C++ SkIRect::y方法代码示例

// This function is used to scale an image and extract a scaled fragment.
//
// ALGORITHM
//
// Because the scaled image size has to be integers, we approximate the real
// scale with the following formula (only X direction is shown):
//
// scaledImageWidth = round(scaleX * imageRect.width())
// approximateScaleX = scaledImageWidth / imageRect.width()
//
// With this method we maintain a constant scale factor among fragments in
// the scaled image. This allows fragments to stitch together to form the
// full scaled image. The downside is there will be a small difference
// between |scaleX| and |approximateScaleX|.
//
// A scaled image fragment is identified by:
//
// - Scaled image size
// - Scaled image fragment rectangle (IntRect)
//
// Scaled image size has been determined and the next step is to compute the
// rectangle for the scaled image fragment which needs to be an IntRect.
//
// scaledSrcRect = srcRect * (approximateScaleX, approximateScaleY)
// enclosingScaledSrcRect = enclosingIntRect(scaledSrcRect)
//
// Finally we extract the scaled image fragment using
// (scaledImageSize, enclosingScaledSrcRect).
//
SkBitmap NativeImageSkia::extractScaledImageFragment(const SkRect& srcRect, float scaleX, float scaleY, SkRect* scaledSrcRect) const
{
    SkISize imageSize = SkISize::Make(bitmap().width(), bitmap().height());
    SkISize scaledImageSize = SkISize::Make(clampToInteger(roundf(imageSize.width() * scaleX)),
        clampToInteger(roundf(imageSize.height() * scaleY)));

    SkRect imageRect = SkRect::MakeWH(imageSize.width(), imageSize.height());
    SkRect scaledImageRect = SkRect::MakeWH(scaledImageSize.width(), scaledImageSize.height());

    SkMatrix scaleTransform;
    scaleTransform.setRectToRect(imageRect, scaledImageRect, SkMatrix::kFill_ScaleToFit);
    scaleTransform.mapRect(scaledSrcRect, srcRect);

    bool ok = scaledSrcRect->intersect(scaledImageRect);
    ASSERT_UNUSED(ok, ok);
    SkIRect enclosingScaledSrcRect = enclosingIntRect(*scaledSrcRect);

    // |enclosingScaledSrcRect| can be larger than |scaledImageSize| because
    // of float inaccuracy so clip to get inside.
    ok = enclosingScaledSrcRect.intersect(SkIRect::MakeSize(scaledImageSize));
    ASSERT_UNUSED(ok, ok);

    // scaledSrcRect is relative to the pixel snapped fragment we're extracting.
    scaledSrcRect->offset(-enclosingScaledSrcRect.x(), -enclosingScaledSrcRect.y());

    return resizedBitmap(scaledImageSize, enclosingScaledSrcRect);
}

bool SkPixmap::readPixels(const SkImageInfo& requestedDstInfo, void* dstPixels, size_t dstRB,
                          int x, int y) const {
    if (kUnknown_SkColorType == requestedDstInfo.colorType()) {
        return false;
    }
    if (nullptr == dstPixels || dstRB < requestedDstInfo.minRowBytes()) {
        return false;
    }
    if (0 == requestedDstInfo.width() || 0 == requestedDstInfo.height()) {
        return false;
    }
    
    SkIRect srcR = SkIRect::MakeXYWH(x, y, requestedDstInfo.width(), requestedDstInfo.height());
    if (!srcR.intersect(0, 0, this->width(), this->height())) {
        return false;
    }
    
    // the intersect may have shrunk info's logical size
    const SkImageInfo dstInfo = requestedDstInfo.makeWH(srcR.width(), srcR.height());
    
