NAME

XIfEvent, XCheckIfEvent, XPeekIfEvent − check the event queue

SYNTAX

XIfEvent(display, event_return, predicate, arg)
      Display ∗display;
      XEvent ∗event_return;
      Bool (∗predicate)();
      char ∗arg;

Bool XCheckIfEvent(display, event_return, predicate, arg)
      Display ∗display;
      XEvent ∗event_return;
      Bool (∗predicate)();
      char ∗arg;

XPeekIfEvent(display, event_return, predicate, arg)
      Display ∗display;
      XEvent ∗event_return;
      Bool (∗predicate)();
      char ∗arg;

ARGUMENTS

argSpecifies the user-supplied argument that will be passed to the predicate procedure. 

displaySpecifies the connection to the X server. 

event_returnThe function copies the matched event’s associated structure into this client-supplied structure. 

predicateSpecifies the procedure that is to be called to determine if the next event in the queue matches the one specified by the event argument. 

DESCRIPTION

The XIfEvent function checks the event queue for the specified event. If the events match as determined by your predicate procedure, XIfEvent removes the event from the queue and, when it returns, copies the structure into the client-supplied XEvent structure.

The XCheckIfEvent function checks the event queue for the specified event.

The XPeekIfEvent function returns only when the specified predicate procedure returns a nonzero (true) for the next event in the queue that matches the specified event.

SEE ALSO

XFlush(3X), XPutBackEvent(3X)
Xlib − C Language X Interface

1 March 1988