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1 | |
2 /* | |
3 * Copyright 2013 Google Inc. | |
4 * | |
5 * Use of this source code is governed by a BSD-style license that can be | |
6 * found in the LICENSE file. | |
7 */ | |
8 | |
9 #include "GrTypes.h" | |
10 #include "SkTLogic.h" | |
11 #include "GrXferProcessor.h" | |
12 | |
13 #ifndef GrBlend_DEFINED | |
14 #define GrBlend_DEFINED | |
15 | |
16 template<GrBlendCoeff Coeff> | |
17 struct GrTBlendCoeffRefsSrc : SkTBool<kSC_GrBlendCoeff == Coeff || | |
18 kISC_GrBlendCoeff == Coeff || | |
19 kSA_GrBlendCoeff == Coeff || | |
20 kISA_GrBlendCoeff == Coeff> {}; | |
21 | |
22 #define GR_BLEND_COEFF_REFS_SRC(COEFF) \ | |
23 GrTBlendCoeffRefsSrc<COEFF>::value | |
24 | |
25 inline bool GrBlendCoeffRefsSrc(GrBlendCoeff coeff) { | |
26 switch (coeff) { | |
27 case kSC_GrBlendCoeff: | |
28 case kISC_GrBlendCoeff: | |
29 case kSA_GrBlendCoeff: | |
30 case kISA_GrBlendCoeff: | |
31 return true; | |
32 default: | |
33 return false; | |
34 } | |
35 } | |
36 | |
37 | |
38 template<GrBlendCoeff Coeff> | |
39 struct GrTBlendCoeffRefsDst : SkTBool<kDC_GrBlendCoeff == Coeff || | |
40 kIDC_GrBlendCoeff == Coeff || | |
41 kDA_GrBlendCoeff == Coeff || | |
42 kIDA_GrBlendCoeff == Coeff> {}; | |
43 | |
44 #define GR_BLEND_COEFF_REFS_DST(COEFF) \ | |
45 GrTBlendCoeffRefsDst<COEFF>::value | |
46 | |
47 inline bool GrBlendCoeffRefsDst(GrBlendCoeff coeff) { | |
48 switch (coeff) { | |
49 case kDC_GrBlendCoeff: | |
50 case kIDC_GrBlendCoeff: | |
51 case kDA_GrBlendCoeff: | |
52 case kIDA_GrBlendCoeff: | |
53 return true; | |
54 default: | |
55 return false; | |
56 } | |
57 } | |
58 | |
59 | |
60 template<GrBlendCoeff Coeff> | |
61 struct GrTBlendCoeffRefsSrc2 : SkTBool<kS2C_GrBlendCoeff == Coeff || | |
62 kIS2C_GrBlendCoeff == Coeff || | |
63 kS2A_GrBlendCoeff == Coeff || | |
64 kIS2A_GrBlendCoeff == Coeff> {}; | |
65 | |
66 #define GR_BLEND_COEFF_REFS_SRC2(COEFF) \ | |
67 GrTBlendCoeffRefsSrc2<COEFF>::value | |
68 | |
69 inline bool GrBlendCoeffRefsSrc2(GrBlendCoeff coeff) { | |
70 switch (coeff) { | |
71 case kS2C_GrBlendCoeff: | |
72 case kIS2C_GrBlendCoeff: | |
73 case kS2A_GrBlendCoeff: | |
74 case kIS2A_GrBlendCoeff: | |
75 return true; | |
76 default: | |
77 return false; | |
78 } | |
79 } | |
80 | |
81 | |
82 template<GrBlendCoeff SrcCoeff, GrBlendCoeff DstCoeff> | |
83 struct GrTBlendCoeffsUseSrcColor : SkTBool<kZero_GrBlendCoeff != SrcCoeff || | |
84 GR_BLEND_COEFF_REFS_SRC(DstCoeff)> {}
; | |
85 | |
86 #define GR_BLEND_COEFFS_USE_SRC_COLOR(SRC_COEFF, DST_COEFF) \ | |
87 GrTBlendCoeffsUseSrcColor<SRC_COEFF, DST_COEFF>::value | |
88 | |
89 | |
90 template<GrBlendCoeff SrcCoeff, GrBlendCoeff DstCoeff> | |
91 struct GrTBlendCoeffsUseDstColor : SkTBool<GR_BLEND_COEFF_REFS_DST(SrcCoeff) || | |
92 kZero_GrBlendCoeff != DstCoeff> {}; | |
93 | |
94 #define GR_BLEND_COEFFS_USE_DST_COLOR(SRC_COEFF, DST_COEFF) \ | |
