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dix: Work around non-premultiplied ARGB cursor data

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Some games incorrectly use non-premultiplied ARGB cursor data, presumably
because that's what Windows uses. On some hardware (and with SWcursor),
this breaks areas of the cursor which are supposed to be transparent
(and presumably also translucent areas, but that's less noticeable).

This change checks for pixels with alpha == 0 and any non-alpha component
!= 0. If any such pixel is found, the data is assumed to be
non-premultiplied and fixed up by multiplying the RGB components with the
alpha component.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92309
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Michel Dänzer 2016-06-28 17:22:47 +09:00 committed by Adam Jackson
parent 033888e776
commit 401a8d6e13
1 changed files with 23 additions and 0 deletions
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23
dix/cursor.c
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@ -288,6 +288,29 @@ AllocARGBCursor(unsigned char *psrcbits, unsigned char *pmaskbits,
goto error;
*ppCurs = pCurs;
if (argb) {
size_t i, size = bits->width * bits->height;
for (i = 0; i < size; i++) {
if ((argb[i] & 0xff000000) == 0 && (argb[i] & 0xffffff) != 0) {
/* ARGB data doesn't seem pre-multiplied, fix it */
for (i = 0; i < size; i++) {
CARD32 a, ar, ag, ab;
a = argb[i] >> 24;
ar = a * ((argb[i] >> 16) & 0xff) / 0xff;
ag = a * ((argb[i] >> 8) & 0xff) / 0xff;
ab = a * (argb[i] & 0xff) / 0xff;
argb[i] = a << 24 | ar << 16 | ag << 8 | ab;
}
break;
}
}
}
return Success;
error: