First pass at Rect Effect

src/gpu/effects/GrRectEffect.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 GrRectEffect_DEFINED
+#define GrRectEffect_DEFINED
+
+#include "GrEffect.h"
+
+class GrGLRectEffect;

[bsalomon, 2013/04/08 15:48:39]

What do you think of putting this in the AARectRenderer's cpp? We've done that
for ovals, etc. Maybe there are other callers for this? But otherwise it seems
nice to have the vert setup and shader code in the same file (unless the size
gets out of control).

[robertphillips, 2013/04/08 19:33:20]

Done - we can always move it out if line drawing needs it elsewhere.

+
+/**
+ * The output of this effect is a modulation of the input color and coverage 
+ * for an arbitrarily oriented rect. The rect is specified as:
+ *      Center of the rect
+ *      Unit vector point down the height of the rect
+ *      Half width + 0.5
+ *      Half height + 0.5

[bsalomon, 2013/04/08 15:48:39]

Maybe comment here on what varying that this effect takes?

[robertphillips, 2013/04/08 19:33:20]

Done.

+ */
+class GrRectEffect : public GrEffect {
+public:
+    static GrEffectRef* Create() {
+        static SkAutoTUnref<GrEffectRef> gRectEffectRef(
+                        CreateEffectRef(AutoEffectUnref(SkNEW(GrRectEffect))));
+        gRectEffectRef.get()->ref();
+        return gRectEffectRef;
+    }
+
+    virtual ~GrRectEffect() {}
+
+    static const char* Name() { return "RectEdge"; }
+
+    virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
+
+    typedef GrGLRectEffect GLEffect;
+
+    virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
+
+private:
+    GrRectEffect();
+
+    virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE {
+        return true;
+    }
+
+    GR_DECLARE_EFFECT_TEST;
+
+    typedef GrEffect INHERITED;
+};
+
+#endif