1 /* Cairo - a vector graphics library with display and print output
2 *
3 * Copyright © 2008 Red Hat, Inc.
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it either under the terms of the GNU Lesser General Public
7 * License version 2.1 as published by the Free Software Foundation
8 * (the "LGPL") or, at your option, under the terms of the Mozilla
9 * Public License Version 1.1 (the "MPL"). If you do not alter this
10 * notice, a recipient may use your version of this file under either
11 * the MPL or the LGPL.
12 *
13 * You should have received a copy of the LGPL along with this library
14 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
15 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
16 * You should have received a copy of the MPL along with this library
17 * in the file COPYING-MPL-1.1
18 *
19 * The contents of this file are subject to the Mozilla Public License
20 * Version 1.1 (the "License"); you may not use this file except in
21 * compliance with the License. You may obtain a copy of the License at
22 * http://www.mozilla.org/MPL/
23 *
24 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
25 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
26 * the specific language governing rights and limitations.
27 *
28 * The Original Code is the cairo graphics library.
29 *
30 * The Initial Developer of the Original Code is Red Hat, Inc.
31 *
32 * Contributor(s):
33 * Carl D. Worth <cworth@cworth.org>
34 */
35
36 #include "cairoint.h"
37
38 #if !CAIRO_HAS_XLIB_XCB_FUNCTIONS
39
40 #include "cairo-xlib-private.h"
41
42 #include "cairo-error-private.h"
43 #include "cairo-list-inline.h"
44
45 /* A perceptual distance metric between two colors. No sqrt needed
46 * since the square of the distance is still a valid metric. */
47
48 /* XXX: This is currently using linear distance in RGB space which is
49 * decidedly not perceptually linear. If someone cared a lot about the
50 * quality, they might choose something else here. Then again, they
51 * might also choose not to use a PseudoColor visual... */
52 static inline int
_color_distance(unsigned short r1,unsigned short g1,unsigned short b1,unsigned short r2,unsigned short g2,unsigned short b2)53 _color_distance (unsigned short r1, unsigned short g1, unsigned short b1,
54 unsigned short r2, unsigned short g2, unsigned short b2)
55 {
56 r1 >>= 8; g1 >>= 8; b1 >>= 8;
57 r2 >>= 8; g2 >>= 8; b2 >>= 8;
58
59 return ((r2 - r1) * (r2 - r1) +
60 (g2 - g1) * (g2 - g1) +
61 (b2 - b1) * (b2 - b1));
62 }
63
64 cairo_status_t
_cairo_xlib_visual_info_create(Display * dpy,int screen,VisualID visualid,cairo_xlib_visual_info_t ** out)65 _cairo_xlib_visual_info_create (Display *dpy,
66 int screen,
67 VisualID visualid,
68 cairo_xlib_visual_info_t **out)
69 {
70 cairo_xlib_visual_info_t *info;
71 Colormap colormap = DefaultColormap (dpy, screen);
72 XColor color;
73 int gray, red, green, blue;
74 int i, j, distance, min_distance = 0;
75 XColor colors[256];
76 unsigned short cube_index_to_short[CUBE_SIZE];
77 unsigned short ramp_index_to_short[RAMP_SIZE];
78 unsigned char gray_to_pseudocolor[RAMP_SIZE];
79
80 for (i = 0; i < CUBE_SIZE; i++)
81 cube_index_to_short[i] = (0xffff * i + ((CUBE_SIZE-1)>>1)) / (CUBE_SIZE-1);
82 for (i = 0; i < RAMP_SIZE; i++)
83 ramp_index_to_short[i] = (0xffff * i + ((RAMP_SIZE-1)>>1)) / (RAMP_SIZE-1);
84
85 info = _cairo_malloc (sizeof (cairo_xlib_visual_info_t));
86 if (unlikely (info == NULL))
87 return _cairo_error (CAIRO_STATUS_NO_MEMORY);
88
89 cairo_list_init (&info->link);
90 info->visualid = visualid;
91
92 /* Allocate a gray ramp and a color cube.
