Implement GL support for buffer textures

include/gpu/GrTextureAccess.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrTextureAccess_DEFINED
 #define GrTextureAccess_DEFINED
 
@@ skipping 15 matching lines @@
     GrTextureAccess();
 
     GrTextureAccess(GrTexture*, const GrTextureParams&);
 
     explicit GrTextureAccess(GrTexture*,
                              GrTextureParams::FilterMode = GrTextureParams::kNone_FilterMode,
                              SkShader::TileMode tileXAndY = SkShader::kClamp_TileMode,
                              GrShaderFlags visibility = kFragment_GrShaderFlag,
                              GrSLPrecision = kDefault_GrSLPrecision);
 
+    // This constructor is only for textures that do not support texture params.
+    explicit GrTextureAccess(GrTexture*, GrShaderFlags visibility, GrSLPrecision);
+
     void reset(GrTexture*, const GrTextureParams&,
                GrShaderFlags visibility = kFragment_GrShaderFlag,
                GrSLPrecision = kDefault_GrSLPrecision);
     void reset(GrTexture*,
                GrTextureParams::FilterMode = GrTextureParams::kNone_FilterMode,
                SkShader::TileMode tileXAndY = SkShader::kClamp_TileMode,
                GrShaderFlags visibility = kFragment_GrShaderFlag,
                GrSLPrecision = kDefault_GrSLPrecision);
 
+    // This version is only for textures that do not support texture params.
+    void reset(GrTexture*, GrShaderFlags visibility, GrSLPrecision);
+
     bool operator==(const GrTextureAccess& that) const {
         return this->getTexture() == that.getTexture() &&
                fParams == that.fParams &&
                fVisibility == that.fVisibility &&
                fPrecision == that.fPrecision;
     }
 
     bool operator!=(const GrTextureAccess& other) const { return !(*this == other); }
 
     GrTexture* getTexture() const { return fTexture.get(); }
     GrShaderFlags getVisibility() const { return fVisibility; }
     GrSLPrecision getPrecision() const { return fPrecision; }
 
     /**
      * For internal use by GrProcessor.
      */
     const GrGpuResourceRef* getProgramTexture() const { return &fTexture; }
 
-    const GrTextureParams& getParams() const { return fParams; }
+    const GrTextureParams& getParams() const {
+        SkASSERT(this->getTexture()->supportsTextureParams());
+        return fParams;
+    }
 
 private:
 
     typedef GrTGpuResourceRef<GrTexture> ProgramTexture;
 
     ProgramTexture                  fTexture;
     GrTextureParams                 fParams;
     GrShaderFlags                   fVisibility;
     GrSLPrecision                   fPrecision;
 
     typedef SkNoncopyable INHERITED;
 };
 
 #endif