XFlush(3X) XFlush(3X)
NAME
XFlush, XSync, XEventsQueued, XPending - handle output
buffer or event queue
SYNOPSIS
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.
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XFlush(3X) XFlush(3X)
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 Programming Manual
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