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/*!
  \class SoTimerQueueSensor SoTimerQueueSensor.h Inventor/sensors/SoTimerQueueSensor.h
  \brief The SoTimerQueueSensor class is the abstract base class for sensors triggering on certain timer events.
  \ingroup sensors

  Timer sensors triggers upon specific points in time.

  This class is an abstract superclass which collects the common
  interface of the various non-abstract timer sensor classes. See the
  documentation of the subclasses for information on what ways there
  are to specify base times, intervals, alarm-style single triggering,
  repeated triggers, etc.

  Note that Coin timer sensors should in no way be considered "hard
  real-time". That is, you can \e not expect a timer to always trigger
  at the exact moment it was set up for. Delays in triggering could be
  due to other activities in Coin, a task suspended, or heavy load
  from other applications on the system. These situations could all
  cause the processing of sensor queues (from SoQt / SoWin / SoXt /
  whatever) to be slightly delayed, thereby causing delays in timer
  sensor triggering.

  On modern systems, a timer will usually trigger within a few
  milliseconds of it's designated time, though.

  If a timer sensor can not trigger at the exact moment it has been
  scheduled, it will be triggered at the first opportunity after the
  scheduled time has passed.

  Here's a simple usage example. It's a stand-alone example, which
  only demonstrates how to set up a repeating timer sensor with a
  callback:

  \code
  #include <Inventor/Xt/SoXt.h>
  #include <Inventor/sensors/SoTimerSensor.h>
  #include <stdio.h>
  
  static void
  timeSensorCallback(void * data, SoSensor * sensor)
  {
    SbTime time = SbTime::getTimeOfDay();
    SbString string = time.format("%S.%i");
    (void)printf("%s\n", string.getString());
  }
  
  
  int
  main(int argc, char ** argv)
  { 
    SoXt::init("test");
  
    SoTimerSensor * timeSensor = new SoTimerSensor;
    timeSensor->setFunction(timeSensorCallback);
    timeSensor->setBaseTime(SbTime::getTimeOfDay());
    timeSensor->setInterval(1.0f);
    timeSensor->schedule();
  
    SoXt::mainLoop();
    return 0;
  }
  \endcode
*/

#include <Inventor/sensors/SoTimerQueueSensor.h>
#include <Inventor/SoDB.h>
#include <assert.h>

#if COIN_DEBUG
#include <Inventor/errors/SoDebugError.h>
#endif // COIN_DEBUG

/*!
  \var SbBool SoTimerQueueSensor::scheduled
  \c TRUE if the sensor is currently scheduled.
*/


/*!
  Default constructor.
 */
SoTimerQueueSensor::SoTimerQueueSensor(void)
  : scheduled(FALSE)
{
}

/*!
  Constructor taking as arguments the sensor callback function and the
  userdata which will be passed the callback.

  \sa setFunction(), setData()
 */
SoTimerQueueSensor::SoTimerQueueSensor(SoSensorCB * func, void * data)
  : inherited(func, data), scheduled(FALSE)
{
}

/*!
  Destructor.
*/
SoTimerQueueSensor::~SoTimerQueueSensor(void)
{
  // Note: it won't work to move this to the SoSensor destructor
  // (where it really belongs), because you can't use pure virtual
  // methods from a destructor.
  if (this->isScheduled()) this->unschedule();
}

/*!
  Returns the time at which the sensor will trigger.

  \sa setTriggerTime()
 */
const SbTime &
SoTimerQueueSensor::getTriggerTime(void) const
{
  return this->triggertime;
}

/*!
  Set absolute time at which to trigger sensor.

  \sa getTriggerTime()
 */
void
SoTimerQueueSensor::setTriggerTime(const SbTime & time)
{
  if (time != this->triggertime) {
    this->triggertime = time;
    if (this->isScheduled()) {
      SoSensorManager * sm = SoDB::getSensorManager();
      sm->removeTimerSensor(this);
      sm->insertTimerSensor(this);
    }
  }
}

// Documented in superclass.
void
SoTimerQueueSensor::trigger(void)
{
  this->scheduled = FALSE;
  inherited::trigger();
}

/*!
  Put the sensor in the global timer queue.

  \sa unschedule(), isScheduled()
 */
void
SoTimerQueueSensor::schedule(void)
{
#if COIN_DEBUG
  assert(this->scheduled == TRUE || this->scheduled == FALSE);
  if (this->isScheduled()) {
    SoDebugError::postWarning("SoTimerQueueSensor::schedule",
                              "already scheduled!");
    return;
  }
#endif // COIN_DEBUG

  SoDB::getSensorManager()->insertTimerSensor(this);
  this->scheduled = TRUE;
}

/*!
  Remove sensor from the timer queue, without triggering it first.

  \sa schedule(), isScheduled()
 */
void
SoTimerQueueSensor::unschedule(void)
{
#if COIN_DEBUG
  assert(this->scheduled == TRUE || this->scheduled == FALSE);
  if (!this->isScheduled()) {
    SoDebugError::postWarning("SoTimerQueueSensor::unschedule",
                              "not scheduled!");
    return;
  }
#endif // COIN_DEBUG
  SoDB::getSensorManager()->removeTimerSensor(this);
  this->scheduled = FALSE;
}

/*!
  Check if this sensor is scheduled for triggering.

  \sa schedule(), unschedule()
 */
SbBool
SoTimerQueueSensor::isScheduled(void) const
{
  return this->scheduled;
}

SbBool
SoTimerQueueSensor::isBefore(const SoSensor * s) const
{
  return (this->triggertime < ((SoTimerQueueSensor *)s)->triggertime);
}
