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XdbeGetVisualInfo(3)		  X FUNCTIONS		  XdbeGetVisualInfo(3)

NAME
       XdbeGetVisualInfo - Get dbe Visual Information

SYNOPSIS
       #include	<X11/extensions/Xdbe.h>

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

DESCRIPTION
       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.

ERRORS
       BadDrawable
	      One  or  more  values passed in screen_specifiers	is not a valid
	      drawable.

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

X Version 11			 libXext 1.3.6		  XdbeGetVisualInfo(3)

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