    // if x or y are negative, then we have to adjust pixels
    if (x > 0) {
        x = 0;
    }
    if (y > 0) {
        y = 0;
    }
    // here x,y are either 0 or negative
    dstPixels = ((char*)dstPixels - y * dstRB - x * dstInfo.bytesPerPixel());

    const SkImageInfo srcInfo = this->info().makeWH(dstInfo.width(), dstInfo.height());
    const void* srcPixels = this->addr(srcR.x(), srcR.y());
    return SkPixelInfo::CopyPixels(dstInfo, dstPixels, dstRB,
                                   srcInfo, srcPixels, this->rowBytes(), this->ctable());
}

bool SkMagnifierImageFilter::asFragmentProcessor(GrFragmentProcessor** fp,
                                                 GrProcessorDataManager* procDataManager,
                                                 GrTexture* texture, const SkMatrix&,
                                                 const SkIRect&bounds) const {
    if (fp) {
        SkScalar yOffset = texture->origin() == kTopLeft_GrSurfaceOrigin ? fSrcRect.y() :
           texture->height() - fSrcRect.height() * texture->height() / bounds.height()
                             - fSrcRect.y();
        int boundsY = (texture->origin() == kTopLeft_GrSurfaceOrigin) ? bounds.y() :
                      (texture->height() - bounds.height());
        SkRect effectBounds = SkRect::MakeXYWH(
            SkIntToScalar(bounds.x()) / texture->width(),
            SkIntToScalar(boundsY) / texture->height(),
            SkIntToScalar(texture->width()) / bounds.width(),
            SkIntToScalar(texture->height()) / bounds.height());
        SkScalar invInset = fInset > 0 ? SkScalarInvert(fInset) : SK_Scalar1;
        *fp = GrMagnifierEffect::Create(procDataManager,
                                        texture,
                                        effectBounds,
                                        fSrcRect.x() / texture->width(),
                                        yOffset / texture->height(),
                                        fSrcRect.width() / bounds.width(),
                                        fSrcRect.height() / bounds.height(),
                                        bounds.width() * invInset,
                                        bounds.height() * invInset);
    }
    return true;
}

bool SkWritePixelsRec::trim(int dstWidth, int dstHeight) {
    if (nullptr == fPixels || fRowBytes < fInfo.minRowBytes()) {
        return false;
    }
    if (0 >= fInfo.width() || 0 >= fInfo.height()) {
        return false;
    }

    int x = fX;
    int y = fY;
    SkIRect dstR = SkIRect::MakeXYWH(x, y, fInfo.width(), fInfo.height());
    if (!dstR.intersect(0, 0, dstWidth, dstHeight)) {
        return false;
    }

    // if x or y are negative, then we have to adjust pixels
    if (x > 0) {
        x = 0;
    }
    if (y > 0) {
        y = 0;
    }
    // here x,y are either 0 or negative
    fPixels = ((const char*)fPixels - y * fRowBytes - x * fInfo.bytesPerPixel());
    // the intersect may have shrunk info's logical size
    fInfo = fInfo.makeWH(dstR.width(), dstR.height());
    fX = dstR.x();
    fY = dstR.y();

    return true;
}

 void updateHandle(Handle hndl, const SkMatrix& ctm, const SkIRect& clip) override {
     CGContextRef cg = (CGContextRef)hndl;
     
     CGContextRestoreGState(cg);
     CGContextSaveGState(cg);
     CGContextClipToRect(cg, CGRectMake(clip.x(), clip.y(), clip.width(), clip.height()));
     CGContextConcatCTM(cg, matrix_to_transform(cg, ctm));
 }

// Much of readPixels is exercised by copyTo testing, since readPixels is the backend for that
// method. Here we explicitly test subset copies.
//
DEF_TEST(BitmapReadPixels, reporter) {
    const int W = 4;
    const int H = 4;
    const size_t rowBytes = W * sizeof(SkPMColor);
    const SkImageInfo srcInfo = SkImageInfo::MakeN32Premul(W, H);
    SkPMColor srcPixels[16];
    fill_4x4_pixels(srcPixels);
    SkBitmap srcBM;
    srcBM.installPixels(srcInfo, srcPixels, rowBytes);

