Make SVG painting independent of GraphicsContext's alpha state

Source/platform/graphics/GraphicsContextState.cpp

Index: Source/platform/graphics/GraphicsContextState.cpp
diff --git a/Source/platform/graphics/GraphicsContextState.cpp b/Source/platform/graphics/GraphicsContextState.cpp
index a87bafe2a852ecdb0f916795e79e5982ed1f8cec..1dc94d67a50d4da0c9522c686aeb138a2dfad931 100644
--- a/Source/platform/graphics/GraphicsContextState.cpp
+++ b/Source/platform/graphics/GraphicsContextState.cpp
@@ -5,8 +5,6 @@
 #include "config.h"
 #include "platform/graphics/GraphicsContextState.h"
 
-#include "platform/graphics/skia/SkiaUtils.h"
-
 namespace blink {
 
 GraphicsContextState::GraphicsContextState()
@@ -99,12 +97,12 @@ void GraphicsContextState::setStrokeColor(const Color& color)
     m_strokePaint.setShader(0);
 }
 
-void GraphicsContextState::setStrokeGradient(const PassRefPtr<Gradient> gradient)
+void GraphicsContextState::setStrokeGradient(const PassRefPtr<Gradient> gradient, float alpha)
 {
     m_strokeColor = Color::black;
     m_strokePattern.clear();
     m_strokeGradient = gradient;
-    m_strokePaint.setColor(applyAlpha(SK_ColorBLACK));
+    m_strokePaint.setColor(multiplyAlpha(applyAlpha(SK_ColorBLACK), alpha));
     m_strokePaint.setShader(m_strokeGradient->shader());
 }
 
@@ -115,12 +113,12 @@ void GraphicsContextState::clearStrokeGradient()
     m_strokePaint.setColor(applyAlpha(m_strokeColor.rgb()));
 }
 
-void GraphicsContextState::setStrokePattern(const PassRefPtr<Pattern> pattern)
+void GraphicsContextState::setStrokePattern(const PassRefPtr<Pattern> pattern, float alpha)
 {
     m_strokeColor = Color::black;
     m_strokeGradient.clear();
     m_strokePattern = pattern;
-    m_strokePaint.setColor(applyAlpha(SK_ColorBLACK));
+    m_strokePaint.setColor(multiplyAlpha(applyAlpha(SK_ColorBLACK), alpha));
     m_strokePaint.setShader(m_strokePattern->shader());
 }
 
@@ -158,12 +156,12 @@ void GraphicsContextState::setFillColor(const Color& color)
     m_fillPaint.setShader(0);
 }
 
-void GraphicsContextState::setFillGradient(const PassRefPtr<Gradient> gradient)
+void GraphicsContextState::setFillGradient(const PassRefPtr<Gradient> gradient, float alpha)
 {
     m_fillColor = Color::black;
     m_fillPattern.clear();
     m_fillGradient = gradient;
-    m_fillPaint.setColor(applyAlpha(SK_ColorBLACK));
+    m_fillPaint.setColor(multiplyAlpha(applyAlpha(SK_ColorBLACK), alpha));
     m_fillPaint.setShader(m_fillGradient->shader());
 }
 
@@ -174,12 +172,12 @@ void GraphicsContextState::clearFillGradient()
     m_fillPaint.setColor(applyAlpha(m_fillColor.rgb()));
 }
 
-void GraphicsContextState::setFillPattern(const PassRefPtr<Pattern> pattern)
+void GraphicsContextState::setFillPattern(const PassRefPtr<Pattern> pattern, float alpha)
 {
     m_fillColor = Color::black;
     m_fillGradient.clear();
     m_fillPattern = pattern;
-    m_fillPaint.setColor(applyAlpha(SK_ColorBLACK));
+    m_fillPaint.setColor(multiplyAlpha(applyAlpha(SK_ColorBLACK), alpha));
     m_fillPaint.setShader(m_fillPattern->shader());
 }
 
@@ -217,13 +215,7 @@ void GraphicsContextState::clearDropShadowImageFilter()
 
 void GraphicsContextState::setAlphaAsFloat(float alpha)
 {
-    if (alpha < 0) {
-        m_alpha = 0;
-    } else {
-        m_alpha = roundf(alpha * 256);
-        if (m_alpha > 256)
-            m_alpha = 256;
-    }
+    m_alpha = clampedAlphaForBlending(alpha);
     m_strokePaint.setColor(applyAlpha(m_strokeColor.rgb()));
     m_fillPaint.setColor(applyAlpha(m_fillColor.rgb()));
 }