C++ SkMatrix::preTranslate方法代码示例

void SkSVGDevice::drawSprite(const SkDraw& draw, const SkBitmap& bitmap,
                             int x, int y, const SkPaint& paint) {
    SkMatrix adjustedMatrix = *draw.fMatrix;
    adjustedMatrix.preTranslate(SkIntToScalar(x), SkIntToScalar(y));
    SkDraw adjustedDraw(draw);
    adjustedDraw.fMatrix = &adjustedMatrix;

    drawBitmapCommon(adjustedDraw, bitmap, paint);
}

bool SkLayerRasterizer::onRasterize(const SkPath& path, const SkMatrix& matrix,
                                    const SkIRect* clipBounds,
                                    SkMask* mask, SkMask::CreateMode mode) const {
    SkASSERT(fLayers);
    if (fLayers->empty()) {
        return false;
    }

    if (SkMask::kJustRenderImage_CreateMode != mode) {
        if (!compute_bounds(*fLayers, path, matrix, clipBounds, &mask->fBounds))
            return false;
    }

    if (SkMask::kComputeBoundsAndRenderImage_CreateMode == mode) {
        mask->fFormat   = SkMask::kA8_Format;
        mask->fRowBytes = mask->fBounds.width();
        size_t size = mask->computeImageSize();
        if (0 == size) {
            return false;   // too big to allocate, abort
        }
        mask->fImage = SkMask::AllocImage(size);
        memset(mask->fImage, 0, size);
    }

    if (SkMask::kJustComputeBounds_CreateMode != mode) {
        SkBitmap        device;
        SkRasterClip    rectClip;
        SkDraw          draw;
        SkMatrix        translatedMatrix;  // this translates us to our local pixels
        SkMatrix        drawMatrix;        // this translates the path by each layer's offset

        rectClip.setRect(SkIRect::MakeWH(mask->fBounds.width(), mask->fBounds.height()));

        translatedMatrix = matrix;
        translatedMatrix.postTranslate(-SkIntToScalar(mask->fBounds.fLeft),
                                       -SkIntToScalar(mask->fBounds.fTop));

        device.installMaskPixels(*mask);

        draw.fBitmap    = &device;
        draw.fMatrix    = &drawMatrix;
        draw.fRC        = &rectClip;
        draw.fClip      = &rectClip.bwRgn();
        // we set the matrixproc in the loop, as the matrix changes each time (potentially)

        SkDeque::F2BIter        iter(*fLayers);
        SkLayerRasterizer_Rec*  rec;

        while ((rec = (SkLayerRasterizer_Rec*)iter.next()) != NULL) {
            drawMatrix = translatedMatrix;
            drawMatrix.preTranslate(rec->fOffset.fX, rec->fOffset.fY);
            draw.drawPath(path, rec->fPaint);
        }
    }
    return true;
}

bool SkLayerRasterizer::onRasterize(const SkPath& path, const SkMatrix& matrix,
                                    const SkIRect* clipBounds,
                                    SkMask* mask, SkMask::CreateMode mode)
{
    if (fLayers.empty())
        return false;

    if (SkMask::kJustRenderImage_CreateMode != mode)
    {
        if (!compute_bounds(fLayers, path, matrix, clipBounds, &mask->fBounds))
            return false;
    }

    if (SkMask::kComputeBoundsAndRenderImage_CreateMode == mode)
    {
        mask->fFormat   = SkMask::kA8_Format;
        mask->fRowBytes = SkToU16(mask->fBounds.width());
        mask->fImage = SkMask::AllocImage(mask->computeImageSize());
        memset(mask->fImage, 0, mask->computeImageSize());
    }

    if (SkMask::kJustComputeBounds_CreateMode != mode)
    {    
        SkBitmap device;
        SkDraw   draw;
        SkMatrix translatedMatrix;  // this translates us to our local pixels
        SkMatrix drawMatrix;        // this translates the path by each layer's offset
        SkRegion rectClip;
        
        rectClip.setRect(0, 0, mask->fBounds.width(), mask->fBounds.height());

        translatedMatrix = matrix;
        translatedMatrix.postTranslate(-SkIntToScalar(mask->fBounds.fLeft),
                                       -SkIntToScalar(mask->fBounds.fTop));

        device.setConfig(SkBitmap::kA8_Config, mask->fBounds.width(), mask->fBounds.height(), mask->fRowBytes);
        device.setPixels(mask->fImage);

        draw.fBitmap    = &device;
        draw.fMatrix    = &drawMatrix;
        draw.fClip      = &rectClip;
        // we set the matrixproc in the loop, as the matrix changes each time (potentially)
        draw.fBounder   = NULL;
        
