#ifndef _PERIODICHANDLER_H
#define _PERIODICHANDLER_H
static char PeriodicHandler_h_id[] = "$Header: /usr/tiburon/unix/gui/tmacs/RCS/PeriodicHandler.h,v 1.5 1997/10/03 09:38:41 oreilly Exp $";

/*
$Log: PeriodicHandler.h,v $
Revision 1.5  1997/10/03 09:38:41  oreilly
*** empty log message ***

 * Revision 1.4  97/03/20  12:36:19  12:36:19  oreilly (Thomas C. O'Reilly)
 * *** empty log message ***
 * 
 * Revision 1.3  96/10/28  09:13:53  09:13:53  oreilly (Thomas C. O'Reilly)
 * *** empty log message ***
 * 
*/

#include "SList.h"
#include "DmGuiObject.h"
#include "RegisteredItem.h"

class PeriodicHandler;

/* 
RegisteredPeriod lists DmGuiObjects to be updated at a specific
interval.
*/
class RegisteredPeriod : public RegisteredItem
{
  friend class PeriodicHandler;

  public:
  
  RegisteredPeriod(int interval);
  ~RegisteredPeriod() 
  {
  }

  private:
  int _interval;
};


class DmGuiApp;

/*
PeriodicHandler maintains list of update periods and associated
DmGuiObjects; invokes updateGui() method of DmGuiObjects at appropriate
intervals.
*/ 
class PeriodicHandler
{
  friend class DmGuiApp;
  
  public:
  PeriodicHandler();
  ~PeriodicHandler() 
  {
    ;
  }
  
  /* Register DmGuiObject at requested interval */
  registerObj(DmGuiObject *guiObj, int interval);
  
  /* Unregister DmGuiObject item */
  unregisterObj(DmGuiObject *);
  
  /* Start periodic timer, reset accumulated time */
  void start(void) 
  {
    _running = TRUE;
    _accumulated = 0;
    timerInterval();
    restart();
  }
  
  /* Stop handler's timer */
  void stop(void)
  {
    XtRemoveTimeOut(_timerId);
    _running = FALSE;
  }
  

  /* Restart periodic timer */
  void restart(void) 
  {
     _timerId = XtAppAddTimeOut(theApplication->appContext(), _timerInterval, 
			       &PeriodicHandler::timerCallback, 
			       (XtPointer )this);
  }

  
  protected:

  int _accumulated;       // Accumulated time since timers started
  int _timerInterval;
  int _maxInterval;
  
  XtIntervalId _timerId;
  
  SList<RegisteredPeriod *> _periodList;

  // Called when timer expires
  void handleTimeout(void);

  /* Determine interval at which to run timer, such that all registered
  intervals will get sampled. This is the greatest integer by which all
  intervals are divisible. */
  int timerInterval(void);
  
  MBool _running;
  
  private:
  
  // timerCallback() is called when timer expires 
  static void timerCallback(XtPointer clientData, XtIntervalId *id);
};


#endif