1XtInsertEventTypeHandler(3) XT FUNCTIONS XtInsertEventTypeHandler(3)
2
6 XtInsertEventTypeHandler, XtRemoveEventTypeHandler, XtRegisterExten‐
7 sionSelector, XtSetEventDispatcher, XtDispatchEventToWidget - extension
8 event handling
9
11 #include <X11/Intrinsic.h>
12 void XtInsertEventTypeHandler(Widget widget, int event_type, XtPointer
14 select_data, XtEventHandler proc, XtPointer client_data, XtList‐
15 Position position);
16 void XtRemoveEventTypeHandler(Widget widget, int event_type, XtPointer
18 select_data, XtEventHandler proc, XtPointer client_data);
19 void XtRegisterExtensionSelector(Display* display, int min_event_type,
21 int max_event_type, XtExtensionSelectProc proc, XtPointer
22 client_data);
23 XtEventDispatchProc XtSetEventDispatcher(Display* display, int
25 event_type, XtEventDispatchProc proc);
26 Boolean XtDispatchEventToWidget(Widget widget, XEvent* event);
28
30 widget Specifies the widget for this event handler. Must be of
31 class Core or any subclass thereof.
32 event_type
34 Specifies the event type.
35 select_data
37 Specifies data used to select or deselect events from the
38 server.
39 proc Specifies the proc.
41 client_data
43 Specifies additional data to be passed to the event handler.
44 position Specifies when the event handler is to be called relative to
46 other previously registered handlers.
47 display Specifies the display.
49 min_event_type, max_event_type
51 Specifies the range of event types for this extension.
52 event Specifies a pointer to the event to be dispatched.
54
56 The XtInsertEventTypeHandler function registers a procedure with the
57 dispatch mechanism that is to be called when an event that matches the
58 specified event_type is dispatched to the specified widget.
59 If event_type is one of the core X protocol events then select_data
61 must be a pointer to a value of type EventMask, indicating the event
62 mask to be used to select for the desired event. This event mask will
63 be included in the value returned by XtBuildEventMask. If the widget
64 is realized XtInsertEventTypeHandler calls XSelectInput if necessary.
65 Specifying NULL for select_data is equivalent to specifying a pointer
66 to an event mask containing 0. This is similar to the XtInsertRawEven‐
67 tHandler function.
68 If event_type specifies an extension event type then the semantics of
70 the data pointed to by select_data are defined by the extension selec‐
71 tor registered for the specified event type.
72 In either case the Intrinsics are not required to copy the data pointed
74 to by select_data, so the caller must ensure that it remains valid as
75 long as the event handler remains registered with this value of
76 select_data.
77 The position argument allows the client to control the order of the
79 invocation of event handlers registered for the same event type. If
80 the client does not care about the order, it should normally specify
81 XtListTail, which registers this event handler after any previously
82 registered handlers for this event type.
83 The XtRemoveEventTypeHandler function unregisters an even handler reg‐
85 istered with XtInsertEventTypeHandler for the specified event type.
86 The request is ignored if client_data does not match the value given
87 with the handler was registered.
88 If event_type specifies on of the core X protocol events, select_data
90 must be a pointer to a value of type EventMask, indicating the mask to
91 be used to deselect for the appropriate event. If the widget is real‐
92 ized, XtRemoveEventTypeHandler calls XSelectInput if necessary. Speci‐
93 fying NULL for select_data is equivalent to specifying a pointer to an
94 event mask containing 0. This is similar to the XtRemoveRawEven‐
95 tHandler function.
96 If event_type specifies an extension event type then the semantics of
98 the data pointed to by select_data are defined by the extension selec‐
99 tor registered for the specified event type.
100 The XtRegisterExtensionSelector function registers a procedure to
102 arrange for the delivery of extension events to widgets.
103 If min_event_type and max_event_type match the parameters to a previous
105 call to XtRegisterExtensionSelector for the same display, the proc and
106 client_data replace the previously registered values. If the range
107 specified by min_event_type and max_event_type overlaps the range of
108 the parameters to a previous call for the same display in any other
109 way, an error results.
110 The XtSetEventDispatcher function registers the event dispatcher proce‐
112 dure specified by proc for events with the type event_type. The previ‐
113 ously registered dispatcher (or the default dispatcher if there was no
114 previously registered dispatcher) is returned. If proc is NULL, the
115 default procedure is restored for the specified type.
116 In the future, when XtDispatchEvent is called with an event of
118 event_type, the specified proc (or the default dispatcher) will be
119 invoked to determine a widget ot which to dispatch the event.
120 The XtDispatchEventToWidget function scans the list of registered event
122 handlers for the specified widget and calls each handler that has been
123 registered for the specified event type, subject to the con‐
124 tinue_to_dispatch value returned by each handler. The Intrinsics
125 behave as if event handlers were registered at the head of the list for
126 Expose, NoExpose, GraphicsExpose, and VisibilityNotify events to invoke
127 the widget's expose procedure according to the exposure compression
128 rules and to update the widget's visible field if visible_interest is
129 True. These internal event handlers never set continue_to_dispatch to
130 False.
131 XtDispatchEventToWidget returns True if any event handler was called
133 and False otherwise.
134
136 XtGetKeyboardFocusWidget(3)
137 X Toolkit Intrinsics - C Language Interface
138 Xlib - C Language X Interface
139X Version 11 libXt 1.2.0 XtInsertEventTypeHandler(3)