        SkDeque::Iter           iter(fLayers);
        SkLayerRasterizer_Rec*  rec;

        while ((rec = (SkLayerRasterizer_Rec*)iter.next()) != NULL) {
            drawMatrix = translatedMatrix;
            drawMatrix.preTranslate(rec->fOffset.fX, rec->fOffset.fY);
            draw.drawPath(path, rec->fPaint);
        }
    }
    return true;
}

static SkBitmap make_bmp(int w, int h) {
    SkBitmap bmp;
    bmp.allocN32Pixels(w, h, true);

    SkCanvas canvas(bmp);
    SkScalar wScalar = SkIntToScalar(w);
    SkScalar hScalar = SkIntToScalar(h);

    SkPoint     pt = { wScalar / 2, hScalar / 2 };

    SkScalar    radius = 3 * SkMaxScalar(wScalar, hScalar);

    SkColor     colors[] = { SK_ColorDKGRAY, 0xFF222255,
                             0xFF331133, 0xFF884422,
                             0xFF000022, SK_ColorWHITE,
                             0xFFAABBCC};

    SkScalar    pos[] = {0,
                         SK_Scalar1 / 6,
                         2 * SK_Scalar1 / 6,
                         3 * SK_Scalar1 / 6,
                         4 * SK_Scalar1 / 6,
                         5 * SK_Scalar1 / 6,
                         SK_Scalar1};

    SkPaint paint;
    SkRect rect = SkRect::MakeWH(wScalar, hScalar);
    SkMatrix mat = SkMatrix::I();
    for (int i = 0; i < 4; ++i) {
        paint.setShader(SkGradientShader::CreateRadial(
                        pt, radius,
                        colors, pos,
                        SK_ARRAY_COUNT(colors),
                        SkShader::kRepeat_TileMode,
                        0, &mat))->unref();
        canvas.drawRect(rect, paint);
        rect.inset(wScalar / 8, hScalar / 8);
        mat.preTranslate(6 * wScalar, 6 * hScalar);
        mat.postScale(SK_Scalar1 / 3, SK_Scalar1 / 3);
    }

    paint.setAntiAlias(true);
    sk_tool_utils::set_portable_typeface(&paint);
    paint.setTextSize(wScalar / 2.2f);
    paint.setShader(0);
    paint.setColor(SK_ColorLTGRAY);
    static const char kTxt[] = "Skia";
    SkPoint texPos = { wScalar / 17, hScalar / 2 + paint.getTextSize() / 2.5f };
    canvas.drawText(kTxt, SK_ARRAY_COUNT(kTxt)-1, texPos.fX, texPos.fY, paint);
    paint.setColor(SK_ColorBLACK);
    paint.setStyle(SkPaint::kStroke_Style);
    paint.setStrokeWidth(SK_Scalar1);
    canvas.drawText(kTxt, SK_ARRAY_COUNT(kTxt)-1, texPos.fX, texPos.fY, paint);
    return bmp;
}

void GrLayerHoister::DrawLayersToAtlas(GrContext* context,
                                       const SkTDArray<GrHoistedLayer>& atlased) {
    if (atlased.count() > 0) {
        // All the atlased layers are rendered into the same GrTexture
        SkAutoTUnref<SkSurface> surface(SkSurface::NewRenderTargetDirect(
                                        atlased[0].fLayer->texture()->asRenderTarget(), NULL));

        SkCanvas* atlasCanvas = surface->getCanvas();

        SkPaint clearPaint;
        clearPaint.setColor(SK_ColorTRANSPARENT);
        clearPaint.setXfermode(SkXfermode::Create(SkXfermode::kSrc_Mode))->unref();

        for (int i = 0; i < atlased.count(); ++i) {
            const GrCachedLayer* layer = atlased[i].fLayer;
            const SkPicture* pict = atlased[i].fPicture;
            const SkIPoint offset = atlased[i].fOffset;
            SkDEBUGCODE(const SkPaint* layerPaint = layer->paint();)

            SkASSERT(!layerPaint || !layerPaint->getImageFilter());

            atlasCanvas->save();

            // Add a rect clip to make sure the rendering doesn't
            // extend beyond the boundaries of the atlased sub-rect
            SkRect bound = SkRect::MakeXYWH(SkIntToScalar(layer->rect().fLeft),
                                            SkIntToScalar(layer->rect().fTop),
                                            SkIntToScalar(layer->rect().width()),
                                            SkIntToScalar(layer->rect().height()));
            atlasCanvas->clipRect(bound);

