfo());
        for (int i = 0; i < info.numPlanes(); ++i) {
            SkASSERT(planes[i].colorType() == kAlpha_8_SkColorType);
            SkASSERT(info.planeInfo(i) == planes[i].info());
        }
    }
#endif
 
    // Build a JSAMPIMAGE to handle output from libjpeg-turbo.  A JSAMPIMAGE has
    // a 2-D array of pixels for each of the components (Y, U, V) in the image.
    // Cheat Sheet:
    //     JSAMPIMAGE == JSAMPLEARRAY* == JSAMPROW** == JSAMPLE***
    JSAMPARRAY yuv[3];
 
    // Set aside enough space for pointers to rows of Y, U, and V.
    JSAMPROW rowptrs[2 * DCTSIZE + DCTSIZE + DCTSIZE];
    yuv[0] = &rowptrs[0];            // Y rows (DCTSIZE or 2 * DCTSIZE)
    yuv[1] = &rowptrs[2 * DCTSIZE];  // U rows (DCTSIZE)
    yuv[2] = &rowptrs[3 * DCTSIZE];  // V rows (DCTSIZE)
 
    // Initialize rowptrs.
    int numYRowsPerBlock = DCTSIZE * dinfo->comp_info[0].v_samp_factor;
    static_assert(sizeof(JSAMPLE) == 1);
    for (int i = 0; i < numYRowsPerBlock; i++) {
        rowptrs[i] = static_cast<JSAMPLE*>(planes[0].writable_addr()) + i* planes[0].rowBytes();
    }
    for (int i = 0; i < DCTSIZE; i++) {
        rowptrs[i + 2 * DCTSIZE] =
                static_cast<JSAMPLE*>(planes[1].writable_addr()) + i* planes[1].rowBytes();
        rowptrs[i + 3 * DCTSIZE] =
                static_cast<JSAMPLE*>(planes[2].writable_addr()) + i* planes[2].rowBytes();
    }
 
    // After each loop iteration, we will increment pointers to Y, U, and V.
    size_t blockIncrementY = numYRowsPerBlock * planes[0].rowBytes();
    size_t blockIncrementU = DCTSIZE * planes[1].rowBytes();
    size_t blockIncrementV = DCTSIZE * planes[2].rowBytes();
 
    uint32_t numRowsPerBlock = numYRowsPerBlock;
 
    // We intentionally round down here, as this first loop will only handle
    // full block rows.  As a special case at the end, we will handle any
    // remaining rows that do not make up a full block.
    const int numIters = dinfo->output_height / numRowsPerBlock;
    for (int i = 0; i < numIters; i++) {
        JDIMENSION linesRead = jpeg_read_raw_data(dinfo, yuv, numRowsPerBlock);
        if (linesRead < numRowsPerBlock) {
            // FIXME: Handle incomplete YUV decodes without signalling an error.
            return kInvalidInput;
        }
 
        // Update rowptrs.
        for (int j = 0; j < numYRowsPerBlock; j++) {
            rowptrs[j] += blockIncrementY;
        }
        for (int j = 0; j < DCTSIZE; j++) {
            rowptrs[j + 2 * DCTSIZE] += blockIncrementU;
            rowptrs[j + 3 * DCTSIZE] += blockIncrementV;
        }
    }
 
    uint32_t remainingRows = dinfo->output_height - dinfo->output_scanline;
    SkASSERT(remainingRows == dinfo->output_height % numRowsPerBlock);
    SkASSERT(dinfo->output_scanline == numIters * numRowsPerBlock);
    if (remainingRows > 0) {
        // libjpeg-turbo needs memory to be padded by the block sizes.  We will fulfill
        // this requirement using an extra row buffer.
        // FIXME: Should SkCodec have an extra memory buffer that can be shared among
        //        all of the implementations that use temporary/garbage memory?
        AutoTMalloc<JSAMPLE> extraRow(planes[0].rowBytes());
        for (int i = remainingRows; i < numYRowsPerBlock; i++) {
            rowptrs[i] = extraRow.get();
        }
        int remainingUVRows = dinfo->comp_info[1].downsampled_height - DCTSIZE * numIters;
        for (int i = remainingUVRows; i < DCTSIZE; i++) {
            rowptrs[i + 2 * DCTSIZE] = extraRow.get();
            rowptrs[i + 3 * DCTSIZE] = extraRow.get();
        }
 
        JDIMENSION linesRead = jpeg_read_raw_data(dinfo, yuv, numRowsPerBlock);
        if (linesRead < remainingRows) {
            // FIXME: Handle incomplete YUV decodes without signalling an error.
            return kInvalidInput;
        }
    }
 
    return kSuccess;
}

◆ onQueryYUVAInfo()

bool SkJpegCodec::onQueryYUVAInfo	(	const SkYUVAPixmapInfo::SupportedDataTypes &	supportedDataTypes,
		SkYUVAPixmapInfo *	yuvaPixmapInfo
	)		const

overrideprotectedvirtual

Reimplemented from SkCodec.

Definition at line 961 of file SkJpegCodec.cpp.

                                                                          {
    jpeg_decompress_struct* dinfo = fDecoderMgr->dinfo();
    return is_yuv_supported(dinfo, *this, &supportedDataTypes, yuvaPixmapInfo);
}

◆ onRewind()

bool SkJpegCodec::onRewind ( )

overrideprotectedvirtual

Called by rewindIfNeeded, if the stream needed to be rewound.