93 * Give up as soon as failures start. */
94
95 for (gray = 0; gray < RAMP_SIZE; gray++) {
96 color.red = color.green = color.blue = ramp_index_to_short[gray];
97 if (! XAllocColor (dpy, colormap, &color))
98 goto DONE_ALLOCATE;
99 }
100
101 /* XXX: Could do this in a more clever order to have the best
102 * possible results from early failure. Could also choose a cube
103 * uniformly distributed in a better space than RGB. */
104 for (red = 0; red < CUBE_SIZE; red++) {
105 for (green = 0; green < CUBE_SIZE; green++) {
106 for (blue = 0; blue < CUBE_SIZE; blue++) {
107 color.red = cube_index_to_short[red];
108 color.green = cube_index_to_short[green];
109 color.blue = cube_index_to_short[blue];
110 color.pixel = 0;
111 color.flags = 0;
112 color.pad = 0;
113 if (! XAllocColor (dpy, colormap, &color))
114 goto DONE_ALLOCATE;
115 }
116 }
117 }
118 DONE_ALLOCATE:
119
120 for (i = 0; i < ARRAY_LENGTH (colors); i++)
121 colors[i].pixel = i;
122 XQueryColors (dpy, colormap, colors, ARRAY_LENGTH (colors));
123
124 /* Search for nearest colors within allocated colormap. */
125 for (gray = 0; gray < RAMP_SIZE; gray++) {
126 for (i = 0; i < 256; i++) {
127 distance = _color_distance (ramp_index_to_short[gray],
128 ramp_index_to_short[gray],
129 ramp_index_to_short[gray],
130 colors[i].red,
131 colors[i].green,
132 colors[i].blue);
133 if (i == 0 || distance < min_distance) {
134 gray_to_pseudocolor[gray] = colors[i].pixel;
135 min_distance = distance;
136 if (!min_distance)
137 break;
138 }
139 }
140 }
141 for (red = 0; red < CUBE_SIZE; red++) {
142 for (green = 0; green < CUBE_SIZE; green++) {
143 for (blue = 0; blue < CUBE_SIZE; blue++) {
144 for (i = 0; i < 256; i++) {
145 distance = _color_distance (cube_index_to_short[red],
146 cube_index_to_short[green],
147 cube_index_to_short[blue],
148 colors[i].red,
149 colors[i].green,
150 colors[i].blue);
151 if (i == 0 || distance < min_distance) {
152 info->cube_to_pseudocolor[red][green][blue] = colors[i].pixel;
153 min_distance = distance;
154 if (!min_distance)
155 break;
156 }
157 }
158 }
159 }
160 }
161
162 for (i = 0, j = 0; i < 256; i++) {
163 if (j < CUBE_SIZE - 1 && (((i<<8)+i) - (int)cube_index_to_short[j]) > ((int)cube_index_to_short[j+1] - ((i<<8)+i)))
164 j++;
165 info->field8_to_cube[i] = j;
166
167 info->dither8_to_cube[i] = ((int)i - 128) / (CUBE_SIZE - 1);
168 }
169 for (i = 0, j = 0; i < 256; i++) {
170 if (j < RAMP_SIZE - 1 && (((i<<8)+i) - (int)ramp_index_to_short[j]) > ((int)ramp_index_to_short[j+1] - ((i<<8)+i)))
171 j++;
172 info->gray8_to_pseudocolor[i] = gray_to_pseudocolor[j];
173 }
174
175 for (i = 0; i < 256; i++) {
176 info->colors[i].a = 0xff;
177 info->colors[i].r = colors[i].red >> 8;
178 info->colors[i].g = colors[i].green >> 8;
179 info->colors[i].b = colors[i].blue >> 8;
180 }
181
182 *out = info;
183 return CAIRO_STATUS_SUCCESS;
184 }
185
186 void
_cairo_xlib_visual_info_destroy(cairo_xlib_visual_info_t * info)187 _cairo_xlib_visual_info_destroy (cairo_xlib_visual_info_t *info)
188 {
189 /* No need for XFreeColors() whilst using DefaultColormap */
190 _cairo_list_del (&info->link);
191 free (info);
192 }
193
194 #endif /* !CAIRO_HAS_XLIB_XCB_FUNCTIONS */
195