            // Since 'clear' doesn't respect the clip we need to draw a rect
            atlasCanvas->drawRect(bound, clearPaint);

            // '-offset' maps the layer's top/left to the origin.
            // Since this layer is atlased, the top/left corner needs
            // to be offset to the correct location in the backing texture.
            SkMatrix initialCTM;
            initialCTM.setTranslate(SkIntToScalar(-offset.fX), SkIntToScalar(-offset.fY));
            initialCTM.preTranslate(bound.fLeft, bound.fTop);
            initialCTM.preConcat(atlased[i].fPreMat);

            atlasCanvas->setMatrix(initialCTM);
            atlasCanvas->concat(atlased[i].fLocalMat);

            SkRecordPartialDraw(*pict->fRecord.get(), atlasCanvas, bound,
                                layer->start() + 1, layer->stop(), initialCTM);

            atlasCanvas->restore();
        }

        atlasCanvas->flush();
    }

void GrLayerHoister::DrawLayersToAtlas(GrContext* context,
                                       const SkTDArray<GrHoistedLayer>& atlased) {
    if (atlased.count() > 0) {
        // All the atlased layers are rendered into the same GrTexture
        SkSurfaceProps props(0, kUnknown_SkPixelGeometry);
        SkAutoTUnref<SkSurface> surface(SkSurface::NewRenderTargetDirect(
                                        atlased[0].fLayer->texture()->asRenderTarget(), &props));

        SkCanvas* atlasCanvas = surface->getCanvas();

        for (int i = 0; i < atlased.count(); ++i) {
            const GrCachedLayer* layer = atlased[i].fLayer;
            const SkBigPicture* pict = atlased[i].fPicture->asSkBigPicture();
            if (!pict) {
                // TODO: can we assume / assert this?
                continue;
            }
            const SkIPoint offset = SkIPoint::Make(layer->srcIR().fLeft, layer->srcIR().fTop);
            SkDEBUGCODE(const SkPaint* layerPaint = layer->paint();)

            SkASSERT(!layerPaint || !layerPaint->getImageFilter());
            SkASSERT(!layer->filter());

            atlasCanvas->save();

            // Add a rect clip to make sure the rendering doesn't
            // extend beyond the boundaries of the atlased sub-rect
            const SkRect bound = SkRect::Make(layer->rect());
            atlasCanvas->clipRect(bound);
            atlasCanvas->clear(0);

            // '-offset' maps the layer's top/left to the origin.
            // Since this layer is atlased, the top/left corner needs
            // to be offset to the correct location in the backing texture.
            SkMatrix initialCTM;
            initialCTM.setTranslate(SkIntToScalar(-offset.fX), SkIntToScalar(-offset.fY));
            initialCTM.preTranslate(bound.fLeft, bound.fTop);
            initialCTM.preConcat(atlased[i].fPreMat);

            atlasCanvas->setMatrix(initialCTM);
            atlasCanvas->concat(atlased[i].fLocalMat);

            pict->partialPlayback(atlasCanvas, layer->start() + 1, layer->stop(), initialCTM);
            atlasCanvas->restore();
        }

        atlasCanvas->flush();
    }

////////////////////////////////////////////////////////////////////////////////
// set up the draw state to enable the aa clipping mask. Besides setting up the
// stage matrix this also alters the vertex layout
static const GrFragmentProcessor* create_fp_for_mask(GrTexture* result, const SkIRect &devBound) {
    SkMatrix mat;
    // We use device coords to compute the texture coordinates. We set our matrix to be a
    // translation to the devBound, and then a scaling matrix to normalized coords.
    mat.setIDiv(result->width(), result->height());
    mat.preTranslate(SkIntToScalar(-devBound.fLeft),
                     SkIntToScalar(-devBound.fTop));