95 GrTBlendCoeffsUseDstColor<SRC_COEFF, DST_COEFF>::value | |
96 | |
97 | |
98 template<GrBlendEquation Equation> | |
99 struct GrTBlendEquationIsAdvanced : SkTBool<Equation >= kFirstAdvancedGrBlendEqu
ation> {}; | |
100 | |
101 #define GR_BLEND_EQUATION_IS_ADVANCED(EQUATION) \ | |
102 GrTBlendEquationIsAdvanced<EQUATION>::value | |
103 | |
104 inline bool GrBlendEquationIsAdvanced(GrBlendEquation equation) { | |
105 return equation >= kFirstAdvancedGrBlendEquation; | |
106 } | |
107 | |
108 | |
109 template<GrBlendEquation BlendEquation, GrBlendCoeff SrcCoeff, GrBlendCoeff DstC
oeff> | |
110 struct GrTBlendModifiesDst : SkTBool<(kAdd_GrBlendEquation != BlendEquation && | |
111 kReverseSubtract_GrBlendEquation != BlendE
quation) || | |
112 kZero_GrBlendCoeff != SrcCoeff || | |
113 kOne_GrBlendCoeff != DstCoeff> {}; | |
114 | |
115 #define GR_BLEND_MODIFIES_DST(EQUATION, SRC_COEFF, DST_COEFF) \ | |
116 GrTBlendModifiesDst<EQUATION, SRC_COEFF, DST_COEFF>::value | |
117 | |
118 | |
119 /** | |
120 * Advanced blend equations can always tweak alpha for coverage. (See GrCustomXf
ermode.cpp) | |
121 * | |
122 * For "add" and "reverse subtract" the blend equation with f=coverage is: | |
123 * | |
124 * D' = f * (S * srcCoeff + D * dstCoeff) + (1-f) * D | |
125 * = f * S * srcCoeff + D * (f * dstCoeff + (1 - f)) | |
126 * | |
127 * (Let srcCoeff be negative for reverse subtract.) We can tweak alpha for cover
age when the | |
128 * following relationship holds: | |
129 * | |
130 * (f*S) * srcCoeff' + D * dstCoeff' == f * S * srcCoeff + D * (f * dstCoeff +
(1 - f)) | |
131 * | |
132 * (Where srcCoeff' and dstCoeff' have any reference to S pre-multiplied by f.) | |
133 * | |
134 * It's easy to see this works for the src term as long as srcCoeff' == srcCoeff
(meaning srcCoeff | |
135 * does not reference S). For the dst term, this will work as long as the follow
ing is true: | |
136 *| | |
137 * dstCoeff' == f * dstCoeff + (1 - f) | |
138 * dstCoeff' == 1 - f * (1 - dstCoeff) | |
139 * | |
140 * By inspection we can see this will work as long as dstCoeff has a 1, and any
other term in | |
141 * dstCoeff references S. | |
142 */ | |
143 template<GrBlendEquation Equation, GrBlendCoeff SrcCoeff, GrBlendCoeff DstCoeff> | |
144 struct GrTBlendCanTweakAlphaForCoverage : SkTBool<GR_BLEND_EQUATION_IS_ADVANCED(
Equation) || | |
145 ((kAdd_GrBlendEquation == Equa
tion || | |
146 kReverseSubtract_GrBlendEqua
tion == Equation) && | |
147 !GR_BLEND_COEFF_REFS_SRC(SrcC
oeff) && | |
148 (kOne_GrBlendCoeff == DstCoef
f || | |
149 kISC_GrBlendCoeff == DstCoef
f || | |
150 kISA_GrBlendCoeff == DstCoef
f))> {}; | |
151 | |
152 #define GR_BLEND_CAN_TWEAK_ALPHA_FOR_COVERAGE(EQUATION, SRC_COEFF, DST_COEFF) \ | |
153 GrTBlendCanTweakAlphaForCoverage<EQUATION, SRC_COEFF, DST_COEFF>::value | |
154 | |
155 #endif | |
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