Implement filter primitive subregion for reference CSS filters. This required refactoring determin…

Source/core/platform/graphics/filters/Filter.h

Index: Source/core/platform/graphics/filters/Filter.h
diff --git a/Source/core/platform/graphics/filters/Filter.h b/Source/core/platform/graphics/filters/Filter.h
index 51d0bb68092faaf978eb7c0134025a9bef8a8d1f..120de231ca20e009c1f61af0aa6819ffefec5d97 100644
--- a/Source/core/platform/graphics/filters/Filter.h
+++ b/Source/core/platform/graphics/filters/Filter.h
@@ -32,7 +32,7 @@ class FilterEffect;
 
 class Filter : public RefCounted<Filter> {
 public:
-    Filter(const AffineTransform& absoluteTransform) : m_absoluteTransform(absoluteTransform), m_renderingMode(Unaccelerated) { }
+    Filter(const AffineTransform& absoluteTransform) : m_renderingMode(Unaccelerated), m_absoluteTransform(absoluteTransform) { }
     virtual ~Filter() { }
 
     void setSourceImage(PassOwnPtr<ImageBuffer> sourceImage) { m_sourceImage = sourceImage; }
@@ -42,6 +42,7 @@ public:
     void setFilterResolution(const FloatSize& filterResolution) { m_filterResolution = filterResolution; }
 
     const AffineTransform& absoluteTransform() const { return m_absoluteTransform; }
+    void setAbsoluteTransform(const AffineTransform& absoluteTransform) { m_absoluteTransform = absoluteTransform; }
     FloatPoint mapAbsolutePointToLocalPoint(const FloatPoint& point) const { return m_absoluteTransform.inverse().mapPoint(point); }
 
     RenderingMode renderingMode() const { return m_renderingMode; }
@@ -51,14 +52,20 @@ public:
     virtual float applyVerticalScale(float value) const { return value * m_filterResolution.height(); }
     
     virtual FloatRect sourceImageRect() const = 0;
-    virtual FloatRect filterRegion() const = 0;
-    
+
+    FloatRect absoluteFilterRegion() const { return m_absoluteFilterRegion; }
+    void setAbsoluteFilterRegion(const FloatRect& rect) { m_absoluteFilterRegion = rect; }
+
+    FloatRect filterRegion() const { return m_filterRegion; }
+    void setFilterRegion(const FloatRect& rect) { m_filterRegion = rect; }
 
 private:
     OwnPtr<ImageBuffer> m_sourceImage;
     FloatSize m_filterResolution;
     RenderingMode m_renderingMode;
     AffineTransform m_absoluteTransform;
+    FloatRect m_absoluteFilterRegion;
+    FloatRect m_filterRegion;
 };
 
 } // namespace WebCore