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cogl-winsys-glx: fix texture format detection

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The previous detection was based on color depth only to determine the
texture format to use in GLX. If that worked fine at depths 24 (RGB8)
and 32 (ARGB8), that would fail at depth 30 (BGR10) and fallback to
software instead of using the TFP extension.

This commit uses an efficient population count implementation to
compare the number of 1-bits in color masks against the color depth
requested by the X client. If they are not equal this means that an
alpha channel has been requested.

Reviewed-by: Robert Bragg <robert@linux.intel.com>
This commit is contained in:
Damien Leone 2011-09-26 14:01:27 -07:00 committed by Robert Bragg
parent 6c0dd4aab1
commit 895055c836
1 changed files with 27 additions and 7 deletions
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34
cogl/winsys/cogl-winsys-glx.c
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@ -1632,6 +1632,22 @@ should_use_rectangle (CoglContext *context)
return context->rectangle_state == COGL_WINSYS_RECTANGLE_STATE_ENABLE;
}
/* GCC's population count builtin is available since version 3.4 */
#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
#define POPCOUNTL(n) __builtin_popcountl(n)
#else
/* HAKMEM 169 */
static int
hakmem_popcountl (unsigned long n)
{
unsigned long tmp;
tmp = n - ((n >> 1) & 033333333333) - ((n >> 2) & 011111111111);
return ((tmp + (tmp >> 3)) & 030707070707) % 63;
}
#define POPCOUNTL(n) hakmem_popcountl(n)
#endif
static gboolean
try_create_glx_pixmap (CoglContext *context,
CoglTexturePixmapX11 *tex_pixmap,
@ -1651,17 +1667,19 @@ try_create_glx_pixmap (CoglContext *context,
GLenum target;
CoglXlibTrapState trap_state;
unsigned int depth = tex_pixmap->depth;
Visual* visual = tex_pixmap->visual;
renderer = context->display->renderer;
xlib_renderer = renderer->winsys;
glx_renderer = renderer->winsys;
dpy = xlib_renderer->xdpy;
if (!get_fbconfig_for_depth (context,
tex_pixmap->depth, &fb_config,
if (!get_fbconfig_for_depth (context, depth, &fb_config,
&glx_tex_pixmap->can_mipmap))
{
COGL_NOTE (TEXTURE_PIXMAP, "No suitable FBConfig found for depth %i",
tex_pixmap->depth);
depth);
return FALSE;
}
@ -1678,12 +1696,14 @@ try_create_glx_pixmap (CoglContext *context,
attribs[i++] = GLX_TEXTURE_FORMAT_EXT;
if (tex_pixmap->depth == 24)
/* Check whether an alpha channel is used by comparing the total
* number of 1-bits in color masks against the color depth requested
* by the client.
*/
if (POPCOUNTL(visual->red_mask|visual->green_mask|visual->blue_mask) == depth)
attribs[i++] = GLX_TEXTURE_FORMAT_RGB_EXT;
else if (tex_pixmap->depth == 32)
attribs[i++] = GLX_TEXTURE_FORMAT_RGBA_EXT;
else
return FALSE;
attribs[i++] = GLX_TEXTURE_FORMAT_RGBA_EXT;
attribs[i++] = GLX_MIPMAP_TEXTURE_EXT;
attribs[i++] = mipmap;