src/effects/imagefilters/SkBlendImageFilter.cpp

/*
 * Copyright 2013 The Android Open Source Project
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "include/core/SkAlphaType.h"
#include "include/core/SkBlendMode.h"
#include "include/core/SkBlender.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkClipOp.h"
#include "include/core/SkFlattenable.h"
#include "include/core/SkImageFilter.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkPaint.h"
#include "include/core/SkPoint.h"
#include "include/core/SkRect.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkSamplingOptions.h"
#include "include/core/SkScalar.h"
#include "include/core/SkSurfaceProps.h"
#include "include/core/SkTypes.h"
#include "include/effects/SkImageFilters.h"
#include "include/private/SkColorData.h"
#include "src/core/SkBlendModePriv.h"
#include "src/core/SkBlenderBase.h"
#include "src/core/SkImageFilter_Base.h"
#include "src/core/SkReadBuffer.h"
#include "src/core/SkSpecialImage.h"
#include "src/core/SkSpecialSurface.h"
#include "src/core/SkWriteBuffer.h"

#include <cstdint>
#include <memory>
#include <optional>
#include <utility>

#if defined(SK_GANESH)
#include "include/gpu/GrRecordingContext.h"
#include "src/gpu/SkBackingFit.h"
#include "src/gpu/ganesh/GrColorSpaceXform.h"
#include "src/gpu/ganesh/GrFPArgs.h"
#include "src/gpu/ganesh/GrFragmentProcessor.h"
#include "src/gpu/ganesh/GrImageInfo.h"
#include "src/gpu/ganesh/GrRecordingContextPriv.h"
#include "src/gpu/ganesh/GrSamplerState.h"
#include "src/gpu/ganesh/GrSurfaceProxyView.h"
#include "src/gpu/ganesh/SurfaceFillContext.h"
#include "src/gpu/ganesh/effects/GrTextureEffect.h"
#endif

namespace {

class SkBlendImageFilter : public SkImageFilter_Base {
public:
    SkBlendImageFilter(sk_sp<SkBlender> blender, sk_sp<SkImageFilter> inputs[2],
                       const SkRect* cropRect)
          : INHERITED(inputs, 2, cropRect)
          , fBlender(std::move(blender))
    {
        SkASSERT(fBlender);
    }

protected:
    sk_sp<SkSpecialImage> onFilterImage(const Context&, SkIPoint* offset) const override;

    SkIRect onFilterBounds(const SkIRect&, const SkMatrix& ctm,
                           MapDirection, const SkIRect* inputRect) const override;

#if defined(SK_GANESH)
    sk_sp<SkSpecialImage> filterImageGPU(const Context& ctx,
                                         sk_sp<SkSpecialImage> background,
                                         const SkIPoint& backgroundOffset,
                                         sk_sp<SkSpecialImage> foreground,
                                         const SkIPoint& foregroundOffset,
                                         const SkIRect& bounds) const;
#endif

    void flatten(SkWriteBuffer&) const override;

    void drawForeground(SkCanvas* canvas, SkSpecialImage*, const SkIRect&) const;

private:
    friend void ::SkRegisterBlendImageFilterFlattenable();
    SK_FLATTENABLE_HOOKS(SkBlendImageFilter)

    sk_sp<SkBlender> fBlender;

    using INHERITED = SkImageFilter_Base;
};

} // end namespace

sk_sp<SkImageFilter> SkImageFilters::Blend(SkBlendMode mode,
                                           sk_sp<SkImageFilter> background,
                                           sk_sp<SkImageFilter> foreground,
                                           const CropRect& cropRect) {
    sk_sp<SkImageFilter> inputs[2] = { std::move(background), std::move(foreground) };
    return sk_sp<SkImageFilter>(new SkBlendImageFilter(SkBlender::Mode(mode), inputs, cropRect));
}

sk_sp<SkImageFilter> SkImageFilters::Blend(sk_sp<SkBlender> blender,
                                           sk_sp<SkImageFilter> background,
                                           sk_sp<SkImageFilter> foreground,
                                           const CropRect& cropRect) {
    if (!blender) {
        blender = SkBlender::Mode(SkBlendMode::kSrcOver);
    }
    sk_sp<SkImageFilter> inputs[2] = { std::move(background), std::move(foreground) };
    return sk_sp<SkImageFilter>(new SkBlendImageFilter(blender, inputs, cropRect));
}

void SkRegisterBlendImageFilterFlattenable() {
    SK_REGISTER_FLATTENABLE(SkBlendImageFilter);
    // TODO (michaelludwig) - Remove after grace period for SKPs to stop using old name
    SkFlattenable::Register("SkXfermodeImageFilter_Base", SkBlendImageFilter::CreateProc);
    SkFlattenable::Register("SkXfermodeImageFilterImpl", SkBlendImageFilter::CreateProc);
}

