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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 "SkSGNode.h"
#include "SkColorFilter.h"
class SkCanvas;
class SkPaint;
namespace sksg {
/**
* Base class for nodes which can render to a canvas.
*/
class RenderNode : public Node {
protected:
struct RenderContext;
public:
// Render the node and its descendants to the canvas.
void render(SkCanvas*, const RenderContext* = nullptr) const;
protected:
RenderNode();
virtual void onRender(SkCanvas*, const RenderContext*) 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;
float fOpacity = 1;
// Returns true if the paint was modified.
bool modulatePaint(SkPaint*) const;
};
class ScopedRenderContext final {
public:
ScopedRenderContext(SkCanvas*, const RenderContext*);
~ScopedRenderContext();
ScopedRenderContext(ScopedRenderContext&& that) { *this = std::move(that); }
ScopedRenderContext& operator=(ScopedRenderContext&& that) {
fCanvas = that.fCanvas;
fCtx = std::move(that.fCtx);
fRestoreCount = that.fRestoreCount;
// scope ownership is being transferred
that.fRestoreCount = -1;
return *this;
}
operator const RenderContext* () const { return &fCtx; }
// Add (cumulative) paint overrides to a render node sub-DAG.
ScopedRenderContext&& modulateOpacity(float opacity);
ScopedRenderContext&& modulateColorFilter(sk_sp<SkColorFilter>);
// Force content isolation for a node sub-DAG by applying the RenderContext
// overrides via a layer.
ScopedRenderContext&& setIsolation(const SkRect& bounds, bool do_isolate);
private:
// 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;
int fRestoreCount;
};
private:
typedef Node INHERITED;
};
} // namespace sksg
#endif // SkSGRenderNode_DEFINED