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comparison: gfx/thebes/gfxColor.h

gfx/thebes/gfxColor.h

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1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 4 -*-
2 * This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
5
6 #ifndef GFX_COLOR_H
7 #define GFX_COLOR_H
8
9 #include "gfxTypes.h"
10
11 #include "mozilla/Attributes.h" // for MOZ_ALWAYS_INLINE
12 #include "mozilla/Endian.h" // for mozilla::NativeEndian::swapToBigEndian
13
14 #define GFX_UINT32_FROM_BPTR(pbptr,i) (((uint32_t*)(pbptr))[i])
15
16 /**
17 * GFX_0XFF_PPIXEL_FROM_BPTR(x)
18 *
19 * Avoid tortured construction of 32-bit ARGB pixel from 3 individual bytes
20 * of memory plus constant 0xFF. RGB bytes are already contiguous!
21 * Equivalent to: GFX_PACKED_PIXEL(0xff,r,g,b)
22 *
23 * Attempt to use fast byte-swapping instruction(s), e.g. bswap on x86, in
24 * preference to a sequence of shift/or operations.
25 */
26 #define GFX_0XFF_PPIXEL_FROM_UINT32(x) \
27 ( (mozilla::NativeEndian::swapToBigEndian(uint32_t(x)) >> 8) | (0xFFU << 24) )
28
29 #define GFX_0XFF_PPIXEL_FROM_BPTR(x) \
30 ( GFX_0XFF_PPIXEL_FROM_UINT32(GFX_UINT32_FROM_BPTR((x),0)) )
31
32 /**
33 * GFX_BLOCK_RGB_TO_FRGB(from,to)
34 * sizeof(*from) == sizeof(char)
35 * sizeof(*to) == sizeof(uint32_t)
36 *
37 * Copy 4 pixels at a time, reading blocks of 12 bytes (RGB x4)
38 * and writing blocks of 16 bytes (FRGB x4)
39 */
40 #define GFX_BLOCK_RGB_TO_FRGB(from,to) \
41 PR_BEGIN_MACRO \
42 uint32_t m0 = GFX_UINT32_FROM_BPTR(from,0), \
43 m1 = GFX_UINT32_FROM_BPTR(from,1), \
44 m2 = GFX_UINT32_FROM_BPTR(from,2), \
45 rgbr = mozilla::NativeEndian::swapToBigEndian(m0), \
46 gbrg = mozilla::NativeEndian::swapToBigEndian(m1), \
47 brgb = mozilla::NativeEndian::swapToBigEndian(m2), \
48 p0, p1, p2, p3; \
49 p0 = 0xFF000000 | ((rgbr) >> 8); \
50 p1 = 0xFF000000 | ((rgbr) << 16) | ((gbrg) >> 16); \
51 p2 = 0xFF000000 | ((gbrg) << 8) | ((brgb) >> 24); \
52 p3 = 0xFF000000 | (brgb); \
53 to[0] = p0; to[1] = p1; to[2] = p2; to[3] = p3; \
54 PR_END_MACRO
55
56 /**
57 * Fast approximate division by 255. It has the property that
58 * for all 0 <= n <= 255*255, GFX_DIVIDE_BY_255(n) == n/255.
59 * But it only uses two adds and two shifts instead of an
60 * integer division (which is expensive on many processors).
61 *
62 * equivalent to ((v)/255)
63 */
64 #define GFX_DIVIDE_BY_255(v) \
65 (((((unsigned)(v)) << 8) + ((unsigned)(v)) + 255) >> 16)
66
67 /**
68 * Fast premultiply
69 *
70 * equivalent to (((c)*(a))/255)
71 */
72 uint8_t MOZ_ALWAYS_INLINE gfxPreMultiply(uint8_t c, uint8_t a) {
73 return GFX_DIVIDE_BY_255((c)*(a));
74 }
75
76 /**
77 * Pack the 4 8-bit channels (A,R,G,B)
78 * into a 32-bit packed NON-premultiplied pixel.
79 */
80 uint32_t MOZ_ALWAYS_INLINE
81 gfxPackedPixelNoPreMultiply(uint8_t a, uint8_t r, uint8_t g, uint8_t b) {
82 return (((a) << 24) | ((r) << 16) | ((g) << 8) | (b));
83 }
84
85 /**
86 * Pack the 4 8-bit channels (A,R,G,B)
87 * into a 32-bit packed premultiplied pixel.
88 */
89 uint32_t MOZ_ALWAYS_INLINE
90 gfxPackedPixel(uint8_t a, uint8_t r, uint8_t g, uint8_t b) {
91 if (a == 0x00)
92 return 0x00000000;
93 else if (a == 0xFF) {
94 return gfxPackedPixelNoPreMultiply(a, r, g, b);
95 } else {
96 return ((a) << 24) |
97 (gfxPreMultiply(r,a) << 16) |
98 (gfxPreMultiply(g,a) << 8) |
99 (gfxPreMultiply(b,a));
100 }
101 }
102
103 /**
