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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 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 per-flevels perflevels
       flevels 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().




X Version 11                                    libXext 1.0.5                           XdbeGetVisualInfo(3)