    SkIRect domainTexels = SkIRect::MakeWH(devBound.width(), devBound.height());
    return GrTextureDomainEffect::Create(result,
                                         mat,
                                         GrTextureDomain::MakeTexelDomain(result, domainTexels),
                                         GrTextureDomain::kDecal_Mode,
                                         GrTextureParams::kNone_FilterMode,
                                         kDevice_GrCoordSet);
}

void draw(SkCanvas* canvas) {
    SkPaint paint;
    SkPictureRecorder recorder;
    SkCanvas* recordingCanvas = recorder.beginRecording(50, 50);
    for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xff007f00 } ) {
        paint.setColor(color);
        recordingCanvas->drawRect({10, 10, 30, 40}, paint);
        recordingCanvas->translate(10, 10);
        recordingCanvas->scale(1.2f, 1.4f);
    }
    sk_sp<SkPicture> playback = recorder.finishRecordingAsPicture();
    const SkPicture* playbackPtr = playback.get();
    SkMatrix matrix;
    matrix.reset();
    for (auto alpha : { 70, 140, 210 } ) {
    paint.setAlpha(alpha);
    canvas->drawPicture(playbackPtr, &matrix, &paint);
    matrix.preTranslate(70, 70);
    }
}

static void morphpoints(SkPoint dst[], const SkPoint src[], int count,
                        SkPathMeasure& meas, SkScalar dist) {
    for (int i = 0; i < count; i++) {
        SkPoint pos;
        SkVector tangent;
        
        SkScalar sx = src[i].fX;
        SkScalar sy = src[i].fY;
        
        meas.getPosTan(dist + sx, &pos, &tangent);
        
        SkMatrix    matrix;
        SkPoint     pt;
        
        pt.set(sx, sy);
        matrix.setSinCos(tangent.fY, tangent.fX, 0, 0);
        matrix.preTranslate(-sx, 0);
        matrix.postTranslate(pos.fX, pos.fY);
        matrix.mapPoints(&dst[i], &pt, 1);
    }
}

static bool compute_bounds(const SkDeque& layers, const SkPath& path,
                           const SkMatrix& matrix,
                           const SkIRect* clipBounds, SkIRect* bounds) {
    SkDeque::F2BIter        iter(layers);
    SkLayerRasterizer_Rec*  rec;

    bounds->set(SK_MaxS32, SK_MaxS32, SK_MinS32, SK_MinS32);

    while ((rec = (SkLayerRasterizer_Rec*)iter.next()) != NULL) {
        const SkPaint&  paint = rec->fPaint;
        SkPath          fillPath, devPath;
        const SkPath*   p = &path;

        if (paint.getPathEffect() || paint.getStyle() != SkPaint::kFill_Style) {
            paint.getFillPath(path, &fillPath);
            p = &fillPath;
        }
        if (p->isEmpty()) {
            continue;
        }

        // apply the matrix and offset
        {
            SkMatrix m = matrix;
            m.preTranslate(rec->fOffset.fX, rec->fOffset.fY);
            p->transform(m, &devPath);
        }

        SkMask  mask;
        if (!SkDraw::DrawToMask(devPath, clipBounds, paint.getMaskFilter(),
                                &matrix, &mask,
                                SkMask::kJustComputeBounds_CreateMode,
                                SkPaint::kFill_Style)) {
            return false;
        }

        bounds->join(mask.fBounds);
    }
    return true;
}

void GrSWMaskHelper::DrawToTargetWithPathMask(GrTexture* texture,
                                              GrDrawContext* drawContext,
                                              const GrPaint* paint,
                                              const GrUserStencilSettings* userStencilSettings,
                                              const GrClip& clip,
                                              GrColor color,
                                              const SkMatrix& viewMatrix,
                                              const SkIRect& rect) {
    SkMatrix invert;
    if (!viewMatrix.invert(&invert)) {
        return;
    }

    SkRect dstRect = SkRect::MakeLTRB(SK_Scalar1 * rect.fLeft,
                                      SK_Scalar1 * rect.fTop,
                                      SK_Scalar1 * rect.fRight,
                                      SK_Scalar1 * rect.fBottom);

    // We use device coords to compute the texture coordinates. We take the device coords and apply
    // a translation so that the top-left of the device bounds maps to 0,0, and then a scaling
    // matrix to normalized coords.
    SkMatrix maskMatrix;
    maskMatrix.setIDiv(texture->width(), texture->height());
    maskMatrix.preTranslate(SkIntToScalar(-rect.fLeft), SkIntToScalar(-rect.fTop));

    GrPipelineBuilder pipelineBuilder(*paint, drawContext->isUnifiedMultisampled());
    pipelineBuilder.setRenderTarget(drawContext->accessRenderTarget());
    pipelineBuilder.setUserStencil(userStencilSettings);

    pipelineBuilder.addCoverageFragmentProcessor(
                         GrSimpleTextureEffect::Create(texture,
                                                       maskMatrix,
                                                       GrTextureParams::kNone_FilterMode,
                                                       kDevice_GrCoordSet))->unref();

