C++ SkImageInfo::makeColorType方法代码示例

SkImageInfo SkImage_Lazy::buildCacheInfo(CachedFormat format) const {
    switch (format) {
        case kLegacy_CachedFormat:
            return fInfo.makeColorSpace(nullptr);
        case kLinearF16_CachedFormat:
            return fInfo.makeColorType(kRGBA_F16_SkColorType)
                        .makeColorSpace(fInfo.colorSpace()->makeLinearGamma());
        case kSRGB8888_CachedFormat:
            // If the transfer function is nearly (but not exactly) sRGB, we don't want the codec
            // to bother trans-coding. It would be slow, and do more harm than good visually,
            // so we make sure to leave the colorspace as-is.
            if (fInfo.colorSpace()->gammaCloseToSRGB()) {
                return fInfo.makeColorType(kRGBA_8888_SkColorType);
            } else {
                return fInfo.makeColorType(kRGBA_8888_SkColorType)
                            .makeColorSpace(fInfo.colorSpace()->makeSRGBGamma());
            }
        case kSBGR8888_CachedFormat:
            // See note above about not-quite-sRGB transfer functions.
            if (fInfo.colorSpace()->gammaCloseToSRGB()) {
                return fInfo.makeColorType(kBGRA_8888_SkColorType);
            } else {
                return fInfo.makeColorType(kBGRA_8888_SkColorType)
                            .makeColorSpace(fInfo.colorSpace()->makeSRGBGamma());
            }
        default:
            SkDEBUGFAIL("Invalid cached format");
            return fInfo;
    }
}

// Test Fill() with different combinations of dimensions, alignment, and padding
DEF_TEST(SwizzlerFill, r) {
    // Test on an invalid width and representative widths
    const uint32_t widths[] = { 0, 10, 50 };

    // In order to call Fill(), there must be at least one row to fill
    // Test on the smallest possible height and representative heights
    const uint32_t heights[] = { 1, 5, 10 };

    // Test on interesting possibilities for row padding
    const uint32_t paddings[] = { 0, 4 };

    // Iterate over test dimensions
    for (uint32_t width : widths) {
        for (uint32_t height : heights) {

            // Create image info objects
            const SkImageInfo colorInfo = SkImageInfo::MakeN32(width, height, kUnknown_SkAlphaType);
            const SkImageInfo grayInfo = colorInfo.makeColorType(kGray_8_SkColorType);
            const SkImageInfo indexInfo = colorInfo.makeColorType(kIndex_8_SkColorType);
            const SkImageInfo color565Info = colorInfo.makeColorType(kRGB_565_SkColorType);

            for (uint32_t padding : paddings) {

                // Calculate row bytes
                const size_t colorRowBytes = SkColorTypeBytesPerPixel(kN32_SkColorType) * width
                        + padding;
                const size_t indexRowBytes = width + padding;
                const size_t grayRowBytes = indexRowBytes;
                const size_t color565RowBytes =
                        SkColorTypeBytesPerPixel(kRGB_565_SkColorType) * width + padding;

                // If there is padding, we can invent an offset to change the memory alignment
                for (uint32_t offset = 0; offset <= padding; offset += 4) {

                    // Test all possible start rows with all possible end rows
                    for (uint32_t startRow = 0; startRow < height; startRow++) {
                        for (uint32_t endRow = startRow; endRow < height; endRow++) {

                            // Test fill with each color type
                            check_fill(r, colorInfo, startRow, endRow, colorRowBytes, offset,
                                    kFillColor);
                            check_fill(r, indexInfo, startRow, endRow, indexRowBytes, offset,
                                    kFillIndex);
                            check_fill(r, grayInfo, startRow, endRow, grayRowBytes, offset,
                                    kFillGray);
                            check_fill(r, color565Info, startRow, endRow, color565RowBytes, offset,
                                    kFill565);
                        }
                    }
                }
            }
        }
    }
}

    static std::unique_ptr<Dst> Create(Options options) {
        SkImageInfo info = SkImageInfo::MakeN32Premul(0,0);
        if (options("ct") == "565") { info = info.makeColorType(kRGB_565_SkColorType); }
        if (options("ct") == "f16") { info = info.makeColorType(kRGBA_F16_SkColorType); }

        if (options("cs") == "srgb") {
            auto cs = info.colorType() == kRGBA_F16_SkColorType ? SkColorSpace::MakeSRGBLinear()
                                                                : SkColorSpace::MakeSRGB();
            info = info.makeColorSpace(std::move(cs));
        }

