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/* Cairo - a vector graphics library with display and print output
*
* Copyright © 2008 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it either under the terms of the GNU Lesser General Public
* License version 2.1 as published by the Free Software Foundation
* (the "LGPL") or, at your option, under the terms of the Mozilla
* Public License Version 1.1 (the "MPL"). If you do not alter this
* notice, a recipient may use your version of this file under either
* the MPL or the LGPL.
*
* You should have received a copy of the LGPL along with this library
* in the file COPYING-LGPL-2.1; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
* You should have received a copy of the MPL along with this library
* in the file COPYING-MPL-1.1
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
* OF ANY KIND, either express or implied. See the LGPL or the MPL for
* the specific language governing rights and limitations.
*
* The Original Code is the cairo graphics library.
*
* The Initial Developer of the Original Code is Red Hat, Inc.
*
* Contributor(s):
* Carl D. Worth <cworth@cworth.org>
*/
#include "cairoint.h"
#if !CAIRO_HAS_XLIB_XCB_FUNCTIONS
#include "cairo-xlib-private.h"
#include "cairo-error-private.h"
#include "cairo-list-inline.h"
/* A perceptual distance metric between two colors. No sqrt needed
* since the square of the distance is still a valid metric. */
/* XXX: This is currently using linear distance in RGB space which is
* decidedly not perceptually linear. If someone cared a lot about the
* quality, they might choose something else here. Then again, they
* might also choose not to use a PseudoColor visual... */
static inline int
_color_distance (unsigned short r1, unsigned short g1, unsigned short b1,
unsigned short r2, unsigned short g2, unsigned short b2)
{
r1 >>= 8; g1 >>= 8; b1 >>= 8;
r2 >>= 8; g2 >>= 8; b2 >>= 8;
return ((r2 - r1) * (r2 - r1) +
(g2 - g1) * (g2 - g1) +
(b2 - b1) * (b2 - b1));
}
cairo_status_t
_cairo_xlib_visual_info_create (Display *dpy,
int screen,
VisualID visualid,
cairo_xlib_visual_info_t **out)
{
cairo_xlib_visual_info_t *info;
Colormap colormap = DefaultColormap (dpy, screen);
XColor color;
int gray, red, green, blue;
int i, j, distance, min_distance = 0;
XColor colors[256];
unsigned short cube_index_to_short[CUBE_SIZE];
unsigned short ramp_index_to_short[RAMP_SIZE];
unsigned char gray_to_pseudocolor[RAMP_SIZE];
for (i = 0; i < CUBE_SIZE; i++)
cube_index_to_short[i] = (0xffff * i + ((CUBE_SIZE-1)>>1)) / (CUBE_SIZE-1);
for (i = 0; i < RAMP_SIZE; i++)
ramp_index_to_short[i] = (0xffff * i + ((RAMP_SIZE-1)>>1)) / (RAMP_SIZE-1);
info = _cairo_malloc (sizeof (cairo_xlib_visual_info_t));
if (unlikely (info == NULL))
return _cairo_error (CAIRO_STATUS_NO_MEMORY);
cairo_list_init (&info->link);
info->visualid = visualid;
/* Allocate a gray ramp and a color cube.
* Give up as soon as failures start. */
for (gray = 0; gray < RAMP_SIZE; gray++) {
color.red = color.green = color.blue = ramp_index_to_short[gray];
if (! XAllocColor (dpy, colormap, &color))
goto DONE_ALLOCATE;
}
/* XXX: Could do this in a more clever order to have the best
* possible results from early failure. Could also choose a cube
* uniformly distributed in a better space than RGB. */
for (red = 0; red < CUBE_SIZE; red++) {
for (green = 0; green < CUBE_SIZE; green++) {
for (blue = 0; blue < CUBE_SIZE; blue++) {
color.red = cube_index_to_short[red];
color.green = cube_index_to_short[green];
color.blue = cube_index_to_short[blue];
color.pixel = 0;
color.flags = 0;
color.pad = 0;
if (! XAllocColor (dpy, colormap, &color))
goto DONE_ALLOCATE;
}
}
}
DONE_ALLOCATE:
for (i = 0; i < ARRAY_LENGTH (colors); i++)
colors[i].pixel = i;
XQueryColors (dpy, colormap, colors, ARRAY_LENGTH (colors));
/* Search for nearest colors within allocated colormap. */
for (gray = 0; gray < RAMP_SIZE; gray++) {
for (i = 0; i < 256; i++) {
distance = _color_distance (ramp_index_to_short[gray],
ramp_index_to_short[gray],
ramp_index_to_short[gray],
colors[i].red,
colors[i].green,
colors[i].blue);
if (i == 0 || distance < min_distance) {
gray_to_pseudocolor[gray] = colors[i].pixel;
min_distance = distance;
if (!min_distance)
break;
}
}
}
for (red = 0; red < CUBE_SIZE; red++) {
for (green = 0; green < CUBE_SIZE; green++) {
for (blue = 0; blue < CUBE_SIZE; blue++) {
for (i = 0; i < 256; i++) {
distance = _color_distance (cube_index_to_short[red],
cube_index_to_short[green],
cube_index_to_short[blue],
colors[i].red,
colors[i].green,
colors[i].blue);
if (i == 0 || distance < min_distance) {
info->cube_to_pseudocolor[red][green][blue] = colors[i].pixel;
min_distance = distance;
if (!min_distance)
break;
}
}
}
}
}
for (i = 0, j = 0; i < 256; i++) {
if (j < CUBE_SIZE - 1 && (((i<<8)+i) - (int)cube_index_to_short[j]) > ((int)cube_index_to_short[j+1] - ((i<<8)+i)))
j++;
info->field8_to_cube[i] = j;
info->dither8_to_cube[i] = ((int)i - 128) / (CUBE_SIZE - 1);
}
for (i = 0, j = 0; i < 256; i++) {
if (j < RAMP_SIZE - 1 && (((i<<8)+i) - (int)ramp_index_to_short[j]) > ((int)ramp_index_to_short[j+1] - ((i<<8)+i)))
j++;
info->gray8_to_pseudocolor[i] = gray_to_pseudocolor[j];
}
for (i = 0; i < 256; i++) {
info->colors[i].a = 0xff;
info->colors[i].r = colors[i].red >> 8;
info->colors[i].g = colors[i].green >> 8;
info->colors[i].b = colors[i].blue >> 8;
}
*out = info;
return CAIRO_STATUS_SUCCESS;
}
void
_cairo_xlib_visual_info_destroy (cairo_xlib_visual_info_t *info)
{
/* No need for XFreeColors() whilst using DefaultColormap */
_cairo_list_del (&info->link);
free (info);
}
#endif /* !CAIRO_HAS_XLIB_XCB_FUNCTIONS */