XFlush(3X11) XLIB FUNCTIONS XFlush(3X11)NAME
XFlush, XSync, XEventsQueued, XPending - handle output
buffer or event queue
SYNTAXXFlush(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 gener-
ated 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
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XFlush(3X11) XLIB FUNCTIONS XFlush(3X11)
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 out-
put 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 iden-
tical 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 ALSOAllPlanes(3X11), XIfEvent(3X11), XNextEvent(3X11), XPut-
BackEvent(3X11)
Xlib - C Language X Interface
X Version 11 Release 6.4 2