NAME

       XFlush, XSync, XEventsQueued, XPending - handle output buffer or event queue

SYNTAX

       int XFlush(Display *display);

       int XSync(Display *display, Bool discard);

       int XEventsQueued(Display *display, int mode);

       int XPending(Display *display);

ARGUMENTS

       discard   Specifies  a  Boolean  value that indicates whether XSync discards all events on
                 the event queue.

       display   Specifies the connection to the X server.

       mode      Specifies  the  mode.   You  can  pass   QueuedAlready,   QueuedAfterFlush,   or
                 QueuedAfterReading.

DESCRIPTION

       The XFlush function flushes the output buffer.  Most client applications need not use this
       function because the output  buffer  is  automatically  flushed  as  needed  by  calls  to
       XPending,  XNextEvent,  and  XWindowEvent.  Events generated by the server may be enqueued
       into the library's event queue.

       The XSync function flushes the output buffer and then waits until all requests  have  been
       received and processed by the X server.  Any errors generated must be handled by the error
       handler.  For each protocol error received by Xlib, XSync calls the  client  application's
       error  handling  routine  (see  section  11.8.2).   Any events generated by the server are
       enqueued into the library's event queue.

       Finally, if you passed False, XSync does not discard the events  in  the  queue.   If  you
       passed  True,  XSync discards all events in the queue, including those events that were on
       the queue before XSync was called.  Client applications seldom need to call XSync.

       If mode is QueuedAlready, XEventsQueued returns the number of events already in the  event
       queue  (and  never  performs  a  system call).  If mode is QueuedAfterFlush, XEventsQueued
       returns the number of events already in the queue if the number is nonzero.  If there  are
       no  events  in  the  queue, XEventsQueued flushes the output buffer, attempts to read more
       events out of the application's connection, and returns  the  number  read.   If  mode  is
       QueuedAfterReading, XEventsQueued returns the number of events already in the queue if the
       number is nonzero.  If there are no events in the queue, XEventsQueued  attempts  to  read
       more  events  out  of  the application's connection without flushing the output buffer and
       returns the number read.

       XEventsQueued always returns immediately without I/O if there are events  already  in  the
       queue.   XEventsQueued  with  mode  QueuedAfterFlush is identical in behavior to XPending.
       XEventsQueued with mode QueuedAlready is identical to the XQLength function.

       The XPending function returns the number of events that have  been  received  from  the  X
       server  but  have  not  been  removed  from  the  event  queue.   XPending is identical to
       XEventsQueued with the mode QueuedAfterFlush specified.

SEE ALSO

       AllPlanes(3), XIfEvent(3), XNextEvent(3), XPutBackEvent(3)
       Xlib - C Language X Interface