    SkImageInfo dstInfo = SkImageInfo::MakeN32Premul(W, H);
    SkPMColor dstPixels[16];

    const struct {
        bool     fExpectedSuccess;
        SkIPoint fRequestedSrcLoc;
        SkISize  fRequestedDstSize;
        // If fExpectedSuccess, check these, otherwise ignore
        SkIPoint fExpectedDstLoc;
        SkIRect  fExpectedSrcR;
    } gRec[] = {
        { true,  { 0, 0 }, { 4, 4 }, { 0, 0 }, { 0, 0, 4, 4 } },
        { true,  { 1, 1 }, { 2, 2 }, { 0, 0 }, { 1, 1, 3, 3 } },
        { true,  { 2, 2 }, { 4, 4 }, { 0, 0 }, { 2, 2, 4, 4 } },
        { true,  {-1,-1 }, { 2, 2 }, { 1, 1 }, { 0, 0, 1, 1 } },
        { false, {-1,-1 }, { 1, 1 }, { 0, 0 }, { 0, 0, 0, 0 } },
    };

    for (size_t i = 0; i < SK_ARRAY_COUNT(gRec); ++i) {
        clear_4x4_pixels(dstPixels);

        dstInfo = dstInfo.makeWH(gRec[i].fRequestedDstSize.width(),
                                 gRec[i].fRequestedDstSize.height());
        bool success = srcBM.readPixels(dstInfo, dstPixels, rowBytes,
                                        gRec[i].fRequestedSrcLoc.x(), gRec[i].fRequestedSrcLoc.y());

        REPORTER_ASSERT(reporter, gRec[i].fExpectedSuccess == success);
        if (success) {
            const SkIRect srcR = gRec[i].fExpectedSrcR;
            const int dstX = gRec[i].fExpectedDstLoc.x();
            const int dstY = gRec[i].fExpectedDstLoc.y();
            // Walk the dst pixels, and check if we got what we expected
            for (int y = 0; y < H; ++y) {
                for (int x = 0; x < W; ++x) {
                    SkPMColor dstC = dstPixels[y*4+x];
                    // get into src coordinates
                    int sx = x - dstX + srcR.x();
                    int sy = y - dstY + srcR.y();
                    if (srcR.contains(sx, sy)) {
                        REPORTER_ASSERT(reporter, check_4x4_pixel(dstC, sx, sy));
                    } else {
                        REPORTER_ASSERT(reporter, 0 == dstC);
                    }
                }
            }
        }
    }
}

// Return true if the rectangle is aligned to integer boundaries.
// See comments for computeBitmapDrawRects() for how this is used.
static bool areBoundariesIntegerAligned(const SkRect& rect)
{
    // Value is 1.19209e-007. This is the tolerance threshold.
    const float epsilon = std::numeric_limits<float>::epsilon();
    SkIRect roundedRect = roundedIntRect(rect);

    return fabs(rect.x() - roundedRect.x()) < epsilon
        && fabs(rect.y() - roundedRect.y()) < epsilon
        && fabs(rect.right() - roundedRect.right()) < epsilon
        && fabs(rect.bottom() - roundedRect.bottom()) < epsilon;
}

static void make_unstretched_key(GrUniqueKey* key, uint32_t imageID, const SkIRect& subset) {
    SkASSERT(SkIsU16(subset.width()));
    SkASSERT(SkIsU16(subset.height()));

    static const GrUniqueKey::Domain kDomain = GrUniqueKey::GenerateDomain();
    GrUniqueKey::Builder builder(key, kDomain, 4);
    builder[0] = imageID;
    builder[1] = subset.x();
    builder[2] = subset.y();
    builder[3] = subset.width() | (subset.height() << 16);
}

sk_sp<SkImage> SkImage_Generator::onMakeSubset(const SkIRect& subset) const {
    // TODO: make this lazy, by wrapping the subset inside a new generator or something
    // For now, we do effectively what we did before, make it a raster

    const SkImageInfo info = SkImageInfo::MakeN32(subset.width(), subset.height(),
                                      this->isOpaque() ? kOpaque_SkAlphaType : kPremul_SkAlphaType);
    auto surface(SkSurface::MakeRaster(info));
    if (!surface) {
        return nullptr;
    }
    surface->getCanvas()->clear(0);
    surface->getCanvas()->drawImage(this, SkIntToScalar(-subset.x()), SkIntToScalar(-subset.y()),
                                    nullptr);
    return surface->makeImageSnapshot();
}

