/**************************************************************************\
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 *  Copyright (C) 1998-2007 by Systems in Motion.  All rights reserved.
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 *  See the file LICENSE.GPL at the root directory of this source
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\**************************************************************************/

/*!
  \class SoElapsedTime SoElapsedTime.h Inventor/engines/SoElapsedTime.h
  \brief The SoElapsedTime class is a controllable time source engine.
  \ingroup engines

  The additional functionality provided by this engine versus just
  connecting to the realTime global field is the ability to control
  the speed of the time source plus logic to reset, stop and restart
  it.

  Simple usage example, combined with SoComposeRotation:

  \code
  #Inventor V2.1 ascii
  
  Separator {
     Transform {
        rotation =
        ComposeRotation { axis 0 1 0  angle =
           ElapsedTime { }.timeOut
        }.rotation
     }
     Cube { }
  }
  \endcode

  \sa SoTimeCounter
*/

// *************************************************************************

#include <Inventor/engines/SoElapsedTime.h>

#include <Inventor/SoDB.h>
#include <Inventor/engines/SoSubEngineP.h>
#include <Inventor/errors/SoDebugError.h>
#include <Inventor/lists/SoEngineOutputList.h>

// *************************************************************************

/*!
  \var SoSFTime SoElapsedTime::timeIn
  Input time value. Default connected to the global realTime field.
*/
/*!
  \var SoSFFloat SoElapsedTime::speed

  Decides how fast the timer should run, measured versus "real time"
  from the timeIn field. Default value is 1.0.

  A negative value makes the time go backward.
*/
/*!
  \var SoSFBool SoElapsedTime::on

  Shuts timer on and off. Will restart at the same position.
*/
/*!
  \var SoSFBool SoElapsedTime::pause
  
  Shuts timer on and off. Will restart at the position it would have
  been if not paused (i.e. doesn't "lose time").
*/
/*!
  \var SoSFTrigger SoElapsedTime::reset

  Restart timer at 0.
*/

/*!
  \var SoEngineOutput SoElapsedTime::timeOut
  (SoSFTime) Output time value. Starts at 0.
*/

// *************************************************************************

SO_ENGINE_SOURCE(SoElapsedTime);

// *************************************************************************

// Documented in superclass.
void
SoElapsedTime::initClass(void)
{
  SO_ENGINE_INTERNAL_INIT_CLASS(SoElapsedTime);
}

/*!
  Default constructor.
*/
SoElapsedTime::SoElapsedTime(void)
{
  SO_ENGINE_INTERNAL_CONSTRUCTOR(SoElapsedTime);

  SO_ENGINE_ADD_INPUT(timeIn, (SbTime::zero()));
  SO_ENGINE_ADD_INPUT(speed, (1));
  SO_ENGINE_ADD_INPUT(on, (TRUE));
  SO_ENGINE_ADD_INPUT(pause, (FALSE));
  SO_ENGINE_ADD_INPUT(reset, ());

  SO_ENGINE_ADD_OUTPUT(timeOut, SoSFTime);

  SoField * realtime = SoDB::getGlobalField("realTime");
  this->timeIn.connectFrom(realtime);

  this->currtime = SbTime::zero();
  this->lasttime = ((SoSFTime *)realtime)->getValue();
  this->status = SoElapsedTime::RUNNING;
}

/*!
  Destructor.
*/
SoElapsedTime::~SoElapsedTime()
{
}

// *************************************************************************

// Documented in superclass.
void
SoElapsedTime::evaluate(void)
{
  if (this->status == SoElapsedTime::STOPPED) {
    SO_ENGINE_OUTPUT(timeOut, SoSFTime, setValue(this->currtime));
  }
  else {
    SbTime now = this->timeIn.getValue();
    this->currtime += (now-this->lasttime) * this->speed.getValue();
    this->lasttime = now;
    if (this->status == SoElapsedTime::PAUSED) {
      SO_ENGINE_OUTPUT(timeOut, SoSFTime, setValue(this->pausetime));
    }
    else {
      SO_ENGINE_OUTPUT(timeOut, SoSFTime, setValue(this->currtime));
    }
  }
}

// Documented in superclass.
void
SoElapsedTime::inputChanged(SoField * which)
{
  if (which == &this->timeIn) return;

  // Default to turn output off, only turn it back on if the engine is
  // running.
  this->timeOut.enable(FALSE);

  if (which == &this->reset) {
    this->currtime = SbTime::zero();
    this->lasttime = this->timeIn.getValue();
  }
  else if (which == &this->pause) {
    if (this->pause.getValue() && this->status == SoElapsedTime::RUNNING) {
      this->status = SoElapsedTime::PAUSED;
      this->pausetime = this->currtime;
    }
    else if (!this->pause.getValue() && this->status == SoElapsedTime::PAUSED) {
      this->status = SoElapsedTime::RUNNING;
    }
  }
  else if (which == &this->on) {
    if (this->on.getValue() && this->status == SoElapsedTime::STOPPED) {
      this->status = SoElapsedTime::RUNNING;
      this->lasttime = this->timeIn.getValue();
    }
    else if (!this->on.getValue() && this->status != SoElapsedTime::STOPPED) {
      this->status = SoElapsedTime::STOPPED;
    }
  }

  this->timeOut.enable(this->status == SoElapsedTime::RUNNING);
}

// Documented in superclass. Overridden to not write connection to
// realTime global field.
void
SoElapsedTime::writeInstance(SoOutput * out)
{
  // Note: the code in this method matches that of SoTimeCounter and
  // SoOneShot, so if any bugs are found and corrected, remember to
  // pass on the updates.

  // Disconnect from realTime field.
  SoField * connectfield = NULL;
  SbBool connectfromrealTime =
    this->timeIn.getConnectedField(connectfield) &&
    connectfield == SoDB::getGlobalField("realTime");
  SbBool defaultflag = this->timeIn.isDefault();
  if (connectfromrealTime) {
    this->timeIn.disconnect();
    this->timeIn.setDefault(TRUE);
  }

  inherited::writeInstance(out);

  // Re-connect to realTime field.
  if (connectfromrealTime) {
    // Don't send notification when reconnecting to preserve the state
    // of the scenegraph between write passes.
    this->timeIn.connectFrom(connectfield, TRUE);
    this->timeIn.setDefault(defaultflag);
  }
}

// *************************************************************************