HPUX DoWhenIdle[3]

 Tk_DoWhenIdle(3)                    Tk                     Tk_DoWhenIdle(3)

 Tk Library Procedures                                 Tk Library Procedures





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 NAME
      Tk_DoWhenIdle, Tk_CancelIdleCall - invoke a procedure when  there  are
      no pending events

 SYNOPSIS
      #include <tk.h>

      Tk_DoWhenIdle(proc, clientData)

      Tk_CancelIdleCall(proc, clientData)                                      |

 ARGUMENTS
      Tk_IdleProc   *proc        (in)      Procedure to invoke.

      ClientData    clientData   (in)      Arbitrary one-word value to  pass
                                           to proc.
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 DESCRIPTION
      Tk_DoWhenIdle arranges for proc to be  invoked  when  the  application
      becomes   idle.   The  application  is  considered  to  be  idle  when
      Tk_DoOneEvent has been called, it couldn't find any events to  handle,
      and it is about to go to sleep waiting for an event to occur.  At this
      point all pending Tk_DoWhenIdle handlers are invoked.  For  each  call
      to  Tk_DoWhenIdle  there will be a single call to proc;  after proc is
      invoked the handler is automatically removed.  Tk_DoWhenIdle  is  only
      useable in programs that use Tk_DoOneEvent to dispatch events.

      Proc should have arguments and result that match the type Tk_IdleProc:
           typedef void Tk_IdleProc(ClientData clientData);
      The clientData parameter to proc is a copy of the clientData  argument
      given  to  Tk_DoWhenIdle.   Typically,  clientData  points  to  a data
      structure containing application-specific information about what  proc
      should do.

      Tk_CancelIdleCall may be used to cancel one or more previous calls  to  |
      Tk_DoWhenIdle:   if  there  is  a Tk_DoWhenIdle handler registered for  |
      proc and clientData, then it is removed without invoking it.  If there  |
      is  more  than  one  handler  on the idle list that refers to proc and  |
      clientData, all of the handlers are removed.  If no existing  handlers  |
      match proc and clientData then nothing happens.                         |

      Tk_DoWhenIdle is most useful in situations where (a) a piece  of  work
      will  have to be done but (b) it's possible that something will happen
      in the near future that will change what has to be  done,  or  require
      something  different to be done.  Tk_DoWhenIdle allows the actual work



                                    - 1 -        Formatted:  August 11, 1996






 Tk_DoWhenIdle(3)                    Tk                     Tk_DoWhenIdle(3)

 Tk Library Procedures                                 Tk Library Procedures





      to be deferred until all pending events have been processed.  At  this
      point the exact work to be done will presumably be known and it can be
      done exactly once.

      For example, Tk_DoWhenIdle might be used by an editor to defer display
      updates  until all pending commands have been processed.  Without this
      feature, redundant redisplays might occur in some situations, such  as
      the processing of a command file.


 KEYWORDS
      callback, defer, handler, idle








































                                    - 2 -        Formatted:  August 11, 1996