timerhndlr(3Tk)

NAME
     Tk_CreateTimerHandler, Tk_DeleteTimerHandler - call a procedure at a
     given time

SYNOPSIS
     #include <tk.h>

     Tk_TimerToken
     Tk_CreateTimerHandler(milliseconds, proc, clientData)

     Tk_DeleteTimerHandler(token)

ARGUMENTS
     int             milliseconds   (in)      How many milliseconds to wait
                                              before invoking proc.

     Tk_TimerProc    *proc          (in)      Procedure to invoke after
                                              milliseconds have elapsed.

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

     Tk_TimerToken   token          (in)      Token for previously-created
                                              timer handler (the return value
                                              from some previous call to
                                              Tk_CreateTimerHandler).


DESCRIPTION
     Tk_CreateTimerHandler arranges for proc to be invoked at a time
     milliseconds milliseconds in the future.  The callback to proc will be
     made by Tk_DoOneEvent, so Tk_CreateTimerHandler is only useful in
     programs that dispatch events through Tk_DoOneEvent or through other Tk
     procedures that call Tk_DoOneEvent, such as Tk_MainLoop.  The call to
     proc may not be made at the exact time given by milliseconds:  it will be
     made at the next opportunity after that time.  For example, if
     Tk_DoOneEvent isn't called until long after the time has elapsed, or if
     there are other pending events to process before the call to proc, then
     the call to proc will be delayed.

     Proc should have arguments and return value that match the type
     Tk_TimerProc:
          typedef void Tk_TimerProc(ClientData clientData);
     The clientData parameter to proc is a copy of the clientData argument
     given to Tcl_CreateTimerHandler when the callback was created.
     Typically, clientData points to a data structure containing application-
     specific information about what to do in proc.

     Tk_DeleteTimerHandler may be called to delete a previously-created timer
     handler.  It deletes the handler indicated by token so that no call to
     proc will be made;  if that handler no longer exists (e.g. because the
     time period has already elapsed and proc has been invoked) then
     Tk_DeleteTimerHandler does nothing.


KEYWORDS
     callback, clock, handler, timer