1XFlush(3)                       XLIB FUNCTIONS                       XFlush(3)
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NAME

6       XFlush, XSync, XEventsQueued, XPending - handle output buffer or event
7       queue
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SYNTAX

10       int XFlush(Display *display);
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12       int XSync(Display *display, Bool discard);
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14       int XEventsQueued(Display *display, int mode);
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16       int XPending(Display *display);
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ARGUMENTS

19       discard   Specifies a Boolean value that indicates whether XSync dis‐
20                 cards all events on the event queue.
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22       display   Specifies the connection to the X server.
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24       mode      Specifies the mode.  You can pass QueuedAlready, QueuedAfter‐
25                 Flush, or QueuedAfterReading.
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DESCRIPTION

28       The XFlush function flushes the output buffer.  Most client applica‐
29       tions need not use this function because the output buffer is automati‐
30       cally flushed as needed by calls to XPending, XNextEvent, and XWindow‐
31       Event.  Events generated by the server may be enqueued into the
32       library's event queue.
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34       The XSync function flushes the output buffer and then waits until all
35       requests have been received and processed by the X server.  Any errors
36       generated must be handled by the error handler.  For each protocol
37       error received by Xlib, XSync calls the client application's error han‐
38       dling routine (see section 11.8.2).  Any events generated by the server
39       are enqueued into the library's event queue.
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41       Finally, if you passed False, XSync does not discard the events in the
42       queue.  If you passed True, XSync discards all events in the queue,
43       including those events that were on the queue before XSync was called.
44       Client applications seldom need to call XSync.
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46       If mode is QueuedAlready, XEventsQueued returns the number of events
47       already in the event queue (and never performs a system call).  If mode
48       is QueuedAfterFlush, XEventsQueued returns the number of events already
49       in the queue if the number is nonzero.  If there are no events in the
50       queue, XEventsQueued flushes the output buffer, attempts to read more
51       events out of the application's connection, and returns the number
52       read.  If mode is QueuedAfterReading, XEventsQueued returns the number
53       of events already in the queue if the number is nonzero.  If there are
54       no events in the queue, XEventsQueued attempts to read more events out
55       of the application's connection without flushing the output buffer and
56       returns the number read.
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58       XEventsQueued always returns immediately without I/O if there are
59       events already in the queue.  XEventsQueued with mode QueuedAfterFlush
60       is identical in behavior to XPending.  XEventsQueued with mode
61       QueuedAlready is identical to the XQLength function.
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63       The XPending function returns the number of events that have been
64       received from the X server but have not been removed from the event
65       queue.  XPending is identical to XEventsQueued with the mode
66       QueuedAfterFlush specified.
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SEE ALSO

69       AllPlanes(3), XIfEvent(3), XNextEvent(3), XPutBackEvent(3)
70       Xlib - C Language X Interface
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74X Version 11                     libX11 1.6.7                        XFlush(3)
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