X Version 11 (Release 5)

XtAddEventHandler(Xt)

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

client_data: Specifies additional data to be passed to the client's event handler.
event_mask: Specifies the event mask for which to call or unregister this procedure.
nonmaskable: Specifies a Boolean value that indicates whether this procedure 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 client_data, the specified mask is ORed into the existing mask. If the widget is realized, XtAddEventHandler calls XSelectInput, if necessary.

The XtAddRawEventHandler function is similar to XtAddEventHandler except that it does not affect the widget's mask and never causes an XSelectInput 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 client_data 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.

XtAddEventHandler(Xt)

Syntax

Arguments

Description

See also