bool SkBlurImageFilter::filterImageGPUDeprecated(Proxy* proxy, const SkBitmap& src,
                                                 const Context& ctx,
                                                 SkBitmap* result, SkIPoint* offset) const {
#if SK_SUPPORT_GPU
    SkBitmap input = src;
    SkIPoint srcOffset = SkIPoint::Make(0, 0);
    if (!this->filterInputGPUDeprecated(0, proxy, src, ctx, &input, &srcOffset)) {
        return false;
    }
    SkIRect srcBounds = input.bounds();
    srcBounds.offset(srcOffset);
    SkIRect dstBounds;
    if (!this->applyCropRect(this->mapContext(ctx), srcBounds, &dstBounds)) {
        return false;
    }
    if (!srcBounds.intersect(dstBounds)) {
        return false;
    }
    SkVector sigma = map_sigma(fSigma, ctx.ctm());
    if (sigma.x() == 0 && sigma.y() == 0) {
        input.extractSubset(result, srcBounds);
        offset->fX = srcBounds.x();
        offset->fY = srcBounds.y();
        return true;
    }
    offset->fX = dstBounds.fLeft;
    offset->fY = dstBounds.fTop;
    srcBounds.offset(-srcOffset);
    dstBounds.offset(-srcOffset);
    SkRect srcBoundsF(SkRect::Make(srcBounds));
    GrTexture* inputTexture = input.getTexture();
    SkAutoTUnref<GrTexture> tex(SkGpuBlurUtils::GaussianBlur(inputTexture->getContext(),
                                                             inputTexture,
                                                             false,
                                                             SkRect::Make(dstBounds),
                                                             &srcBoundsF,
                                                             sigma.x(),
                                                             sigma.y()));
    if (!tex) {
        return false;
    }
    GrWrapTextureInBitmap(tex, dstBounds.width(), dstBounds.height(), false, result);
    return true;
#else
    SkDEBUGFAIL("Should not call in GPU-less build");
    return false;
#endif
}

GrAlphaThresholdFragmentProcessor::GrAlphaThresholdFragmentProcessor(GrTexture* texture,
                                                                     GrTexture* maskTexture,
                                                                     float innerThreshold,
                                                                     float outerThreshold,
                                                                     const SkIRect& bounds)
    : fInnerThreshold(innerThreshold)
    , fOuterThreshold(outerThreshold)
    , fImageCoordTransform(kLocal_GrCoordSet,
                           GrCoordTransform::MakeDivByTextureWHMatrix(texture), texture,
                           GrTextureParams::kNone_FilterMode)
    , fImageTextureAccess(texture)
    , fMaskCoordTransform(kLocal_GrCoordSet,
                          make_div_and_translate_matrix(maskTexture, -bounds.x(), -bounds.y()),
                          maskTexture,
                          GrTextureParams::kNone_FilterMode)
    , fMaskTextureAccess(maskTexture) {
    this->initClassID<GrAlphaThresholdFragmentProcessor>();
    this->addCoordTransform(&fImageCoordTransform);
    this->addTextureAccess(&fImageTextureAccess);
    this->addCoordTransform(&fMaskCoordTransform);
    this->addTextureAccess(&fMaskTextureAccess);
}

SkImage* SkImage_Base::onApplyFilter(SkImageFilter* filter, SkIPoint* offsetResult,
                                     bool forceResultToOriginalSize) const {
    SkBitmap src;
    if (!this->getROPixels(&src)) {
        return nullptr;
    }

    const SkIRect srcBounds = SkIRect::MakeWH(this->width(), this->height());

    if (forceResultToOriginalSize) {
        const SkIRect clipBounds = srcBounds;
        SkRasterImageFilterProxy proxy;
        SkImageFilter::Context ctx(SkMatrix::I(), clipBounds, SkImageFilter::Cache::Get(),
                                   SkImageFilter::kExact_SizeConstraint);

