XtInsertEventTypeHanXlVersion 11 (ReXtInsertEventTypeHandler(3Xt)
NAME
XtInsertEventTypeHandler, XtRemoveEventTypeHandler,
XtRegisterExtensionSelector, XtSetEventDispatcher,
XtDispatchEventToWidget - extension event handling
SYNTAX
void XtInsertEventTypeHandler(widget, event_type,
select_data, proc, client_data, position)
Widget wdget;
int event_type;
XtPointer select_data;
XtEventHandler proc;
XtPointer client_data;
XtListPosition position;
void XtRemoveEventTypeHandler(widget, event_type,
select_data, proc, client_data)
Widget wdget;
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
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.
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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 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 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
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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 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 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
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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
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