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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 GrBackendEffectFactory_DEFINED
      9 #define GrBackendEffectFactory_DEFINED
     10 
     11 #include "GrTypes.h"
     12 #include "SkTemplates.h"
     13 #include "SkThread.h"
     14 #include "SkTypes.h"
     15 
     16 /** Given a GrEffect of a particular type, creates the corresponding graphics-backend-specific
     17     effect object. Also tracks equivalence of shaders generated via a key. Each factory instance
     18     is assigned a generation ID at construction. The ID of the return of GrEffect::getFactory()
     19     is used as a type identifier. Thus a GrEffect subclass must return a singleton from
     20     getFactory(). GrEffect subclasses should use the derived class GrTBackendEffectFactory that is
     21     templated on the GrEffect subclass as their factory object. It requires that the GrEffect
     22     subclass has a nested class (or typedef) GLEffect which is its GL implementation and a subclass
     23     of GrGLEffect.
     24  */
     25 
     26 class GrEffectRef;
     27 class GrGLEffect;
     28 class GrGLCaps;
     29 class GrDrawEffect;
     30 
     31 class GrBackendEffectFactory : SkNoncopyable {
     32 public:
     33     typedef uint32_t EffectKey;
     34     enum {
     35         kNoEffectKey = 0,
     36         kEffectKeyBits = 10,
     37         /**
     38          * The framework automatically includes coord transforms and texture accesses in their
     39          * effect's EffectKey, so effects don't need to account for them in GenKey().
     40          */
     41         kTextureKeyBits = 4,
     42         kTransformKeyBits = 6,
     43         kAttribKeyBits = 6,
     44         kClassIDBits = 6
     45     };
     46 
     47     virtual EffectKey glEffectKey(const GrDrawEffect&, const GrGLCaps&) const = 0;
     48     virtual GrGLEffect* createGLInstance(const GrDrawEffect&) const = 0;
     49 
     50     bool operator ==(const GrBackendEffectFactory& b) const {
     51         return fEffectClassID == b.fEffectClassID;
     52     }
     53     bool operator !=(const GrBackendEffectFactory& b) const {
     54         return !(*this == b);
     55     }
     56 
     57     virtual const char* name() const = 0;
     58 
     59     static EffectKey GetTransformKey(EffectKey key) {
     60         return key >> (kEffectKeyBits + kTextureKeyBits) & ((1U << kTransformKeyBits) - 1);
     61     }
     62 
     63 protected:
     64     enum {
     65         kIllegalEffectClassID = 0,
     66     };
     67 
     68     GrBackendEffectFactory() {
     69         fEffectClassID = kIllegalEffectClassID;
     70     }
     71     virtual ~GrBackendEffectFactory() {}
     72 
     73     static EffectKey GenID() {
     74         SkDEBUGCODE(static const int32_t kClassIDBits = 8 * sizeof(EffectKey) -
     75                            kTextureKeyBits - kEffectKeyBits - kAttribKeyBits);
     76         // fCurrEffectClassID has been initialized to kIllegalEffectClassID. The
     77         // atomic inc returns the old value not the incremented value. So we add
     78         // 1 to the returned value.
     79         int32_t id = sk_atomic_inc(&fCurrEffectClassID) + 1;
     80         SkASSERT(id < (1 << kClassIDBits));
     81         return static_cast<EffectKey>(id);
     82     }
     83 
     84     EffectKey fEffectClassID;
     85 
     86 private:
     87     static int32_t fCurrEffectClassID;
     88 };
     89 
     90 #endif
     91