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XIfEvent(3X11)
X11R6
NAME
  XIfEvent, XCheckIfEvent, XPeekIfEvent - check the event queue with a
  predicate procedure

SYNOPSIS
  XIfEvent(display, event_return, predicate, arg)
	  Display *display;
	  XEvent *event_return;
	  Bool (*predicate)();
	  XPointer arg;

  Bool XCheckIfEvent(display, event_return, predicate, arg)
	  Display *display;
	  XEvent *event_return;
	  Bool (*predicate)();
	  XPointer arg;

  XPeekIfEvent(display, event_return, predicate, arg)
	  Display *display;
	  XEvent *event_return;
	  Bool (*predicate)();
	  XPointer arg;

ARGUMENTS
  arg Specifies the user-supplied argument that will be passed to the
      predicate procedure.

  display
      Specifies the connection to the X server.

  event_return
      Returns either a copy of or the matched event's associated structure.

  predicate
      Specifies the procedure that is to be called to determine if the next
      event in the queue matches what you want.

DESCRIPTION
  The XIfEvent function completes only when the specified predicate procedure
  returns True for an event, which indicates an event in the queue matches.
  XIfEvent flushes the output buffer if it blocks waiting for additional
  events.  XIfEvent removes the matching event from the queue and copies the
  structure into the client-supplied XEvent structure.

  When the predicate procedure finds a match, XCheckIfEvent copies the
  matched event into the client-supplied XEvent structure and returns True.
  (This event is removed from the queue.) If the predicate procedure finds no
  match, XCheckIfEvent returns False, and the output buffer will have been
  flushed. All earlier events stored in the queue are not discarded.

  The XPeekIfEvent function returns only when the specified predicate
  procedure returns True for an event. After the predicate procedure finds a
  match, XPeekIfEvent copies the matched event into the client-supplied
  XEvent structure without removing the event from the queue.  XPeekIfEvent
  flushes the output buffer if it blocks waiting for additional events.

SEE ALSO
  XAnyEvent(3X11), XNextEvent(3X11), XPutBackEvent(3X11), XSendEvent(3X11)

  Xlib -- C Language X Interface

Index for Section 3X11

Alphabetical listing for X

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