        SkBitmap dst;
        if (filter->filterImage(&proxy, src, ctx, &dst, offsetResult)) {
            dst.setImmutable();
            return SkImage::NewFromBitmap(dst);
        }
    } else {
        const SkIRect dstR = compute_fast_ibounds(filter, srcBounds);

        SkImageInfo info = SkImageInfo::MakeN32Premul(dstR.width(), dstR.height());
        SkAutoTUnref<SkSurface> surface(this->onNewSurface(info));

        SkPaint paint;
        paint.setImageFilter(filter);
        surface->getCanvas()->drawImage(this, SkIntToScalar(-dstR.x()), SkIntToScalar(-dstR.y()),
                                        &paint);

        offsetResult->set(dstR.x(), dstR.y());
        return surface->newImageSnapshot();
    }
    return nullptr;
}

bool SkJPEGImageDecoder::onDecodeRegion(SkBitmap* bm, SkIRect region) {
    if (index == NULL) {
        return false;
    }
    jpeg_decompress_struct *cinfo = index->cinfo;

    SkIRect rect = SkIRect::MakeWH(this->imageWidth, this->imageHeight);
    if (!rect.intersect(region)) {
        // If the requested region is entirely outsides the image, just
        // returns false
        return false;
    }
    SkAutoMalloc  srcStorage;
    skjpeg_error_mgr        sk_err;
    cinfo->err = jpeg_std_error(&sk_err);
    sk_err.error_exit = skjpeg_error_exit;
    if (setjmp(sk_err.fJmpBuf)) {
        return false;
    }
    int requestedSampleSize = this->getSampleSize();
    cinfo->scale_denom = requestedSampleSize;

    if (this->getPreferQualityOverSpeed()) {
        cinfo->dct_method = JDCT_ISLOW;
    } else {
        cinfo->dct_method = JDCT_IFAST;
    }

    SkBitmap::Config config = this->getPrefConfig(k32Bit_SrcDepth, false);
    if (config != SkBitmap::kARGB_8888_Config &&
        config != SkBitmap::kARGB_4444_Config &&
        config != SkBitmap::kRGB_565_Config) {
        config = SkBitmap::kARGB_8888_Config;
    }

    /* default format is RGB */
    cinfo->out_color_space = JCS_RGB;

#ifdef ANDROID_RGB
    cinfo->dither_mode = JDITHER_NONE;
    if (config == SkBitmap::kARGB_8888_Config) {
        cinfo->out_color_space = JCS_RGBA_8888;
    } else if (config == SkBitmap::kRGB_565_Config) {
        cinfo->out_color_space = JCS_RGB_565;
        if (this->getDitherImage()) {
            cinfo->dither_mode = JDITHER_ORDERED;
        }
    }
#endif
    int startX = rect.fLeft;
    int startY = rect.fTop;
    int width = rect.width();
    int height = rect.height();

    jpeg_init_read_tile_scanline(cinfo, index->index,
                                 &startX, &startY, &width, &height);
    int skiaSampleSize = recompute_sampleSize(requestedSampleSize, *cinfo);
    int actualSampleSize = skiaSampleSize * (DCTSIZE / cinfo->min_DCT_scaled_size);

    SkBitmap *bitmap = new SkBitmap;
    SkAutoTDelete<SkBitmap> adb(bitmap);

#ifdef ANDROID_RGB
    /* short-circuit the SkScaledBitmapSampler when possible, as this gives
       a significant performance boost.
    */
    if (skiaSampleSize == 1 &&
        ((config == SkBitmap::kARGB_8888_Config &&
                cinfo->out_color_space == JCS_RGBA_8888) ||
        (config == SkBitmap::kRGB_565_Config &&
                cinfo->out_color_space == JCS_RGB_565)))
    {
        bitmap->setConfig(config, cinfo->output_width, height);
        bitmap->setIsOpaque(true);

