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Return actual color cell count in x-display-color-cells

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* src/xfns.c (Fx_display_color_cells): Return the actual amount
of color cells, or the amount of individual combinations of
components.
This commit is contained in:
Po Lu 2022-03-08 14:15:01 +08:00
parent 5f87550f53
commit 39a2eb04f3
1 changed files with 9 additions and 6 deletions
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15
src/xfns.c
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@ -5131,14 +5131,17 @@ If omitted or nil, that stands for the selected frame's display.
{
struct x_display_info *dpyinfo = check_x_display_info (terminal);
int nr_planes = DisplayPlanes (dpyinfo->display,
XScreenNumberOfScreen (dpyinfo->screen));
if (dpyinfo->visual_info.class != TrueColor
&& dpyinfo->visual_info.class != DirectColor)
return make_fixnum (dpyinfo->visual_info.colormap_size);
/* Truncate nr_planes to 24 to avoid integer overflow.
Some displays says 32, but only 24 bits are actually significant.
int nr_planes = dpyinfo->n_planes;
/* Truncate nr_planes to 24 to avoid integer overflow. Some
displays says 32, but only 24 bits are actually significant.
There are only very few and rare video cards that have more than
24 significant bits. Also 24 bits is more than 16 million colors,
it "should be enough for everyone". */
24 significant bits. Also 24 bits is more than 16 million
colors, it "should be enough for everyone". */
if (nr_planes > 24) nr_planes = 24;
return make_fixnum (1 << nr_planes);