104 * A color value, storing red, green, blue and alpha components.
105 * This class does not use premultiplied alpha.
106 *
107 * XXX should this use doubles (instead of gfxFloat), for consistency with
108 * cairo?
109 */
110 struct gfxRGBA {
111 gfxFloat r, g, b, a;
112
113 enum PackedColorType {
114 PACKED_ABGR,
115 PACKED_ABGR_PREMULTIPLIED,
116
117 PACKED_ARGB,
118 PACKED_ARGB_PREMULTIPLIED,
119
120 PACKED_XRGB
121 };
122
123 gfxRGBA() { }
124 /**
125 * Intialize this color using explicit red, green, blue and alpha
126 * values.
127 */
128 MOZ_CONSTEXPR gfxRGBA(gfxFloat _r, gfxFloat _g, gfxFloat _b, gfxFloat _a=1.0) : r(_r), g(_g), b(_b), a(_a) {}
129
130 /**
131 * Initialize this color from a packed 32-bit color.
132 * The color value is interpreted based on colorType;
133 * all values use the native platform endianness.
134 *
135 * Resulting gfxRGBA stores non-premultiplied data.
136 *
137 * @see gfxRGBA::Packed
138 */
139 gfxRGBA(uint32_t c, PackedColorType colorType = PACKED_ABGR) {
140 if (colorType == PACKED_ABGR ||
141 colorType == PACKED_ABGR_PREMULTIPLIED)
142 {
143 r = ((c >> 0) & 0xff) * (1.0 / 255.0);
144 g = ((c >> 8) & 0xff) * (1.0 / 255.0);
145 b = ((c >> 16) & 0xff) * (1.0 / 255.0);
146 a = ((c >> 24) & 0xff) * (1.0 / 255.0);
147 } else if (colorType == PACKED_ARGB ||
148 colorType == PACKED_XRGB ||
149 colorType == PACKED_ARGB_PREMULTIPLIED)
150 {
151 b = ((c >> 0) & 0xff) * (1.0 / 255.0);
152 g = ((c >> 8) & 0xff) * (1.0 / 255.0);
153 r = ((c >> 16) & 0xff) * (1.0 / 255.0);
154 a = ((c >> 24) & 0xff) * (1.0 / 255.0);
155 }
156
157 if (colorType == PACKED_ABGR_PREMULTIPLIED ||
158 colorType == PACKED_ARGB_PREMULTIPLIED)
159 {
160 if (a > 0.0) {
161 r /= a;
162 g /= a;
163 b /= a;
164 }
165 } else if (colorType == PACKED_XRGB) {
166 a = 1.0;
167 }
168 }
169
170 bool operator==(const gfxRGBA& other) const
171 {
172 return r == other.r && g == other.g && b == other.b && a == other.a;
173 }
174 bool operator!=(const gfxRGBA& other) const
175 {
176 return !(*this == other);
177 }
178
179 /**
180 * Returns this color value as a packed 32-bit integer. This reconstructs
181 * the int32_t based on the given colorType, always in the native byte order.
182 *
183 * Note: gcc 4.2.3 on at least Ubuntu (x86) does something strange with
184 * (uint8_t)(c * 255.0) << x, where the result is different than
185 * double d = c * 255.0; v = ((uint8_t) d) << x.
186 */
187 uint32_t Packed(PackedColorType colorType = PACKED_ABGR) const {
188 gfxFloat rb = (r * 255.0);
189 gfxFloat gb = (g * 255.0);
190 gfxFloat bb = (b * 255.0);
191 gfxFloat ab = (a * 255.0);
192
193 if (colorType == PACKED_ABGR) {
194 return (uint8_t(ab) << 24) |
195 (uint8_t(bb) << 16) |
196 (uint8_t(gb) << 8) |
197 (uint8_t(rb) << 0);
198 }
199 if (colorType == PACKED_ARGB || colorType == PACKED_XRGB) {
200 return (uint8_t(ab) << 24) |
201 (uint8_t(rb) << 16) |
202 (uint8_t(gb) << 8) |
203 (uint8_t(bb) << 0);
204 }
205
206 rb *= a;
207 gb *= a;
208 bb *= a;
209
210 if (colorType == PACKED_ABGR_PREMULTIPLIED) {
211 return (((uint8_t)(ab) << 24) |
212 ((uint8_t)(bb) << 16) |
213 ((uint8_t)(gb) << 8) |
214 ((uint8_t)(rb) << 0));
215 }
216 if (colorType == PACKED_ARGB_PREMULTIPLIED) {
217 return (((uint8_t)(ab) << 24) |
218 ((uint8_t)(rb) << 16) |
219 ((uint8_t)(gb) << 8) |
220 ((uint8_t)(bb) << 0));
221 }
222
223 return 0;
224 }
225 };
226
227 #endif /* _GFX_COLOR_H */

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