XtInsertEventTypeHandler(3Xt)XtInsertEventTypeHandler(3Xt)NAME
XtInsertEventTypeHandler, XtRemoveEventTypeHandler, XtRegisterExten‐
sionSelector, XtSetEventDispatcher, XtDispatchEventToWidget - extension
event handling
SYNOPSIS
void XtInsertEventTypeHandler(widget, event_type, select_data, proc,
client_data, position)
Widget widget;
int event_type;
XtPointer select_data;
XtEventHandler proc;
XtPointer client_data;
XtListPosition position;
void XtRemoveEventTypeHandler(widget, event_type, select_data, proc,
client_data)
Widget widget;
int event_type;
XtPointer select_data;
XtEventHandler proc;
XtPointer client_data;
void XtRegisterExtensionSelector(display, min_event_type,
max_event_type, proc, client_data)
Display* display;
int min_event_type;
int max_event_type;
XtExtensionSelectProc proc;
XtPointer client_data;
XtEventDispatchProc XtSetEventDispatcher(display, event_type, proc)
Widget widget;
int event_type;
XtEventDispatchProc proc;
Boolean XtDispatchEventToWidget(widget, event)
Widget widget;
XEvent* event;
ARGUMENTS
Specifies the widget for this event handler. Must be of class Core or
any subclass thereof. Specifies the event type. Specifies data used
to select or deselect events from the server. Specifies the proc.
Specifies additional data to be passed to the event handler. Specifies
when the event handler is to be called relative to other previously
registered handlers. Specifies the display. Specifies the range of
event types for this extension. 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 XtInsertRawEven‐
tHandler 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 selec‐
tor 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 reg‐
istered 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 real‐
ized, XtRemoveEventTypeHandler calls XSelectInput if necessary. Speci‐
fying 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 selec‐
tor 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 proce‐
dure specified by proc for events with the type event_type. The previ‐
ously 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 con‐
tinue_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 ALSOXtGetKeyboardFocusWidget(3Xt)
X Toolkit Intrinsics -- C Language Interface
Xlib -- C Language X Interface
XtInsertEventTypeHandler(3Xt)