sk_sp<SkFlattenable> SkBlendImageFilter::CreateProc(SkReadBuffer& buffer) {
    SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 2);

    sk_sp<SkBlender> blender;
    const uint32_t mode = buffer.read32();
    if (mode == kCustom_SkBlendMode) {
        blender = buffer.readBlender();
    } else {
        if (mode > (unsigned)SkBlendMode::kLastMode) {
            buffer.validate(false);
            return nullptr;
        }
        blender = SkBlender::Mode((SkBlendMode)mode);
    }
    return SkImageFilters::Blend(std::move(blender), common.getInput(0), common.getInput(1),
                                 common.cropRect());
}

void SkBlendImageFilter::flatten(SkWriteBuffer& buffer) const {
    this->INHERITED::flatten(buffer);
    if (auto bm = as_BB(fBlender)->asBlendMode()) {
        buffer.write32((unsigned)bm.value());
    } else {
        buffer.write32(kCustom_SkBlendMode);
        buffer.writeFlattenable(fBlender.get());
    }
}

///////////////////////////////////////////////////////////////////////////////////////////////////

sk_sp<SkSpecialImage> SkBlendImageFilter::onFilterImage(const Context& ctx,
                                                        SkIPoint* offset) const {
    SkIPoint backgroundOffset = SkIPoint::Make(0, 0);
    sk_sp<SkSpecialImage> background(this->filterInput(0, ctx, &backgroundOffset));

    SkIPoint foregroundOffset = SkIPoint::Make(0, 0);
    sk_sp<SkSpecialImage> foreground(this->filterInput(1, ctx, &foregroundOffset));

    SkIRect foregroundBounds = SkIRect::MakeEmpty();
    if (foreground) {
        foregroundBounds = SkIRect::MakeXYWH(foregroundOffset.x(), foregroundOffset.y(),
                                             foreground->width(), foreground->height());
    }

    SkIRect srcBounds = SkIRect::MakeEmpty();
    if (background) {
        srcBounds = SkIRect::MakeXYWH(backgroundOffset.x(), backgroundOffset.y(),
                                      background->width(), background->height());
    }

    srcBounds.join(foregroundBounds);
    if (srcBounds.isEmpty()) {
        return nullptr;
    }

    SkIRect bounds;
    if (!this->applyCropRect(ctx, srcBounds, &bounds)) {
        return nullptr;
    }

    offset->fX = bounds.left();
    offset->fY = bounds.top();

#if defined(SK_GANESH)
    if (ctx.gpuBacked()) {
        return this->filterImageGPU(ctx, background, backgroundOffset,
                                    foreground, foregroundOffset, bounds);
    }
#endif

    sk_sp<SkSpecialSurface> surf(ctx.makeSurface(bounds.size()));
    if (!surf) {
        return nullptr;
    }

    SkCanvas* canvas = surf->getCanvas();
    SkASSERT(canvas);

    canvas->clear(0x0); // can't count on background to fully clear the background
    canvas->translate(SkIntToScalar(-bounds.left()), SkIntToScalar(-bounds.top()));

    if (background) {
        SkPaint paint;
        paint.setBlendMode(SkBlendMode::kSrc);
        background->draw(canvas,
                         SkIntToScalar(backgroundOffset.fX), SkIntToScalar(backgroundOffset.fY),
                         SkSamplingOptions(), &paint);
    }

    this->drawForeground(canvas, foreground.get(), foregroundBounds);

    return surf->makeImageSnapshot();
}

SkIRect SkBlendImageFilter::onFilterBounds(const SkIRect& src,
                                           const SkMatrix& ctm,
                                           MapDirection dir,
                                           const SkIRect* inputRect) const {
    if (kReverse_MapDirection == dir) {
        return INHERITED::onFilterBounds(src, ctm, dir, inputRect);
    }

