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#include "SkColor.h"
16#include "SkColorPriv.h"
17#include "SkUnPreMultiply.h"
18
19/**
20 * GrColor is 4 bytes for R, G, B, A, in a specific order defined below. Whether the color is
21 * premultiplied or not depends on the context in which it is being used.
22 */
23typedef uint32_t GrColor;
24
25// shift amount to assign a component to a GrColor int
26// These shift values are chosen for compatibility with GL attrib arrays
27// ES doesn't allow BGRA vertex attrib order so if they were not in this order
28// we'd have to swizzle in shaders.
29#ifdef SK_CPU_BENDIAN
30    #define GrColor_SHIFT_R     24
31    #define GrColor_SHIFT_G     16
32    #define GrColor_SHIFT_B     8
33    #define GrColor_SHIFT_A     0
34#else
35    #define GrColor_SHIFT_R     0
36    #define GrColor_SHIFT_G     8
37    #define GrColor_SHIFT_B     16
38    #define GrColor_SHIFT_A     24
39#endif
40
41/**
42 *  Pack 4 components (RGBA) into a GrColor int
43 */
44static inline GrColor GrColorPackRGBA(unsigned r, unsigned g, unsigned b, unsigned a) {
45    SkASSERT((uint8_t)r == r);
46    SkASSERT((uint8_t)g == g);
47    SkASSERT((uint8_t)b == b);
48    SkASSERT((uint8_t)a == a);
49    return  (r << GrColor_SHIFT_R) |
50            (g << GrColor_SHIFT_G) |
51            (b << GrColor_SHIFT_B) |
52            (a << GrColor_SHIFT_A);
53}
54
55/**
56 *  Packs a color with an alpha channel replicated across all four channels.
57 */
58static inline GrColor GrColorPackA4(unsigned a) {
59    SkASSERT((uint8_t)a == a);
60    return  (a << GrColor_SHIFT_R) |
61            (a << GrColor_SHIFT_G) |
62            (a << GrColor_SHIFT_B) |
63            (a << GrColor_SHIFT_A);
64}
65
66// extract a component (byte) from a GrColor int
67
68#define GrColorUnpackR(color)   (((color) >> GrColor_SHIFT_R) & 0xFF)
69#define GrColorUnpackG(color)   (((color) >> GrColor_SHIFT_G) & 0xFF)
70#define GrColorUnpackB(color)   (((color) >> GrColor_SHIFT_B) & 0xFF)
71#define GrColorUnpackA(color)   (((color) >> GrColor_SHIFT_A) & 0xFF)
72
73/**
74 *  Since premultiplied means that alpha >= color, we construct a color with
75 *  each component==255 and alpha == 0 to be "illegal"
76 */
77#define GrColor_ILLEGAL     (~(0xFF << GrColor_SHIFT_A))
78
79#define GrColor_WHITE 0xFFFFFFFF
80#define GrColor_TRANSPARENT_BLACK 0x0
81
82/**
83 * Assert in debug builds that a GrColor is premultiplied.
