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 GrAssert((uint8_t)r == r);
39 GrAssert((uint8_t)g == g);
40 GrAssert((uint8_t)b == b);
41 GrAssert((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 #endif
62
63