HPUX EventHndlr[3]

 Tk_CreateEventHandler(3)            Tk             Tk_CreateEventHandler(3)

 Tk Library Procedures                                 Tk Library Procedures





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 NAME
      Tk_CreateEventHandler,  Tk_DeleteEventHandler  -  associate  procedure
      callback with an X event

 SYNOPSIS
      #include <tk.h>

      Tk_CreateEventHandler(tkwin, mask, proc, clientData)

      Tk_DeleteEventHandler(tkwin, mask, proc, clientData)

 ARGUMENTS
      Tk_Window       tkwin        (in)       Token  for  window  in   which
                                             events may occur.

      unsigned long   mask         (in)      Bit-mask  of  events  (such  as
                                             ButtonPressMask) for which proc
                                             should be called.

      Tk_EventProc    *proc        (in)      Procedure to invoke whenever an
                                             event  in  mask  occurs  in the
                                             window given by tkwin.

      ClientData      clientData   (in)       Arbitrary  one-word  value  to
                                             pass to proc.
 ___________________________________________________________________________


 DESCRIPTION
      Tk_CreateEventHandler arranges for proc to be invoked  in  the  future
      whenever one of the event types specified by mask occurs in the window
      specified  by  tkwin.   The  callback  to  proc  will   be   made   by
      Tk_HandleEvent;  this  mechanism  only works in programs that dispatch
      events through Tk_HandleEvent (or through  other  Tk  procedures  that
      call Tk_HandleEvent, such as Tk_DoOneEvent or Tk_MainLoop).

      Proc  should  have  arguments  and  result   that   match   the   type
      Tk_EventProc:
           typedef void Tk_EventProc(
                ClientData clientData,
                XEvent *eventPtr);
      The clientData parameter to proc is a copy of the clientData  argument
      given   to   Tk_CreateEventHandler  when  the  callback  was  created.
      Typically,  clientData  points  to   a   data   structure   containing
      application-specific  information  about the window in which the event
      occurred.  EventPtr is a pointer to the X event, which will be one  of
      the ones specified in the mask argument to Tk_CreateEventHandler.



                                    - 1 -        Formatted:  August 11, 1996






 Tk_CreateEventHandler(3)            Tk             Tk_CreateEventHandler(3)

 Tk Library Procedures                                 Tk Library Procedures





      Tk_DeleteEventHandler may be called  to  delete  a  previously-created
      event  handler:   it  deletes  the  first  handler  it  finds  that is
      associated with tkwin and  matches  the  mask,  proc,  and  clientData
      arguments.   If  no  such handler exists, then Tk_EventHandler returns
      without doing anything.  Although Tk supports it, it's probably a  bad
      idea  to  have  more  than  one callback with the same mask, proc, and
      clientData arguments.  When a window is deleted all  of  its  handlers
      will  be deleted automatically;  in this case there is no need to call
      Tk_DeleteEventHandler.

      If mutliple handlers are declared for the same type of X event on  the
      same  window, then the handlers will be invoked in the order they were
      created.


 KEYWORDS
      bind, callback, event, handler



































                                    - 2 -        Formatted:  August 11, 1996