C++ SkImageDecoder::setSkipWritingZeroes方法代码示例

// since we "may" create a purgeable imageref, we require the stream be ref'able
// i.e. dynamically allocated, since its lifetime may exceed the current stack
// frame.
static jobject doDecode(JNIEnv* env, SkStreamRewindable* stream, jobject padding,
        jobject options, bool allowPurgeable, bool forcePurgeable = false) {

    int sampleSize = 1;

    SkImageDecoder::Mode mode = SkImageDecoder::kDecodePixels_Mode;
    SkBitmap::Config prefConfig = SkBitmap::kARGB_8888_Config;

    bool doDither = true;
    bool isMutable = false;
    float scale = 1.0f;
    bool isPurgeable = forcePurgeable || (allowPurgeable && optionsPurgeable(env, options));
    bool preferQualityOverSpeed = false;
    bool requireUnpremultiplied = false;

    jobject javaBitmap = NULL;

    if (options != NULL) {
        sampleSize = env->GetIntField(options, gOptions_sampleSizeFieldID);
        if (optionsJustBounds(env, options)) {
            mode = SkImageDecoder::kDecodeBounds_Mode;
        }

        // initialize these, in case we fail later on
        env->SetIntField(options, gOptions_widthFieldID, -1);
        env->SetIntField(options, gOptions_heightFieldID, -1);
        env->SetObjectField(options, gOptions_mimeFieldID, 0);

        jobject jconfig = env->GetObjectField(options, gOptions_configFieldID);
        prefConfig = GraphicsJNI::getNativeBitmapConfig(env, jconfig);
        isMutable = env->GetBooleanField(options, gOptions_mutableFieldID);
        doDither = env->GetBooleanField(options, gOptions_ditherFieldID);
        preferQualityOverSpeed = env->GetBooleanField(options,
                gOptions_preferQualityOverSpeedFieldID);
        requireUnpremultiplied = !env->GetBooleanField(options, gOptions_premultipliedFieldID);
        javaBitmap = env->GetObjectField(options, gOptions_bitmapFieldID);

        if (env->GetBooleanField(options, gOptions_scaledFieldID)) {
            const int density = env->GetIntField(options, gOptions_densityFieldID);
            const int targetDensity = env->GetIntField(options, gOptions_targetDensityFieldID);
            const int screenDensity = env->GetIntField(options, gOptions_screenDensityFieldID);
            if (density != 0 && targetDensity != 0 && density != screenDensity) {
                scale = (float) targetDensity / density;
            }
        }
    }

    const bool willScale = scale != 1.0f;
    isPurgeable &= !willScale;

    SkImageDecoder* decoder = SkImageDecoder::Factory(stream);
    if (decoder == NULL) {
        return nullObjectReturn("SkImageDecoder::Factory returned null");
    }

    decoder->setSampleSize(sampleSize);
    decoder->setDitherImage(doDither);
    decoder->setPreferQualityOverSpeed(preferQualityOverSpeed);
    decoder->setRequireUnpremultipliedColors(requireUnpremultiplied);

    SkBitmap* outputBitmap = NULL;
    unsigned int existingBufferSize = 0;
    if (javaBitmap != NULL) {
        outputBitmap = (SkBitmap*) env->GetIntField(javaBitmap, gBitmap_nativeBitmapFieldID);
        if (outputBitmap->isImmutable()) {
            ALOGW("Unable to reuse an immutable bitmap as an image decoder target.");
            javaBitmap = NULL;
            outputBitmap = NULL;
        } else {
            existingBufferSize = GraphicsJNI::getBitmapAllocationByteCount(env, javaBitmap);
        }
    }

    SkAutoTDelete<SkBitmap> adb(outputBitmap == NULL ? new SkBitmap : NULL);
    if (outputBitmap == NULL) outputBitmap = adb.get();

    NinePatchPeeker peeker(decoder);
    decoder->setPeeker(&peeker);

    SkImageDecoder::Mode decodeMode = isPurgeable ? SkImageDecoder::kDecodeBounds_Mode : mode;