        SWDst dst;
        dst.info = info;
        return move_unique(dst);
    }

static void test_bigwidth(skiatest::Reporter* reporter) {
    SkBitmap bm;
    int width = 1 << 29;    // *4 will be the high-bit of 32bit int

    SkImageInfo info = SkImageInfo::MakeA8(width, 1);
    REPORTER_ASSERT(reporter, bm.setInfo(info));
    REPORTER_ASSERT(reporter, bm.setInfo(info.makeColorType(kRGB_565_SkColorType)));

    // for a 4-byte config, this width will compute a rowbytes of 0x80000000,
    // which does not fit in a int32_t. setConfig should detect this, and fail.

    // TODO: perhaps skia can relax this, and only require that rowBytes fit
    //       in a uint32_t (or larger), but for now this is the constraint.

    REPORTER_ASSERT(reporter, !bm.setInfo(info.makeColorType(kN32_SkColorType)));
}

// Test Fill() with different combinations of dimensions, alignment, and padding
DEF_TEST(SwizzlerFill, r) {
    // Set up a color table
    SkPMColor colorTable[kFillIndex + 1];
    colorTable[kFillIndex] = kFillColor;
    // Apart from the fill index, we will leave the other colors in the color table uninitialized.
    // If we incorrectly try to fill with this uninitialized memory, the bots will catch it.

    // Test on an invalid width and representative widths
    const uint32_t widths[] = { 0, 10, 50 };

    // In order to call Fill(), there must be at least one row to fill
    // Test on the smallest possible height and representative heights
    const uint32_t heights[] = { 1, 5, 10 };

    // Test on interesting possibilities for row padding
    const uint32_t paddings[] = { 0, 1, 2, 3, 4 };

    // Iterate over test dimensions
    for (uint32_t width : widths) {
        for (uint32_t height : heights) {

            // Create image info objects
            const SkImageInfo colorInfo = SkImageInfo::MakeN32(width, height,
                kUnknown_SkAlphaType);
            const SkImageInfo indexInfo = colorInfo.makeColorType(kIndex_8_SkColorType);

            for (uint32_t padding : paddings) {

                // Calculate row bytes
                size_t colorRowBytes = SkColorTypeBytesPerPixel(kN32_SkColorType) * width +
                        padding;
                size_t indexRowBytes = width + padding;

                // If there is padding, we can invent an offset to change the memory alignment
                for (uint32_t offset = 0; offset <= padding; offset++) {

                    // Test all possible start rows with all possible end rows
                    for (uint32_t startRow = 0; startRow < height; startRow++) {
                        for (uint32_t endRow = startRow; endRow < height; endRow++) {

                            // Fill with an index that we use to look up a color
                            check_fill(r, colorInfo, startRow, endRow, colorRowBytes, offset,
                                    kFillIndex, colorTable);

                            // Fill with a color
                            check_fill(r, colorInfo, startRow, endRow, colorRowBytes, offset,
                                    kFillColor, NULL);

                            // Fill with an index
                            check_fill(r, indexInfo, startRow, endRow, indexRowBytes, offset,
                                    kFillIndex, NULL);
                        }
                    }
                }
            }
        }
    }
}

void SkHeifCodec::initializeSwizzler(
        const SkImageInfo& dstInfo, const Options& options) {
    SkImageInfo swizzlerDstInfo = dstInfo;
    if (this->colorXform()) {
        // The color xform will be expecting RGBA 8888 input.
        swizzlerDstInfo = swizzlerDstInfo.makeColorType(kRGBA_8888_SkColorType);
    }

    fSwizzler.reset(SkSwizzler::CreateSwizzler(this->getEncodedInfo(), nullptr,
            swizzlerDstInfo, options, nullptr, true));
    SkASSERT(fSwizzler);
}

bool SkPngCodec::initializeXforms(const SkImageInfo& dstInfo, const Options& options,
                                  SkPMColor ctable[], int* ctableCount) {
    if (setjmp(png_jmpbuf(fPng_ptr))) {
        SkCodecPrintf("Failed on png_read_update_info.\n");
        return false;
    }
    png_read_update_info(fPng_ptr, fInfo_ptr);

