XdbeGetVisualInfo(3)						    X FUNCTIONS 					      XdbeGetVisualInfo(3)

NAME

       XdbeGetVisualInfo - Get dbe Visual Informations

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
       requested.   If	num_screens  is zero, information for all screens is requested.  In this case, upon return from this function, num_screens
       will be set to the number of screens that were found.  If an error occurs, this function returns NULL, else it returns a pointer to a  list
       of  XdbeScreenVisualInfo  structures  of  length  num_screens.  The nth element 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  corre-
       sponds to the nth screen of the server, starting with screen zero.  The XdbeScreenVisualInfo 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 performance than the visual  having  the  lower  perflevel.   Nothing  can	be
       deduced from the following: the magnitude of the difference of two perflevels, 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(),  XdbeDeallocateBackBufferName(),  XdbeEndIdiom(),  XdbeFreeVisualInfo(),  XdbeGetBack-
       BufferAttributes(), XdbeQueryExtension(), XdbeSwapBuffers().

X Version 11							   libXext 1.1.1					      XdbeGetVisualInfo(3)