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* Copyright 2017 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef SkSGRenderNode_DEFINED
#define SkSGRenderNode_DEFINED
#include "modules/sksg/include/SkSGNode.h"
#include "include/core/SkBlendMode.h"
#include "include/core/SkColorFilter.h"
#include "include/core/SkShader.h"
class SkCanvas;
class SkImageFilter;
class SkPaint;
namespace sksg {
* Base class for nodes which can render to a canvas.
class RenderNode : public Node {
struct RenderContext;
// Render the node and its descendants to the canvas.
void render(SkCanvas*, const RenderContext* = nullptr) const;
// Perform a front-to-back hit-test, and return the RenderNode located at |point|.
// Normally, hit-testing stops at leaf Draw nodes.
const RenderNode* nodeAt(const SkPoint& point) const;
// Controls the visibility of the render node. Invisible nodes are not rendered,
// but they still participate in revalidation.
bool isVisible() const;
void setVisible(bool);
explicit RenderNode(uint32_t inval_traits = 0);
virtual void onRender(SkCanvas*, const RenderContext*) const = 0;
virtual const RenderNode* onNodeAt(const SkPoint& p) const = 0;
// Paint property overrides.
// These are deferred until we can determine whether they can be applied to the individual
// draw paints, or whether they require content isolation (applied to a layer).
struct RenderContext {
sk_sp<SkColorFilter> fColorFilter;
sk_sp<SkShader> fShader;
sk_sp<SkShader> fMaskShader;
SkMatrix fShaderCTM = SkMatrix::I(),
fMaskCTM = SkMatrix::I();
float fOpacity = 1;
SkBlendMode fBlendMode = SkBlendMode::kSrcOver;
// Returns true if the paint overrides require a layer when applied to non-atomic draws.
bool requiresIsolation() const;
void modulatePaint(const SkMatrix& ctm, SkPaint*, bool is_layer_paint = false) const;
class ScopedRenderContext final {
ScopedRenderContext(SkCanvas*, const RenderContext*);
ScopedRenderContext(ScopedRenderContext&& that) { *this = std::move(that); }
ScopedRenderContext& operator=(ScopedRenderContext&& that) {
fCanvas = that.fCanvas;
fCtx = std::move(that.fCtx);
fMaskShader = std::move(that.fMaskShader);
fRestoreCount = that.fRestoreCount;
// scope ownership is being transferred
that.fRestoreCount = -1;
return *this;
operator const RenderContext* () const { return &fCtx; }
const RenderContext* operator->() const { return &fCtx; }
// Add (cumulative) paint overrides to a render node sub-DAG.
ScopedRenderContext&& modulateOpacity(float opacity);
ScopedRenderContext&& modulateColorFilter(sk_sp<SkColorFilter>);
ScopedRenderContext&& modulateShader(sk_sp<SkShader>, const SkMatrix& shader_ctm);
ScopedRenderContext&& modulateMaskShader(sk_sp<SkShader>, const SkMatrix& ms_ctm);
ScopedRenderContext&& modulateBlendMode(SkBlendMode);
// Force content isolation for a node sub-DAG by applying the RenderContext
// overrides via a layer.
ScopedRenderContext&& setIsolation(const SkRect& bounds, const SkMatrix& ctm,
bool do_isolate);
// Similarly, force content isolation by applying the RenderContext overrides and
// an image filter via a single layer.
ScopedRenderContext&& setFilterIsolation(const SkRect& bounds, const SkMatrix& ctm,
// stack-only
void* operator new(size_t) = delete;
void* operator new(size_t, void*) = delete;
// Scopes cannot be copied.
ScopedRenderContext(const ScopedRenderContext&) = delete;
ScopedRenderContext& operator=(const ScopedRenderContext&) = delete;
SkCanvas* fCanvas;
RenderContext fCtx;
sk_sp<SkShader> fMaskShader; // to be applied at isolation layer restore time
int fRestoreCount;
friend class ImageFilterEffect;
typedef Node INHERITED;
* Clients outside SkSG looking to implement custom render nodes,
* should derive from this class instead of RenderNode. It handles
* various book-keeping, and provides a controlled extension point.
class CustomRenderNode : public RenderNode {
explicit CustomRenderNode(std::vector<sk_sp<RenderNode>>&& children);
~CustomRenderNode() override;
const std::vector<sk_sp<RenderNode>>& children() const { return fChildren; }
bool hasChildrenInval() const;
std::vector<sk_sp<RenderNode>> fChildren;
using INHERITED = RenderNode;
} // namespace sksg
#endif // SkSGRenderNode_DEFINED