Commit 5efd304b authored by Paul Eggert's avatar Paul Eggert

* xterm.c (x_alloc_nearest_color_1): Use a more-precise algorithm

for nearest color, one that neither overflows nor relies on unsigned
arithmetic.
parent 578c21e6
2011-06-13 Paul Eggert <eggert@cs.ucla.edu>
* xterm.c (x_alloc_nearest_color_1): Use a more-precise algorithm
for nearest color, one that neither overflows nor relies on unsigned
arithmetic.
Remove unnecessary casts.
* xterm.c (x_term_init):
* xfns.c (x_set_border_pixel):
......
......@@ -1693,16 +1693,18 @@ x_alloc_nearest_color_1 (Display *dpy, Colormap cmap, XColor *color)
a least-squares matching, which is what X uses for closest
color matching with StaticColor visuals. */
int nearest, i;
unsigned long nearest_delta = ~ (unsigned long) 0;
int max_color_delta = (1 << (16 - 2)) - 1;
int max_delta = 3 * max_color_delta;
int nearest_delta = max_delta + 1;
int ncells;
const XColor *cells = x_color_cells (dpy, &ncells);
for (nearest = i = 0; i < ncells; ++i)
{
long dred = (color->red >> 8) - (cells[i].red >> 8);
long dgreen = (color->green >> 8) - (cells[i].green >> 8);
long dblue = (color->blue >> 8) - (cells[i].blue >> 8);
unsigned long delta = dred * dred + dgreen * dgreen + dblue * dblue;
int dred = (color->red >> 2) - (cells[i].red >> 2);
int dgreen = (color->green >> 2) - (cells[i].green >> 2);
int dblue = (color->blue >> 2) - (cells[i].blue >> 2);
int delta = dred * dred + dgreen * dgreen + dblue * dblue;
if (delta < nearest_delta)
{
......
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