src/capture/SkCaptureCanvas.h

/*
 * Copyright 2025 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkCaptureCanvas_DEFINED
#define SkCaptureCanvas_DEFINED

#include <cstddef>
#include "include/core/SkPictureRecorder.h"
#include "include/core/SkSurface.h"
#include "include/utils/SkNWayCanvas.h"

class SkCaptureManager;

/**
 * SkCaptureCanvas is designed to service a subset of client capture. It wraps a base canvas and
 * manages the life cycle of the recording canvases used for capture. When capture starts, it will
 * spin up the recording canvas. On a snapSKP call, it will generate an SKP, remove the now invalid
 * recording canvas, and replace it with a new one.
 *
 */
class SkCaptureCanvas : public SkNWayCanvas {
public:
    SkCaptureCanvas(SkCanvas*, SkCaptureManager*);
    ~SkCaptureCanvas() override;

    sk_sp<SkPicture> snapPicture();
    SkSurface* getBaseCanvasSurface() const {
        return fBaseCanvas ? fBaseCanvas->getSurface() : nullptr;
    }

protected:
    void willSave() override;
    SaveLayerStrategy getSaveLayerStrategy(const SaveLayerRec&) override;
    bool onDoSaveBehind(const SkRect*) override;
    void willRestore() override;

    void didConcat44(const SkM44&) override;
    void didSetM44(const SkM44&) override;
    void didScale(SkScalar, SkScalar) override;
    void didTranslate(SkScalar, SkScalar) override;

    void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&) override;
    void onDrawGlyphRunList(const sktext::GlyphRunList&, const SkPaint&) override;
    void onDrawTextBlob(const SkTextBlob* blob,
                        SkScalar x,
                        SkScalar y,
                        const SkPaint& paint) override;
    void onDrawSlug(const sktext::gpu::Slug* slug, const SkPaint& paint) override;
    void onDrawPatch(const SkPoint cubics[12],
                     const SkColor colors[4],
                     const SkPoint texCoords[4],
                     SkBlendMode,
                     const SkPaint& paint) override;

    void onDrawPaint(const SkPaint&) override;
    void onDrawBehind(const SkPaint&) override;
    void onDrawPoints(PointMode, size_t count, const SkPoint pts[], const SkPaint&) override;
    void onDrawRect(const SkRect&, const SkPaint&) override;
    void onDrawRegion(const SkRegion&, const SkPaint&) override;
    void onDrawOval(const SkRect&, const SkPaint&) override;
    void onDrawArc(const SkRect&, SkScalar, SkScalar, bool, const SkPaint&) override;
    void onDrawRRect(const SkRRect&, const SkPaint&) override;
    void onDrawPath(const SkPath&, const SkPaint&) override;

    void onDrawImage2(
            const SkImage*, SkScalar, SkScalar, const SkSamplingOptions&, const SkPaint*) override;
    void onDrawImageRect2(const SkImage*,
                          const SkRect&,
                          const SkRect&,
                          const SkSamplingOptions&,
                          const SkPaint*,
                          SrcRectConstraint) override;
    void onDrawImageLattice2(
            const SkImage*, const Lattice&, const SkRect&, SkFilterMode, const SkPaint*) override;
    void onDrawAtlas2(const SkImage*,
                      const SkRSXform[],
                      const SkRect[],
                      const SkColor[],
                      int,
                      SkBlendMode,
                      const SkSamplingOptions&,
                      const SkRect*,
                      const SkPaint*) override;
    void onDrawMesh(const SkMesh&, sk_sp<SkBlender>, const SkPaint&) override;

    void onDrawVerticesObject(const SkVertices*, SkBlendMode, const SkPaint&) override;
    void onDrawShadowRec(const SkPath&, const SkDrawShadowRec&) override;

    void onClipRect(const SkRect&, SkClipOp, ClipEdgeStyle) override;
    void onClipRRect(const SkRRect&, SkClipOp, ClipEdgeStyle) override;
    void onClipPath(const SkPath&, SkClipOp, ClipEdgeStyle) override;
    void onClipShader(sk_sp<SkShader>, SkClipOp) override;
    void onClipRegion(const SkRegion&, SkClipOp) override;
    void onResetClip() override;

    void onDrawPicture(const SkPicture*, const SkMatrix*, const SkPaint*) override;
    void onDrawDrawable(SkDrawable*, const SkMatrix*) override;
    void onDrawAnnotation(const SkRect&, const char[], SkData*) override;

    void onDrawEdgeAAQuad(
            const SkRect&, const SkPoint[4], QuadAAFlags, const SkColor4f&, SkBlendMode) override;
    void onDrawEdgeAAImageSet2(const ImageSetEntry[],
                               int count,
                               const SkPoint[],
                               const SkMatrix[],
                               const SkSamplingOptions&,
                               const SkPaint*,
                               SrcRectConstraint) override;

    // Unlike a standard NWayCanvas, SkCaptureCanvas has a single main SkCanvas that we can forward
    // these surface-oriented functions to. This is part of making SkCaptureCanvas act like the
    // surface-backed canvas its wrapping even though as an n-way canvas it does not have any pixels
    sk_sp<SkSurface> onNewSurface(const SkImageInfo& info, const SkSurfaceProps& props) override;
    bool onPeekPixels(SkPixmap* pixmap) override;
    bool onAccessTopLayerPixels(SkPixmap* pixmap) override;
    SkImageInfo onImageInfo() const override;
    bool onGetProps(SkSurfaceProps* props, bool top) const override;
    sk_sp<sktext::gpu::Slug> onConvertGlyphRunListToSlug(
            const sktext::GlyphRunList& glyphRunList, const SkPaint& paint) override;

    // NOTE: We intentionally do not override onDiscard() to notify the base canvas's surface that
    // it can be discarded. This would produce redundant discards, since presumably whatever draw
    // operation triggered the discard detection for the SkNWayCanvas will trigger again when it
    // delegates to the base canvas (which has a surface and then the surface will be discarded).
private:
    void pollCapturingStatus();
    void attachRecordingCanvas();
    void detachRecordingCanvas();

    bool fCapturing = false;
    SkPictureRecorder fRecorder;
    SkCanvas* fBaseCanvas = nullptr;
    SkCaptureManager* fManager = nullptr;

    // Hide NWay management functions as clients shouldn't be using these directly.
    void addCanvas(SkCanvas* canvas) override {SkNWayCanvas::addCanvas(canvas);}
    void removeCanvas(SkCanvas* canvas) override {SkNWayCanvas::removeCanvas(canvas);}
    void removeAll() override {SkNWayCanvas::removeAll();}
};

#endif  // SkCaptureCanvas_DEFINED