Make SVG painting independent of GraphicsContext's alpha state

Source/platform/graphics/GraphicsContextState.cpp

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "platform/graphics/GraphicsContextState.h"
 
-#include "platform/graphics/skia/SkiaUtils.h"
-
 namespace blink {
 
 GraphicsContextState::GraphicsContextState()
     : m_strokeColor(Color::black)
     , m_fillColor(Color::black)
     , m_fillRule(RULE_NONZERO)
     , m_textDrawingMode(TextModeFill)
     , m_alpha(256)
     , m_compositeOperation(SkXfermode::kSrcOver_Mode)
     , m_interpolationQuality(InterpolationDefault)
@@ skipping 72 matching lines @@
 
 void GraphicsContextState::setStrokeColor(const Color& color)
 {
     m_strokeGradient.clear();
     m_strokePattern.clear();
     m_strokeColor = color;
     m_strokePaint.setColor(applyAlpha(color.rgb()));
     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());
 }
 
 void GraphicsContextState::clearStrokeGradient()
 {
     m_strokeGradient.clear();
     ASSERT(!m_strokePattern);
     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());
 }
 
 void GraphicsContextState::clearStrokePattern()
 {
     m_strokePattern.clear();
     ASSERT(!m_strokeGradient);
     m_strokePaint.setColor(applyAlpha(m_strokeColor.rgb()));
 }
 
@@ skipping 17 matching lines @@
 
 void GraphicsContextState::setFillColor(const Color& color)
 {
     m_fillColor = color;
     m_fillGradient.clear();
     m_fillPattern.clear();
     m_fillPaint.setColor(applyAlpha(color.rgb()));
     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());
 }
 
 void GraphicsContextState::clearFillGradient()
 {
     m_fillGradient.clear();
     ASSERT(!m_fillPattern);
     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());
 }
 
 void GraphicsContextState::clearFillPattern()
 {
     m_fillPattern.clear();
     ASSERT(!m_fillGradient);
     m_fillPaint.setColor(applyAlpha(m_fillColor.rgb()));
 }
 
@@ skipping 17 matching lines @@
     m_dropShadowImageFilter = dropShadowImageFilter;
 }
 
 void GraphicsContextState::clearDropShadowImageFilter()
 {
     m_dropShadowImageFilter.clear();
 }
 
 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()));
 }
 
 void GraphicsContextState::setLineDash(const DashArray& dashes, float dashOffset)
 {
     m_strokeData.setLineDash(dashes, dashOffset);
 }
 
 void GraphicsContextState::setColorFilter(PassRefPtr<SkColorFilter> colorFilter)
@@ skipping 29 matching lines @@
     return m_hasComplexClip;
 }
 
 void GraphicsContextState::setHasComplexClip()
 {
     m_hasComplexClip = true;
 }
 
 
 } // namespace blink