XFlush(3)

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 dis-
                 cards all events on the event queue.

       display   Specifies the connection to the X server.

       mode      Specifies the mode.  You can pass QueuedAlready, QueuedAfter-
                 Flush, or QueuedAfterReading.

DESCRIPTION

       The XFlush function flushes the output buffer.  Most client applica-
       tions need not use this function because the output buffer is automati-
       cally flushed as needed by calls to XPending, XNextEvent, and XWindow-
       Event.  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 han-
       dling 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(3X11), XIfEvent(3X11), XNextEvent(3X11), XPutBackEvent(3X11)
       Xlib - C Language X Interface

X Version 11                     libX11 1.1.1                        XFlush(3)