1 /* cairo - a vector graphics library with display and print output
2 *
3 * Copyright © 2002 University of Southern California
4 * Copyright © 2005 Red Hat, Inc.
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it either under the terms of the GNU Lesser General Public
8 * License version 2.1 as published by the Free Software Foundation
9 * (the "LGPL") or, at your option, under the terms of the Mozilla
10 * Public License Version 1.1 (the "MPL"). If you do not alter this
11 * notice, a recipient may use your version of this file under either
12 * the MPL or the LGPL.
13 *
14 * You should have received a copy of the LGPL along with this library
15 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
17 * You should have received a copy of the MPL along with this library
18 * in the file COPYING-MPL-1.1
19 *
20 * The contents of this file are subject to the Mozilla Public License
21 * Version 1.1 (the "License"); you may not use this file except in
22 * compliance with the License. You may obtain a copy of the License at
23 * http://www.mozilla.org/MPL/
24 *
25 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
26 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
27 * the specific language governing rights and limitations.
28 *
29 * The Original Code is the cairo graphics library.
30 *
31 * The Initial Developer of the Original Code is University of Southern
32 * California.
33 *
34 * Contributor(s):
35 * Carl D. Worth <cworth@cworth.org>
36 */
37
38 #include "cairoint.h"
39
40 static cairo_color_t const cairo_color_white = {
41 1.0, 1.0, 1.0, 1.0,
42 0xffff, 0xffff, 0xffff, 0xffff
43 };
44
45 static cairo_color_t const cairo_color_black = {
46 0.0, 0.0, 0.0, 1.0,
47 0x0, 0x0, 0x0, 0xffff
48 };
49
50 static cairo_color_t const cairo_color_transparent = {
51 0.0, 0.0, 0.0, 0.0,
52 0x0, 0x0, 0x0, 0x0
53 };
54
55 static cairo_color_t const cairo_color_magenta = {
56 1.0, 0.0, 1.0, 1.0,
57 0xffff, 0x0, 0xffff, 0xffff
58 };
59
60 const cairo_color_t *
_cairo_stock_color(cairo_stock_t stock)61 _cairo_stock_color (cairo_stock_t stock)
62 {
63 switch (stock) {
64 case CAIRO_STOCK_WHITE:
65 return &cairo_color_white;
66 case CAIRO_STOCK_BLACK:
67 return &cairo_color_black;
68 case CAIRO_STOCK_TRANSPARENT:
69 return &cairo_color_transparent;
70
71 case CAIRO_STOCK_NUM_COLORS:
72 default:
73 ASSERT_NOT_REACHED;
74 /* If the user can get here somehow, give a color that indicates a
75 * problem. */
76 return &cairo_color_magenta;
77 }
78 }
79
80 void
_cairo_color_init(cairo_color_t * color)81 _cairo_color_init (cairo_color_t *color)
82 {
83 *color = cairo_color_white;
84 }
85
86 void
_cairo_color_init_rgb(cairo_color_t * color,double red,double green,double blue)87 _cairo_color_init_rgb (cairo_color_t *color,
88 double red, double green, double blue)
89 {
90 _cairo_color_init_rgba (color, red, green, blue, 1.0);
91 }
92
93 /* Convert a double in [0.0, 1.0] to an integer in [0, 65535]
94 * The conversion is designed to divide the input range into 65536
95 * equally-sized regions. This is achieved by multiplying by 65536 and
96 * then special-casing the result of an input value of 1.0 so that it
97 * maps to 65535 instead of 65536.
98 */
99 uint16_t
_cairo_color_double_to_short(double d)100 _cairo_color_double_to_short (double d)
101 {
102 uint32_t i;
103 i = (uint32_t) (d * 65536);
104 i -= (i >> 16);
105 return i;
106 }
107
108 static void
_cairo_color_compute_shorts(cairo_color_t * color)109 _cairo_color_compute_shorts (cairo_color_t *color)
110 {
111 color->red_short = _cairo_color_double_to_short (color->red * color->alpha);
112 color->green_short = _cairo_color_double_to_short (color->green * color->alpha);
113 color->blue_short = _cairo_color_double_to_short (color->blue * color->alpha);
114 color->alpha_short = _cairo_color_double_to_short (color->alpha);
115 }
116
117 void
_cairo_color_init_rgba(cairo_color_t * color,double red,double green,double blue,double alpha)118 _cairo_color_init_rgba (cairo_color_t *color,
119 double red, double green, double blue,
120 double alpha)
121 {
122 color->red = red;
123 color->green = green;
124 color->blue = blue;
125 color->alpha = alpha;
126
127 _cairo_color_compute_shorts (color);
128 }
129
130 void
_cairo_color_multiply_alpha(cairo_color_t * color,double alpha)131 _cairo_color_multiply_alpha (cairo_color_t *color,
132 double alpha)
133 {
134 color->alpha *= alpha;
135
136 _cairo_color_compute_shorts (color);
137 }
138
139 void
_cairo_color_get_rgba(cairo_color_t * color,double * red,double * green,double * blue,double * alpha)140 _cairo_color_get_rgba (cairo_color_t *color,
141 double *red,
142 double *green,
143 double *blue,
144 double *alpha)
145 {
146 *red = color->red;
147 *green = color->green;
148 *blue = color->blue;
149 *alpha = color->alpha;
150 }
151
152 void
_cairo_color_get_rgba_premultiplied(cairo_color_t * color,double * red,double * green,double * blue,double * alpha)153 _cairo_color_get_rgba_premultiplied (cairo_color_t *color,
154 double *red,
155 double *green,
156 double *blue,
157 double *alpha)
158 {
159 *red = color->red * color->alpha;
160 *green = color->green * color->alpha;
161 *blue = color->blue * color->alpha;
162 *alpha = color->alpha;
163 }
164
165 /* NB: This function works both for unmultiplied and premultiplied colors */
166 cairo_bool_t
_cairo_color_equal(const cairo_color_t * color_a,const cairo_color_t * color_b)167 _cairo_color_equal (const cairo_color_t *color_a,
168 const cairo_color_t *color_b)
169 {
170 if (color_a == color_b)
171 return TRUE;
172
173 if (color_a->alpha_short != color_b->alpha_short)
174 return FALSE;
175
176 if (color_a->alpha_short == 0)
177 return TRUE;
178
179 return color_a->red_short == color_b->red_short &&
180 color_a->green_short == color_b->green_short &&
181 color_a->blue_short == color_b->blue_short;
182 }
183
184 cairo_bool_t
_cairo_color_stop_equal(const cairo_color_stop_t * color_a,const cairo_color_stop_t * color_b)185 _cairo_color_stop_equal (const cairo_color_stop_t *color_a,
186 const cairo_color_stop_t *color_b)
187 {
188 if (color_a == color_b)
189 return TRUE;
190
191 return color_a->alpha_short == color_b->alpha_short &&
192 color_a->red_short == color_b->red_short &&
193 color_a->green_short == color_b->green_short &&
194 color_a->blue_short == color_b->blue_short;
195 }
196
197 cairo_content_t
_cairo_color_get_content(const cairo_color_t * color)198 _cairo_color_get_content (const cairo_color_t *color)
199 {
200 if (CAIRO_COLOR_IS_OPAQUE (color))
201 return CAIRO_CONTENT_COLOR;
202
203 if (color->red_short == 0 &&
204 color->green_short == 0 &&
205 color->blue_short == 0)
206 {
207 return CAIRO_CONTENT_ALPHA;
208 }
209
210 return CAIRO_CONTENT_COLOR_ALPHA;
211 }
212