Add GrEllipseEdgeEffect

src/gpu/effects/GrEllipseEdgeEffect.h

+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrEllipseEdgeEffect_DEFINED
+#define GrEllipseEdgeEffect_DEFINED
+
+#include "GrEffect.h"
+
+class GrGLEllipseEdgeEffect;
+
+/**
+ * The output of this effect is a modulation of the input color and coverage for an axis-aligned
+ * ellipse, specified as center_x, center_y, x_radius, x_radius/y_radius in window space (y-down).
+ */
+
+class GrEllipseEdgeEffect : public GrEffect {
+public:
+    static GrEffectRef* Create() {
+        // maybe only have one static copy?
+        AutoEffectUnref effect(SkNEW(GrEllipseEdgeEffect));
+        return CreateEffectRef(effect);
+    }
+
+    virtual ~GrEllipseEdgeEffect() {}
+
+    static const char* Name() { return "EllipseEdge"; }
+
+    virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
+
+    typedef GrGLEllipseEdgeEffect GLEffect;
+
+    virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
+
+private:
+    GrEllipseEdgeEffect();
+
+    virtual bool onIsEqual(const GrEffect& other) const SK_OVERRIDE {
+        return true;
+    }
+
+    GR_DECLARE_EFFECT_TEST;
+
+    typedef GrEffect INHERITED;
+};
+
+#endif