84 */
85static inline void GrColorIsPMAssert(GrColor SkDEBUGCODE(c)) {
86#ifdef SK_DEBUG
87    unsigned a = GrColorUnpackA(c);
88    unsigned r = GrColorUnpackR(c);
89    unsigned g = GrColorUnpackG(c);
90    unsigned b = GrColorUnpackB(c);
91
92    SkASSERT(r <= a);
93    SkASSERT(g <= a);
94    SkASSERT(b <= a);
95#endif
96}
97
98/** Inverts each color channel. */
99static inline GrColor GrInvertColor(GrColor c) {
100    U8CPU a = GrColorUnpackA(c);
101    U8CPU r = GrColorUnpackR(c);
102    U8CPU g = GrColorUnpackG(c);
103    U8CPU b = GrColorUnpackB(c);
104    return GrColorPackRGBA(0xff - r, 0xff - g, 0xff - b, 0xff - a);
105}
106
107static inline GrColor GrColorMul(GrColor c0, GrColor c1) {
108    U8CPU r = SkMulDiv255Round(GrColorUnpackR(c0), GrColorUnpackR(c1));
109    U8CPU g = SkMulDiv255Round(GrColorUnpackG(c0), GrColorUnpackG(c1));
110    U8CPU b = SkMulDiv255Round(GrColorUnpackB(c0), GrColorUnpackB(c1));
111    U8CPU a = SkMulDiv255Round(GrColorUnpackA(c0), GrColorUnpackA(c1));
112    return GrColorPackRGBA(r, g, b, a);
113}
114
115static inline GrColor GrColorSatAdd(GrColor c0, GrColor c1) {
116    unsigned r = SkTMin<unsigned>(GrColorUnpackR(c0) + GrColorUnpackR(c1), 0xff);
117    unsigned g = SkTMin<unsigned>(GrColorUnpackG(c0) + GrColorUnpackG(c1), 0xff);
118    unsigned b = SkTMin<unsigned>(GrColorUnpackB(c0) + GrColorUnpackB(c1), 0xff);
119    unsigned a = SkTMin<unsigned>(GrColorUnpackA(c0) + GrColorUnpackA(c1), 0xff);
120    return GrColorPackRGBA(r, g, b, a);
121}
122
123/** Converts a GrColor to an rgba array of GrGLfloat */
124static inline void GrColorToRGBAFloat(GrColor color, float rgba[4]) {
125    static const float ONE_OVER_255 = 1.f / 255.f;
126    rgba[0] = GrColorUnpackR(color) * ONE_OVER_255;
127    rgba[1] = GrColorUnpackG(color) * ONE_OVER_255;
128    rgba[2] = GrColorUnpackB(color) * ONE_OVER_255;
129    rgba[3] = GrColorUnpackA(color) * ONE_OVER_255;
130}
131
132/** Normalizes and coverts an uint8_t to a float. [0, 255] -> [0.0, 1.0] */
133static inline float GrNormalizeByteToFloat(uint8_t value) {
134    static const float ONE_OVER_255 = 1.f / 255.f;
135    return value * ONE_OVER_255;
136}
137
138/** Determines whether the color is opaque or not. */
139static inline bool GrColorIsOpaque(GrColor color) {
140    return (color & (0xFFU << GrColor_SHIFT_A)) == (0xFFU << GrColor_SHIFT_A);
141}
142
143static inline GrColor GrPremulColor(GrColor color) {
144    unsigned r = GrColorUnpackR(color);
145    unsigned g = GrColorUnpackG(color);
146    unsigned b = GrColorUnpackB(color);
147    unsigned a = GrColorUnpackA(color);
148    return GrColorPackRGBA(SkMulDiv255Round(r, a),
149                           SkMulDiv255Round(g, a),
150                           SkMulDiv255Round(b, a),
151                           a);
152}
153
154/** Returns an unpremuled version of the GrColor. */
155static inline GrColor GrUnpremulColor(GrColor color) {
156    GrColorIsPMAssert(color);
157    unsigned r = GrColorUnpackR(color);
158    unsigned g = GrColorUnpackG(color);
159    unsigned b = GrColorUnpackB(color);
160    unsigned a = GrColorUnpackA(color);
161    SkPMColor colorPM = SkPackARGB32(a, r, g, b);
162    SkColor colorUPM = SkUnPreMultiply::PMColorToColor(colorPM);
163
164    r = SkColorGetR(colorUPM);
165    g = SkColorGetG(colorUPM);
166    b = SkColorGetB(colorUPM);
167    a = SkColorGetA(colorUPM);
168
169    return GrColorPackRGBA(r, g, b, a);
170}
171
172/**
173 * Flags used for bitfields of color components. They are defined so that the bit order reflects the
174 * GrColor shift order.
