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74 lines
2.2 KiB
C
74 lines
2.2 KiB
C
/* $Xorg: PeekIfEv.c,v 1.4 2001/02/09 02:03:35 xorgcvs Exp $ */
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/*
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Copyright 1986, 1998 The Open Group
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Permission to use, copy, modify, distribute, and sell this software and its
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documentation for any purpose is hereby granted without fee, provided that
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the above copyright notice appear in all copies and that both that
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copyright notice and this permission notice appear in supporting
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documentation.
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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Except as contained in this notice, the name of The Open Group shall not be
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used in advertising or otherwise to promote the sale, use or other dealings
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in this Software without prior written authorization from The Open Group.
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*/
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/* $XFree86: xc/lib/X11/PeekIfEv.c,v 1.5 2003/11/17 22:20:08 dawes Exp $ */
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#define NEED_EVENTS
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#include "Xlibint.h"
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/*
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* return the next event in the queue that satisfies the predicate.
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* BUT do not remove it from the queue.
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* If none found, flush, and then wait until one satisfies the predicate.
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*/
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int
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XPeekIfEvent (dpy, event, predicate, arg)
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register Display *dpy;
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register XEvent *event;
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Bool (*predicate)(
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Display* /* display */,
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XEvent* /* event */,
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char* /* arg */
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);
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char *arg;
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{
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register _XQEvent *prev, *qelt;
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unsigned long qe_serial = 0;
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LockDisplay(dpy);
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prev = NULL;
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while (1) {
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for (qelt = prev ? prev->next : dpy->head;
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qelt;
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prev = qelt, qelt = qelt->next) {
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if(qelt->qserial_num > qe_serial
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&& (*predicate)(dpy, &qelt->event, arg)) {
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*event = qelt->event;
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UnlockDisplay(dpy);
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return 0;
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}
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}
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if (prev)
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qe_serial = prev->qserial_num;
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_XReadEvents(dpy);
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if (prev && prev->qserial_num != qe_serial)
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/* another thread has snatched this event */
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prev = NULL;
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}
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}
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