first cut at HQ GPU scaling; refactored existing bicubic scaler

src/gpu/effects/GrBicubicEffect.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 GrBicubicTextureEffect_DEFINED
+#define GrBicubicTextureEffect_DEFINED
+
+#include "GrSingleTextureEffect.h"
+#include "GrDrawEffect.h"
+#include "gl/GrGLEffect.h"
+#include "gl/GrGLEffectMatrix.h"
+#include "GrTBackendEffectFactory.h"
+
+class GrGLBicubicEffect;
+
+#define DS(x) SkDoubleToScalar(x)
+
+static const SkScalar gMitchellCoefficients[16] = {
+    DS( 1.0 / 18.0), DS(-9.0 / 18.0), DS( 15.0 / 18.0), DS( -7.0 / 18.0),
+    DS(16.0 / 18.0), DS( 0.0 / 18.0), DS(-36.0 / 18.0), DS( 21.0 / 18.0),
+    DS( 1.0 / 18.0), DS( 9.0 / 18.0), DS( 27.0 / 18.0), DS(-21.0 / 18.0),
+    DS( 0.0 / 18.0), DS( 0.0 / 18.0), DS( -6.0 / 18.0), DS(  7.0 / 18.0),
+};
+
+class GrBicubicEffect : public GrSingleTextureEffect {
+public:
+    virtual ~GrBicubicEffect();
+
+    static const char* Name() { return "Bicubic"; }
+    const float* coefficients() const { return fCoefficients; }
+
+    typedef GrGLBicubicEffect GLEffect;
+
+    virtual const GrBackendEffectFactory& getFactory() const SK_OVERRIDE;
+    virtual void getConstantColorComponents(GrColor* color, uint32_t* validFlags) const SK_OVERRIDE;
+
+    static GrEffectRef* Create(GrTexture* tex, const SkScalar coefficients[16]) {
+        AutoEffectUnref effect(SkNEW_ARGS(GrBicubicEffect, (tex, coefficients)));
+        return CreateEffectRef(effect);
+    }
+
+    static GrEffectRef* Create(GrTexture* tex, const SkScalar coefficients[16], 
+                               const SkMatrix& matrix,
+                               const GrTextureParams& p,
+                               CoordsType coordsType = kLocal_CoordsType) {
+        AutoEffectUnref effect(SkNEW_ARGS(GrBicubicEffect, (tex, coefficients, matrix, p, coordsType)));
+        return CreateEffectRef(effect);
+    }
+
+    static GrEffectRef* Create(GrTexture* tex) {
+        return Create(tex, gMitchellCoefficients);
+    }
+
+    static GrEffectRef* Create(GrTexture* tex, 
+                               const SkMatrix& matrix,
+                               const GrTextureParams& p,
+                               CoordsType coordsType = kLocal_CoordsType) {
+        return Create(tex, gMitchellCoefficients, matrix, p, coordsType);
+    }
+
+private:
+    GrBicubicEffect(GrTexture*, const SkScalar coefficients[16]);
+    GrBicubicEffect(GrTexture*, const SkScalar coefficients[16], 
+                    const SkMatrix &matrix, const GrTextureParams &p, CoordsType coordsType);
+    virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
+    float    fCoefficients[16];
+
+    GR_DECLARE_EFFECT_TEST;
+
+    typedef GrSingleTextureEffect INHERITED;
+};
+
+#endif