    // It's important to reset fColorXform to nullptr.  We don't do this on rewinding
    // because the interlaced scanline decoder may need to rewind.
    fColorXform = nullptr;
    SkImageInfo swizzlerInfo = dstInfo;
    bool needsColorXform = needs_color_xform(dstInfo, this->getInfo());
    if (needsColorXform) {
        switch (dstInfo.colorType()) {
            case kRGBA_8888_SkColorType:
            case kBGRA_8888_SkColorType:
            case kRGBA_F16_SkColorType:
                swizzlerInfo = swizzlerInfo.makeColorType(kRGBA_8888_SkColorType);
                if (kPremul_SkAlphaType == dstInfo.alphaType()) {
                    swizzlerInfo = swizzlerInfo.makeAlphaType(kUnpremul_SkAlphaType);
                }
                break;
            case kIndex_8_SkColorType:
                break;
            default:
                return false;
        }

        fColorXform = SkColorSpaceXform::New(sk_ref_sp(this->getInfo().colorSpace()),
                                             sk_ref_sp(dstInfo.colorSpace()));

        if (!fColorXform && kRGBA_F16_SkColorType == dstInfo.colorType()) {
            return false;
        }
    }

    if (SkEncodedInfo::kPalette_Color == this->getEncodedInfo().color()) {
        if (!this->createColorTable(dstInfo, ctableCount)) {
            return false;
        }
    }

    // Copy the color table to the client if they request kIndex8 mode
    copy_color_table(swizzlerInfo, fColorTable, ctable, ctableCount);

    // Create the swizzler.  SkPngCodec retains ownership of the color table.
    const SkPMColor* colors = get_color_ptr(fColorTable.get());
    fSwizzler.reset(SkSwizzler::CreateSwizzler(this->getEncodedInfo(), colors, swizzlerInfo,
                                               options));
    SkASSERT(fSwizzler);
    return true;
}

static void test_codec(skiatest::Reporter* r, Codec* codec, SkBitmap& bm, const SkImageInfo& info,
        const SkISize& size, SkCodec::Result expectedResult, SkMD5::Digest* digest,
        const SkMD5::Digest* goodDigest) {

    REPORTER_ASSERT(r, info.dimensions() == size);
    bm.allocPixels(info);
    SkAutoLockPixels autoLockPixels(bm);

    SkCodec::Result result = codec->getPixels(info, bm.getPixels(), bm.rowBytes());
    REPORTER_ASSERT(r, result == expectedResult);

    md5(bm, digest);
    if (goodDigest) {
        REPORTER_ASSERT(r, *digest == *goodDigest);
    }

    {
        // Test decoding to 565
        SkImageInfo info565 = info.makeColorType(kRGB_565_SkColorType);
        SkCodec::Result expected565 = info.alphaType() == kOpaque_SkAlphaType ?
                expectedResult : SkCodec::kInvalidConversion;
        test_info(r, codec, info565, expected565, nullptr);
    }

    // Verify that re-decoding gives the same result.  It is interesting to check this after
    // a decode to 565, since choosing to decode to 565 may result in some of the decode
    // options being modified.  These options should return to their defaults on another
    // decode to kN32, so the new digest should match the old digest.
    test_info(r, codec, info, expectedResult, digest);

