MirOS Manual: XEventsQueued(3), XFlush(3), XPending(3), XSync(3)


XFlush(3X11)             XLIB FUNCTIONS              XFlush(3X11)

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 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 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

XFree86                   Version 4.5.0                         1

XFlush(3X11)             XLIB FUNCTIONS              XFlush(3X11)

     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

XFree86                   Version 4.5.0                         2

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