SkJpegMetadataDecoderImpl Class Reference

#include <SkJpegMetadataDecoderImpl.h>

Inheritance diagram for SkJpegMetadataDecoderImpl:

Public Member Functions
	SkJpegMetadataDecoderImpl (SkJpegMarkerList markerList)
	SkJpegMetadataDecoderImpl (sk_sp< SkData > data)
bool	findGainmapImage (SkJpegSourceMgr *sourceMgr, sk_sp< SkData > &outGainmapImageData, SkGainmapInfo &outGainmapInfo) const
sk_sp< SkData >	getExifMetadata (bool copyData) const override
sk_sp< SkData >	getICCProfileData (bool copyData) const override
sk_sp< SkData >	getISOGainmapMetadata (bool copyData) const override
bool	mightHaveGainmapImage () const override
bool	findGainmapImage (sk_sp< SkData > baseImageData, sk_sp< SkData > &outGainmapImageData, SkGainmapInfo &outGainmapInfo) override
Public Member Functions inherited from SkJpegMetadataDecoder
	SkJpegMetadataDecoder ()
virtual	~SkJpegMetadataDecoder ()
	SkJpegMetadataDecoder (const SkJpegMetadataDecoder &)=delete
SkJpegMetadataDecoder &	operator= (const SkJpegMetadataDecoder &)=delete
virtual sk_sp< SkData >	getExifMetadata (bool copyData) const =0
virtual sk_sp< SkData >	getICCProfileData (bool copyData) const =0
virtual sk_sp< SkData >	getISOGainmapMetadata (bool copyData) const =0
virtual bool	mightHaveGainmapImage () const =0
virtual bool	findGainmapImage (sk_sp< SkData > baseImageData, sk_sp< SkData > &outGainmapImagedata, SkGainmapInfo &outGainmapInfo)=0

Additional Inherited Members
Static Public Member Functions inherited from SkJpegMetadataDecoder
static std::unique_ptr< SkJpegMetadataDecoder >	Make (std::vector< Segment > headerSegments)

Detailed Description

Definition at line 27 of file SkJpegMetadataDecoderImpl.h.

Constructor & Destructor Documentation

SkJpegMetadataDecoderImpl() [1/2]

SkJpegMetadataDecoderImpl::SkJpegMetadataDecoderImpl

(

SkJpegMarkerList

markerList

)

Definition at line 413 of file SkJpegMetadataDecoderImpl.cpp.

        : fMarkerList(std::move(markerList)) {}

SkJpegMetadataDecoderImpl() [2/2]

SkJpegMetadataDecoderImpl::SkJpegMetadataDecoderImpl

(

sk_sp< SkData >

data

)

Definition at line 416 of file SkJpegMetadataDecoderImpl.cpp.

                                                                       {
#ifdef SK_CODEC_DECODES_JPEG_GAINMAPS
    SkJpegSegmentScanner scan(kJpegMarkerStartOfScan);
    scan.onBytes(data->data(), data->size());
    if (scan.hadError() || !scan.isDone()) {
        SkCodecPrintf("Failed to scan header of MP image.\n");
        return;
    }
    for (const auto& segment : scan.getSegments()) {
        // Save the APP1 and APP2 parameters (which includes Exif, XMP, ICC, and MPF).
        if (segment.marker != kJpegMarkerAPP0 + 1 && segment.marker != kJpegMarkerAPP0 + 2) {
            continue;
        }
        auto parameters = SkJpegSegmentScanner::GetParameters(data.get(), segment);
        if (!parameters) {
            continue;
        }
        fMarkerList.emplace_back(segment.marker, std::move(parameters));
    }
#endif
}

Member Function Documentation

findGainmapImage() [1/2]

bool SkJpegMetadataDecoderImpl::findGainmapImage ( sk_sp< SkData >  baseImageData, sk_sp< SkData > &  outGainmapImagedata, SkGainmapInfo &  outGainmapInfo  )

overridevirtual

Given a JPEG encoded image |baseImageData|, return in |outGainmapImageData| the JPEG encoded gainmap image and return in |outGainmapInfo| its gainmap rendering parameters. Return true if both output variables were successfully populated, otherwise return false.

Implements SkJpegMetadataDecoder.

Definition at line 477 of file SkJpegMetadataDecoderImpl.cpp.

                                                                                {
#ifdef SK_CODEC_DECODES_JPEG_GAINMAPS
    auto baseImageStream = SkMemoryStream::Make(baseImageData);
    auto sourceMgr = SkJpegSourceMgr::Make(baseImageStream.get());
    return findGainmapImage(sourceMgr.get(), outGainmapImageData, outGainmapInfo);
#else
    return false;
#endif
}

findGainmapImage() [2/2]

bool SkJpegMetadataDecoderImpl::findGainmapImage	(	SkJpegSourceMgr *	sourceMgr,
		sk_sp< SkData > &	outGainmapImageData,
		SkGainmapInfo &	outGainmapInfo
	)		const

Definition at line 170 of file SkJpegMetadataDecoderImpl.cpp.

