HQ filtering for tiled/bleed drawBitmap

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 "GrTBackendEffectFactory.h"
 
 class GrGLBicubicEffect;
 
 class GrBicubicEffect : public GrSingleTextureEffect {
 public:
+    enum {
+        kFilterTexelPad = 2, // Given a src rect in texels to be filtered, this number of
+                             // surrounding texels are needed by the kernel in x and y.
+    };
     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;
 
@@ skipping 29 matching lines @@
     float    fCoefficients[16];
 
     GR_DECLARE_EFFECT_TEST;
 
     static const SkScalar gMitchellCoefficients[16];
 
     typedef GrSingleTextureEffect INHERITED;
 };
 
 #endif