1XtInsertEventTypeHandler(3) XT FUNCTIONS XtInsertEventTypeHandler(3)
2
6 XtInsertEventTypeHandler, XtRemoveEventTypeHandler, XtRegisterExten‐
7 sionSelector, XtSetEventDispatcher, XtDispatchEventToWidget - extension
8 event handling
9
11 void XtInsertEventTypeHandler(Widget widget, int event_type, XtPointer
12 select_data, XtEventHandler proc, XtPointer client_data, XtList‐
13 Position position);
14 void XtRemoveEventTypeHandler(Widget widget, int event_type, XtPointer
16 select_data, XtEventHandler proc, XtPointer client_data);
17 void XtRegisterExtensionSelector(Display* display, int min_event_type,
19 int max_event_type, XtExtensionSelectProc proc, XtPointer
20 client_data);
21 XtEventDispatchProc XtSetEventDispatcher(Widget widget, int event_type,
23 XtEventDispatchProc proc);
24 Boolean XtDispatchEventToWidget(Widget widget, XEvent* event);
26
28 widget Specifies the widget for this event handler. Must be of
29 class Core or any subclass thereof.
30 event_type
32 Specifies the event type.
33 select_data
35 Specifies data used to select or deselect events from the
36 server.
37 proc Specifies the proc.
39 client_data
41 Specifies additional data to be passed to the event handler.
42 position Specifies when the event handler is to be called relative to
44 other previously registered handlers.
45 display Specifies the display.
47 min_event_type, max_event_type
49 Specifies the range of event types for this extension.
50 event Specifies a pointer to the event to be dispatched.
52
54 The XtInsertEventTypeHandler function registers a procedure with the
55 dispatch mechanism that is to be called when an event that matches the
56 specified event_type is dispatched to the specified widget.
57 If event_type is one of the core X protocol events then select_data
59 must be a pointer to a value of type EventMask, indicating the event
60 mask to be used to select for the desired event. This event mask will
61 be included in the value returned by XtBuildEventMask. If the widget
62 is realized XtInsertEventTypeHandler calls XSelectInput if necessary.
63 Specifying NULL for select_data is equivalent to specifying a pointer
64 to an event mask containing 0. This is similar to the XtInsertRawEven‐
65 tHandler function.
66 If event_type specifies an extension event type then the semantics of
68 the data pointed to by select_data are defined by the extension selec‐
69 tor registered for the specified event type.
70 In either case the Intrinsics are not required to copy the data pointed
72 to by select_data, so the caller must ensure that it remains valid as
73 long as the event handler remains registered with this value of
74 select_data.
75 The position argument allows the client to control the order of the
77 invocation of event handlers registered for the same event type. If the
78 client does not care about the order, it should normally specify
79 XtListTail, which registers this event handler after any previously
80 registered handlers for this event type.
81 The XtRemoveEventTypeHandler function unregisters an even handler reg‐
83 istered with XtInsertEventTypeHandler for the specified event type. The
84 request is ignored if client_data does not match the value given with
85 the handler was registered.
86 If event_type specifies on of the core X protocol events, select_data
88 must be a pointer to a value of type EventMask, indicating the mask to
89 be used to deselect for the appropriate event. If the widget is real‐
90 ized, XtRemoveEventTypeHandler calls XSelectInput if necessary. Speci‐
91 fying NULL for select_data is equivalent to specifying a pointer to an
92 event mask containing 0. This is similar to the XtRemoveRawEventHandler
93 function.
94 If event_type specifies an extension event type then the semantics of
96 the data pointed to by select_data are defined by the extension selec‐
97 tor registered for the specified event type.
98 The XtRegisterExtensionSelector function registers a procedure to
100 arrange for the delivery of extension events to widgets.
101 If min_event_type and max_event_type match the parameters to a previous
103 call to XtRegisterExtensionSelector for the same display, the proc and
104 client_data replace the previously registered values. If the range
105 specified by min_event_type and max_event_type overlaps the range of
106 the parameters to a previous call for the same display in any other
107 way, an error results.
108 The XtSetEventDispatcher function registers the event dispatcher proce‐
110 dure specified by proc for events with the type event_type. The previ‐
111 ously registered dispatcher (or the default dispatcher if there was no
112 previously registered dispatcher) is returned. If proc is NULL, the
113 default procedure is restored for the specified type.
114 In the future, when XtDispatchEvent is called with an event of
116 event_type, the specified proc (or the default dispatcher) will be
117 invoked to determine a widget ot which to dispatch the event.
118 The XtDispatchEventToWidget function scans the list of registered event
120 handlers for the specified widget and calls each handler that has been
121 registered for the specified event type, subject to the con‐
122 tinue_to_dispatch value returned by each handler. The Intrinsics behave
123 as if event handlers were registered at the head of the list for
124 Expose, NoExpose, GraphicsExpose, and VisibilityNotify events to invoke
125 the widget's expose procedure according to the exposure compression
126 rules and to update the widget's visible field if visible_interest is
127 True. These internal event handlers never set continue_to_dispatch to
128 False.
129 XtDispatchEventToWidget returns True if any event handler was called
131 and False otherwise.
132
134 XtGetKeyboardFocusWidget(3)
135 X Toolkit Intrinsics - C Language Interface
136 Xlib - C Language X Interface
137X Version 11 libXt 1.1.5 XtInsertEventTypeHandler(3)