C++ SkImageInfo::makeAlphaType方法代码示例

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);
        }
    }
}

static void draw_image(SkCanvas* canvas, SkImage* image, SkColorType dstColorType,
                       SkAlphaType dstAlphaType, sk_sp<SkColorSpace> dstColorSpace,
                       SkImage::CachingHint hint) {
    size_t rowBytes = image->width() * SkColorTypeBytesPerPixel(dstColorType);
    sk_sp<SkData> data = SkData::MakeUninitialized(rowBytes * image->height());
    dstColorSpace = fix_for_colortype(dstColorSpace.get(), dstColorType);
    SkImageInfo dstInfo = SkImageInfo::Make(image->width(), image->height(), dstColorType,
                                            dstAlphaType, dstColorSpace);
    if (!image->readPixels(dstInfo, data->writable_data(), rowBytes, 0, 0, hint)) {
        memset(data->writable_data(), 0, rowBytes * image->height());
    }

    // SkImage must be premul, so manually premul the data if we unpremul'd during readPixels
    if (kUnpremul_SkAlphaType == dstAlphaType) {
        auto xform = SkColorSpaceXform::New(dstColorSpace.get(), dstColorSpace.get());
        if (!xform->apply(select_xform_format(dstColorType), data->writable_data(),
                          select_xform_format(dstColorType), data->data(),
                          image->width() * image->height(), kPremul_SkAlphaType)) {
            memset(data->writable_data(), 0, rowBytes * image->height());
        }
        dstInfo = dstInfo.makeAlphaType(kPremul_SkAlphaType);
    }

    // readPixels() does not always clamp F16.  The drawing code expects pixels in the 0-1 range.
    clamp_if_necessary(dstInfo, data->writable_data());

    // Now that we have called readPixels(), dump the raw pixels into an srgb image.
    sk_sp<SkColorSpace> srgb = fix_for_colortype(
            SkColorSpace::MakeSRGB().get(), dstColorType);
    sk_sp<SkImage> raw = SkImage::MakeRasterData(dstInfo.makeColorSpace(srgb), data, rowBytes);
    canvas->drawImage(raw.get(), 0.0f, 0.0f, nullptr);
}

static SkImageInfo make_premul(const SkImageInfo& info) {
    if (kUnpremul_SkAlphaType == info.alphaType()) {
        return info.makeAlphaType(kPremul_SkAlphaType);
    }

    return info;
}

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 bool compatibleInfo(const SkImageInfo& src, const SkImageInfo& dst)
{
    if (src == dst)
        return true;

    // It is legal to write kOpaque_SkAlphaType pixels into a kPremul_SkAlphaType buffer.
    // This can happen when DeferredImageDecoder allocates an kOpaque_SkAlphaType image
    // generator based on cached frame info, while the ImageFrame-allocated dest bitmap
    // stays kPremul_SkAlphaType.
    if (src.alphaType() == kOpaque_SkAlphaType && dst.alphaType() == kPremul_SkAlphaType) {
        const SkImageInfo& tmp = src.makeAlphaType(kPremul_SkAlphaType);
        return tmp == dst;
    }

    return false;
}

static SkImageInfo fix_embedded_alpha(const SkImageInfo& dstInfo, SkAlphaType embeddedAlpha) {
    // FIXME (msarett): ICO is considered non-opaque, even if the embedded BMP
    // incorrectly claims it has no alpha.
    switch (embeddedAlpha) {
    case kPremul_SkAlphaType:
    case kUnpremul_SkAlphaType:
        // Use the requested alpha type if the embedded codec supports alpha.
        embeddedAlpha = dstInfo.alphaType();
        break;
    case kOpaque_SkAlphaType:
        // If the embedded codec claims it is opaque, decode as if it is opaque.
        break;
    default:
        SkASSERT(false);
        break;
    }
    return dstInfo.makeAlphaType(embeddedAlpha);
}

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;
}

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;
}

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);
        }
    }
}

static SkImageInfo validate_info(const SkImageInfo& info) {
    SkAlphaType newAlphaType = info.alphaType();
    SkAssertResult(SkColorTypeValidateAlphaType(info.colorType(), info.alphaType(), &newAlphaType));
    return info.makeAlphaType(newAlphaType);
}

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.........