Subclasses should do any set up needed after a rewind.

Reimplemented from SkCodec.

Definition at line 442 of file SkJpegCodec.cpp.

                           {
    JpegDecoderMgr* decoderMgr = nullptr;
    if (kSuccess != ReadHeader(this->stream(), nullptr, &decoderMgr, nullptr)) {
        return fDecoderMgr->returnFalse("onRewind");
    }
    SkASSERT(nullptr != decoderMgr);
    fDecoderMgr.reset(decoderMgr);
 
    fSwizzler.reset(nullptr);
    fSwizzleSrcRow = nullptr;
    fColorXformSrcRow = nullptr;
    fStorage.reset();
 
    return true;
}

◆ onSkipScanlines()

bool SkJpegCodec::onSkipScanlines ( int count )

overrideprivatevirtual

Reimplemented from SkCodec.

Definition at line 858 of file SkJpegCodec.cpp.

                                           {
    // Set the jump location for libjpeg errors
    skjpeg_error_mgr::AutoPushJmpBuf jmp(fDecoderMgr->errorMgr());
    if (setjmp(jmp)) {
        return fDecoderMgr->returnFalse("onSkipScanlines");
    }
 
    return (uint32_t) count == jpeg_skip_scanlines(fDecoderMgr->dinfo(), count);
}

◆ onStartScanlineDecode()

SkCodec::Result SkJpegCodec::onStartScanlineDecode	(	const SkImageInfo &	dstInfo,
		const Options &	options
	)

overrideprivatevirtual

Reimplemented from SkCodec.

Definition at line 782 of file SkJpegCodec.cpp.

                                {
    // Set the jump location for libjpeg errors
    skjpeg_error_mgr::AutoPushJmpBuf jmp(fDecoderMgr->errorMgr());
    if (setjmp(jmp)) {
        SkCodecPrintf("setjmp: Error from libjpeg\n");
        return kInvalidInput;
    }
 
    if (!jpeg_start_decompress(fDecoderMgr->dinfo())) {
        SkCodecPrintf("start decompress failed\n");
        return kInvalidInput;
    }
 
    bool needsCMYKToRGB = needs_swizzler_to_convert_from_cmyk(
            fDecoderMgr->dinfo()->out_color_space, this->getEncodedInfo().profile(),
            this->colorXform());
    if (options.fSubset) {
        uint32_t startX = options.fSubset->x();
        uint32_t width = options.fSubset->width();
 
        // libjpeg-turbo may need to align startX to a multiple of the IDCT
        // block size.  If this is the case, it will decrease the value of
        // startX to the appropriate alignment and also increase the value
        // of width so that the right edge of the requested subset remains
        // the same.
        jpeg_crop_scanline(fDecoderMgr->dinfo(), &startX, &width);
 
        SkASSERT(startX <= (uint32_t) options.fSubset->x());
        SkASSERT(width >= (uint32_t) options.fSubset->width());
        SkASSERT(startX + width >= (uint32_t) options.fSubset->right());
 
        // Instruct the swizzler (if it is necessary) to further subset the
        // output provided by libjpeg-turbo.
        //
        // We set this here (rather than in the if statement below), so that
        // if (1) we don't need a swizzler for the subset, and (2) we need a
        // swizzler for CMYK, the swizzler will still use the proper subset
        // dimensions.
        //
        // Note that the swizzler will ignore the y and height parameters of
        // the subset.  Since the scanline decoder (and the swizzler) handle
        // one row at a time, only the subsetting in the x-dimension matters.
        fSwizzlerSubset.setXYWH(options.fSubset->x() - startX, 0,
                options.fSubset->width(), options.fSubset->height());
 
        // We will need a swizzler if libjpeg-turbo cannot provide the exact
        // subset that we request.
        if (startX != (uint32_t) options.fSubset->x() ||
                width != (uint32_t) options.fSubset->width()) {
            this->initializeSwizzler(dstInfo, options, needsCMYKToRGB);
        }
    }
 
    // Make sure we have a swizzler if we are converting from CMYK.
    if (!fSwizzler && needsCMYKToRGB) {
        this->initializeSwizzler(dstInfo, options, true);
    }
 
    if (!this->allocateStorage(dstInfo)) {
        return kInternalError;
    }
 
    return kSuccess;
}

Friends And Related Symbol Documentation

◆ SkRawCodec

friend class SkRawCodec

friend

Definition at line 161 of file SkJpegCodec.h.

The documentation for this class was generated from the following files:

third_party/skia/src/codec/SkJpegCodec.h
third_party/skia/src/codec/SkJpegCodec.cpp

Public Member Functions

Static Public Member Functions

Protected Member Functions

Private Member Functions

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ ~SkJpegCodec()

Member Function Documentation

◆ conversionSupported()

◆ getSampler()

◆ IsJpeg()

◆ MakeFromStream()

◆ onDimensionsSupported()

◆ onGetEncodedFormat()

◆ onGetGainmapInfo()

◆ onGetPixels()

◆ onGetScaledDimensions()

◆ onGetScanlines()

◆ onGetYUVAPlanes()

◆ onQueryYUVAInfo()

◆ onRewind()

◆ onSkipScanlines()

◆ onStartScanlineDecode()

Friends And Related Symbol Documentation

◆ SkRawCodec