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Text File  |  1994-09-20  |  4KB  |  133 lines
  1.  
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  4. Tk_CreateTimerHandler(3T)k Library Procedures
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  7.  
  8. _________________________________________________________________
  9.  
  10. NAME
  11.      Tk_CreateTimerHandler, Tk_DeleteTimerHandler - call  a  pro-
  12.      cedure at a given time
  13.  
  14. SYNOPSIS
  15.      #include <tk.h>
  16.  
  17.      Tk_TimerToken
  18.      Tk_CreateTimerHandler(_m_i_l_l_i_s_e_c_o_n_d_s, _p_r_o_c, _c_l_i_e_n_t_D_a_t_a)
  19.  
  20.      Tk_DeleteTimerHandler(_t_o_k_e_n)
  21.  
  22. ARGUMENTS
  23.      int             _m_i_l_l_i_s_e_c_o_n_d_s   (in)      How    many    mil-
  24.                                               liseconds  to  wait
  25.                                               before     invoking
  26.                                               _p_r_o_c.
  27.  
  28.      Tk_TimerProc    *_p_r_o_c          (in)      Procedure to invoke
  29.                                               after  _m_i_l_l_i_s_e_c_o_n_d_s
  30.                                               have elapsed.
  31.  
  32.      ClientData      _c_l_i_e_n_t_D_a_t_a     (in)      Arbitrary  one-word
  33.                                               value  to  pass  to
  34.                                               _p_r_o_c.
  35.  
  36.      Tk_TimerToken   _t_o_k_e_n          (in)      Token           for
  37.                                               previously-created
  38.                                               timer handler  (the
  39.                                               return  value  from
  40.                                               some previous  call
  41.                                               to
  42.                                               Tk_CreateTimerHandler).
  43. _________________________________________________________________
  44.  
  45.  
  46. DESCRIPTION
  47.      Tk_CreateTimerHandler arranges for _p_r_o_c to be invoked  at  a
  48.      time  _m_i_l_l_i_s_e_c_o_n_d_s milliseconds in the future.  The callback
  49.      to   _p_r_o_c   will    be    made    by    Tk_DoOneEvent,    so
  50.      Tk_CreateTimerHandler   is  only  useful  in  programs  that
  51.      dispatch events through Tk_DoOneEvent or  through  other  Tk
  52.      procedures  that  call  Tk_DoOneEvent,  such as Tk_MainLoop.
  53.      The call to _p_r_o_c may not be made at the exact time given  by
  54.      _m_i_l_l_i_s_e_c_o_n_d_s:  it will be made at the next opportunity after
  55.      that time.  For example, if Tk_DoOneEvent isn't called until
  56.      long after the time has elapsed, or if there are other pend-
  57.      ing events to process before the call to _p_r_o_c, then the call
  58.      to _p_r_o_c will be delayed.
  59.  
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  62.  
  63. Tk                                                              1
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  68.  
  69.  
  70. Tk_CreateTimerHandler(3T)k Library Procedures
  71.  
  72.  
  73.  
  74.      _P_r_o_c should have arguments and return value that  match  the
  75.      type Tk_TimerProc:
  76.           typedef void Tk_TimerProc(ClientData _c_l_i_e_n_t_D_a_t_a);
  77.      The _c_l_i_e_n_t_D_a_t_a parameter to _p_r_o_c is a copy of the _c_l_i_e_n_t_D_a_t_a
  78.      argument  given  to Tcl_CreateTimerHandler when the callback
  79.      was created.  Typically, _c_l_i_e_n_t_D_a_t_a points to a data  struc-
  80.      ture  containing application-specific information about what
  81.      to do in _p_r_o_c.
  82.  
  83.      Tk_DeleteTimerHandler may be called to delete a  previously-
  84.      created  timer handler.  It deletes the handler indicated by
  85.      _t_o_k_e_n so that no call to _p_r_o_c will be made;  if that handler
  86.      no  longer  exists (e.g. because the time period has already
  87.      elapsed    and    _p_r_o_c    has     been     invoked)     then
  88.      Tk_DeleteTimerHandler does nothing.
  89.  
  90.  
  91. KEYWORDS
  92.      callback, clock, handler, timer
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  129. Tk                                                              2
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