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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
+ * http://www.mozilla.org/MPL/
+ *
+ * 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 = 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 */