XFlush(3X11)                         BSD                          XFlush(3X11)



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

SYNTAX
     XFlush(display)
           Display *display;

     XSync(display, discard)
           Display *display;
           Bool discard;

     int XEventsQueued(display, mode)
          Display *display;
          int mode;

     int XPending(display)
           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 error event
     received by Xlib, XSync calls the client application's error handling
     routine (see section 8.12.2).  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
     XIfEvent(3X11), XNextEvent(3X11), XPutBackEvent(3X11)
     Xlib - C Language X Interface