> I would rather use XPutImage for fast display, but
> after reading about the XVisualInfo struct, I need Alexander
> Keith's beer.
Actually, although there's a lot there, you only need to deal with a
few parameters. If you're using the same Visual as the form itself,
XVisualInfo is available in the FL_STATE vector for your current
visual. If you need some other Visual, for instance if your Canvas is
TrueColor and your form is PseudoColor, you'll need to look it up -- I
don't believe that the FL_STATE vector member for TrueColor will be
correct (TC, did I get that right?). Anyhow, being a belt and
suspenders kind of programmer, I tend to look it up just to be
certain.
Here's a little routine to fish up the XVisualInfo given a Window,
should you need it:
XVisualInfo *get_window_visual_info( Window window,
Colormap *colormap_ptr )
{
XWindowAttributes attributes;
XVisualInfo template_visual_info;
XVisualInfo *matching_visual_info;
int structures;
XGetWindowAttributes( fl_get_display(), window, &attributes );
template_visual_info.visualid = XVisualIDFromVisual( attributes.visual );
matching_visual_info = XGetVisualInfo( fl_get_display(),
VisualIDMask,
&template_visual_info,
&structures );
*colormap_ptr = attributes.colormap;
return matching_visual_info;
}
In this routine, I also return a pointer to the colormap, since it's
something I happen to generally need in this context.
I probably should be slightly more paranoid and test that the
XVisualInfo actually match but if they don't, something's pretty badly
broken elsewhere, anyhow.
spl
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