C++ SkBitmap::canCopyTo方法代码示例

bool DecodingImageGenerator::getPixels(const SkImageInfo& info,
                                         void* pixels,
                                         size_t rowBytes) {
    if (NULL == pixels) {
        return false;
    }
    if (fInfo != info) {
        // The caller has specified a different info.  This is an
        // error for this kind of SkImageGenerator.  Use the Options
        // to change the settings.
        return false;
    }
    if (info.minRowBytes() > rowBytes) {
        // The caller has specified a bad rowBytes.
        return false;
    }

    SkAssertResult(fStream->rewind());
    SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(fStream));
    if (NULL == decoder.get()) {
        return false;
    }
    decoder->setDitherImage(fDitherImage);
    decoder->setSampleSize(fSampleSize);
    decoder->setRequireUnpremultipliedColors(
            info.fAlphaType == kUnpremul_SkAlphaType);

    SkBitmap bitmap;
    TargetAllocator allocator(fInfo, pixels, rowBytes);
    decoder->setAllocator(&allocator);
    // TODO: need to be able to pass colortype directly to decoder
    SkBitmap::Config legacyConfig = SkColorTypeToBitmapConfig(info.colorType());
    bool success = decoder->decode(fStream, &bitmap, legacyConfig,
                                   SkImageDecoder::kDecodePixels_Mode);
    decoder->setAllocator(NULL);
    if (!success) {
        return false;
    }
    if (allocator.isReady()) {  // Did not use pixels!
        SkBitmap bm;
        SkASSERT(bitmap.canCopyTo(info.colorType()));
        bool copySuccess = bitmap.copyTo(&bm, info.colorType(), &allocator);
        if (!copySuccess || allocator.isReady()) {
            SkDEBUGFAIL("bitmap.copyTo(requestedConfig) failed.");
            // Earlier we checked canCopyto(); we expect consistency.
            return false;
        }
        SkASSERT(check_alpha(info.alphaType(), bm.alphaType()));
    } else {
        SkASSERT(check_alpha(info.alphaType(), bitmap.alphaType()));
    }
    return true;
}

// A contructor-type function that returns NULL on failure.  This
// prevents the returned SkImageGenerator from ever being in a bad
// state.  Called by both Create() functions
SkImageGenerator* CreateDecodingImageGenerator(
        SkData* data,
        SkStreamRewindable* stream,
        const SkDecodingImageGenerator::Options& opts) {
    SkASSERT(stream);
    SkAutoTUnref<SkStreamRewindable> autoStream(stream);  // always unref this.
    if (opts.fUseRequestedColorType &&
        (kIndex_8_SkColorType == opts.fRequestedColorType)) {
        // We do not support indexed color with SkImageGenerators,
        return NULL;
    }
    SkAssertResult(autoStream->rewind());
    SkAutoTDelete<SkImageDecoder> decoder(SkImageDecoder::Factory(autoStream));
    if (NULL == decoder.get()) {
        return NULL;
    }
    SkBitmap bitmap;
    decoder->setSampleSize(opts.fSampleSize);
    decoder->setRequireUnpremultipliedColors(opts.fRequireUnpremul);
    if (!decoder->decode(stream, &bitmap,
                         SkImageDecoder::kDecodeBounds_Mode)) {
        return NULL;
    }
    if (bitmap.config() == SkBitmap::kNo_Config) {
        return NULL;
    }

    SkImageInfo info = bitmap.info();

    if (!opts.fUseRequestedColorType) {
        // Use default
        if (kIndex_8_SkColorType == bitmap.colorType()) {
            // We don't support kIndex8 because we don't support
            // colortables in this workflow.
            info.fColorType = kN32_SkColorType;
        }
    } else {
        if (!bitmap.canCopyTo(opts.fRequestedColorType)) {
            SkASSERT(bitmap.colorType() != opts.fRequestedColorType);
            return NULL;  // Can not translate to needed config.
        }
        info.fColorType = opts.fRequestedColorType;
    }

    if (opts.fRequireUnpremul && info.fAlphaType != kOpaque_SkAlphaType) {
        info.fAlphaType = kUnpremul_SkAlphaType;
    }
    return SkNEW_ARGS(DecodingImageGenerator,
                      (data, autoStream.detach(), info,
                       opts.fSampleSize, opts.fDitherImage));
}