Additional clipping logic for vk webview

#include "RecordingCanvas.h"

#include "pipeline/skia/FunctorDrawable.h"

#include "VectorDrawable.h"

#include <GrRecordingContext.h>

#include <experimental/type_traits>

#include "SkAndroidFrameworkUtils.h"

#include "SkCanvas.h"

#include "SkCanvasPriv.h"

#include "SkColor.h"

#include "SkData.h"

#include "SkDrawShadowInfo.h"

#include "SkImage.h"

#include "SkRegion.h"

#include "SkTextBlob.h"

#include "SkVertices.h"

#include <experimental/type_traits>

#include "VectorDrawable.h"

#include "pipeline/skia/FunctorDrawable.h"

namespace android {

namespace uirenderer {

    // SkDrawable::onSnapGpuDrawHandler callback instead of SkDrawable::onDraw.

    // SkCanvas::drawDrawable/SkGpuDevice::drawDrawable has the logic to invoke

    // onSnapGpuDrawHandler.

    void draw(SkCanvas* c, const SkMatrix&) const { c->drawDrawable(drawable.get()); }

private:

    // Unfortunately WebView does not have complex clip information serialized, and we only perform

    // best-effort stencil fill for GLES. So for Vulkan we create an intermediate layer if the

    // canvas clip is complex.

    static bool needsCompositedLayer(SkCanvas* c) {

        if (Properties::getRenderPipelineType() != RenderPipelineType::SkiaVulkan) {

            return false;

        }

        SkRegion clipRegion;

        // WebView's rasterizer has access to simple clips, so for Vulkan we only need to check if

        // the clip is more complex than a rectangle.

        c->temporary_internal_getRgnClip(&clipRegion);

        return clipRegion.isComplex();

    }

    mutable SkImageInfo mLayerImageInfo;

    mutable sk_sp<SkSurface> mLayerSurface = nullptr;

public:

    void draw(SkCanvas* c, const SkMatrix&) const {

        if (needsCompositedLayer(c)) {

            // What we do now is create an offscreen surface, sized by the clip bounds.

            // We won't apply a clip while drawing - clipping will be performed when compositing the

            // surface back onto the original canvas. Note also that we're not using saveLayer

            // because the webview functor still doesn't respect the canvas clip stack.

            const SkIRect deviceBounds = c->getDeviceClipBounds();

            if (mLayerSurface == nullptr || c->imageInfo() != mLayerImageInfo) {

                GrRecordingContext* directContext = c->recordingContext();

                mLayerImageInfo =

                        c->imageInfo().makeWH(deviceBounds.width(), deviceBounds.height());

                mLayerSurface = SkSurface::MakeRenderTarget(directContext, SkBudgeted::kYes,

                                                            mLayerImageInfo, 0,

                                                            kTopLeft_GrSurfaceOrigin, nullptr);

            }

            SkCanvas* layerCanvas = mLayerSurface->getCanvas();

            SkAutoCanvasRestore(layerCanvas, true);

            layerCanvas->clear(SK_ColorTRANSPARENT);

            // Preserve the transform from the original canvas, but now the clip rectangle is

            // anchored at the origin so we need to transform the clipped content to the origin.

            SkM44 mat4(c->getLocalToDevice());

            mat4.postTranslate(-deviceBounds.fLeft, -deviceBounds.fTop);

            layerCanvas->concat(mat4);

            layerCanvas->drawDrawable(drawable.get());

            SkAutoCanvasRestore acr(c, true);

            // Temporarily use an identity transform, because this is just blitting to the parent

            // canvas with an offset.

            SkMatrix invertedMatrix;

            if (!c->getTotalMatrix().invert(&invertedMatrix)) {

                ALOGW("Unable to extract invert canvas matrix; aborting VkFunctor draw");

                return;

            }

            c->concat(invertedMatrix);

            mLayerSurface->draw(c, deviceBounds.fLeft, deviceBounds.fTop, nullptr);

        } else {

            c->drawDrawable(drawable.get());

        }

    }

};

}