plucky (3) XdbeGetVisualInfo.3.gz

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 corresponds 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(), XdbeGetBackBufferAttributes(), XdbeQueryExtension(), XdbeSwapBuffers().