XFlush(3X)                                             XFlush(3X)



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

SYNOPSIS
     XFlush (display)
     Display *display;

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

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

     int XPending (display)
     Display *display;

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 XPend-
     ing,
     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 in Xlib - C Language Interface ). Any events generat-
     ed by the server are enqueued into the library's event
     queue.  Finally, if you pass FALSE, XSync does not discard
     the events in the queue.  If you pass TRUE, XSync discards
     all events in the queue, including those events that were on
     the queue before XSync was called.  Client applications sel-
     dom 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 of the
     application's connection without flushing the output buffer



November, 1990                                                  1

XFlush(3X)                                             XFlush(3X)



     and returns the number read.

     XEventsQueued always returns immediately without I/O if
     there are events already in the queue.  XEventsQueued with a
     mode of XQueuedAfterFlush is identical in behavior to XPend-
     ing.  XEventsQueued with a mode of
     QueuedAlready is identical in behavior to the XQLength func-
     tion.

     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 XE-
     ventsQueued with a mode of QueuedAfterFlush.

   Arguments
     These functions accept the following arguments:

     discard Specifies whether XSync discards all events on the
             event queue.  You can pass the value 0 or 1.

     display Specifies the connection to the X server.

     mode    Specifies the mode.  One of the following constants
             can be passed:  QueuedAlready, QueuedAfterFlush, or
             QueuedAfterReading.

SEE ALSO
     AllPlanes(3X), XIfEvent(3X), XNextEvent(3X),
     XPutBackEvent(3X)

     Xlib - C Language Interface

























2                                                  November, 1990