Manual Pages for UNIX Operating System command usage for man XdbeGetVisualInfo

X FUNCTIONS                              XdbeGetVisualInfo(3xext)



NAME
     XdbeGetVisualInfo - Get dbe Visual Informations

SYNOPSIS
     cc [ flag... ] file... -lXext [ library... ]
     #include 

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

DESCRIPTION
     This function returns information about which  visuals  sup-
     port  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 struc-
     ture 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.  per-
     flevel 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



X Version 11       Last change: libXext 1.1.2                   1






X FUNCTIONS                              XdbeGetVisualInfo(3xext)



     the lower perflevel. Nothing can be deduced from the follow-
     ing:  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(),  XdbeFreeV-
     isualInfo(), XdbeGetBackBufferAttributes(),  XdbeQueryExten-
     sion(), XdbeSwapBuffers().



ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | x11/library/libxext         |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | See XInitThreads(3X11)      |
    |_____________________________|_____________________________|























X Version 11       Last change: libXext 1.1.2                   2