Use GrTextureDomain in GrBicubicEffect to perform non-bleeding HQ filter 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 "GrTextureDomain.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;
 
-    /**
-     * Create a simple Mitchell filter effect.
-     */
-    static GrEffectRef* Create(GrTexture* tex) {
-        return Create(tex, gMitchellCoefficients);
-    }
+    const GrTextureDomain& domain() const { return fDomain; }
 
     /**
-     * Create a simple filter effect with custom bicubic coefficients.
+     * Create a simple filter effect with custom bicubic coefficients and optional domain.
      */
     static GrEffectRef* Create(GrTexture* tex, const SkScalar coefficients[16]) {

[Stephen White, 2013/12/12 01:50:07]

Maybe this variant of the factory function should take a texture domain too, and
default to no domain (and clamp mode) if not specified. (The comment above seems
to suggest it does this, but it doesn't.)

[bsalomon, 2013/12/13 20:53:26]

Done.

-        const SkShader::TileMode tm[] = { SkShader::kClamp_TileMode, SkShader::kClamp_TileMode };
-        return Create(tex, coefficients, MakeDivByTextureWHMatrix(tex), tm);
+        static const SkShader::TileMode kTileModes[] = { SkShader::kClamp_TileMode,
+                                                         SkShader::kClamp_TileMode };
+        return Create(tex, coefficients, MakeDivByTextureWHMatrix(tex), kTileModes);
     }
 
     /**
      * Create a Mitchell filter effect with specified texture matrix and x/y tile modes.
      */
-    static GrEffectRef* Create(GrTexture* tex,
-                               const SkMatrix& matrix,
+    static GrEffectRef* Create(GrTexture* tex, const SkMatrix& matrix,
                                SkShader::TileMode tileModes[2]) {
         return Create(tex, gMitchellCoefficients, matrix, tileModes);
     }
 
     /**
-     * The most general Create method. This allows specification of the bicubic coefficients, the
-     * texture matrix, and the x/y tilemodes.
+     * Create a filter effect with custom bicubic coefficients, the texture matrix, and the x/y
+     * tilemodes.
      */
     static GrEffectRef* Create(GrTexture* tex, const SkScalar coefficients[16],
-                               const SkMatrix& matrix,
-                               const SkShader::TileMode tileModes[2]) {
+                               const SkMatrix& matrix, const SkShader::TileMode tileModes[2]) {
         AutoEffectUnref effect(SkNEW_ARGS(GrBicubicEffect, (tex, coefficients, matrix, tileModes)));
         return CreateEffectRef(effect);
     }
 
+    /**
+     * Create a Mitchell filter effect with a texture matrix and a domain.
+     */
+    static GrEffectRef* Create(GrTexture* tex, const SkMatrix& matrix, const SkRect& domain) {
+        AutoEffectUnref effect(SkNEW_ARGS(GrBicubicEffect, (tex, gMitchellCoefficients, matrix,
+                                                            domain)));
+        return CreateEffectRef(effect);
+    }
+
 private:
     GrBicubicEffect(GrTexture*, const SkScalar coefficients[16],
                     const SkMatrix &matrix, const SkShader::TileMode tileModes[2]);
+    GrBicubicEffect(GrTexture*, const SkScalar coefficients[16],
+                    const SkMatrix &matrix, const SkRect& domain);
     virtual bool onIsEqual(const GrEffect&) const SK_OVERRIDE;
-    float    fCoefficients[16];
+
+    float           fCoefficients[16];
+    GrTextureDomain fDomain;
 
     GR_DECLARE_EFFECT_TEST;
 
     static const SkScalar gMitchellCoefficients[16];
 
     typedef GrSingleTextureEffect INHERITED;
 };
 
 #endif