        // Check ahead of time if the swap(dest, src) is possible or not.
        // If yes, then we will stick to AllocPixelRef since it's cheaper
        // with the swap happening. If no, then we will use alloc to allocate
        // pixels to prevent garbage collection.
        //
        // Not using a recycled-bitmap and the output rect is same as the
        // decoded region.
        int w = rect.width() / actualSampleSize;
        int h = rect.height() / actualSampleSize;
        bool swapOnly = (rect == region) && bm->isNull() &&
                        (w == bitmap->width()) && (h == bitmap->height()) &&
                        ((startX - rect.x()) / actualSampleSize == 0) &&
                        ((startY - rect.y()) / actualSampleSize == 0);
        if (swapOnly) {
            if (!this->allocPixelRef(bitmap, NULL)) {
                return return_false(*cinfo, *bitmap, "allocPixelRef");
            }
        } else {
            if (!bitmap->allocPixels()) {
                return return_false(*cinfo, *bitmap, "allocPixels");
            }
        }

        SkAutoLockPixels alp(*bitmap);
        JSAMPLE* rowptr = (JSAMPLE*)bitmap->getPixels();
//.........这里部分代码省略.........

bool SkDisplacementMapEffect::filterImageGPU(Proxy* proxy, const SkBitmap& src, const Context& ctx,
                                             SkBitmap* result, SkIPoint* offset) const {
    SkBitmap colorBM = src;
    SkIPoint colorOffset = SkIPoint::Make(0, 0);
    if (getColorInput() && !getColorInput()->getInputResultGPU(proxy, src, ctx, &colorBM,
                                                               &colorOffset)) {
        return false;
    }
    SkBitmap displacementBM = src;
    SkIPoint displacementOffset = SkIPoint::Make(0, 0);
    if (getDisplacementInput() &&
        !getDisplacementInput()->getInputResultGPU(proxy, src, ctx, &displacementBM,
                                                   &displacementOffset)) {
        return false;
    }
    SkIRect bounds;
    // Since GrDisplacementMapEffect does bounds checking on color pixel access, we don't need to
    // pad the color bitmap to bounds here.
    if (!this->applyCropRect(ctx, colorBM, colorOffset, &bounds)) {
        return false;
    }
    SkIRect displBounds;
    if (!this->applyCropRect(ctx, proxy, displacementBM,
                             &displacementOffset, &displBounds, &displacementBM)) {
        return false;
    }
    if (!bounds.intersect(displBounds)) {
        return false;
    }
    GrTexture* color = colorBM.getTexture();
    GrTexture* displacement = displacementBM.getTexture();
    GrContext* context = color->getContext();

    GrSurfaceDesc desc;
    desc.fFlags = kRenderTarget_GrSurfaceFlag;
    desc.fWidth = bounds.width();
    desc.fHeight = bounds.height();
    desc.fConfig = kSkia8888_GrPixelConfig;

    SkAutoTUnref<GrTexture> dst(
        context->refScratchTexture(desc, GrContext::kApprox_ScratchTexMatch));

    if (!dst) {
        return false;
    }

    SkVector scale = SkVector::Make(fScale, fScale);
    ctx.ctm().mapVectors(&scale, 1);

    GrPaint paint;
    SkMatrix offsetMatrix = GrCoordTransform::MakeDivByTextureWHMatrix(displacement);
    offsetMatrix.preTranslate(SkIntToScalar(colorOffset.fX - displacementOffset.fX),
                              SkIntToScalar(colorOffset.fY - displacementOffset.fY));

    paint.addColorProcessor(
        GrDisplacementMapEffect::Create(fXChannelSelector,
                                        fYChannelSelector,
                                        scale,
                                        displacement,
                                        offsetMatrix,
                                        color,
                                        colorBM.dimensions()))->unref();
    SkIRect colorBounds = bounds;
    colorBounds.offset(-colorOffset);
    SkMatrix matrix;
    matrix.setTranslate(-SkIntToScalar(colorBounds.x()),
                        -SkIntToScalar(colorBounds.y()));
    context->drawRect(dst->asRenderTarget(), GrClip::WideOpen(), paint, matrix,
                      SkRect::Make(colorBounds));
    offset->fX = bounds.left();
    offset->fY = bounds.top();
    WrapTexture(dst, bounds.width(), bounds.height(), result);
    return true;
}

sk_sp<SkSpecialImage> SkDisplacementMapEffect::onFilterImage(SkSpecialImage* source,
                                                             const Context& ctx,
                                                             SkIPoint* offset) const {
    SkIPoint colorOffset = SkIPoint::Make(0, 0);
    sk_sp<SkSpecialImage> color(this->filterInput(1, source, ctx, &colorOffset));
    if (!color) {
        return nullptr;
    }

