Line data Source code
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 : #include "cairo-xlib-private.h"
39 :
40 : #include "cairo-error-private.h"
41 :
42 : /* A perceptual distance metric between two colors. No sqrt needed
43 : * since the square of the distance is still a valid metric. */
44 :
45 : /* XXX: This is currently using linear distance in RGB space which is
46 : * decidedly not perceptually linear. If someone cared a lot about the
47 : * quality, they might choose something else here. Then again, they
48 : * might also choose not to use a PseudoColor visual... */
49 : static inline int
50 0 : _color_distance (unsigned short r1, unsigned short g1, unsigned short b1,
51 : unsigned short r2, unsigned short g2, unsigned short b2)
52 : {
53 0 : r1 >>= 8; g1 >>= 8; b1 >>= 8;
54 0 : r2 >>= 8; g2 >>= 8; b2 >>= 8;
55 :
56 0 : return ((r2 - r1) * (r2 - r1) +
57 0 : (g2 - g1) * (g2 - g1) +
58 0 : (b2 - b1) * (b2 - b1));
59 : }
60 :
61 : cairo_status_t
62 0 : _cairo_xlib_visual_info_create (Display *dpy,
63 : int screen,
64 : VisualID visualid,
65 : cairo_xlib_visual_info_t **out)
66 : {
67 : cairo_xlib_visual_info_t *info;
68 0 : Colormap colormap = DefaultColormap (dpy, screen);
69 : XColor color;
70 : int gray, red, green, blue;
71 0 : int i, j, distance, min_distance = 0;
72 : XColor colors[256];
73 : unsigned short cube_index_to_short[CUBE_SIZE];
74 : unsigned short ramp_index_to_short[RAMP_SIZE];
75 : unsigned char gray_to_pseudocolor[RAMP_SIZE];
76 :
77 0 : for (i = 0; i < CUBE_SIZE; i++)
78 0 : cube_index_to_short[i] = (0xffff * i + ((CUBE_SIZE-1)>>1)) / (CUBE_SIZE-1);
79 0 : for (i = 0; i < RAMP_SIZE; i++)
80 0 : ramp_index_to_short[i] = (0xffff * i + ((RAMP_SIZE-1)>>1)) / (RAMP_SIZE-1);
81 :
82 0 : info = malloc (sizeof (cairo_xlib_visual_info_t));
83 0 : if (unlikely (info == NULL))
84 0 : return _cairo_error (CAIRO_STATUS_NO_MEMORY);
85 :
86 0 : info->visualid = visualid;
87 :
88 : /* Allocate a gray ramp and a color cube.
89 : * Give up as soon as failures start. */
90 :
91 0 : for (gray = 0; gray < RAMP_SIZE; gray++) {
92 0 : color.red = color.green = color.blue = ramp_index_to_short[gray];
93 0 : if (! XAllocColor (dpy, colormap, &color))
94 0 : goto DONE_ALLOCATE;
95 : }
96 :
97 : /* XXX: Could do this in a more clever order to have the best
98 : * possible results from early failure. Could also choose a cube
99 : * uniformly distributed in a better space than RGB. */
100 0 : for (red = 0; red < CUBE_SIZE; red++) {
101 0 : for (green = 0; green < CUBE_SIZE; green++) {
102 0 : for (blue = 0; blue < CUBE_SIZE; blue++) {
103 0 : color.red = cube_index_to_short[red];
104 0 : color.green = cube_index_to_short[green];
105 0 : color.blue = cube_index_to_short[blue];
106 0 : color.pixel = 0;
107 0 : color.flags = 0;
108 0 : color.pad = 0;
109 0 : if (! XAllocColor (dpy, colormap, &color))
110 0 : goto DONE_ALLOCATE;
111 : }
112 : }
113 : }
114 : DONE_ALLOCATE:
115 :
116 0 : for (i = 0; i < ARRAY_LENGTH (colors); i++)
117 0 : colors[i].pixel = i;
118 0 : XQueryColors (dpy, colormap, colors, ARRAY_LENGTH (colors));
119 :
120 : /* Search for nearest colors within allocated colormap. */
121 0 : for (gray = 0; gray < RAMP_SIZE; gray++) {
122 0 : for (i = 0; i < 256; i++) {
123 0 : distance = _color_distance (ramp_index_to_short[gray],
124 0 : ramp_index_to_short[gray],
125 0 : ramp_index_to_short[gray],
126 0 : colors[i].red,
127 0 : colors[i].green,
128 0 : colors[i].blue);
129 0 : if (i == 0 || distance < min_distance) {
130 0 : gray_to_pseudocolor[gray] = colors[i].pixel;
131 0 : min_distance = distance;
132 0 : if (!min_distance)
133 0 : break;
134 : }
135 : }
136 : }
137 0 : for (red = 0; red < CUBE_SIZE; red++) {
138 0 : for (green = 0; green < CUBE_SIZE; green++) {
139 0 : for (blue = 0; blue < CUBE_SIZE; blue++) {
140 0 : for (i = 0; i < 256; i++) {
141 0 : distance = _color_distance (cube_index_to_short[red],
142 0 : cube_index_to_short[green],
143 0 : cube_index_to_short[blue],
144 0 : colors[i].red,
145 0 : colors[i].green,
146 0 : colors[i].blue);
147 0 : if (i == 0 || distance < min_distance) {
148 0 : info->cube_to_pseudocolor[red][green][blue] = colors[i].pixel;
149 0 : min_distance = distance;
150 0 : if (!min_distance)
151 0 : break;
152 : }
153 : }
154 : }
155 : }
156 : }
157 :
158 0 : for (i = 0, j = 0; i < 256; i++) {
159 0 : if (j < CUBE_SIZE - 1 && (((i<<8)+i) - (int)cube_index_to_short[j]) > ((int)cube_index_to_short[j+1] - ((i<<8)+i)))
160 0 : j++;
161 0 : info->field8_to_cube[i] = j;
162 :
163 0 : info->dither8_to_cube[i] = ((int)i - 128) / (CUBE_SIZE - 1);
164 : }
165 0 : for (i = 0, j = 0; i < 256; i++) {
166 0 : if (j < RAMP_SIZE - 1 && (((i<<8)+i) - (int)ramp_index_to_short[j]) > ((int)ramp_index_to_short[j+1] - ((i<<8)+i)))
167 0 : j++;
168 0 : info->gray8_to_pseudocolor[i] = gray_to_pseudocolor[j];
169 : }
170 :
171 0 : for (i = 0; i < 256; i++) {
172 0 : info->colors[i].a = 0xff;
173 0 : info->colors[i].r = colors[i].red >> 8;
174 0 : info->colors[i].g = colors[i].green >> 8;
175 0 : info->colors[i].b = colors[i].blue >> 8;
176 : }
177 :
178 0 : *out = info;
179 0 : return CAIRO_STATUS_SUCCESS;
180 : }
181 :
182 : void
183 0 : _cairo_xlib_visual_info_destroy (cairo_xlib_visual_info_t *info)
184 : {
185 : /* No need for XFreeColors() whilst using DefaultColormap */
186 0 : free (info);
187 0 : }
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