    {
        // Check alpha type conversions
        if (info.alphaType() == kOpaque_SkAlphaType) {
            test_info(r, codec, info.makeAlphaType(kUnpremul_SkAlphaType),
                      expectedResult, digest);
            test_info(r, codec, info.makeAlphaType(kPremul_SkAlphaType),
                      expectedResult, digest);
        } else {
            // Decoding to opaque should fail
            test_info(r, codec, info.makeAlphaType(kOpaque_SkAlphaType),
                      SkCodec::kInvalidConversion, nullptr);
            SkAlphaType otherAt = info.alphaType();
            if (kPremul_SkAlphaType == otherAt) {
                otherAt = kUnpremul_SkAlphaType;
            } else {
                otherAt = kPremul_SkAlphaType;
            }
            // The other non-opaque alpha type should always succeed, but not match.
            test_info(r, codec, info.makeAlphaType(otherAt), expectedResult, nullptr);
        }
    }
}

void SkHeifCodec::initializeSwizzler(
        const SkImageInfo& dstInfo, const Options& options) {
    SkImageInfo swizzlerDstInfo = dstInfo;
    if (this->colorXform()) {
        // The color xform will be expecting RGBA 8888 input.
        swizzlerDstInfo = swizzlerDstInfo.makeColorType(kRGBA_8888_SkColorType);
    }

    int srcBPP = 4;
    if (dstInfo.colorType() == kRGB_565_SkColorType && !this->colorXform()) {
        srcBPP = 2;
    }

    fSwizzler = SkSwizzler::MakeSimple(srcBPP, swizzlerDstInfo, options);
    SkASSERT(fSwizzler);
}

SkCodec::Result SkBmpMaskCodec::onPrepareToDecode(const SkImageInfo& dstInfo,
        const SkCodec::Options& options) {
    if (this->colorXform()) {
        this->resetXformBuffer(dstInfo.width());
    }

    SkImageInfo swizzlerInfo = dstInfo;
    if (this->colorXform()) {
        swizzlerInfo = swizzlerInfo.makeColorType(kXformSrcColorType);
        if (kPremul_SkAlphaType == dstInfo.alphaType()) {
            swizzlerInfo = swizzlerInfo.makeAlphaType(kUnpremul_SkAlphaType);
        }
    }

    bool srcIsOpaque = this->getEncodedInfo().opaque();
    fMaskSwizzler.reset(SkMaskSwizzler::CreateMaskSwizzler(swizzlerInfo, srcIsOpaque,
            fMasks.get(), this->bitsPerPixel(), options));
    SkASSERT(fMaskSwizzler);

    return SkCodec::kSuccess;
}

SkCodec::Result SkBmpMaskCodec::onPrepareToDecode(const SkImageInfo& dstInfo,
        const SkCodec::Options& options, SkPMColor inputColorPtr[], int* inputColorCount) {
    if (this->colorXform()) {
        this->resetXformBuffer(dstInfo.width());
    }

    SkImageInfo swizzlerInfo = dstInfo;
    if (this->colorXform()) {
        swizzlerInfo = swizzlerInfo.makeColorType(kXformSrcColorType);
        if (kPremul_SkAlphaType == dstInfo.alphaType()) {
            swizzlerInfo = swizzlerInfo.makeAlphaType(kUnpremul_SkAlphaType);
        }
    }

    // Initialize the mask swizzler
    fMaskSwizzler.reset(SkMaskSwizzler::CreateMaskSwizzler(swizzlerInfo, this->getInfo(),
            fMasks.get(), this->bitsPerPixel(), options));
    SkASSERT(fMaskSwizzler);

    return SkCodec::kSuccess;
}

size_t SkImage::getDeferredTextureImageData(const GrContextThreadSafeProxy& proxy,
                                            const DeferredTextureImageUsageParams params[],
                                            int paramCnt, void* buffer,
                                            SkColorSpace* dstColorSpace) const {
    // Extract relevant min/max values from the params array.
    int lowestPreScaleMipLevel = params[0].fPreScaleMipLevel;
    SkFilterQuality highestFilterQuality = params[0].fQuality;
    bool useMipMaps = should_use_mip_maps(params[0]);
    for (int i = 1; i < paramCnt; ++i) {
        if (lowestPreScaleMipLevel > params[i].fPreScaleMipLevel)
            lowestPreScaleMipLevel = params[i].fPreScaleMipLevel;
        if (highestFilterQuality < params[i].fQuality)
            highestFilterQuality = params[i].fQuality;
        useMipMaps |= should_use_mip_maps(params[i]);
    }

    const bool fillMode = SkToBool(buffer);
    if (fillMode && !SkIsAlign8(reinterpret_cast<intptr_t>(buffer))) {
        return 0;
    }

