[SVGDom] Only apply opacity when needed

experimental/svg/model/SkSVGRenderContext.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvas.h"
 #include "SkSVGAttribute.h"
 #include "SkSVGNode.h"
@@ skipping 249 matching lines @@
     ApplyLazyInheritedAttribute(Stroke);
     ApplyLazyInheritedAttribute(StrokeLineCap);
     ApplyLazyInheritedAttribute(StrokeLineJoin);
     ApplyLazyInheritedAttribute(StrokeOpacity);
     ApplyLazyInheritedAttribute(StrokeWidth);
 
 #undef ApplyLazyInheritedAttribute
 
     // Uninherited attributes.  Only apply to the current context.
 
-    if (auto* opacity = attrs.fOpacity.getMaybeNull()) {
+    auto* opacity = attrs.fOpacity.getMaybeNull();
+    if (opacity && opacity->value() < 1) {

[reed1, 2016/09/19 12:47:38]

// How is the restore conditionally execute, balancing this saveLayer?

[f(malita), 2016/09/19 13:08:30]

Comment a few lines below:

// Balanced in the destructor, via restoreToCount().

         SkPaint opacityPaint;
         opacityPaint.setAlpha(opacity_to_alpha(opacity->value()));
         // Balanced in the destructor, via restoreToCount().
         fCanvas->saveLayer(nullptr, &opacityPaint);
     }
 }
 
 const SkPaint* SkSVGRenderContext::fillPaint() const {
     const SkSVGPaint::Type paintType = fPresentationContext->fInherited.fFill.get()->type();
     return paintType != SkSVGPaint::Type::kNone ? &fPresentationContext->fFillPaint : nullptr;
 }
 
 const SkPaint* SkSVGRenderContext::strokePaint() const {
     const SkSVGPaint::Type paintType = fPresentationContext->fInherited.fStroke.get()->type();
     return paintType != SkSVGPaint::Type::kNone ? &fPresentationContext->fStrokePaint : nullptr;
 }