1 /* 2 * Copyright 2017 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #ifndef SkSGRenderNode_DEFINED 9 #define SkSGRenderNode_DEFINED 10 11 #include "SkSGNode.h" 12 13 #include "SkColorFilter.h" 14 15 class SkCanvas; 16 class SkPaint; 17 18 namespace sksg { 19 20 /** 21 * Base class for nodes which can render to a canvas. 22 */ 23 class RenderNode : public Node { 24 protected: 25 struct RenderContext; 26 27 public: 28 // Render the node and its descendants to the canvas. 29 void render(SkCanvas*, const RenderContext* = nullptr) const; 30 31 protected: 32 RenderNode(); 33 34 virtual void onRender(SkCanvas*, const RenderContext*) const = 0; 35 36 // Paint property overrides. 37 // These are deferred until we can determine whether they can be applied to the individual 38 // draw paints, or whether they require content isolation (applied to a layer). 39 struct RenderContext { 40 sk_sp<SkColorFilter> fColorFilter; 41 float fOpacity = 1; 42 43 // Returns true if the paint was modified. 44 bool modulatePaint(SkPaint*) const; 45 }; 46 47 class ScopedRenderContext final { 48 public: 49 ScopedRenderContext(SkCanvas*, const RenderContext*); 50 ~ScopedRenderContext(); 51 ScopedRenderContext(ScopedRenderContext && that)52 ScopedRenderContext(ScopedRenderContext&& that) { *this = std::move(that); } 53 54 ScopedRenderContext& operator=(ScopedRenderContext&& that) { 55 fCanvas = that.fCanvas; 56 fCtx = std::move(that.fCtx); 57 fRestoreCount = that.fRestoreCount; 58 59 // scope ownership is being transferred 60 that.fRestoreCount = -1; 61 62 return *this; 63 } 64 65 operator const RenderContext* () const { return &fCtx; } 66 67 // Add (cumulative) paint overrides to a render node sub-DAG. 68 ScopedRenderContext&& modulateOpacity(float opacity); 69 ScopedRenderContext&& modulateColorFilter(sk_sp<SkColorFilter>); 70 71 // Force content isolation for a node sub-DAG by applying the RenderContext 72 // overrides via a layer. 73 ScopedRenderContext&& setIsolation(const SkRect& bounds, bool do_isolate); 74 75 private: 76 // stack-only 77 void* operator new(size_t) = delete; 78 void* operator new(size_t, void*) = delete; 79 80 // Scopes cannot be copied. 81 ScopedRenderContext(const ScopedRenderContext&) = delete; 82 ScopedRenderContext& operator=(const ScopedRenderContext&) = delete; 83 84 SkCanvas* fCanvas; 85 RenderContext fCtx; 86 int fRestoreCount; 87 }; 88 89 private: 90 typedef Node INHERITED; 91 }; 92 93 } // namespace sksg 94 95 #endif // SkSGRenderNode_DEFINED 96