    // Calculate scaling parameters.
    bool isScaled = lowestPreScaleMipLevel != 0;

    SkISize scaledSize;
    if (isScaled) {
        // SkMipMap::ComputeLevelSize takes an index into an SkMipMap. SkMipMaps don't contain the
        // base level, so to get an SkMipMap index we must subtract one from the GL MipMap level.
        scaledSize = SkMipMap::ComputeLevelSize(this->width(), this->height(),
                                                lowestPreScaleMipLevel - 1);
    } else {
        scaledSize = SkISize::Make(this->width(), this->height());
    }

    // We never want to scale at higher than SW medium quality, as SW medium matches GPU high.
    SkFilterQuality scaleFilterQuality = highestFilterQuality;
    if (scaleFilterQuality > kMedium_SkFilterQuality) {
        scaleFilterQuality = kMedium_SkFilterQuality;
    }

    const int maxTextureSize = proxy.fCaps->maxTextureSize();
    if (scaledSize.width() > maxTextureSize || scaledSize.height() > maxTextureSize) {
        return 0;
    }

    SkAutoPixmapStorage pixmap;
    SkImageInfo info;
    size_t pixelSize = 0;
    if (!isScaled && this->peekPixels(&pixmap) && !pixmap.ctable()) {
        info = pixmap.info();
        pixelSize = SkAlign8(pixmap.getSafeSize());
    } else {
        // Here we're just using presence of data to know whether there is a codec behind the image.
        // In the future we will access the cacherator and get the exact data that we want to (e.g.
        // yuv planes) upload.
        sk_sp<SkData> data(this->refEncoded());
        if (!data && !this->peekPixels(nullptr)) {
            return 0;
        }
        if (SkImageCacherator* cacher = as_IB(this)->peekCacherator()) {
            // Generator backed image. Tweak info to trigger correct kind of decode.
            SkImageCacherator::CachedFormat cacheFormat = cacher->chooseCacheFormat(
                dstColorSpace, proxy.fCaps.get());
            info = cacher->buildCacheInfo(cacheFormat).makeWH(scaledSize.width(),
                                                              scaledSize.height());
        } else {
            info = as_IB(this)->onImageInfo().makeWH(scaledSize.width(), scaledSize.height());
        }
        if (kIndex_8_SkColorType == info.colorType()) {
            // Force Index8 to be N32 instead. Index8 is unsupported in Ganesh.
            info = info.makeColorType(kN32_SkColorType);
        }
        pixelSize = SkAlign8(SkAutoPixmapStorage::AllocSize(info, nullptr));
        if (fillMode) {
            pixmap.alloc(info);
            if (isScaled) {
                if (!this->scalePixels(pixmap, scaleFilterQuality,
                                       SkImage::kDisallow_CachingHint)) {
                    return 0;
                }
            } else {
                if (!this->readPixels(pixmap, 0, 0, SkImage::kDisallow_CachingHint)) {
                    return 0;
                }
            }
            SkASSERT(!pixmap.ctable());
        }
    }
    int mipMapLevelCount = 1;
    if (useMipMaps) {
        // SkMipMap only deals with the mipmap levels it generates, which does
        // not include the base level.
        // That means it generates and holds levels 1-x instead of 0-x.
        // So the total mipmap level count is 1 more than what
        // SkMipMap::ComputeLevelCount returns.
        mipMapLevelCount = SkMipMap::ComputeLevelCount(scaledSize.width(), scaledSize.height()) + 1;

        // We already initialized pixelSize to the size of the base level.
        // SkMipMap will generate the extra mipmap levels. Their sizes need to
        // be added to the total.
//.........这里部分代码省略.........

static void test_codec(skiatest::Reporter* r, Codec* codec, SkBitmap& bm, const SkImageInfo& info,
        const SkISize& size, SkCodec::Result expectedResult, SkMD5::Digest* digest,
        const SkMD5::Digest* goodDigest) {

    REPORTER_ASSERT(r, info.dimensions() == size);
    bm.allocPixels(info);
    SkAutoLockPixels autoLockPixels(bm);

