NAME
XtInsertEventTypeHandler, XtRemoveEventTypeHandler,
XtRegisterExtensionSelector, XtSetEventDispatcher,
XtDispatchEventToWidget - extension event handling
SYNTAX
void XtInsertEventTypeHandler(Widget widget, int event_type, XtPointer
select_data, XtEventHandler proc, XtPointer client_data,
XtListPosition position);
void XtRemoveEventTypeHandler(Widget widget, 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 XtInsertEventTypeHandler function registers 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 EventMask, indicating the event
mask to be used to select for the desired event. This event mask will
be included in the value returned by XtBuildEventMask. If the widget
is realized XtInsertEventTypeHandler calls XSelectInput if necessary.
Specifying NULL for select_data is equivalent to specifying a pointer
to an event mask containing 0. This is similar to the
XtInsertRawEventHandler 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
XtListTail, which registers this event handler after any previously
registered handlers for this event type.
The XtRemoveEventTypeHandler function unregisters an even handler
registered with XtInsertEventTypeHandler 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 EventMask, indicating the mask to
be used to deselect for the appropriate event. If the widget is
realized, XtRemoveEventTypeHandler calls XSelectInput if necessary.
Specifying NULL for select_data is equivalent to specifying a pointer
to an event mask containing 0. This is similar to the
XtRemoveRawEventHandler 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 XtRegisterExtensionSelector 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 XtRegisterExtensionSelector 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 XtSetEventDispatcher function registers the event dispatcher
procedure specified by proc for events with the type event_type. The
previously registered dispatcher (or the default dispatcher if there
was no previously registered dispatcher) is returned. If proc is NULL,
the default procedure is restored for the specified type.
In the future, when XtDispatchEvent 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 XtDispatchEventToWidget 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
Expose, NoExpose, GraphicsExpose, and VisibilityNotify 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
True. These internal event handlers never set continue_to_dispatch to
False.
XtDispatchEventToWidget returns True if any event handler was called
and False otherwise.
SEE ALSO
XtGetKeyboardFocusWidget(3Xt)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface