1Tk_CreateEventHandler(3) Tk Library Procedures Tk_CreateEventHandler(3)
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8 Tk_CreateEventHandler, Tk_DeleteEventHandler - associate procedure
9 callback with an X event
10
12 #include <tk.h>
13 Tk_CreateEventHandler(tkwin, mask, proc, clientData)
15 Tk_DeleteEventHandler(tkwin, mask, proc, clientData)
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19 Tk_Window tkwin (in) Token for window in which events
20 may occur.
21 unsigned long mask (in) Bit-mask of events (such as But‐
23 tonPressMask) for which proc
24 should be called.
25 Tk_EventProc *proc (in) Procedure to invoke whenever an
27 event in mask occurs in the win‐
28 dow given by tkwin.
29 ClientData clientData (in) Arbitrary one-word value to pass
31 to proc.
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36 Tk_CreateEventHandler arranges for proc to be invoked in the future
37 whenever one of the event types specified by mask occurs in the window
38 specified by tkwin. The callback to proc will be made by Tk_Han‐
39 dleEvent; this mechanism only works in programs that dispatch events
40 through Tk_HandleEvent (or through other Tk procedures that call
41 Tk_HandleEvent, such as Tk_DoOneEvent or Tk_MainLoop).
42 Proc should have arguments and result that match the type Tk_EventProc:
44 typedef void Tk_EventProc(
45 ClientData clientData,
46 XEvent *eventPtr);
47 The clientData parameter to proc is a copy of the clientData argument
48 given to Tk_CreateEventHandler when the callback was created. Typi‐
49 cally, clientData points to a data structure containing application-
50 specific information about the window in which the event occurred.
51 EventPtr is a pointer to the X event, which will be one of the ones
52 specified in the mask argument to Tk_CreateEventHandler.
53 Tk_DeleteEventHandler may be called to delete a previously-created
55 event handler: it deletes the first handler it finds that is associ‐
56 ated with tkwin and matches the mask, proc, and clientData arguments.
57 If no such handler exists, then Tk_HandleEvent returns without doing
58 anything. Although Tk supports it, it's probably a bad idea to have
59 more than one callback with the same mask, proc, and clientData argu‐
60 ments. When a window is deleted all of its handlers will be deleted
61 automatically; in this case there is no need to call Tk_DeleteEven‐
62 tHandler.
63 If multiple handlers are declared for the same type of X event on the
65 same window, then the handlers will be invoked in the order they were
66 created.
67
70 bind, callback, event, handler
71Tk Tk_CreateEventHandler(3)