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 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
       deduced 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 1.0.3            XdbeGetVisualInfo(3)