bool SkImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, const SkMatrix& ctm,
                                   SkBitmap* result, SkIPoint* offset) {
#if SK_SUPPORT_GPU
    SkBitmap input;
    SkASSERT(fInputCount == 1);
    if (!SkImageFilterUtils::GetInputResultGPU(this->getInput(0), proxy, src, ctm, &input, offset)) {
        return false;
    }
    GrTexture* srcTexture = input.getTexture();
    SkIRect bounds;
    src.getBounds(&bounds);
    if (!this->applyCropRect(&bounds, ctm)) {
        return false;
    }
    SkRect srcRect = SkRect::Make(bounds);
    SkRect dstRect = SkRect::MakeWH(srcRect.width(), srcRect.height());
    GrContext* context = srcTexture->getContext();

    GrTextureDesc desc;
    desc.fFlags = kRenderTarget_GrTextureFlagBit,
    desc.fWidth = bounds.width();
    desc.fHeight = bounds.height();
    desc.fConfig = kRGBA_8888_GrPixelConfig;

    GrAutoScratchTexture dst(context, desc);
    GrContext::AutoMatrix am;
    am.setIdentity(context);
    GrContext::AutoRenderTarget art(context, dst.texture()->asRenderTarget());
    GrContext::AutoClip acs(context, dstRect);
    GrEffectRef* effect;
    SkMatrix matrix(ctm);
    matrix.postTranslate(SkIntToScalar(-bounds.left()), SkIntToScalar(-bounds.top()));
    this->asNewEffect(&effect, srcTexture, matrix, bounds);
    SkASSERT(effect);
    SkAutoUnref effectRef(effect);
    GrPaint paint;
    paint.addColorEffect(effect);
    context->drawRectToRect(paint, dstRect, srcRect);

    SkAutoTUnref<GrTexture> resultTex(dst.detach());
    SkImageFilterUtils::WrapTexture(resultTex, bounds.width(), bounds.height(), result);
    offset->fX += bounds.left();
    offset->fY += bounds.top();
    return true;
#else
    return false;
#endif
}
bool SkImageFilter::filterImageGPU(Proxy* proxy, const SkBitmap& src, SkBitmap* result) {
#if SK_SUPPORT_GPU
    SkBitmap input;
    SkASSERT(fInputCount == 1);
    if (!SkImageFilterUtils::GetInputResultGPU(this->getInput(0), proxy, src, &input)) {
        return false;
    }
    GrTexture* srcTexture = (GrTexture*) input.getTexture();
    SkRect rect;
    src.getBounds(&rect);
    GrContext* context = srcTexture->getContext();

    GrTextureDesc desc;
    desc.fFlags = kRenderTarget_GrTextureFlagBit,
    desc.fWidth = input.width();
    desc.fHeight = input.height();
    desc.fConfig = kRGBA_8888_GrPixelConfig;

    GrAutoScratchTexture dst(context, desc);
    GrContext::AutoMatrix am;
    am.setIdentity(context);
    GrContext::AutoRenderTarget art(context, dst.texture()->asRenderTarget());
    GrContext::AutoClip acs(context, rect);
    GrEffectRef* effect;
    this->asNewEffect(&effect, srcTexture);
    SkASSERT(effect);
    SkAutoUnref effectRef(effect);
    GrPaint paint;
    paint.colorStage(0)->setEffect(effect);
    context->drawRect(paint, rect);
    SkAutoTUnref<GrTexture> resultTex(dst.detach());
    SkImageFilterUtils::WrapTexture(resultTex, input.width(), input.height(), result);
    return true;
#else
    return false;
#endif
}
GrTexture* GaussianBlur(GrContext* context,
                        GrTexture* srcTexture,
                        bool canClobberSrc,
                        const SkRect& rect,
                        bool cropToRect,
                        float sigmaX,
                        float sigmaY) {
    SkASSERT(NULL != context);

    GrContext::AutoRenderTarget art(context);

    GrContext::AutoMatrix am;
    am.setIdentity(context);

    SkIRect clearRect;
    int scaleFactorX, radiusX;
    int scaleFactorY, radiusY;
    sigmaX = adjust_sigma(sigmaX, &scaleFactorX, &radiusX);
    sigmaY = adjust_sigma(sigmaY, &scaleFactorY, &radiusY);

    SkRect srcRect(rect);
    scale_rect(&srcRect, 1.0f / scaleFactorX, 1.0f / scaleFactorY);
    srcRect.roundOut();
    scale_rect(&srcRect, static_cast<float>(scaleFactorX),
                         static_cast<float>(scaleFactorY));

    GrContext::AutoClip acs(context, SkRect::MakeWH(srcRect.width(), srcRect.height()));

    SkASSERT(kBGRA_8888_GrPixelConfig == srcTexture->config() ||
             kRGBA_8888_GrPixelConfig == srcTexture->config() ||
             kAlpha_8_GrPixelConfig == srcTexture->config());

    GrTextureDesc desc;
    desc.fFlags = kRenderTarget_GrTextureFlagBit | kNoStencil_GrTextureFlagBit;
    desc.fWidth = SkScalarFloorToInt(srcRect.width());
    desc.fHeight = SkScalarFloorToInt(srcRect.height());
    desc.fConfig = srcTexture->config();

