1
2 /*
3 * Copyright 2010 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
10
11 #ifndef GrColor_DEFINED
12 #define GrColor_DEFINED
13
14 #include "GrTypes.h"
15
16 /**
17 * GrColor is 4 bytes for R, G, B, A, in a compile-time specific order. The
18 * components are stored premultiplied.
19 */
20 typedef uint32_t GrColor;
21
22
23 // shift amount to assign a component to a GrColor int
24 // These shift values are chosen for compatibility with GL attrib arrays
25 // ES doesn't allow BGRA vertex attrib order so if they were not in this order
26 // we'd have to swizzle in shaders. Note the assumption that the cpu is little
27 // endian.
28 #define GrColor_SHIFT_R 0
29 #define GrColor_SHIFT_G 8
30 #define GrColor_SHIFT_B 16
31 #define GrColor_SHIFT_A 24
32
33 /**
34 * Pack 4 components (RGBA) into a GrColor int
35 */
GrColorPackRGBA(unsigned r,unsigned g,unsigned b,unsigned a)36 static inline GrColor GrColorPackRGBA(unsigned r, unsigned g,
37 unsigned b, unsigned a) {
38 SkASSERT((uint8_t)r == r);
39 SkASSERT((uint8_t)g == g);
40 SkASSERT((uint8_t)b == b);
41 SkASSERT((uint8_t)a == a);
42 return (r << GrColor_SHIFT_R) |
43 (g << GrColor_SHIFT_G) |
44 (b << GrColor_SHIFT_B) |
45 (a << GrColor_SHIFT_A);
46 }
47
48 // extract a component (byte) from a GrColor int
49
50 #define GrColorUnpackR(color) (((color) >> GrColor_SHIFT_R) & 0xFF)
51 #define GrColorUnpackG(color) (((color) >> GrColor_SHIFT_G) & 0xFF)
52 #define GrColorUnpackB(color) (((color) >> GrColor_SHIFT_B) & 0xFF)
53 #define GrColorUnpackA(color) (((color) >> GrColor_SHIFT_A) & 0xFF)
54
55 /**
56 * Since premultiplied means that alpha >= color, we construct a color with
57 * each component==255 and alpha == 0 to be "illegal"
58 */
59 #define GrColor_ILLEGAL (~(0xFF << GrColor_SHIFT_A))
60
61 /** Converts a GrColor to an rgba array of GrGLfloat */
GrColorToRGBAFloat(GrColor color,float rgba[4])62 static inline void GrColorToRGBAFloat(GrColor color, float rgba[4]) {
63 static const float ONE_OVER_255 = 1.f / 255.f;
64 rgba[0] = GrColorUnpackR(color) * ONE_OVER_255;
65 rgba[1] = GrColorUnpackG(color) * ONE_OVER_255;
66 rgba[2] = GrColorUnpackB(color) * ONE_OVER_255;
67 rgba[3] = GrColorUnpackA(color) * ONE_OVER_255;
68 }
69
70 /**
71 * Flags used for bitfields of color components. They are defined so that the bit order reflects the
72 * GrColor shift order.
73 */
74 enum GrColorComponentFlags {
75 kR_GrColorComponentFlag = 1 << (GrColor_SHIFT_R / 8),
76 kG_GrColorComponentFlag = 1 << (GrColor_SHIFT_G / 8),
77 kB_GrColorComponentFlag = 1 << (GrColor_SHIFT_B / 8),
78 kA_GrColorComponentFlag = 1 << (GrColor_SHIFT_A / 8),
79
80 kRGB_GrColorComponentFlags = (kR_GrColorComponentFlag | kG_GrColorComponentFlag |
81 kB_GrColorComponentFlag),
82
83 kRGBA_GrColorComponentFlags = (kR_GrColorComponentFlag | kG_GrColorComponentFlag |
84 kB_GrColorComponentFlag | kA_GrColorComponentFlag)
85 };
86
GrColorComponentFlagToChar(GrColorComponentFlags component)87 static inline char GrColorComponentFlagToChar(GrColorComponentFlags component) {
88 SkASSERT(GrIsPow2(component));
89 switch (component) {
90 case kR_GrColorComponentFlag:
91 return 'r';
92 case kG_GrColorComponentFlag:
93 return 'g';
94 case kB_GrColorComponentFlag:
95 return 'b';
96 case kA_GrColorComponentFlag:
97 return 'a';
98 default:
99 GrCrash("Invalid color component flag.");
100 return '\0';
101 }
102 }
103
GrPixelConfigComponentMask(GrPixelConfig config)104 static inline uint32_t GrPixelConfigComponentMask(GrPixelConfig config) {
105 SkASSERT(config >= 0 && config < kGrPixelConfigCnt);
106 static const uint32_t kFlags[] = {
107 0, // kUnknown_GrPixelConfig
108 kA_GrColorComponentFlag, // kAlpha_8_GrPixelConfig
109 kRGBA_GrColorComponentFlags, // kIndex_8_GrPixelConfig
110 kRGB_GrColorComponentFlags, // kRGB_565_GrPixelConfig
111 kRGBA_GrColorComponentFlags, // kRGBA_4444_GrPixelConfig
112 kRGBA_GrColorComponentFlags, // kRGBA_8888_GrPixelConfig
113 kRGBA_GrColorComponentFlags, // kBGRA_8888_GrPixelConfig
114 };
115 return kFlags[config];
116
117 GR_STATIC_ASSERT(0 == kUnknown_GrPixelConfig);
118 GR_STATIC_ASSERT(1 == kAlpha_8_GrPixelConfig);
119 GR_STATIC_ASSERT(2 == kIndex_8_GrPixelConfig);
120 GR_STATIC_ASSERT(3 == kRGB_565_GrPixelConfig);
121 GR_STATIC_ASSERT(4 == kRGBA_4444_GrPixelConfig);
122 GR_STATIC_ASSERT(5 == kRGBA_8888_GrPixelConfig);
123 GR_STATIC_ASSERT(6 == kBGRA_8888_GrPixelConfig);
124 GR_STATIC_ASSERT(SK_ARRAY_COUNT(kFlags) == kGrPixelConfigCnt);
125 }
126
127 #endif
128