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1 | 1 |
2 /* | 2 /* |
3 * Copyright 2011 Google Inc. | 3 * Copyright 2011 Google Inc. |
4 * | 4 * |
5 * Use of this source code is governed by a BSD-style license that can be | 5 * Use of this source code is governed by a BSD-style license that can be |
6 * found in the LICENSE file. | 6 * found in the LICENSE file. |
7 */ | 7 */ |
8 | 8 |
9 | 9 |
10 #ifndef GrPaint_DEFINED | 10 #ifndef GrPaint_DEFINED |
11 #define GrPaint_DEFINED | 11 #define GrPaint_DEFINED |
12 | 12 |
13 #include "GrColor.h" | 13 #include "GrColor.h" |
14 #include "GrFragmentStage.h" | 14 #include "GrFragmentStage.h" |
15 #include "GrXferProcessor.h" | 15 #include "GrXferProcessor.h" |
16 #include "effects/GrPorterDuffXferProcessor.h" | 16 #include "effects/GrPorterDuffXferProcessor.h" |
17 | 17 |
18 #include "SkXfermode.h" | 18 #include "SkXfermode.h" |
19 | 19 |
20 /** | 20 /** |
21 * The paint describes how color and coverage are computed at each pixel by GrCo
ntext draw | 21 * The paint describes how color and coverage are computed at each pixel by GrCo
ntext draw |
22 * functions and the how color is blended with the destination pixel. | 22 * functions and the how color is blended with the destination pixel. |
23 * | 23 * |
24 * The paint allows installation of custom color and coverage stages. New types
of stages are | 24 * The paint allows installation of custom color and coverage stages. New types
of stages are |
25 * created by subclassing GrProcessor. | 25 * created by subclassing GrProcessor. |
26 * | 26 * |
27 * The primitive color computation starts with the color specified by setColor()
. This color is the | 27 * The primitive color computation starts with the color specified by setColor()
. This color is the |
28 * input to the first color stage. Each color stage feeds its output to the next
color stage. The | 28 * input to the first color stage. Each color stage feeds its output to the next
color stage. |
29 * final color stage's output color is input to the color filter specified by | |
30 * setXfermodeColorFilter which produces the final source color, S. | |
31 * | 29 * |
32 * Fractional pixel coverage follows a similar flow. The coverage is initially t
he value specified | 30 * Fractional pixel coverage follows a similar flow. The coverage is initially t
he value specified |
33 * by setCoverage(). This is input to the first coverage stage. Coverage stages
are chained | 31 * by setCoverage(). This is input to the first coverage stage. Coverage stages
are chained |
34 * together in the same manner as color stages. The output of the last stage is
modulated by any | 32 * together in the same manner as color stages. The output of the last stage is
modulated by any |
35 * fractional coverage produced by anti-aliasing. This last step produces the fi
nal coverage, C. | 33 * fractional coverage produced by anti-aliasing. This last step produces the fi
nal coverage, C. |
36 * | 34 * |
37 * setBlendFunc() specifies blending coefficients for S (described above) and D,
the initial value | 35 * setXPFactory is used to control blending between the output color and dest. I
t also implements |
38 * of the destination pixel, labeled Bs and Bd respectively. The final value of
the destination | 36 * the application of fractional coverage from the coverage pipeline. |
39 * pixel is then D' = (1-C)*D + C*(Bd*D + Bs*S). | |
40 * | |
41 * Note that the coverage is applied after the blend. This is why they are compu
ted as distinct | |
42 * values. | |
43 * | |
44 * TODO: Encapsulate setXfermodeColorFilter in a GrProcessor and remove from GrP
aint. | |
45 */ | 37 */ |
46 class GrPaint { | 38 class GrPaint { |
47 public: | 39 public: |
48 GrPaint(); | 40 GrPaint(); |
49 | 41 |
50 GrPaint(const GrPaint& paint) { *this = paint; } | 42 GrPaint(const GrPaint& paint) { *this = paint; } |
51 | 43 |
52 ~GrPaint() {} | 44 ~GrPaint() {} |
53 | 45 |
54 /** | 46 /** |
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148 SkSTArray<4, GrFragmentStage> fColorStages; | 140 SkSTArray<4, GrFragmentStage> fColorStages; |
149 SkSTArray<2, GrFragmentStage> fCoverageStages; | 141 SkSTArray<2, GrFragmentStage> fCoverageStages; |
150 | 142 |
151 bool fAntiAlias; | 143 bool fAntiAlias; |
152 bool fDither; | 144 bool fDither; |
153 | 145 |
154 GrColor fColor; | 146 GrColor fColor; |
155 }; | 147 }; |
156 | 148 |
157 #endif | 149 #endif |
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