    GrAutoScratchTexture temp1, temp2;
    GrTexture* dstTexture = temp1.set(context, desc);
    GrTexture* tempTexture = canClobberSrc ? srcTexture : temp2.set(context, desc);
    if (NULL == dstTexture || NULL == tempTexture) {
        return NULL;
    }

    for (int i = 1; i < scaleFactorX || i < scaleFactorY; i *= 2) {
        GrPaint paint;
        SkMatrix matrix;
        matrix.setIDiv(srcTexture->width(), srcTexture->height());
        context->setRenderTarget(dstTexture->asRenderTarget());
        SkRect dstRect(srcRect);
        if (cropToRect && i == 1) {
            dstRect.offset(-dstRect.fLeft, -dstRect.fTop);
            SkRect domain;
            matrix.mapRect(&domain, rect);
            domain.inset(i < scaleFactorX ? SK_ScalarHalf / srcTexture->width() : 0.0f,
                         i < scaleFactorY ? SK_ScalarHalf / srcTexture->height() : 0.0f);
            SkAutoTUnref<GrEffectRef> effect(GrTextureDomainEffect::Create(
                srcTexture,
                matrix,
                domain,
                GrTextureDomainEffect::kDecal_WrapMode,
                GrTextureParams::kBilerp_FilterMode));
            paint.addColorEffect(effect);
        } else {
            GrTextureParams params(SkShader::kClamp_TileMode, GrTextureParams::kBilerp_FilterMode);
            paint.addColorTextureEffect(srcTexture, matrix, params);
        }
        scale_rect(&dstRect, i < scaleFactorX ? 0.5f : 1.0f,
                             i < scaleFactorY ? 0.5f : 1.0f);
        context->drawRectToRect(paint, dstRect, srcRect);
        srcRect = dstRect;
        srcTexture = dstTexture;
        SkTSwap(dstTexture, tempTexture);
    }

    SkIRect srcIRect;
    srcRect.roundOut(&srcIRect);

    if (sigmaX > 0.0f) {
        if (scaleFactorX > 1) {
            // Clear out a radius to the right of the srcRect to prevent the
            // X convolution from reading garbage.
            clearRect = SkIRect::MakeXYWH(srcIRect.fRight, srcIRect.fTop,
                                          radiusX, srcIRect.height());
            context->clear(&clearRect, 0x0, false);
        }
        context->setRenderTarget(dstTexture->asRenderTarget());
        SkRect dstRect = SkRect::MakeWH(srcRect.width(), srcRect.height());
        convolve_gaussian(context, srcRect, dstRect, srcTexture,
                          Gr1DKernelEffect::kX_Direction, radiusX, sigmaX, cropToRect);
        srcTexture = dstTexture;
        srcRect = dstRect;
        SkTSwap(dstTexture, tempTexture);
    }

    if (sigmaY > 0.0f) {
        if (scaleFactorY > 1 || sigmaX > 0.0f) {
            // Clear out a radius below the srcRect to prevent the Y
            // convolution from reading garbage.
            clearRect = SkIRect::MakeXYWH(srcIRect.fLeft, srcIRect.fBottom,
                                          srcIRect.width(), radiusY);
            context->clear(&clearRect, 0x0, false);
        }

        context->setRenderTarget(dstTexture->asRenderTarget());
        SkRect dstRect = SkRect::MakeWH(srcRect.width(), srcRect.height());
        convolve_gaussian(context, srcRect, dstRect, srcTexture,
                          Gr1DKernelEffect::kY_Direction, radiusY, sigmaY, cropToRect);
        srcTexture = dstTexture;
        srcRect = dstRect;
        SkTSwap(dstTexture, tempTexture);
    }

    if (scaleFactorX > 1 || scaleFactorY > 1) {
        // Clear one pixel to the right and below, to accommodate bilinear
        // upsampling.
        clearRect = SkIRect::MakeXYWH(srcIRect.fLeft, srcIRect.fBottom,
                                      srcIRect.width() + 1, 1);
        context->clear(&clearRect, 0x0, false);
        clearRect = SkIRect::MakeXYWH(srcIRect.fRight, srcIRect.fTop,
                                      1, srcIRect.height());
        context->clear(&clearRect, 0x0, false);
        SkMatrix matrix;
        matrix.setIDiv(srcTexture->width(), srcTexture->height());
        context->setRenderTarget(dstTexture->asRenderTarget());

        GrPaint paint;
        // FIXME:  this should be mitchell, not bilinear.
        GrTextureParams params(SkShader::kClamp_TileMode, GrTextureParams::kBilerp_FilterMode);
        paint.addColorTextureEffect(srcTexture, matrix, params);

        SkRect dstRect(srcRect);
        scale_rect(&dstRect, (float) scaleFactorX, (float) scaleFactorY);
        context->drawRectToRect(paint, dstRect, srcRect);
        srcRect = dstRect;
        srcTexture = dstTexture;
        SkTSwap(dstTexture, tempTexture);
    }
    if (srcTexture == temp1.texture()) {
        return temp1.detach();
    } else if (srcTexture == temp2.texture()) {
        return temp2.detach();
    } else {
        srcTexture->ref();
        return srcTexture;
    }
}