    SkAutoTUnref<GrDrawBatch> batch(GrRectBatchFactory::CreateNonAAFill(color, SkMatrix::I(),
                                                                        dstRect, nullptr, &invert));
    drawContext->drawBatch(pipelineBuilder, clip, batch);
}

void SkBaseDevice::drawTextBlob(const SkDraw& draw, const SkTextBlob* blob, SkScalar x, SkScalar y,
                                const SkPaint &paint) {

    SkMatrix localMatrix;
    SkDraw localDraw(draw);

    if (x || y) {
        localMatrix = *draw.fMatrix;
        localMatrix.preTranslate(x, y);
        localDraw.fMatrix = &localMatrix;
    }

    SkPaint runPaint = paint;
    SkTextBlob::RunIterator it(blob);
    while (!it.done()) {
        size_t textLen = it.glyphCount() * sizeof(uint16_t);
        const SkPoint& offset = it.offset();
        // applyFontToPaint() always overwrites the exact same attributes,
        // so it is safe to not re-seed the paint.
        it.applyFontToPaint(&runPaint);

        switch (it.positioning()) {
        case SkTextBlob::kDefault_Positioning:
            this->drawText(localDraw, it.glyphs(), textLen, offset.x(), offset.y(), runPaint);
            break;
        case SkTextBlob::kHorizontal_Positioning:
        case SkTextBlob::kFull_Positioning:
            this->drawPosText(localDraw, it.glyphs(), textLen, it.pos(), offset.y(),
                              SkTextBlob::ScalarsPerGlyph(it.positioning()), runPaint);
            break;
        default:
            SkFAIL("unhandled positioning mode");
        }

        it.next();
    }
}

SkPDFImageShader::SkPDFImageShader(SkPDFShader::State* state) : fState(state) {
    fState.get()->fImage.lockPixels();

    SkMatrix finalMatrix = fState.get()->fCanvasTransform;
    finalMatrix.preConcat(fState.get()->fShaderTransform);
    SkRect surfaceBBox;
    surfaceBBox.set(fState.get()->fBBox);
    transformBBox(finalMatrix, &surfaceBBox);

    SkMatrix unflip;
    unflip.setTranslate(0, SkScalarRound(surfaceBBox.height()));
    unflip.preScale(SK_Scalar1, -SK_Scalar1);
    SkISize size = SkISize::Make(SkScalarRound(surfaceBBox.width()),
                                 SkScalarRound(surfaceBBox.height()));
    SkPDFDevice pattern(size, size, unflip);
    SkCanvas canvas(&pattern);
    canvas.translate(-surfaceBBox.fLeft, -surfaceBBox.fTop);
    finalMatrix.preTranslate(surfaceBBox.fLeft, surfaceBBox.fTop);

    const SkBitmap* image = &fState.get()->fImage;
    int width = image->width();
    int height = image->height();
    SkShader::TileMode tileModes[2];
    tileModes[0] = fState.get()->fImageTileModes[0];
    tileModes[1] = fState.get()->fImageTileModes[1];

    canvas.drawBitmap(*image, 0, 0);
    SkRect patternBBox = SkRect::MakeXYWH(-surfaceBBox.fLeft, -surfaceBBox.fTop,
                                          width, height);

    // Tiling is implied.  First we handle mirroring.
    if (tileModes[0] == SkShader::kMirror_TileMode) {
        SkMatrix xMirror;
        xMirror.setScale(-1, 1);
        xMirror.postTranslate(2 * width, 0);
        canvas.drawBitmapMatrix(*image, xMirror);
        patternBBox.fRight += width;
    }
    if (tileModes[1] == SkShader::kMirror_TileMode) {
        SkMatrix yMirror;
        yMirror.setScale(SK_Scalar1, -SK_Scalar1);
        yMirror.postTranslate(0, 2 * height);
        canvas.drawBitmapMatrix(*image, yMirror);
        patternBBox.fBottom += height;
    }
    if (tileModes[0] == SkShader::kMirror_TileMode &&
            tileModes[1] == SkShader::kMirror_TileMode) {
        SkMatrix mirror;
        mirror.setScale(-1, -1);
        mirror.postTranslate(2 * width, 2 * height);
        canvas.drawBitmapMatrix(*image, mirror);
    }

    // Then handle Clamping, which requires expanding the pattern canvas to
    // cover the entire surfaceBBox.

