Refactor shadow rendering logic.

Source/core/platform/graphics/GraphicsContext.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 12 matching lines @@
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef GraphicsContext_h
 #define GraphicsContext_h
 
 #include "core/platform/chromium/TraceEvent.h"
 #include "core/platform/graphics/DashArray.h"
+#include "core/platform/graphics/DrawLooper.h"
 #include "core/platform/graphics/FloatRect.h"
 #include "core/platform/graphics/Font.h"
 #include "core/platform/graphics/GraphicsContextState.h"
 #include "core/platform/graphics/ImageOrientation.h"
 #include "core/platform/graphics/skia/OpaqueRegionSkia.h"
 
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkDevice.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "third_party/skia/include/core/SkPath.h"
@@ skipping 266 matching lines @@
     void setUpdatingControlTints(bool);
 
     void beginTransparencyLayer(float opacity);
     void endTransparencyLayer();
     // Begins a layer that is clipped to the image |imageBuffer| at the location
     // |rect|. This layer is implicitly restored when the next restore is invoked.
     // NOTE: |imageBuffer| may be deleted before the |restore| is invoked.
     void beginLayerClippedToImage(const FloatRect&, const ImageBuffer*);
 
     bool hasShadow() const;
-    void setShadow(const FloatSize&, float blur, const Color&, ColorSpace);
+    void setShadow(const FloatSize& offset, float blur, const Color&,
+        DrawLooper::ShadowAlphaMode = DrawLooper::ShadowRespectsAlpha);
+    void clearShadow() { clearDrawLooper(); }
 
-    bool getShadow(FloatSize&, float&, Color&, ColorSpace&) const;
-    void clearShadow();
+    // It is assumed that this draw looper is used only for shadows
+    // (i.e. a draw looper is set if and only if there is a shadow).
+    void setDrawLooper(DrawLooper&);
+    void clearDrawLooper();
 
     void drawFocusRing(const Vector<IntRect>&, int width, int offset, const Color&);
     void drawFocusRing(const Path&, int width, int offset, const Color&);
 
     void setLineCap(LineCap);
     void setLineDash(const DashArray&, float dashOffset);
     void setLineJoin(LineJoin);
     void setMiterLimit(float);
 
     void setAlpha(float);
@@ skipping 171 matching lines @@
     // FIXME: Make this go away: crbug.com/236892
     bool m_updatingControlTints : 1;
     bool m_accelerated : 1;
     bool m_isCertainlyOpaque : 1;
     bool m_printing : 1;
 };
 
 } // namespace WebCore
 
 #endif // GraphicsContext_h