    JavaPixelAllocator javaAllocator(env);
    RecyclingPixelAllocator recyclingAllocator(outputBitmap->pixelRef(), existingBufferSize);
    ScaleCheckingAllocator scaleCheckingAllocator(scale, existingBufferSize);
    SkBitmap::Allocator* outputAllocator = (javaBitmap != NULL) ?
            (SkBitmap::Allocator*)&recyclingAllocator : (SkBitmap::Allocator*)&javaAllocator;
    if (decodeMode != SkImageDecoder::kDecodeBounds_Mode) {
        if (!willScale) {
            // If the java allocator is being used to allocate the pixel memory, the decoder
            // need not write zeroes, since the memory is initialized to 0.
            decoder->setSkipWritingZeroes(outputAllocator == &javaAllocator);
            decoder->setAllocator(outputAllocator);
        } else if (javaBitmap != NULL) {
            // check for eventual scaled bounds at allocation time, so we don't decode the bitmap
            // only to find the scaled result too large to fit in the allocation
            decoder->setAllocator(&scaleCheckingAllocator);
        }
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        decoder->setDynamicCon(dc, 0);
    }
//	(env)->ReleaseIntArrayElements(dynamicCon, pdynamicCon, 0);
#endif

    SkBitmap* outputBitmap = NULL;
    unsigned int existingBufferSize = 0;
    if (javaBitmap != NULL) {
        outputBitmap = (SkBitmap*) env->GetLongField(javaBitmap, gBitmap_nativeBitmapFieldID);
        if (outputBitmap->isImmutable()) {
            ALOGW("Unable to reuse an immutable bitmap as an image decoder target.");
            javaBitmap = NULL;
            outputBitmap = NULL;
        } else {
            existingBufferSize = GraphicsJNI::getBitmapAllocationByteCount(env, javaBitmap);
        }
    }

    SkAutoTDelete<SkBitmap> adb(outputBitmap == NULL ? new SkBitmap : NULL);
    if (outputBitmap == NULL) outputBitmap = adb.get();

    NinePatchPeeker peeker(decoder);
    decoder->setPeeker(&peeker);

    JavaPixelAllocator javaAllocator(env);
    RecyclingPixelAllocator recyclingAllocator(outputBitmap->pixelRef(), existingBufferSize);
    ScaleCheckingAllocator scaleCheckingAllocator(scale, existingBufferSize);
    SkBitmap::Allocator* outputAllocator = (javaBitmap != NULL) ?
            (SkBitmap::Allocator*)&recyclingAllocator : (SkBitmap::Allocator*)&javaAllocator;
    if (decodeMode != SkImageDecoder::kDecodeBounds_Mode) {
        if (!willScale) {
            // If the java allocator is being used to allocate the pixel memory, the decoder
            // need not write zeroes, since the memory is initialized to 0.
            decoder->setSkipWritingZeroes(outputAllocator == &javaAllocator);
            decoder->setAllocator(outputAllocator);
        } else if (javaBitmap != NULL) {
            // check for eventual scaled bounds at allocation time, so we don't decode the bitmap
            // only to find the scaled result too large to fit in the allocation
            decoder->setAllocator(&scaleCheckingAllocator);
        }
    }

    // Only setup the decoder to be deleted after its stack-based, refcounted
    // components (allocators, peekers, etc) are declared. This prevents RefCnt
    // asserts from firing due to the order objects are deleted from the stack.
    SkAutoTDelete<SkImageDecoder> add(decoder);

    AutoDecoderCancel adc(options, decoder);

    // To fix the race condition in case "requestCancelDecode"
    // happens earlier than AutoDecoderCancel object is added
    // to the gAutoDecoderCancelMutex linked list.
    if (options != NULL && env->GetBooleanField(options, gOptions_mCancelID)) {
        return nullObjectReturn("gOptions_mCancelID");
    }

    SkBitmap decodingBitmap;
    if (!decoder->decode(stream, &decodingBitmap, prefColorType, decodeMode)) {
        return nullObjectReturn("decoder->decode returned false");
    }

    int scaledWidth = decodingBitmap.width();
    int scaledHeight = decodingBitmap.height();

    if (willScale && decodeMode != SkImageDecoder::kDecodeBounds_Mode) {
        scaledWidth = int(scaledWidth * scale + 0.5f);