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Table of Contents
XtInsertEventTypeHandler, XtRemoveEventTypeHandler,
XtRegisterExtensionSelector, XtSetEventDispatcher, XtDispatchEventToWidget
- extension event handling
- 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);
- 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.
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 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 event handlers never set continue_to_dispatch to False.
XtDispatchEventToWidget returns True if any event handler was called
and False otherwise.
XtGetKeyboardFocusWidget(3Xt)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
Table of Contents
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