//.........这里部分代码省略.........
        uint32_t offset = get_int(entryBuffer.get(), 12 + i*kIcoDirEntryBytes);

        // Save the vital fields
        directoryEntries.get()[i].offset = offset;
        directoryEntries.get()[i].size = size;
    }

    // It is "customary" that the embedded images will be stored in order of
    // increasing offset.  However, the specification does not indicate that
    // they must be stored in this order, so we will not trust that this is the
    // case.  Here we sort the embedded images by increasing offset.
    struct EntryLessThan {
        bool operator() (Entry a, Entry b) const {
            return a.offset < b.offset;
        }
    };
    EntryLessThan lessThan;
    SkTQSort(directoryEntries.get(), directoryEntries.get() + numImages - 1,
             lessThan);

    // Now will construct a candidate codec for each of the embedded images
    uint32_t bytesRead = kIcoDirectoryBytes + numImages * kIcoDirEntryBytes;
    SkAutoTDelete<SkTArray<SkAutoTDelete<SkCodec>, true>> codecs(
                new (SkTArray<SkAutoTDelete<SkCodec>, true>)(numImages));
    for (uint32_t i = 0; i < numImages; i++) {
        uint32_t offset = directoryEntries.get()[i].offset;
        uint32_t size = directoryEntries.get()[i].size;

        // Ensure that the offset is valid
        if (offset < bytesRead) {
            SkCodecPrintf("Warning: invalid ico offset.\n");
            continue;
        }

        // If we cannot skip, assume we have reached the end of the stream and
        // stop trying to make codecs
        if (inputStream.get()->skip(offset - bytesRead) != offset - bytesRead) {
            SkCodecPrintf("Warning: could not skip to ico offset.\n");
            break;
        }
        bytesRead = offset;

        // Create a new stream for the embedded codec
        SkAutoTUnref<SkData> data(
            SkData::NewFromStream(inputStream.get(), size));
        if (nullptr == data.get()) {
            SkCodecPrintf("Warning: could not create embedded stream.\n");
            break;
        }
        SkAutoTDelete<SkMemoryStream> embeddedStream(new SkMemoryStream(data.get()));
        bytesRead += size;

        // Check if the embedded codec is bmp or png and create the codec
        SkCodec* codec = nullptr;
        if (SkPngCodec::IsPng((const char*) data->bytes(), data->size())) {
            codec = SkPngCodec::NewFromStream(embeddedStream.detach());
        } else {
            codec = SkBmpCodec::NewFromIco(embeddedStream.detach());
        }

        // Save a valid codec
        if (nullptr != codec) {
            codecs->push_back().reset(codec);
        }
    }

    // Recognize if there are no valid codecs
    if (0 == codecs->count()) {
        SkCodecPrintf("Error: could not find any valid embedded ico codecs.\n");
        return nullptr;
    }

    // Use the largest codec as a "suggestion" for image info
    uint32_t maxSize = 0;
    uint32_t maxIndex = 0;
    for (int32_t i = 0; i < codecs->count(); i++) {
        SkImageInfo info = codecs->operator[](i)->getInfo();
        uint32_t size = info.width() * info.height();
        if (size > maxSize) {
            maxSize = size;
            maxIndex = i;
        }
    }
    SkImageInfo info = codecs->operator[](maxIndex)->getInfo();

    // ICOs contain an alpha mask after the image which means we cannot
    // guarantee that an image is opaque, even if the sub-codec thinks it
    // is.
    // FIXME (msarett): The BMP decoder depends on the alpha type in order
    // to decode correctly, otherwise it could report kUnpremul and we would
    // not have to correct it here. Is there a better way?
    // FIXME (msarett): This is only true for BMP in ICO - could a PNG in ICO
    // be opaque? Is it okay that we missed out on the opportunity to mark
    // such an image as opaque?
    info = info.makeAlphaType(kUnpremul_SkAlphaType);

    // Note that stream is owned by the embedded codec, the ico does not need
    // direct access to the stream.
    return new SkIcoCodec(info, codecs.detach());
}