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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 #include "SkTArray.h" | |
16 | |
17 class GrGLEffect; | |
18 class GrGLCaps; | |
19 class GrEffect; | |
20 | |
21 /** | |
22 * Used by effects to build their keys. It incorporates each per-effect key into
a larger shader key. | |
23 */ | |
24 class GrEffectKeyBuilder { | |
25 public: | |
26 GrEffectKeyBuilder(SkTArray<unsigned char, true>* data) : fData(data), fCoun
t(0) { | |
27 SkASSERT(0 == fData->count() % sizeof(uint32_t)); | |
28 } | |
29 | |
30 void add32(uint32_t v) { | |
31 ++fCount; | |
32 fData->push_back_n(4, reinterpret_cast<uint8_t*>(&v)); | |
33 } | |
34 | |
35 /** Inserts count uint32_ts into the key. The returned pointer is only valid
until the next | |
36 add*() call. */ | |
37 uint32_t* SK_WARN_UNUSED_RESULT add32n(int count) { | |
38 SkASSERT(count > 0); | |
39 fCount += count; | |
40 return reinterpret_cast<uint32_t*>(fData->push_back_n(4 * count)); | |
41 } | |
42 | |
43 size_t size() const { return sizeof(uint32_t) * fCount; } | |
44 | |
45 private: | |
46 SkTArray<uint8_t, true>* fData; // unowned ptr to the larger key. | |
47 int fCount; // number of uint32_ts added to fData by the
effect. | |
48 }; | |
49 | |
50 /** | |
51 * This class is used to pass the key that was created for a GrGLEffect back to
it | |
52 * when it emits code. It may allow the emit step to skip calculations that were | |
53 * performed when computing the key. | |
54 */ | |
55 class GrEffectKey { | |
56 public: | |
57 GrEffectKey(const uint32_t* key, int count) : fKey(key), fCount(count) { | |
58 SkASSERT(0 == reinterpret_cast<intptr_t>(key) % sizeof(uint32_t)); | |
59 } | |
60 | |
61 /** Gets the uint32_t values that the effect inserted into the key. */ | |
62 uint32_t get32(int index) const { | |
63 SkASSERT(index >=0 && index < fCount); | |
64 return fKey[index]; | |
65 } | |
66 | |
67 /** Gets the number of uint32_t values that the effect inserted into the key
. */ | |
68 int count32() const { return fCount; } | |
69 | |
70 private: | |
71 const uint32_t* fKey; // unowned ptr into the larger key. | |
72 int fCount; // number of uint32_ts inserted by the effec
t into its key. | |
73 }; | |
74 | |
75 /** | |
76 * Given a GrEffect of a particular type, creates the corresponding graphics-bac
kend-specific | |
77 * effect object. It also tracks equivalence of shaders generated via a key. The
factory for an | |
78 * effect is accessed via GrEffect::getFactory(). Each factory instance is assig
ned an ID at | |
79 * construction. The ID of GrEffect::getFactory() is used as a type identifier.
Thus, a GrEffect | |
80 * subclass must always return the same object from getFactory() and that factor
y object must be | |
81 * unique to the GrEffect subclass (and unique from any further derived subclass
es). | |
82 * | |
83 * Rather than subclassing this class themselves, it is recommended that GrEffec
t authors use | |
84 * the templated subclass GrTBackendEffectFactory by writing their getFactory()
method as: | |
85 * | |
86 * const GrBackendEffectFactory& MyEffect::getFactory() const { | |
87 * return GrTBackendEffectFactory<MyEffect>::getInstance(); | |
88 * } | |
89 * | |
90 * Using GrTBackendEffectFactory places a few constraints on the effect. See tha
t class's comments. | |
91 */ | |
92 class GrBackendEffectFactory : SkNoncopyable { | |
93 public: | |
94 /** | |
95 * Generates an effect's key. The key is based on the aspects of the GrEffec
t object's | |
96 * configuration that affect GLSL code generation. Two GrEffect instances th
at would cause | |
97 * this->createGLInstance()->emitCode() to produce different code must produ
ce different keys. | |
98 */ | |
99 virtual void getGLEffectKey(const GrEffect&, const GrGLCaps&, GrEffectKeyBui
lder*) const = 0; | |
100 | |
101 /** | |
102 * Creates a GrGLEffect instance that is used both to generate code for the
GrEffect in a GLSL | |
103 * program and to manage updating uniforms for the program when it is used. | |
104 */ | |
105 virtual GrGLEffect* createGLInstance(const GrEffect&) const = 0; | |
106 | |
107 /** | |
108 * Produces a human-reable name for the effect. | |
109 */ | |
110 virtual const char* name() const = 0; | |
111 | |
112 /** | |
113 * A unique value for every instance of this factory. It is automatically in
corporated into the | |
114 * effect's key. This allows keys generated by getGLEffectKey() to only be u
nique within a | |
115 * GrEffect subclass and not necessarily across subclasses. | |
116 */ | |
117 uint32_t effectClassID() const { return fEffectClassID; } | |
118 | |
119 protected: | |
120 GrBackendEffectFactory() : fEffectClassID(GenID()) {} | |
121 virtual ~GrBackendEffectFactory() {} | |
122 | |
123 private: | |
124 enum { | |
125 kIllegalEffectClassID = 0, | |
126 }; | |
127 | |
128 static uint32_t GenID() { | |
129 // fCurrEffectClassID has been initialized to kIllegalEffectClassID. The | |
130 // atomic inc returns the old value not the incremented value. So we add | |
131 // 1 to the returned value. | |
132 uint32_t id = static_cast<uint32_t>(sk_atomic_inc(&fCurrEffectClassID))
+ 1; | |
133 if (!id) { | |
134 SkFAIL("This should never wrap as it should only be called once for
each GrEffect " | |
135 "subclass."); | |
136 } | |
137 return id; | |
138 } | |
139 | |
140 const uint32_t fEffectClassID; | |
141 static int32_t fCurrEffectClassID; | |
142 }; | |
143 | |
144 #endif | |
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