175 */
176enum GrColorComponentFlags {
177    kR_GrColorComponentFlag = 1 << (GrColor_SHIFT_R / 8),
178    kG_GrColorComponentFlag = 1 << (GrColor_SHIFT_G / 8),
179    kB_GrColorComponentFlag = 1 << (GrColor_SHIFT_B / 8),
180    kA_GrColorComponentFlag = 1 << (GrColor_SHIFT_A / 8),
181
182    kNone_GrColorComponentFlags = 0,
183
184    kRGB_GrColorComponentFlags = (kR_GrColorComponentFlag | kG_GrColorComponentFlag |
185                                  kB_GrColorComponentFlag),
186
187    kRGBA_GrColorComponentFlags = (kR_GrColorComponentFlag | kG_GrColorComponentFlag |
188                                   kB_GrColorComponentFlag | kA_GrColorComponentFlag)
189};
190
191GR_MAKE_BITFIELD_OPS(GrColorComponentFlags)
192
193static inline char GrColorComponentFlagToChar(GrColorComponentFlags component) {
194    SkASSERT(SkIsPow2(component));
195    switch (component) {
196        case kR_GrColorComponentFlag:
197            return 'r';
198        case kG_GrColorComponentFlag:
199            return 'g';
200        case kB_GrColorComponentFlag:
201            return 'b';
202        case kA_GrColorComponentFlag:
203            return 'a';
204        default:
205            SkFAIL("Invalid color component flag.");
206            return '\0';
207    }
208}
209
210static inline uint32_t GrPixelConfigComponentMask(GrPixelConfig config) {
211    SkASSERT(config >= 0 && config < kGrPixelConfigCnt);
212    static const uint32_t kFlags[] = {
213        0,                              // kUnknown_GrPixelConfig
214        kA_GrColorComponentFlag,        // kAlpha_8_GrPixelConfig
215        kRGBA_GrColorComponentFlags,    // kIndex_8_GrPixelConfig
216        kRGB_GrColorComponentFlags,     // kRGB_565_GrPixelConfig
217        kRGBA_GrColorComponentFlags,    // kRGBA_4444_GrPixelConfig
218        kRGBA_GrColorComponentFlags,    // kRGBA_8888_GrPixelConfig
219        kRGBA_GrColorComponentFlags,    // kBGRA_8888_GrPixelConfig
220        kRGBA_GrColorComponentFlags,    // kSRGBA_8888_GrPixelConfig
221        kRGB_GrColorComponentFlags,     // kETC1_GrPixelConfig
222        kA_GrColorComponentFlag,        // kLATC_GrPixelConfig
223        kA_GrColorComponentFlag,        // kR11_EAC_GrPixelConfig
224        kRGBA_GrColorComponentFlags,    // kASTC_12x12_GrPixelConfig
225        kRGBA_GrColorComponentFlags,    // kRGBA_float_GrPixelConfig
226        kA_GrColorComponentFlag,        // kAlpha_16_GrPixelConfig
227        kRGBA_GrColorComponentFlags,    // kRGBA_half_GrPixelConfig
228    };
229    return kFlags[config];
230
231    GR_STATIC_ASSERT(0  == kUnknown_GrPixelConfig);
232    GR_STATIC_ASSERT(1  == kAlpha_8_GrPixelConfig);
233    GR_STATIC_ASSERT(2  == kIndex_8_GrPixelConfig);
234    GR_STATIC_ASSERT(3  == kRGB_565_GrPixelConfig);
235    GR_STATIC_ASSERT(4  == kRGBA_4444_GrPixelConfig);
236    GR_STATIC_ASSERT(5  == kRGBA_8888_GrPixelConfig);
237    GR_STATIC_ASSERT(6  == kBGRA_8888_GrPixelConfig);
238    GR_STATIC_ASSERT(7  == kSRGBA_8888_GrPixelConfig);
239    GR_STATIC_ASSERT(8  == kETC1_GrPixelConfig);
240    GR_STATIC_ASSERT(9  == kLATC_GrPixelConfig);
241    GR_STATIC_ASSERT(10  == kR11_EAC_GrPixelConfig);
242    GR_STATIC_ASSERT(11 == kASTC_12x12_GrPixelConfig);
243    GR_STATIC_ASSERT(12 == kRGBA_float_GrPixelConfig);
244    GR_STATIC_ASSERT(13 == kAlpha_half_GrPixelConfig);
245    GR_STATIC_ASSERT(14 == kRGBA_half_GrPixelConfig);
246    GR_STATIC_ASSERT(SK_ARRAY_COUNT(kFlags) == kGrPixelConfigCnt);
247}
248
249#endif
250