Don't use setupPaintFill for drawBitmap

 Bug: 6505013
 When drawing a bitmap, don't use setupPaintFill(). The reason is that
 setupPaintFill will use the fillColor to influence the alpha set on the
 SkPaint. However, that fillColor does not apply to the bitmap, and can
 have the result of applying the wrong alpha (as the alpha set is fillColor
 alpha * graphicsContext's alpha). Instead, set the alpha on the
 paint directly and use setupPaintCommon

Change-Id: Ib8d7ef494593a2896e6e3ed03c00d8d4d4b7232a

3 files changed, 15 insertions, 2 deletions

diff --git a/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContext.cpp b/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContext.cpp
index bb5d990..ce9ce5a 100644
--- a/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContext.cpp
+++ b/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContext.cpp
@@ -229,6 +229,16 @@ void PlatformGraphicsContext::setAlpha(float alpha)
     m_state->alpha = alpha;
 }
 
+int PlatformGraphicsContext::getNormalizedAlpha() const
+{
+    int alpha = roundf(m_state->alpha * 256);
+    if (alpha > 255)
+        alpha = 255;
+    else if (alpha < 0)
+        alpha = 0;
+    return alpha;
+}
+
 void PlatformGraphicsContext::setCompositeOperation(CompositeOperator op)
 {
     m_state->mode = WebCoreCompositeToSkiaComposite(op);
diff --git a/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContext.h b/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContext.h
index 601de0f..1916014 100644
--- a/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContext.h
+++ b/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContext.h
@@ -59,6 +59,7 @@ public:
 
     // State values
     virtual void setAlpha(float alpha);
+    int getNormalizedAlpha() const;
     virtual void setCompositeOperation(CompositeOperator op);
     virtual void setFillColor(const Color& c);
     virtual void setFillShader(SkShader* fillShader);
diff --git a/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContextSkia.cpp b/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContextSkia.cpp
index 9b32726..f00bb02 100644
--- a/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContextSkia.cpp
+++ b/Source/WebCore/platform/graphics/android/context/PlatformGraphicsContextSkia.cpp
@@ -234,7 +234,8 @@ void PlatformGraphicsContextSkia::drawBitmapPattern(
                                                     SkShader::kRepeat_TileMode);
     shader->setLocalMatrix(matrix);
     SkPaint paint;
-    setupPaintFill(&paint);
+    setupPaintCommon(&paint);
+    paint.setAlpha(getNormalizedAlpha());
     paint.setShader(shader);
     paint.setXfermodeMode(WebCoreCompositeToSkiaComposite(compositeOp));
     fixPaintForBitmapsThatMaySeam(&paint);
@@ -246,7 +247,8 @@ void PlatformGraphicsContextSkia::drawBitmapRect(const SkBitmap& bitmap,
                                              CompositeOperator op)
 {
     SkPaint paint;
-    setupPaintFill(&paint);
+    setupPaintCommon(&paint);
+    paint.setAlpha(getNormalizedAlpha());
     paint.setXfermodeMode(WebCoreCompositeToSkiaComposite(op));
     fixPaintForBitmapsThatMaySeam(&paint);