    SkASSERT(!inputRect);
    SkASSERT(2 == this->countInputs());
    auto getBackground = [&]() {
        return this->getInput(0) ? this->getInput(0)->filterBounds(src, ctm, dir, inputRect) : src;
    };
    auto getForeground = [&]() {
        return this->getInput(1) ? this->getInput(1)->filterBounds(src, ctm, dir, inputRect) : src;
    };
    if (auto bm = as_BB(fBlender)->asBlendMode()) {
        switch (bm.value()) {
            case SkBlendMode::kClear:
                return SkIRect::MakeEmpty();

            case SkBlendMode::kSrc:
            case SkBlendMode::kDstATop:
                return getForeground();

            case SkBlendMode::kDst:
            case SkBlendMode::kSrcATop:
                return getBackground();

            case SkBlendMode::kSrcIn:
            case SkBlendMode::kDstIn: {
                auto result = getBackground();
                if (!result.intersect(getForeground())) {
                    return SkIRect::MakeEmpty();
                }
                return result;
            }
            default: break;
        }
    }
    auto result = getBackground();
    result.join(getForeground());
    return result;
}

void SkBlendImageFilter::drawForeground(SkCanvas* canvas, SkSpecialImage* img,
                                        const SkIRect& fgBounds) const {
    SkPaint paint;
    paint.setBlender(fBlender);
    if (img) {
        img->draw(canvas, SkIntToScalar(fgBounds.fLeft), SkIntToScalar(fgBounds.fTop),
                  SkSamplingOptions(), &paint);
    }

    SkAutoCanvasRestore acr(canvas, true);
    canvas->clipRect(SkRect::Make(fgBounds), SkClipOp::kDifference);
    paint.setColor(0);
    canvas->drawPaint(paint);
}

#if defined(SK_GANESH)

sk_sp<SkSpecialImage> SkBlendImageFilter::filterImageGPU(const Context& ctx,
                                                         sk_sp<SkSpecialImage> background,
                                                         const SkIPoint& backgroundOffset,
                                                         sk_sp<SkSpecialImage> foreground,
                                                         const SkIPoint& foregroundOffset,
                                                         const SkIRect& bounds) const {
    SkASSERT(ctx.gpuBacked());

    auto rContext = ctx.getContext();

    GrSurfaceProxyView backgroundView, foregroundView;

    if (background) {
        backgroundView = background->view(rContext);
    }

    if (foreground) {
        foregroundView = foreground->view(rContext);
    }

    std::unique_ptr<GrFragmentProcessor> fp;
    const auto& caps = *ctx.getContext()->priv().caps();
    GrSamplerState sampler(GrSamplerState::WrapMode::kClampToBorder,
                           GrSamplerState::Filter::kNearest);

    if (backgroundView.asTextureProxy()) {
        SkRect bgSubset = SkRect::Make(background->subset());
        SkMatrix bgMatrix = SkMatrix::Translate(
                SkIntToScalar(bgSubset.left() - backgroundOffset.fX),
                SkIntToScalar(bgSubset.top()  - backgroundOffset.fY));
        fp = GrTextureEffect::MakeSubset(std::move(backgroundView), background->alphaType(),
                                         bgMatrix, sampler, bgSubset, caps);
        fp = GrColorSpaceXformEffect::Make(std::move(fp), background->getColorSpace(),
                                           background->alphaType(), ctx.colorSpace(),
                                           kPremul_SkAlphaType);
    } else {
        fp = GrFragmentProcessor::MakeColor(SK_PMColor4fTRANSPARENT);
    }

    GrImageInfo info(ctx.grColorType(), kPremul_SkAlphaType, ctx.refColorSpace(), bounds.size());

    if (foregroundView.asTextureProxy()) {
        SkRect fgSubset = SkRect::Make(foreground->subset());
        SkMatrix fgMatrix = SkMatrix::Translate(
                SkIntToScalar(fgSubset.left() - foregroundOffset.fX),
                SkIntToScalar(fgSubset.top()  - foregroundOffset.fY));
        auto fgFP = GrTextureEffect::MakeSubset(std::move(foregroundView), foreground->alphaType(),
                                                fgMatrix, sampler, fgSubset, caps);
        fgFP = GrColorSpaceXformEffect::Make(std::move(fgFP), foreground->getColorSpace(),
                                             foreground->alphaType(), ctx.colorSpace(),
                                             kPremul_SkAlphaType);

        SkSurfaceProps props{}; // default OK; blend-image filters don't render text
        GrFPArgs args(rContext, &info.colorInfo(), props);

        fp = as_BB(fBlender)->asFragmentProcessor(std::move(fgFP), std::move(fp), args);
    }

    auto sfc = rContext->priv().makeSFC(
            info, "BlendImageFilter_FilterImageGPU", SkBackingFit::kApprox);
    if (!sfc) {
        return nullptr;
    }

    sfc->fillRectToRectWithFP(bounds, SkIRect::MakeSize(bounds.size()), std::move(fp));

    return SkSpecialImage::MakeDeferredFromGpu(rContext,
                                               SkIRect::MakeWH(bounds.width(), bounds.height()),
                                               kNeedNewImageUniqueID_SpecialImage,
                                               sfc->readSurfaceView(),
                                               sfc->colorInfo(),
                                               ctx.surfaceProps());
}

#endif