    SkCodec::Result result = codec->getPixels(info, bm.getPixels(), bm.rowBytes());
    REPORTER_ASSERT(r, result == expectedResult);

    md5(bm, digest);
    if (goodDigest) {
        REPORTER_ASSERT(r, *digest == *goodDigest);
    }

    {
        // Test decoding to 565
        SkImageInfo info565 = info.makeColorType(kRGB_565_SkColorType);
        if (info.alphaType() == kOpaque_SkAlphaType) {
            // Decoding to 565 should succeed.
            SkBitmap bm565;
            bm565.allocPixels(info565);
            SkAutoLockPixels alp(bm565);

            // This will allow comparison even if the image is incomplete.
            bm565.eraseColor(SK_ColorBLACK);

            REPORTER_ASSERT(r, expectedResult == codec->getPixels(info565,
                    bm565.getPixels(), bm565.rowBytes()));

            SkMD5::Digest digest565;
            md5(bm565, &digest565);

            // A dumb client's request for non-opaque should also succeed.
            for (auto alpha : { kPremul_SkAlphaType, kUnpremul_SkAlphaType }) {
                info565 = info565.makeAlphaType(alpha);
                test_info(r, codec, info565, expectedResult, &digest565);
            }
        } else {
            test_info(r, codec, info565, SkCodec::kInvalidConversion, nullptr);
        }
    }

    if (codec->getInfo().colorType() == kGray_8_SkColorType) {
        SkImageInfo grayInfo = codec->getInfo();
        SkBitmap grayBm;
        grayBm.allocPixels(grayInfo);
        SkAutoLockPixels alp(grayBm);

        grayBm.eraseColor(SK_ColorBLACK);

        REPORTER_ASSERT(r, expectedResult == codec->getPixels(grayInfo,
                grayBm.getPixels(), grayBm.rowBytes()));

        SkMD5::Digest grayDigest;
        md5(grayBm, &grayDigest);

        for (auto alpha : { kPremul_SkAlphaType, kUnpremul_SkAlphaType }) {
            grayInfo = grayInfo.makeAlphaType(alpha);
            test_info(r, codec, grayInfo, expectedResult, &grayDigest);
        }
    }

    // Verify that re-decoding gives the same result.  It is interesting to check this after
    // a decode to 565, since choosing to decode to 565 may result in some of the decode
    // options being modified.  These options should return to their defaults on another
    // decode to kN32, so the new digest should match the old digest.
    test_info(r, codec, info, expectedResult, digest);

    {
        // Check alpha type conversions
        if (info.alphaType() == kOpaque_SkAlphaType) {
            test_info(r, codec, info.makeAlphaType(kUnpremul_SkAlphaType),
                      expectedResult, digest);
            test_info(r, codec, info.makeAlphaType(kPremul_SkAlphaType),
                      expectedResult, digest);
        } else {
            // Decoding to opaque should fail
            test_info(r, codec, info.makeAlphaType(kOpaque_SkAlphaType),
                      SkCodec::kInvalidConversion, nullptr);
            SkAlphaType otherAt = info.alphaType();
            if (kPremul_SkAlphaType == otherAt) {
                otherAt = kUnpremul_SkAlphaType;
            } else {
                otherAt = kPremul_SkAlphaType;
            }
            // The other non-opaque alpha type should always succeed, but not match.
            test_info(r, codec, info.makeAlphaType(otherAt), expectedResult, nullptr);
        }
    }
}

bool SkBitmapRegionCodec::decodeRegion(SkBitmap* bitmap, SkBRDAllocator* allocator,
        const SkIRect& desiredSubset, int sampleSize, SkColorType prefColorType,
        bool requireUnpremul) {

    // Fix the input sampleSize if necessary.
    if (sampleSize < 1) {
        sampleSize = 1;
    }

