XtInsertEventTypeHandler(3Xt)

NAME
XtInsertEventTypeHandler, XtRemoveEventTypeHandler, XtRegisterExtensionSelector, XtSetEventDispatcher, XtDispatchEventToWidget - extension event handling

SYNTAX

void XtInsertEventTypeHandler(Widget wdget, int event_type, XtPointer select_data, XtEventHandler proc, XtPointer client_data, XtListPosition position);

void XtRemoveEventTypeHandler(Widget wdget, int event_type, XtPointer select_data, XtEventHandler proc, XtPointer client_data);

void XtRegisterExtensionSelector(Display* display, int min_event_type, int max_event_type, XtExtensionSelectProc proc, XtPointer client_data);

XtEventDispatchProc XtSetEventDispatcher(Widget widget, int event_type, XtEventDispatchProc proc);

Boolean XtDispatchEventToWidget(Widget widget, XEvent* event);

ARGUMENTS

widget
    Specifies the widget for this event handler. Must be of class Core or any subclass thereof.

event_type
    Specifies the event type.

select_data
    Specifies data used to select or deselect events from the server.

proc
    Specifies the proc.

client_data
    Specifies additional data to be passed to the event handler.

position
    Specifies when the event handler is to be called relative to other previously registered handlers.

display
    Specifies the display.

min_event_type, max_event_type
    Specifies the range of event types for this extension.

event
    Specifies a pointer to the event to be dispatched.

DESCRIPTION
The function registeres a procedure with the dispatch mechanism that is to be called when an event that matches the specified event_type is dispatched to the specified widget.

If event_type is one of the core X protocol events then select_data must be a pointer to a value of type indicating the event mask to be used to select for the desired event. This event mask will be included in the value returned by If the widget is realized calls if necessary. Specifying NULL for select_data is equivalent to specifying a pointer to an event mask containing 0. This is similar to the function.

If event_type specifies an extension event type then the semantics of the data pointed to by select_data are defined by the extension selector registered for the specified event type.

In either case the Intrinsics are not required to copy the data pointed to by select_data, so the caller must ensure that it remains valid as long as the event handler remains registered with this value of select_data.

The position argument allows the client to control the order of the invocation of event handlers registered for the same event type. If the client does not care about the order, it should normally specify which registers this event handler after any previously registered handlers for this event type.

The function unregisters an even handler registered with for the specified event type. The request is ignored if client_data does not match the value given with the handler was registered.

If event_type specifies on of the core X protocol events, select_data must be a pointer to a value of type indicating the mask to be used to deselect for the appropriate event. If the widget is realized, calls if necessary. Specifying NULL for select_data is equivalent to specifying a pointer to an event mask containing 0. This is similar to the function.

If event_type specifies an extension event type then the semantics of the data pointed to by select_data are defined by the extension selector registered for the specified event type.

The function registers a procedure to arrange for the delivery of extension events to widgets.

If min_event_type and max_event_type match the parameters to a previous call to for the same display, the proc and client_data replace the previously registered values. If the range specified by min_event_type and max_event_type overlaps the range of the parameters to a previous call for the same display in any other way, an error results.

The function registes the event dispatcher procedure specified by proc for event swith the type event_type. The previously registered dispatcher (or the default dispatcher if there was no previousl registered dispatcher) is returned. If proc is NULL, the default procedure is restored for the specified type.

In the future, when is called with an event of event_type, the specified proc (or the default dispatcher) will be invoked to determine a widget ot which to dispatch the event.

The function scans the list of registered event handlers for the specified widget and calls each handler that has been registered for the specified event type, subject to the continue_to_dispatch value returned by each handler. The Intrinsics behave as if event handlers were registered at the head of the list for and events to invoke the widget's expose procedure according to the exposure compression rules and to update the widget's visible field if visible_interest is These internal event handlers never set continue_to_dispatch to

returns if any event handler was called and otherwise.

SEE ALSO
XtGetKeyboardFocusWidget(3Xt)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface