alpha threshold bitmap shader

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
 
 #include "GrNoncopyable.h"
 #include "SkRefCnt.h"
 #include "SkShader.h"
 
 class GrTexture;
 
 /**
  * Represents the filtering and tile modes used to access a texture. It is mostly used with
  * GrTextureAccess (defined below). Also, some of the texture cache methods require knowledge about
  * filtering and tiling to perform a cache lookup. If it wasn't for this latter usage this would
- * be folded into GrTextureAccess.
+ * be folded into GrTextureAccess. The default is clamp tile modes and no filtering.
  */
 class GrTextureParams {
 public:
     GrTextureParams() {
         this->reset();
     }
 
     enum FilterMode {
         kNone_FilterMode,
         kBilerp_FilterMode,
@@ skipping 147 matching lines @@
 
     GrTextureParams         fParams;
     SkAutoTUnref<GrTexture> fTexture;
     uint32_t                fSwizzleMask;
     char                    fSwizzle[5];
 
     typedef GrNoncopyable INHERITED;
 };
 
 #endif