[SVGDom] Opacity optimization

experimental/svg/model/SkSVGRenderContext.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkSVGRenderContext_DEFINED
 #define SkSVGRenderContext_DEFINED
 
@@ skipping 49 matching lines @@
     SkSVGRenderContext(SkCanvas*, const SkSVGIDMapper&, const SkSVGLengthContext&,
                        const SkSVGPresentationContext&);
     SkSVGRenderContext(const SkSVGRenderContext&);
     ~SkSVGRenderContext();
 
     const SkSVGLengthContext& lengthContext() const { return *fLengthContext; }
     SkSVGLengthContext* writableLengthContext() { return fLengthContext.writable(); }
 
     SkCanvas* canvas() const { return fCanvas; }
 
-    void applyPresentationAttributes(const SkSVGPresentationAttributes&);
+    enum ApplyFlags {
+        kLeaf = 1 << 0, // the target node doesn't have descendants
+    };
+    void applyPresentationAttributes(const SkSVGPresentationAttributes&, uint32_t flags);
 
     const SkSVGNode* findNodeById(const SkString&) const;
 
     const SkPaint* fillPaint() const;
     const SkPaint* strokePaint() const;
 
 private:
     // Stack-only
     void* operator new(size_t)                               = delete;
     void* operator new(size_t, void*)                        = delete;
     SkSVGRenderContext& operator=(const SkSVGRenderContext&) = delete;
 
+    void applyOpacity(SkScalar opacity, uint32_t flags);
+
     const SkSVGIDMapper&                          fIDMapper;
     SkTCopyOnFirstWrite<SkSVGLengthContext>       fLengthContext;
     SkTCopyOnFirstWrite<SkSVGPresentationContext> fPresentationContext;
     SkCanvas*                                     fCanvas;
     // The save count on 'fCanvas' at construction time.
     // A restoreToCount() will be issued on destruction.
     int                                           fCanvasSaveCount;
 };
 
 #endif // SkSVGRenderContext_DEFINED