    SkIPoint displOffset = SkIPoint::Make(0, 0);
    sk_sp<SkSpecialImage> displ(this->filterInput(0, source, ctx, &displOffset));
    if (!displ) {
        return nullptr;
    }

    const SkIRect srcBounds = SkIRect::MakeXYWH(colorOffset.x(), colorOffset.y(),
                                                color->width(), color->height());

    // Both paths do bounds checking on color pixel access, we don't need to
    // pad the color bitmap to bounds here.
    SkIRect bounds;
    if (!this->applyCropRect(ctx, srcBounds, &bounds)) {
        return nullptr;
    }

    SkIRect displBounds;
    displ = this->applyCropRect(ctx, displ.get(), &displOffset, &displBounds);
    if (!displ) {
        return nullptr;
    }

    if (!bounds.intersect(displBounds)) {
        return nullptr;
    }

    const SkIRect colorBounds = bounds.makeOffset(-colorOffset.x(), -colorOffset.y());

    SkVector scale = SkVector::Make(fScale, fScale);
    ctx.ctm().mapVectors(&scale, 1);

#if SK_SUPPORT_GPU
    if (source->isTextureBacked()) {
        GrContext* context = source->getContext();

        sk_sp<GrTexture> colorTexture(color->asTextureRef(context));
        sk_sp<GrTexture> displTexture(displ->asTextureRef(context));
        if (!colorTexture || !displTexture) {
            return nullptr;
        }

        GrSurfaceDesc desc;
        desc.fFlags = kRenderTarget_GrSurfaceFlag;
        desc.fWidth = bounds.width();
        desc.fHeight = bounds.height();
        desc.fConfig = kSkia8888_GrPixelConfig;

        SkAutoTUnref<GrTexture> dst(context->textureProvider()->createApproxTexture(desc));
        if (!dst) {
            return nullptr;
        }

        GrPaint paint;
        SkMatrix offsetMatrix = GrCoordTransform::MakeDivByTextureWHMatrix(displTexture.get());
        offsetMatrix.preTranslate(SkIntToScalar(colorOffset.fX - displOffset.fX),
                                  SkIntToScalar(colorOffset.fY - displOffset.fY));

        paint.addColorFragmentProcessor(
            GrDisplacementMapEffect::Create(fXChannelSelector,
                                            fYChannelSelector,
                                            scale,
                                            displTexture.get(),
                                            offsetMatrix,
                                            colorTexture.get(),
                                            SkISize::Make(color->width(),
                                                          color->height())))->unref();
        paint.setPorterDuffXPFactory(SkXfermode::kSrc_Mode);
        SkMatrix matrix;
        matrix.setTranslate(-SkIntToScalar(colorBounds.x()), -SkIntToScalar(colorBounds.y()));

        SkAutoTUnref<GrDrawContext> drawContext(context->drawContext(dst->asRenderTarget()));
        if (!drawContext) {
            return nullptr;
        }

        drawContext->drawRect(GrClip::WideOpen(), paint, matrix, SkRect::Make(colorBounds));

        offset->fX = bounds.left();
        offset->fY = bounds.top();
        return SkSpecialImage::MakeFromGpu(SkIRect::MakeWH(bounds.width(), bounds.height()),
                                           kNeedNewImageUniqueID_SpecialImage,
                                           dst);
    }
#endif

    SkBitmap colorBM, displBM;

    if (!color->getROPixels(&colorBM) || !displ->getROPixels(&displBM)) {
        return nullptr;
    }

//.........这里部分代码省略.........