    // If both x and y are in clamp mode, we start by filling in the corners.
    // (Which are just a rectangles of the corner colors.)
    if (tileModes[0] == SkShader::kClamp_TileMode &&
            tileModes[1] == SkShader::kClamp_TileMode) {
        SkPaint paint;
        SkRect rect;
        rect = SkRect::MakeLTRB(surfaceBBox.fLeft, surfaceBBox.fTop, 0, 0);
        if (!rect.isEmpty()) {
            paint.setColor(image->getColor(0, 0));
            canvas.drawRect(rect, paint);
        }

        rect = SkRect::MakeLTRB(width, surfaceBBox.fTop, surfaceBBox.fRight, 0);
        if (!rect.isEmpty()) {
            paint.setColor(image->getColor(width - 1, 0));
            canvas.drawRect(rect, paint);
        }

        rect = SkRect::MakeLTRB(width, height, surfaceBBox.fRight,
                                surfaceBBox.fBottom);
        if (!rect.isEmpty()) {
            paint.setColor(image->getColor(width - 1, height - 1));
            canvas.drawRect(rect, paint);
        }

        rect = SkRect::MakeLTRB(surfaceBBox.fLeft, height, 0,
                                surfaceBBox.fBottom);
        if (!rect.isEmpty()) {
            paint.setColor(image->getColor(0, height - 1));
            canvas.drawRect(rect, paint);
        }
    }

    // Then expand the left, right, top, then bottom.
    if (tileModes[0] == SkShader::kClamp_TileMode) {
        SkIRect subset = SkIRect::MakeXYWH(0, 0, 1, height);
        if (surfaceBBox.fLeft < 0) {
            SkBitmap left;
            SkAssertResult(image->extractSubset(&left, subset));

            SkMatrix leftMatrix;
            leftMatrix.setScale(-surfaceBBox.fLeft, 1);
            leftMatrix.postTranslate(surfaceBBox.fLeft, 0);
            canvas.drawBitmapMatrix(left, leftMatrix);
//.........这里部分代码省略.........

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.........

bool SkXfermodeImageFilter::filterImageGPU(Proxy* proxy,
                                           const SkBitmap& src,
                                           const Context& ctx,
                                           SkBitmap* result,
                                           SkIPoint* offset) const {
    SkBitmap background = src;
    SkIPoint backgroundOffset = SkIPoint::Make(0, 0);
    if (getInput(0) && !getInput(0)->getInputResultGPU(proxy, src, ctx, &background,
                                                       &backgroundOffset)) {
        return onFilterImage(proxy, src, ctx, result, offset);
    }
    GrTexture* backgroundTex = background.getTexture();
    SkBitmap foreground = src;
    SkIPoint foregroundOffset = SkIPoint::Make(0, 0);
    if (getInput(1) && !getInput(1)->getInputResultGPU(proxy, src, ctx, &foreground,
                                                       &foregroundOffset)) {
        return onFilterImage(proxy, src, ctx, result, offset);
    }
    GrTexture* foregroundTex = foreground.getTexture();
    GrContext* context = foregroundTex->getContext();

    GrEffect* xferEffect = NULL;

    GrTextureDesc desc;
    desc.fFlags = kRenderTarget_GrTextureFlagBit | kNoStencil_GrTextureFlagBit;
    desc.fWidth = src.width();
    desc.fHeight = src.height();
    desc.fConfig = kSkia8888_GrPixelConfig;

    GrAutoScratchTexture ast(context, desc);
    if (NULL == ast.texture()) {
        return false;
    }
    SkAutoTUnref<GrTexture> dst(ast.detach());

    GrContext::AutoRenderTarget art(context, dst->asRenderTarget());

    if (!fMode || !fMode->asNewEffect(&xferEffect, backgroundTex)) {
        // canFilterImageGPU() should've taken care of this
        SkASSERT(false);
        return false;
    }

    SkMatrix foregroundMatrix = GrCoordTransform::MakeDivByTextureWHMatrix(foregroundTex);
    foregroundMatrix.preTranslate(SkIntToScalar(backgroundOffset.fX-foregroundOffset.fX),
                                  SkIntToScalar(backgroundOffset.fY-foregroundOffset.fY));


    SkRect srcRect;
    src.getBounds(&srcRect);

    GrPaint paint;
    paint.addColorTextureEffect(foregroundTex, foregroundMatrix);
    paint.addColorEffect(xferEffect)->unref();
    context->drawRect(paint, srcRect);

    offset->fX = backgroundOffset.fX;
    offset->fY = backgroundOffset.fY;
    WrapTexture(dst, src.width(), src.height(), result);
    return true;
}