Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages


home | help
XdbeGetVisualInfo(3)		  X FUNCTIONS		  XdbeGetVisualInfo(3)

       XdbeGetVisualInfo - Get dbe Visual Informations

       #include	<X11/extensions/Xdbe.h>

       XdbeScreenVisualInfo *XdbeGetVisualInfo(
	   Display  *dpy,
	   Drawable *screen_specifiers,
	   int	    *num_screens)

       This  function  returns	information about which	visuals	support	double
       buffering.  The argument	num_screens specifies how many elements	 there
       are  in the screen_specifiers list.  Each drawable in screen_specifiers
       designates a screen for which  the  supported  visuals  are  being  re-
       quested.	  If  num_screens  is zero, information	for all	screens	is re-
       quested.	 In this case, upon return  from  this	function,  num_screens
       will  be	set to the number of screens that were found.  If an error oc-
       curs, this function returns NULL, else it returns a pointer to  a  list
       of XdbeScreenVisualInfo structures of length num_screens.  The nth ele-
       ment in the returned list  corresponds  to  the	nth  drawable  in  the
       screen_specifiers list, unless num_screens was passed in	with the value
       zero, in	which case the nth element in the returned list	corresponds to
       the  nth	 screen	 of  the server, starting with screen zero.  The Xdbe-
       ScreenVisualInfo	structure has the following fields:

	    int		   count
	    XdbeVisualInfo *visinfo

       count specifies the number of items in visinfo.	 visinfo  specifies  a
       list of visuals,	depths,	and performance	hints for this screen.

       The XdbeVisualInfo structure has	the following fields:

	    VisualID visual
	    int	     depth
	    int	     perflevel

       visual  specifies  one visual ID	that supports double-buffering.	 depth
       specifies the depth of the visual.  perflevel is	a performance hint.

       The only	operation defined on a perflevel is comparison to a  perflevel
       of  another  visual  on	the same screen.  The visual having the	higher
       perflevel is likely to have better  double-buffering  graphics  perfor-
       mance  than  the	visual having the lower	perflevel.  Nothing can	be de-
       duced from the following: the magnitude of the difference of  two  per-
       flevels,	 a  perflevel value in isolation, or comparing perflevels from
       different servers.

	      One or more values passed	in screen_specifiers is	 not  a	 valid

       DBE,  XdbeAllocateBackBufferName(),  XdbeBeginIdiom(),  XdbeDeallocate-
       BackBufferName(),  XdbeEndIdiom(),  XdbeFreeVisualInfo(),  XdbeGetBack-
       BufferAttributes(), XdbeQueryExtension(), XdbeSwapBuffers().

X Version 11			 libXext 1.3.4		  XdbeGetVisualInfo(3)


Want to link to this manual page? Use this URL:

home | help