                                                                               {
#ifdef SK_CODEC_DECODES_JPEG_GAINMAPS
    SkExif::Metadata baseExif;
    SkExif::Parse(baseExif, getExifMetadata(/*copyData=*/false).get());
    auto xmp = getXmpMetadata();
 
    // Determine if a support ISO 21496-1 gain map version is present in the base image.
    bool isoGainmapPresent =
            SkGainmapInfo::ParseVersion(getISOGainmapMetadata(/*copyData=*/false).get());
 
    // Determine if Adobe HDR gain map is indicated in the base image.
    bool adobeGainmapPresent = xmp && xmp->getGainmapInfoAdobe(nullptr);
 
    // Attempt to locate the gainmap from the container XMP.
    size_t containerGainmapOffset = 0;
    size_t containerGainmapSize = 0;
    if (xmp && xmp->getContainerGainmapLocation(&containerGainmapOffset, &containerGainmapSize)) {
        const auto& segments = sourceMgr->getAllSegments();
        if (!segments.empty()) {
            const auto& lastSegment = segments.back();
            if (lastSegment.marker == kJpegMarkerEndOfImage) {
                containerGainmapOffset += lastSegment.offset + kJpegMarkerCodeSize;
            }
        }
    }
 
    // Attempt to find MultiPicture parameters.
    SkJpegSegment mpParamsSegment;
    auto mpParams = find_mp_params(fMarkerList, sourceMgr, &mpParamsSegment);
 
    // First, search through the Multi-Picture images.
    if (mpParams) {
        for (size_t mpImageIndex = 1; mpImageIndex < mpParams->images.size(); ++mpImageIndex) {
            size_t mpImageOffset = SkJpegMultiPictureParameters::GetImageAbsoluteOffset(
                    mpParams->images[mpImageIndex].dataOffset, mpParamsSegment.offset);
            size_t mpImageSize = mpParams->images[mpImageIndex].size;
 
            if (extract_gainmap(sourceMgr,
                                mpImageOffset,
                                mpImageSize,
                                isoGainmapPresent,
                                adobeGainmapPresent,
                                baseExif.fHdrHeadroom,
                                outInfo,
                                outData)) {
                // If the GContainer also suggested an offset and size, assert that we found the
                // image that the GContainer suggested.
                if (containerGainmapOffset) {
                    SkASSERT(containerGainmapOffset == mpImageOffset);
                    SkASSERT(containerGainmapSize == mpImageSize);
                }
                return true;
            }
        }
    }
 
    // Next, try the location suggested by the container XMP.
    if (containerGainmapOffset) {
        if (extract_gainmap(sourceMgr,
                            containerGainmapOffset,
                            containerGainmapSize,
                            /*baseImageHasIsoVersion=*/false,
                            adobeGainmapPresent,
                            /*baseImageAppleHdrHeadroom=*/std::nullopt,
                            outInfo,
                            outData)) {
            return true;
        }
        SkCodecPrintf("Failed to extract container-specified gainmap.\n");
    }
#endif
    return false;
}

getExifMetadata()

sk_sp< SkData > SkJpegMetadataDecoderImpl::getExifMetadata ( bool  copyData ) const

overridevirtual

Return the Exif data attached to the image (if any) and nullptr otherwise. If |copyData| is false, then the returned SkData may directly reference the data provided when this object was created.

Implements SkJpegMetadataDecoder.

Definition at line 438 of file SkJpegMetadataDecoderImpl.cpp.

                                                                            {
    return read_metadata(fMarkerList,
                         kExifMarker,
                         kExifSig,
                         sizeof(kExifSig),
                         /*signaturePadding=*/1,
                         /*bytesInIndex=*/0,
                         copyData);
}

getICCProfileData()

sk_sp< SkData > SkJpegMetadataDecoderImpl::getICCProfileData ( bool  copyData ) const

overridevirtual

Return the ICC profile of the image if any, and nullptr otherwise. If |copyData| is false, then the returned SkData may directly reference the data provided when this object was created.

Implements SkJpegMetadataDecoder.

Definition at line 448 of file SkJpegMetadataDecoderImpl.cpp.

                                                                              {
    return read_metadata(fMarkerList,
                         kICCMarker,
                         kICCSig,
                         sizeof(kICCSig),
                         /*signaturePadding=*/0,
                         kICCMarkerIndexSize,
                         copyData);
}

getISOGainmapMetadata()

sk_sp< SkData > SkJpegMetadataDecoderImpl::getISOGainmapMetadata ( bool  copyData ) const

overridevirtual

Return the ISO 21496-1 metadata, if any, and nullptr otherwise. If |copyData| is false, then the returned SkData may directly reference the data provided when this object was created.

Implements SkJpegMetadataDecoder.

Definition at line 458 of file SkJpegMetadataDecoderImpl.cpp.

                                                                                  {
    return read_metadata(fMarkerList,
                         kISOGainmapMarker,
                         kISOGainmapSig,
                         sizeof(kISOGainmapSig),
                         /*signaturePadding=*/0,
                         /*bytesInIndex=*/0,
                         copyData);
}

mightHaveGainmapImage()

bool SkJpegMetadataDecoderImpl::mightHaveGainmapImage ( ) const

overridevirtual

Return true if there is a possibility that this image contains a gainmap image.

Implements SkJpegMetadataDecoder.

Definition at line 468 of file SkJpegMetadataDecoderImpl.cpp.

                                                            {
#ifdef SK_CODEC_DECODES_JPEG_GAINMAPS
    // All supported gainmap formats require MPF. Reject images that do not have MPF.
    return find_mp_params(fMarkerList, nullptr, nullptr) != nullptr;
#else
    return false;
#endif
}

---

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

• third_party/skia/src/codec/SkJpegMetadataDecoderImpl.h
• third_party/skia/src/codec/SkJpegMetadataDecoderImpl.cpp