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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 
     14 /**
     15  * Implements GrBackendEffectFactory for a GrEffect subclass as a singleton.
     16  */
     17 template <typename EffectClass>
     18 class GrTBackendEffectFactory : public GrBackendEffectFactory {
     19 
     20 public:
     21     typedef typename EffectClass::GLEffect GLEffect;
     22 
     23     /** Returns a human-readable name that is accessible via GrEffect or
     24         GrGLEffect and is consistent between the two of them.
     25      */
     26     virtual const char* name() const SK_OVERRIDE { return EffectClass::Name(); }
     27 
     28     /** Returns a value that identifies the GLSL shader code generated by
     29         a GrEffect. This enables caching of generated shaders. Part of the
     30         id identifies the GrEffect subclass. The remainder is based
     31         on the aspects of the GrEffect object's configuration that affect
     32         GLSL code generation. */
     33     virtual EffectKey glEffectKey(const GrDrawEffect& drawEffect,
     34                                   const GrGLCaps& caps) const SK_OVERRIDE {
     35         GrAssert(kIllegalEffectClassID != fEffectClassID);
     36         EffectKey effectKey = GLEffect::GenKey(drawEffect, caps);
     37         EffectKey textureKey = GLEffect::GenTextureKey(drawEffect, caps);
     38         EffectKey attribKey = GLEffect::GenAttribKey(drawEffect);
     39 #if GR_DEBUG
     40         static const EffectKey kIllegalIDMask = (uint16_t) (~((1U << kEffectKeyBits) - 1));
     41         GrAssert(!(kIllegalIDMask & effectKey));
     42 
     43         static const EffectKey kIllegalTextureKeyMask = (uint16_t) (~((1U << kTextureKeyBits) - 1));
     44         GrAssert(!(kIllegalTextureKeyMask & textureKey));
     45 
     46         static const EffectKey kIllegalAttribKeyMask = (uint16_t) (~((1U << kAttribKeyBits) - 1));
     47         GrAssert(!(kIllegalAttribKeyMask & textureKey));
     48 #endif
     49         return fEffectClassID | (attribKey << (kEffectKeyBits+kTextureKeyBits)) |
     50                (textureKey << kEffectKeyBits) | effectKey;
     51     }
     52 
     53     /** Returns a new instance of the appropriate *GL* implementation class
     54         for the given GrEffect; caller is responsible for deleting
     55         the object. */
     56     virtual GLEffect* createGLInstance(const GrDrawEffect& drawEffect) const SK_OVERRIDE {
     57         return SkNEW_ARGS(GLEffect, (*this, drawEffect));
     58     }
     59 
     60     /** This class is a singleton. This function returns the single instance.
     61      */
     62     static const GrBackendEffectFactory& getInstance() {
     63         static SkAlignedSTStorage<1, GrTBackendEffectFactory> gInstanceMem;
     64         static const GrTBackendEffectFactory* gInstance;
     65         if (!gInstance) {
     66             gInstance = SkNEW_PLACEMENT(gInstanceMem.get(),
     67                                         GrTBackendEffectFactory);
     68         }
     69         return *gInstance;
     70     }
     71 
     72 protected:
     73     GrTBackendEffectFactory() {
     74         fEffectClassID = GenID() << (kAttribKeyBits + kEffectKeyBits + kTextureKeyBits) ;
     75     }
     76 };
     77 
     78 #endif
     79