[SVGDom] Add opacity support

Group opacity support.  Unlike the other presentation attributes we
support thus far, group opacity is not inherited.

R=robertphillips@google.com,stephana@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2246943002

Review-Url: https://codereview.chromium.org/2246943002

5 files changed, 24 insertions, 0 deletions

diff --git a/experimental/svg/model/SkSVGAttribute.h b/experimental/svg/model/SkSVGAttribute.h
index d2f0cf2600..cc3e7a073c 100644
--- a/experimental/svg/model/SkSVGAttribute.h
+++ b/experimental/svg/model/SkSVGAttribute.h
@@ -18,6 +18,7 @@ enum class SkSVGAttribute {
     kFill,
     kFillOpacity,
     kHeight,
+    kOpacity,
     kPoints,
     kRx,
     kRy,
@@ -48,6 +49,8 @@ struct SkSVGPresentationAttributes {
     SkTLazy<SkSVGLineJoin>   fStrokeLineJoin;
     SkTLazy<SkSVGNumberType> fStrokeOpacity;
     SkTLazy<SkSVGLength>     fStrokeWidth;
+
+    SkTLazy<SkSVGNumberType> fOpacity;
 };
 
 #endif // SkSVGAttribute_DEFINED
diff --git a/experimental/svg/model/SkSVGDOM.cpp b/experimental/svg/model/SkSVGDOM.cpp
index c9d9e93f65..8e2667ad20 100644
--- a/experimental/svg/model/SkSVGDOM.cpp
+++ b/experimental/svg/model/SkSVGDOM.cpp
@@ -217,6 +217,7 @@ SortedDictionaryEntry<AttrParseInfo> gAttributeParseInfo[] = {
     { "fill"           , { SkSVGAttribute::kFill          , SetPaintAttribute     }},
     { "fill-opacity"   , { SkSVGAttribute::kFillOpacity   , SetNumberAttribute    }},
     { "height"         , { SkSVGAttribute::kHeight        , SetLengthAttribute    }},
+    { "opacity"        , { SkSVGAttribute::kOpacity       , SetNumberAttribute    }},
     { "points"         , { SkSVGAttribute::kPoints        , SetPointsAttribute    }},
     { "rx"             , { SkSVGAttribute::kRx            , SetLengthAttribute    }},
     { "ry"             , { SkSVGAttribute::kRy            , SetLengthAttribute    }},
diff --git a/experimental/svg/model/SkSVGNode.cpp b/experimental/svg/model/SkSVGNode.cpp
index a039b59ff1..5a73ace548 100644
--- a/experimental/svg/model/SkSVGNode.cpp
+++ b/experimental/svg/model/SkSVGNode.cpp
@@ -42,6 +42,11 @@ void SkSVGNode::setFillOpacity(const SkSVGNumberType& opacity) {
         SkSVGNumberType(SkTPin<SkScalar>(opacity.value(), 0, 1)));
 }
 
+void SkSVGNode::setOpacity(const SkSVGNumberType& opacity) {
+    fPresentationAttributes.fOpacity.set(
+        SkSVGNumberType(SkTPin<SkScalar>(opacity.value(), 0, 1)));
+}
+
 void SkSVGNode::setStroke(const SkSVGPaint& svgPaint) {
     fPresentationAttributes.fStroke.set(svgPaint);
 }
@@ -67,6 +72,11 @@ void SkSVGNode::onSetAttribute(SkSVGAttribute attr, const SkSVGValue& v) {
             this->setFillOpacity(*opacity);
         }
         break;
+    case SkSVGAttribute::kOpacity:
+        if (const SkSVGNumberValue* opacity = v.as<SkSVGNumberValue>()) {
+            this->setOpacity(*opacity);
+        }
+        break;
     case SkSVGAttribute::kStroke:
         if (const SkSVGPaintValue* paint = v.as<SkSVGPaintValue>()) {
             this->setStroke(*paint);
diff --git a/experimental/svg/model/SkSVGNode.h b/experimental/svg/model/SkSVGNode.h
index 8ffc6f9769..0f95d77a6f 100644
--- a/experimental/svg/model/SkSVGNode.h
+++ b/experimental/svg/model/SkSVGNode.h
@@ -39,6 +39,7 @@ public:
 
     void setFill(const SkSVGPaint&);
     void setFillOpacity(const SkSVGNumberType&);
+    void setOpacity(const SkSVGNumberType&);
     void setStroke(const SkSVGPaint&);
     void setStrokeOpacity(const SkSVGNumberType&);
     void setStrokeWidth(const SkSVGLength&);
diff --git a/experimental/svg/model/SkSVGRenderContext.cpp b/experimental/svg/model/SkSVGRenderContext.cpp
index ee92c47d54..8ad881429a 100644
--- a/experimental/svg/model/SkSVGRenderContext.cpp
+++ b/experimental/svg/model/SkSVGRenderContext.cpp
@@ -224,6 +224,15 @@ void SkSVGRenderContext::applyPresentationAttributes(const SkSVGPresentationAttr
     ApplyLazyInheritedAttribute(StrokeWidth);
 
 #undef ApplyLazyInheritedAttribute
+
+    // Uninherited attributes.  Only apply to the current context.
+
+    if (auto* opacity = attrs.fOpacity.getMaybeNull()) {
+        SkPaint opacityPaint;
+        opacityPaint.setAlpha(static_cast<uint8_t>(opacity->value() * 255));
+        // Balanced in the destructor, via restoreToCount().
+        fCanvas->saveLayer(nullptr, &opacityPaint);
+    }
 }
 
 const SkPaint* SkSVGRenderContext::fillPaint() const {