XtAddEventHandler(Xt) X Version 11 (Release 5) XtAddEventHandler(Xt)
6 January 1993
Name
XtAddEventHandler - add and remove event handlers
Syntax
void XtAddEventHandler(w, event_mask, nonmaskable, proc, client_data)
Widget w;
EventMask event_mask;
Boolean nonmaskable;
XtEventHandler proc;
XtPointer client_data;
void XtAddRawEventHandler(w, event_mask, nonmaskable, proc, client_data)
Widget w;
EventMask event_mask;
Boolean nonmaskable;
XtEventHandler proc;
XtPointer client_data;
void XtRemoveEventHandler(w, event_mask, nonmaskable, proc, client_data)
Widget w;
EventMask event_mask;
Boolean nonmaskable;
XtEventHandler proc;
XtPointer client_data;
void XtRemoveRawEventHandler(w, event_mask, nonmaskable, proc, client_data)
Widget w;
EventMask event_mask;
Boolean nonmaskable;
XtEventHandler proc;
XtPointer client_data;
Arguments
clientdata Specifies additional data to be passed to the client's event
handler.
eventmask Specifies the event mask for which to call or unregister this
procedure.
nonmaskable Specifies a Boolean value that indicates whether this pro-
cedure should be called or removed on the nonmaskable events
(GraphicsExpose, NoExpose, SelectionClear, SelectionRequest,
SelectionNotify, ClientMessage, and MappingNotify).
proc Specifies the procedure that is to be added or removed.
w Specifies the widget for which this event handler is being
registered.
Description
The XtAddEventHandler function registers a procedure with the dispatch
mechanism that is to be called when an event that matches the mask occurs
on the specified widget. If the procedure is already registered with the
same clientdata, the specified mask is ORed into the existing mask. If
the widget is realized, XtAddEventHandler calls XSelectInput, if neces-
sary.
The XtAddRawEventHandler function is similar to XtAddEventHandler except
that it does not affect the widget's mask and never causes an XSelect-
Input for its events. Note that the widget might already have those mask
bits set because of other nonraw event handlers registered on it.
The XtRemoveEventHandler stops the specified procedure from being called
in response to the specified events. A handler is removed if both the
procedure proc and clientdata match a registered handler/data pair.
The XtRemoveRawEventHandler function stops the specified procedure from
receiving the specified events. Because the procedure is a raw event
handler, this does not affect the widget's mask and never causes a call
on XSelectInput.
See also
XtAppNextEvent(Xt) and XtBuildEventMask(Xt).
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface