/**********************************************************************
 TERMS OF USE - EASING EQUATIONS
 Open source under the BSD License.
 Copyright (c) 2001 Robert Penner
 JavaScript version copyright (c) 2006 by Philippe Maegerman
 Adapted to work along with Processing.js (c) 2009 by Michael Aufreiter
 
 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 the author nor the names of 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,
 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 *****************************************/
 
Tween = function Tween(obj, prop, func, begin, finish, duration) {
  if (!arguments.length) return;
  this.obj = obj;
  this.prop = prop;
  this.begin = begin;
  this._pos = begin;
  this.setDuration(duration);
  if (func!=null && func!='') {
    this.func = func;
  }
  this.setFinish(finish);
}

Tween.prototype = {
  obj: new Object(),
  func: function (t, b, c, d) { return c*t/d + b; },
  begin: 0,
  change: 0,
  prevTime: 0,
  prevPos: 0,
  looping: false,
  _playing: false,
  _duration: 0,
  _time: 0,
  _pos: 0,
  _position: 0,
  _startTime: 0,
  _finish: 0,
  name: '',
  suffixe: '',
  setTime: function(t) {
  	this.prevTime = this._time;
  	if (t > this.getDuration()) {
  		if (this.looping) {
  			this.rewind (t - this._duration);
  			this.update();
  			// execute onLooped callback
  		} else {
  			this._time = this._duration;
  			this.update();
  			this.stop();
  			// execute onFinished callback
  		}
  	} else if (t < 0) {
  		this.rewind();
  		this.update();
  	} else {
  		this._time = t;
  		this.update();
  	}
  },
  getTime: function(){
  	return this._time;
  },
  setDuration: function(d){
  	this._duration = (d == null || d <= 0) ? 100000 : d;
  },
  getDuration: function(){
  	return this._duration;
  },
  setPosition: function(p){
  	this.prevPos = this._pos;
  	this.obj[this.prop] = p;
  	this._pos = p;
  	// execute onPositionChanged callback
  },
  getPosition: function(t) {
  	if (t == undefined) t = this._time;
  	return this.func(t, this.begin, this.change, this._duration);
  },
  setFinish: function(f) {
  	this.change = f - this.begin;
  },
  getFinish: function() {
  	return this.begin + this.change;
  },
  isPlaying: function() {
    return this._playing;
  },
  init: function(obj, prop, func, begin, finish, duration, suffixe) {
  	if (!arguments.length) return;
  	this._listeners = new Array();
  	this.addListener(this);
  	this.obj = obj;
  	this.prop = prop;
  	this.begin = begin;
  	this._pos = begin;
  	this.setDuration(duration);
  	if (func!=null && func!='') {
  		this.func = func;
  	}
  	this.setFinish(finish);
  },
  
  start: function() {
  	this.rewind();
  	this._playing = true;
  	// execute onStarted callback
  },
  rewind: function(t) {
  	this.stop();
  	this._time = (t == undefined) ? 0 : t;
  	this.fixTime();
  	this.update();
  },
  fforward: function() {
  	this._time = this._duration;
  	this.fixTime();
  	this.update();
  },
  update: function() {
  	this.setPosition(this.getPosition(this._time));
  },
  tick: function() {
    if (this._playing) {
      this.nextFrame();
    }
  },
  nextFrame: function() {
  	this.setTime((this.getTimer() - this._startTime) / 1000);
  },
  stop: function() {
    this._playing = false;
    // execute onStopped callback
  },
  continueTo: function(finish, duration) {
  	this.begin = this._pos;
  	this.setFinish(finish);
  	if (this._duration != undefined) {
  		this.setDuration(duration);
  	}
  	this.start();
  },
  resume: function() {
  	this.fixTime();
  	this._playing = true;
  	// executing onResumed callback
  },
  yoyo: function () {
  	this.continueTo(this.begin,this._time);
  },
  fixTime: function() {
  	this._startTime = this.getTimer() - this._time * 1000;
  },
  getTimer: function() {
  	return new Date().getTime() - this._time;
  }
};

// Tweening functions
Tween.backEaseIn = function(t,b,c,d,a,p) {
	if (s == undefined) var s = 1.70158;
	return c*(t/=d)*t*((s+1)*t - s) + b;
}

Tween.backEaseOut = function(t,b,c,d,a,p) {
	if (s == undefined) var s = 1.70158;
	return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
}

Tween.backEaseInOut = function(t,b,c,d,a,p) {
	if (s == undefined) var s = 1.70158; 
	if ((t/=d/2) < 1) return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
	return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
}

Tween.elasticEaseIn = function(t,b,c,d,a,p) {
	if (t==0) return b;  
	if ((t/=d)==1) return b+c;  
	if (!p) p=d*.3;
	if (!a || a < Math.abs(c)) {
		a=c; var s=p/4;
	}
	else 
		var s = p/(2*Math.PI) * Math.asin (c/a);

	return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
}

Tween.elasticEaseOut = function (t,b,c,d,a,p) {
		if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
		if (!a || a < Math.abs(c)) { a=c; var s=p/4; }
		else var s = p/(2*Math.PI) * Math.asin (c/a);
		return (a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b);
}

Tween.elasticEaseInOut = function (t,b,c,d,a,p) {
	if (t==0) return b;  if ((t/=d/2)==2) return b+c;  if (!p) var p=d*(.3*1.5);
	if (!a || a < Math.abs(c)) {var a=c; var s=p/4; }
	else var s = p/(2*Math.PI) * Math.asin (c/a);
	if (t < 1) return -.5*(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
	return a*Math.pow(2,-10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )*.5 + c + b;
}

Tween.bounceEaseOut = function(t,b,c,d) {
	if ((t/=d) < (1/2.75)) {
		return c*(7.5625*t*t) + b;
	} else if (t < (2/2.75)) {
		return c*(7.5625*(t-=(1.5/2.75))*t + .75) + b;
	} else if (t < (2.5/2.75)) {
		return c*(7.5625*(t-=(2.25/2.75))*t + .9375) + b;
	} else {
		return c*(7.5625*(t-=(2.625/2.75))*t + .984375) + b;
	}
}

Tween.bounceEaseIn = function(t,b,c,d) {
	return c - Tween.bounceEaseOut (d-t, 0, c, d) + b;
}

Tween.bounceEaseInOut = function(t,b,c,d) {
	if (t < d/2) return Tween.bounceEaseIn (t*2, 0, c, d) * .5 + b;
	else return Tween.bounceEaseOut (t*2-d, 0, c, d) * .5 + c*.5 + b;
}

Tween.strongEaseInOut = function(t,b,c,d) {
	return c*(t/=d)*t*t*t*t + b;
}

Tween.regularEaseIn = function(t,b,c,d) {
	return c*(t/=d)*t + b;
}

Tween.regularEaseOut = function(t,b,c,d) {
	return -c *(t/=d)*(t-2) + b;
}

Tween.regularEaseInOut = function(t,b,c,d) {
	if ((t/=d/2) < 1) return c/2*t*t + b;
	return -c/2 * ((--t)*(t-2) - 1) + b;
}

Tween.strongEaseIn = function(t,b,c,d) {
	return c*(t/=d)*t*t*t*t + b;
}

Tween.strongEaseOut = function(t,b,c,d) {
	return c*((t=t/d-1)*t*t*t*t + 1) + b;
}

Tween.strongEaseInOut = function(t,b,c,d) {
	if ((t/=d/2) < 1) return c/2*t*t*t*t*t + b;
	return c/2*((t-=2)*t*t*t*t + 2) + b;
}