///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2006, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
// 
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
// *       Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// *       Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// *       Neither the name of Industrial Light & Magic nor the names of
// its contributors may be used to endorse or promote products derived
// from this software without specific prior written permission. 
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
///////////////////////////////////////////////////////////////////////////

#ifndef INCLUDED_TIMER_H
#define INCLUDED_TIMER_H

//----------------------------------------------------------------------------
//
//	Timing control for the display thread of the playExr prgram
//
//----------------------------------------------------------------------------

#ifdef _WIN32
    #include <windows.h>
#else
    #include <sys/time.h>
#endif

enum PlayState
{
    PREPARE_TO_RUN,
    RUNNING,
    PREPARE_TO_PAUSE,
    PAUSE,
};


class Timer
{
  public:

    //------------
    // Constructor
    //------------

    Timer ();


    //--------------------------------------------------------
    // Timing control to maintain the desired frame rate:
    // the redrawWindow() function in the display thread calls
    // waitUntilNextFrameIsDue() before displaying each frame.
    //
    // If playState == RUNNING, then waitUntilNextFrameIsDue()
    // sleeps until the apropriate amount of time has elapsed
    // since the last call to waitUntilNextFrameIsDue().
    // If playState != RUNNING, then waitUntilNextFrameIsDue()
    // returns immediately.
    //--------------------------------------------------------

    void	waitUntilNextFrameIsDue ();


    //-------------------------------------------------
    // Set and get the frame rate, in frames per second
    //-------------------------------------------------

    void	setDesiredFrameRate (float fps);
    float	actualFrameRate ();


    //-------------------
    // Current play state
    //-------------------

    PlayState	playState;


  private:

    float	_spf;				// desired frame rate,
    						// in seconds per frame

    timeval	_lastFrameTime;			// time when we displayed the
    						// last frame

    float	_timingError;			// cumulative timing error

    timeval	_lastFpsFrameTime;		// state to keep track of the
    int		_framesSinceLastFpsFrame;	// actual frame trate, averaged
    float	_actualFrameRate;		// over several frames
};

#endif