    // The size of the output bitmap is determined by the size of the
    // requested subset, not by the size of the intersection of the subset
    // and the image dimensions.
    // If inputX is negative, we will need to place decoded pixels into the
    // output bitmap starting at a left offset.  Call this outX.
    // If outX is non-zero, subsetX must be zero.
    // If inputY is negative, we will need to place decoded pixels into the
    // output bitmap starting at a top offset.  Call this outY.
    // If outY is non-zero, subsetY must be zero.
    int outX;
    int outY;
    SkIRect subset = desiredSubset;
    SubsetType type = adjust_subset_rect(fCodec->getInfo().dimensions(), &subset, &outX, &outY);
    if (SubsetType::kOutside_SubsetType == type) {
        return false;
    }

    // Ask the codec for a scaled subset
    if (!fCodec->getSupportedSubset(&subset)) {
        SkCodecPrintf("Error: Could not get subset.\n");
        return false;
    }
    SkISize scaledSize = fCodec->getSampledSubsetDimensions(sampleSize, subset);

    // Create the image info for the decode
    SkColorType dstColorType = fCodec->computeOutputColorType(prefColorType);
    SkAlphaType dstAlphaType = fCodec->computeOutputAlphaType(requireUnpremul);
    SkImageInfo decodeInfo = fCodec->getInfo().makeWH(scaledSize.width(), scaledSize.height())
                                              .makeColorType(dstColorType)
                                              .makeAlphaType(dstAlphaType);

    // Construct a color table for the decode if necessary
    SkAutoTUnref<SkColorTable> colorTable(nullptr);
    int maxColors = 256;
    SkPMColor colors[256];
    if (kIndex_8_SkColorType == dstColorType) {
        colorTable.reset(new SkColorTable(colors, maxColors));
    }

    // Initialize the destination bitmap
    int scaledOutX = 0;
    int scaledOutY = 0;
    int scaledOutWidth = scaledSize.width();
    int scaledOutHeight = scaledSize.height();
    if (SubsetType::kPartiallyInside_SubsetType == type) {
        scaledOutX = outX / sampleSize;
        scaledOutY = outY / sampleSize;
        // We need to be safe here because getSupportedSubset() may have modified the subset.
        const int extraX = SkTMax(0, desiredSubset.width() - outX - subset.width());
        const int extraY = SkTMax(0, desiredSubset.height() - outY - subset.height());
        const int scaledExtraX = extraX / sampleSize;
        const int scaledExtraY = extraY / sampleSize;
        scaledOutWidth += scaledOutX + scaledExtraX;
        scaledOutHeight += scaledOutY + scaledExtraY;
    }
    SkImageInfo outInfo = decodeInfo.makeWH(scaledOutWidth, scaledOutHeight);
    if (kGray_8_SkColorType == dstColorType) {
        // The legacy implementations of BitmapFactory and BitmapRegionDecoder
        // used kAlpha8 for grayscale images (before kGray8 existed).  While
        // the codec recognizes kGray8, we need to decode into a kAlpha8
        // bitmap in order to avoid a behavior change.
        outInfo = outInfo.makeColorType(kAlpha_8_SkColorType).makeAlphaType(kPremul_SkAlphaType);
    }
    bitmap->setInfo(outInfo);
    if (!bitmap->tryAllocPixels(allocator, colorTable.get())) {
        SkCodecPrintf("Error: Could not allocate pixels.\n");
        return false;
    }

    // Zero the bitmap if the region is not completely within the image.
    // TODO (msarett): Can we make this faster by implementing it to only
    //                 zero parts of the image that we won't overwrite with
    //                 pixels?
    SkCodec::ZeroInitialized zeroInit = allocator ? allocator->zeroInit() :
            SkCodec::kNo_ZeroInitialized;
    if (SubsetType::kPartiallyInside_SubsetType == type &&
            SkCodec::kNo_ZeroInitialized == zeroInit) {
        void* pixels = bitmap->getPixels();
        size_t bytes = outInfo.getSafeSize(bitmap->rowBytes());
        memset(pixels, 0, bytes);
    }

    // Decode into the destination bitmap
    SkAndroidCodec::AndroidOptions options;
    options.fSampleSize = sampleSize;
    options.fSubset = &subset;
    options.fColorPtr = colors;
    options.fColorCount = &maxColors;
    options.fZeroInitialized = zeroInit;
    void* dst = bitmap->getAddr(scaledOutX, scaledOutY);

//.........这里部分代码省略.........

