NAME

XPeekIfEvent — get an event matched by predicate procedure without removing it from the queue. 

SYNOPSIS

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

ARGUMENTS

displaySpecifies a connection to an X server; returned from XOpenDisplay(). 

event_return
Returns a copy of the matched event.

predicateSpecifies the procedure to be called to determine if each event that arrives in the queue is the desired one. 

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

DESCRIPTION

XPeekIfEvent() returns an event only when the specified predicate procedure returns True for the event.  The event is copied into event_return but not removed from the queue.  The specified predicate is called each time an event is added to the queue, with the arguments display, event_return, and arg. 

XPeekIfEvent() flushes the request buffer if no matching events could be found on the queue, and then waits for the next matching event. 

For more information, see Volume One, Chapter 8, Events. 

SEE ALSO

XQLength(), XAllowEvents(), XCheckIfEvent(), XCheckMaskEvent(), XCheckTypedEvent(), XCheckTypedWindowEvent(), XCheckWindowEvent(), XEventsQueued(), XGetInputFocus(), XGetMotionEvents(), XIfEvent(), XMaskEvent(), XNextEvent(), XPeekEvent(), XPending(), XPutBackEvent(), XSelectInput(), XSendEvent(), XSetInputFocus(), XSynchronize(), XWindowEvent(). 

Xlib Reference Manual