GrBackendEffectFactory.h revision d9947f605a335363b0a0541d6d8cb7a7113ed788 
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
26class GrEffectRef;
27class GrGLEffect;
28class GrGLCaps;
29class GrDrawEffect;
30
31class GrBackendEffectFactory : public SkNoncopyable {
32public:
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
63protected:
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
86private:
87    static int32_t fCurrEffectClassID;
88};
89
90#endif
91