static void check(skiatest::Reporter* r,
                  const char path[],
                  SkISize size,
                  bool supportsScanlineDecoding,
                  bool supportsSubsetDecoding,
                  bool supports565 = true) {
    SkAutoTDelete<SkStream> stream(resource(path));
    if (!stream) {
        SkDebugf("Missing resource '%s'\n", path);
        return;
    }
    SkAutoTDelete<SkCodec> codec(SkCodec::NewFromStream(stream.detach()));
    if (!codec) {
        ERRORF(r, "Unable to decode '%s'", path);
        return;
    }

    // This test is used primarily to verify rewinding works properly.  Using kN32 allows
    // us to test this without the added overhead of creating different bitmaps depending
    // on the color type (ex: building a color table for kIndex8).  DM is where we test
    // decodes to all possible destination color types.
    SkImageInfo info = codec->getInfo().makeColorType(kN32_SkColorType);
    REPORTER_ASSERT(r, info.dimensions() == size);

    {
        // Test decoding to 565
        SkImageInfo info565 = info.makeColorType(kRGB_565_SkColorType);
        SkCodec::Result expected = (supports565 && info.alphaType() == kOpaque_SkAlphaType) ?
                SkCodec::kSuccess : SkCodec::kInvalidConversion;
        test_info(r, codec, info565, expected, NULL);
    }

    SkBitmap bm;
    bm.allocPixels(info);
    SkAutoLockPixels autoLockPixels(bm);
    SkCodec::Result result =
        codec->getPixels(info, bm.getPixels(), bm.rowBytes(), NULL, NULL, NULL);
    REPORTER_ASSERT(r, result == SkCodec::kSuccess);

    SkMD5::Digest digest;
    md5(bm, &digest);

    // verify that re-decoding gives the same result.
    test_info(r, codec, info, SkCodec::kSuccess, &digest);

    {
        // Check alpha type conversions
        if (info.alphaType() == kOpaque_SkAlphaType) {
            test_info(r, codec, info.makeAlphaType(kUnpremul_SkAlphaType),
                      SkCodec::kInvalidConversion, NULL);
            test_info(r, codec, info.makeAlphaType(kPremul_SkAlphaType),
                      SkCodec::kInvalidConversion, NULL);
        } else {
            // Decoding to opaque should fail
            test_info(r, codec, info.makeAlphaType(kOpaque_SkAlphaType),
                      SkCodec::kInvalidConversion, NULL);
            SkAlphaType otherAt = info.alphaType();
            if (kPremul_SkAlphaType == otherAt) {
                otherAt = kUnpremul_SkAlphaType;
            } else {
                otherAt = kPremul_SkAlphaType;
            }
            // The other non-opaque alpha type should always succeed, but not match.
            test_info(r, codec, info.makeAlphaType(otherAt), SkCodec::kSuccess, NULL);
        }
    }

    // Scanline decoding follows.

    stream.reset(resource(path));
    SkAutoTDelete<SkScanlineDecoder> scanlineDecoder(
            SkScanlineDecoder::NewFromStream(stream.detach()));
    if (supportsScanlineDecoding) {
        bm.eraseColor(SK_ColorYELLOW);
        REPORTER_ASSERT(r, scanlineDecoder);

        REPORTER_ASSERT(r, scanlineDecoder->start(info) == SkCodec::kSuccess);

        for (int y = 0; y < info.height(); y++) {
            result = scanlineDecoder->getScanlines(bm.getAddr(0, y), 1, 0);
            REPORTER_ASSERT(r, result == SkCodec::kSuccess);
        }
        // verify that scanline decoding gives the same result.
        compare_to_good_digest(r, digest, bm);
    } else {
        REPORTER_ASSERT(r, !scanlineDecoder);
    }

    // The rest of this function tests decoding subsets, and will decode an arbitrary number of
    // random subsets.
    // Do not attempt to decode subsets of an image of only once pixel, since there is no
    // meaningful subset.
    if (size.width() * size.height() == 1) {
        return;
    }

    SkRandom rand;
    SkIRect subset;
    SkCodec::Options opts;
    opts.fSubset = &subset;
//.........这里部分代码省略.........