alpha threshold bitmap shader

include/gpu/GrEffect.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 GrEffect_DEFINED
 #define GrEffect_DEFINED
 
@@ skipping 186 matching lines @@
         int count = fTextureAccesses.count();
         for (int t = 0; t < count; ++t) {
             fTextureAccesses[t]->getTexture()->decDeferredRefCount();
         }
         this->unref();
     }
 
 protected:
     /**
      * Subclasses call this from their constructor to register GrTextureAccesses. The effect
-     * subclass manages the lifetime of the accesses (this function only stores a pointer). This
-     * must only be called from the constructor because GrEffects are immutable.
+     * subclass manages the lifetime of the accesses (this function only stores a pointer). The
+     * GrTextureAccess is typically a member field of the GrEffet subclass. This must only be
+     * called from the constructor because GrEffects are immutable.
      */
     void addTextureAccess(const GrTextureAccess* textureAccess);
 
     /**
      * Subclasses call this from their constructor to register vertex attributes (at most
      * kMaxVertexAttribs). This must only be called from the constructor because GrEffects are
      * immutable.
      */
     void addVertexAttrib(GrSLType type);
 
@@ skipping 117 matching lines @@
 };                                                                                                \
 static SkAlignedSStorage<k_##NAME##_StorageSize> g_##NAME##_Storage;                              \
 static void* NAME##_RefLocation = (char*)g_##NAME##_Storage.get() + k_##NAME##_EffectRefOffset;   \
 static GrEffect* NAME##_Effect SkNEW_PLACEMENT_ARGS(g_##NAME##_Storage.get(), EFFECT_CLASS, ARGS);\
 static SkAutoTDestroy<GrEffect> NAME##_ad(NAME##_Effect);                                         \
 static GrEffectRef* NAME(GrEffect::CreateStaticEffectRef(NAME##_RefLocation, NAME##_Effect));     \
 static SkAutoTDestroy<GrEffectRef> NAME##_Ref_ad(NAME)
 
 
 #endif