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      1 /*
      2  * Copyright 2012 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef GrTBackendEffectFactory_DEFINED
      9 #define GrTBackendEffectFactory_DEFINED
     10 
     11 #include "GrBackendEffectFactory.h"
     12 #include "GrDrawEffect.h"
     13 #include "gl/GrGLProgramEffects.h"
     14 
     15 /**
     16  * Implements GrBackendEffectFactory for a GrEffect subclass as a singleton.
     17  */
     18 template <typename EffectClass>
     19 class GrTBackendEffectFactory : public GrBackendEffectFactory {
     20 
     21 public:
     22     typedef typename EffectClass::GLEffect GLEffect;
     23 
     24     /** Returns a human-readable name that is accessible via GrEffect or
     25         GrGLEffect and is consistent between the two of them.
     26      */
     27     virtual const char* name() const SK_OVERRIDE { return EffectClass::Name(); }
     28 
     29     /** Returns a value that identifies the GLSL shader code generated by
     30         a GrEffect. This enables caching of generated shaders. Part of the
     31         id identifies the GrEffect subclass. The remainder is based
     32         on the aspects of the GrEffect object's configuration that affect
     33         GLSL code generation. */
     34     virtual EffectKey glEffectKey(const GrDrawEffect& drawEffect,
     35                                   const GrGLCaps& caps) const SK_OVERRIDE {
     36         SkASSERT(kIllegalEffectClassID != fEffectClassID);
     37         EffectKey effectKey = GLEffect::GenKey(drawEffect, caps);
     38         EffectKey textureKey = GrGLProgramEffects::GenTextureKey(drawEffect, caps);
     39         EffectKey transformKey = GrGLProgramEffects::GenTransformKey(drawEffect);
     40         EffectKey attribKey = GrGLProgramEffects::GenAttribKey(drawEffect);
     41 #ifdef SK_DEBUG
     42         static const EffectKey kIllegalEffectKeyMask = (uint16_t) (~((1U << kEffectKeyBits) - 1));
     43         SkASSERT(!(kIllegalEffectKeyMask & effectKey));
     44 
     45         static const EffectKey kIllegalTextureKeyMask = (uint16_t) (~((1U << kTextureKeyBits) - 1));
     46         SkASSERT(!(kIllegalTextureKeyMask & textureKey));
     47 
     48         static const EffectKey kIllegalTransformKeyMask = (uint16_t) (~((1U << kTransformKeyBits) - 1));
     49         SkASSERT(!(kIllegalTransformKeyMask & transformKey));
     50 
     51         static const EffectKey kIllegalAttribKeyMask = (uint16_t) (~((1U << kAttribKeyBits) - 1));
     52         SkASSERT(!(kIllegalAttribKeyMask & textureKey));
     53 
     54         static const EffectKey kIllegalClassIDMask = (uint16_t) (~((1U << kClassIDBits) - 1));
     55         SkASSERT(!(kIllegalClassIDMask & fEffectClassID));
     56 #endif
     57         return (fEffectClassID << (kEffectKeyBits+kTextureKeyBits+kTransformKeyBits+kAttribKeyBits)) |
     58                (attribKey << (kEffectKeyBits+kTextureKeyBits+kTransformKeyBits)) |
     59                (transformKey << (kEffectKeyBits+kTextureKeyBits)) |
     60                (textureKey << kEffectKeyBits) |
     61                (effectKey);
     62     }
     63 
     64     /** Returns a new instance of the appropriate *GL* implementation class
     65         for the given GrEffect; caller is responsible for deleting
     66         the object. */
     67     virtual GrGLEffect* createGLInstance(const GrDrawEffect& drawEffect) const SK_OVERRIDE {
     68         return SkNEW_ARGS(GLEffect, (*this, drawEffect));
     69     }
     70 
     71     /** This class is a singleton. This function returns the single instance.
     72      */
     73     static const GrBackendEffectFactory& getInstance() {
     74         static SkAlignedSTStorage<1, GrTBackendEffectFactory> gInstanceMem;
     75         static const GrTBackendEffectFactory* gInstance;
     76         if (!gInstance) {
     77             gInstance = SkNEW_PLACEMENT(gInstanceMem.get(),
     78                                         GrTBackendEffectFactory);
     79         }
     80         return *gInstance;
     81     }
     82 
     83 protected:
     84     GrTBackendEffectFactory() {
     85         fEffectClassID = GenID();
     86     }
     87 };
     88 
     89 #endif
     90