.\" $Xorg: XtExtEvDis.man,v 1.3 2000/08/17 19:42:00 cpqbld Exp $
.\" $XdotOrg: $
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.\" $XFree86: xc/doc/man/Xt/XtExtEvDis.man,v 1.3 2001/02/09 03:47:50 tsi Exp $
.\"
.ds tk X Toolkit
.ds xT X Toolkit Intrinsics \- C Language Interface
.ds xI Intrinsics
.ds xW X Toolkit Athena Widgets \- C Language Interface
.ds xL Xlib \- C Language X Interface
.ds xC Inter-Client Communication Conventions Manual
.ds Rn 3
.ds Vn 2.2
.hw XtInsert-Event-Type-Handler XtRemove-Event-Type-Handler XtSet-Event-Dispatcher XtDispatch-Event-To-Widget wid-get
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.TH XtInsertEventTypeHandler 3Xt __xorgversion__ "XT FUNCTIONS"
.SH NAME
XtInsertEventTypeHandler, XtRemoveEventTypeHandler,
XtRegisterExtensionSelector, XtSetEventDispatcher, XtDispatchEventToWidget
\- extension event handling
.SH SYNTAX
.HP
void XtInsertEventTypeHandler(Widget \fIwidget\fP, int \fIevent_type\fP,
XtPointer \fIselect_data\fP, XtEventHandler \fIproc\fP, XtPointer
\fIclient_data\fP, XtListPosition \fIposition\fP); 
.HP
void XtRemoveEventTypeHandler(Widget \fIwidget\fP, int \fIevent_type\fP,
XtPointer \fIselect_data\fP, XtEventHandler \fIproc\fP, XtPointer
\fIclient_data\fP); 
.HP
void XtRegisterExtensionSelector(Display* \fIdisplay\fP, int
\fImin_event_type\fP, int \fImax_event_type\fP, XtExtensionSelectProc
\fIproc\fP, XtPointer \fIclient_data\fP); 
.HP
XtEventDispatchProc XtSetEventDispatcher(Widget \fIwidget\fP, int
\fIevent_type\fP, XtEventDispatchProc \fIproc\fP);
.HP
Boolean XtDispatchEventToWidget(Widget \fIwidget\fP, XEvent* \fIevent\fP); 
.SH ARGUMENTS
.IP \fIwidget\fP 1i
Specifies the widget for this event handler.
Must be of class Core or any subclass thereof.
.IP \fIevent_type\fP 1i
Specifies the event type.
.IP \fIselect_data\fP 1i
Specifies data used to select or deselect events from the server.
.IP \fIproc\fP 1i
Specifies the proc.
.IP \fIclient_data\fP 1i
Specifies additional data to be passed to the event handler.
.IP \fIposition\fP 1i
Specifies when the event handler is to be called relative to other
previously registered handlers.
.IP \fIdisplay\fP 1i
Specifies the display.
.IP \fImin_event_type,\ max_event_type\fP 1i
Specifies the range of event types for this extension.
.IP \fIevent\fP 1i
Specifies a pointer to the event to be dispatched.
.SH DESCRIPTION
The
.ZN XtInsertEventTypeHandler
function registers a procedure with the dispatch mechanism that is to
be called when an event that matches the specified \fIevent_type\fP is
dispatched to the specified \fIwidget\fP.
.LP
If \fIevent_type\fP is one of the core X protocol events then 
\fIselect_data\fP must be a pointer to a value of type
.ZN 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
.ZN XtBuildEventMask .
If the widget is realized
.ZN XtInsertEventTypeHandler
calls
.ZN XSelectInput
if necessary. Specifying NULL for \fIselect_data\fP is equivalent to
specifying a pointer to an event mask containing 0. This is similar to the 
.ZN XtInsertRawEventHandler
function.
.LP
If \fIevent_type\fP specifies an extension event type then the semantics
of the data pointed to by \fIselect_data\fP are defined by the extension
selector registered for the specified event type.
.LP
In either case the Intrinsics are not required to copy the data pointed
to by \fIselect_data\fP, so the caller must ensure that it remains valid
as long as the event handler remains registered with this value of
\fIselect_data\fP.
.LP
The \fIposition\fP 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
.ZN XtListTail ,
which registers this event handler after any previously registered
handlers for this event type.
.LP
The
.ZN XtRemoveEventTypeHandler
function unregisters an even handler registered with
.ZN XtInsertEventTypeHandler
for the specified event type. The request is ignored if \fIclient_data\fP
does not match the value given with the handler was registered.
.LP
If \fIevent_type\fP specifies on of the core X protocol events,
\fIselect_data\fP must be a pointer to a value of type
.ZN EventMask ,
indicating the mask to be used to deselect for the appropriate event.
If the widget is realized,
.ZN XtRemoveEventTypeHandler
calls
.ZN XSelectInput
if necessary. Specifying NULL for \fIselect_data\fP is equivalent to
specifying a pointer to an event mask containing 0. This is similar to the
.ZN XtRemoveRawEventHandler
function.
.LP
If \fIevent_type\fP specifies an extension event type then the semantics
of the data pointed to by \fIselect_data\fP are defined by the extension
selector registered for the specified event type.
.LP
The
.ZN XtRegisterExtensionSelector
function registers a procedure to arrange for the delivery of extension
events to widgets.
.LP
If \fImin_event_type\fP and \fImax_event_type\fP match the parameters to
a previous call to
.ZN XtRegisterExtensionSelector
for the same display, the \fIproc\fP and \fIclient_data\fP replace the
previously registered values. If the range specified by \fImin_event_type\fP
and \fImax_event_type\fP overlaps the range of the parameters to a
previous call for the same display in any other way, an error results.
.LP
The
.ZN XtSetEventDispatcher
function registers the event dispatcher procedure specified by \fIproc\fP
for events with the type \fIevent_type\fP. The previously registered
dispatcher (or the default dispatcher if there was no previously registered
dispatcher) is returned. If \fIproc\fP is NULL, the default procedure is
restored for the specified type.
.LP
In the future, when
.ZN XtDispatchEvent
is called with an event of \fIevent_type\fP, the specified \fIproc\fP (or
the default dispatcher) will be invoked to determine a widget ot which
to dispatch the event.
.LP
The
.ZN 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 \fIcontinue_to_dispatch\fP value returned by
each handler. The Intrinsics behave as if event handlers were registered
at the head of the list for
.ZN Expose ,
.ZN NoExpose ,
.ZN GraphicsExpose ,
and
.ZN VisibilityNotify
events to invoke the widget's expose procedure according to the exposure
compression rules and to update the widget's \fIvisible\fP field if
\fIvisible_interest\fP is
.ZN True .
These internal event handlers never set \fIcontinue_to_dispatch\fP to
.ZN False .
.LP
.ZN XtDispatchEventToWidget
returns
.ZN True
if any event handler was called and
.ZN False
otherwise.
.LP
.SH "SEE ALSO"
XtGetKeyboardFocusWidget(3Xt)
.br
\fI\*(xT\fP
.br
\fI\*(xL\fP