XtInsertEventTypeHandler(3XXT FUNCTIXtInsertEventTypeHandler(3Xt)NAME
XtInsertEventTypeHandler, XtRemoveEventTypeHandler, XtReg-
isterExtensionSelector, XtSetEventDispatcher, XtDispatch-
EventToWidget - 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.
proc Specifies the proc.
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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 han-
dlers.
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 dis-
patched.
DESCRIPTION
The XtInsertEventTypeHandler function registeres a proce-
dure with the dispatch mechanism that is to be called when
an event that matches the specified event_type is dis-
patched 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 spec-
ified 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 regis-
ters 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
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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 specify-
ing a pointer to an event mask containing 0. This is simi-
lar 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 spec-
ified event type.
The XtRegisterExtensionSelector function registers a pro-
cedure 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 previ-
ously 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 dis-
patcher procedure specified by proc for event swith the
type event_type. The previously registered dispatcher (or
the default dispatcher if there was no previousl regis-
tered 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 speci-
fied 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 wid-
get'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
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was called and False otherwise.
SEE ALSOXtGetKeyboardFocusWidget(3Xt)
X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface
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