//Tween Object (v1.2.2, 21-07-2009)
//Auteur:	Niels Riekert

//Laatste update: callBack en timeOut toegevoegd als parameter bij de tweenNow methode
//BUGFIX: -> this.returing <-
//
//Properties
//	- tween.object
//	- tween.property
//	- tween.time
//	- tween.returning (boolean)
//	- tween.easType (optional)
//	- tween.unit (optional)

//
//Methods
//	- tweenNow(startValue, endValue, tweenTime(optional))

function Tween(object, property, time, returning, easType, unit, callBack, timeOut){
	this.object = object;
	this.property = property;
	(time)?this.time = time:this.time = 500;
	(returning != undefined)?this.returning = returning:this.returning = true;
	(easType)?this.easType = easType:this.easType = 'linear';
	(unit)?this.unit = unit:this.unit = '';
	if(callBack){this.callBack = callBack;};
	(timeOut)?this.timeOut = timeOut: this.timeOut = 0;
	//standaard waarden
	this.isTweening = false;
	this.timeLeft = time;
	this.lastTime;
	
	//als propery is opacity dan checken of browser IE is
	if(this.property == 'opacity' && this.object.style.filter != undefined){
		this.property = 'filter';
	}

	
	this.tweenNow = function(startValue, endValue, callBack, timeOut, tweenTime){
		//checkt of het object al animeert en of het wel omgedraaid mag worden
		if(this.isTweening == true && this.returning == false){
			//alert('bezig met animatie');
			return;
		}
		else if(this.isTweening == true){
			//draai de animatie om
			var startValueTemp = this.startValue;
			this.startValue = this.endValue;
			this.endValue = startValueTemp;
			this.timeLeft = this.time - this.timeLeft;
			
			return;
		}
		else {
			//de animatie is nog niet gestart, reset de variabelen
			this.isTweening = true;
			if(startValue == "current"){
				if(property == 'height'){
					tempString = this.object.offsetHeight;
				}
				else if(property == 'width') {
					tempString = this.object.offsetWidth;
				}
				else {
					var tempString = this.object.style[this.property];
				}
				if(this.property == 'filter'){
					tempString = this.object.style[this.property].substr(14);
				}
				this.startValue = parseFloat(tempString);
				//alert(this.object.style[this.property] + ' endValue ' + endValue + ' this.startvalue ' + this.startValue);
			}
			else {
				this.startValue = startValue;
			}
			this.endValue = endValue;
			
			
			if(callBack){
				this.callBack = callBack;
			}
			else {
				this.callBack = false;	
			}
			
			if(timeOut){
				this.timeOut = timeOut;
			}
			else {
				this.timeOut = 0;	
			}
			
			
			//IE
			if(this.property == 'filter'){
				this.endValue *= 100;
				if(this.startValue < 1){
					this.startValue *= 100;
				}
			}
			
			if(tweenTime){
				var time = tweenTime;
				this.timeLeft = tweenTime;
			}
			else {
				this.timeLeft = this.time;
				var time = this.time;
			}
		}
		
		var easing = new Easing(this.easType);
		
		function animateTween(){
			//alert(object.object);
			var curTime = new Date().getTime();
			//voor de berekening
			var ellapsedTime = curTime - lastTime;
			object.animLength = object.endValue - object.startValue;
			
			if(object.timeLeft <= ellapsedTime){
				if(object.property == 'filter'){
				//IE + opacity
					object.object.style[object.property] = 'alpha(opacity=' + object.endValue + ')';
					//alert(object.object.style[object.property] + ' in animateTween object.endValue ' + object.endValue);
				}
				else{
					object.object.style[object.property] = object.endValue + object.unit;
				}
				
				object.isTweening = false;
				
				if(object.callBack){
					object.cTimeout = setTimeout(object.callBack, object.timeOut);
					object.callBack = false;
					object.timeOut = 0;	
				}
				return;
			}
			
			//t: current time, b: beginning value, c: change in value, d: duration
			var position = easing.selectedEase(time-object.timeLeft, object.startValue, object.animLength, time);
			//alert("ellapsedTime = " + ellapsedTime + " this.startValue = " + object.startValue + " this.animLength = " + object.animLength + " this.time = " + object.time + " position = " + position);
			
			if(object.property == 'filter'){
				//IE + opacity
				object.object.style[object.property] = 'alpha(opacity=' + position + ')';
			}
			else {
				object.object.style[object.property] = position + object.unit;
			}
			//alert(object.object.style[object.property] + ' - ' + object.object.id);
			//document.getElementById('outputwindow').innerHTML = position + ' animLength: ' + object.animLength + " startValue: " + object.startValue;
			
			object.timeLeft -= ellapsedTime;
			lastTime = curTime;
			window.setTimeout(animateTween, 30);
		}
		var object = this;
		var lastTime = new Date().getTime();
		setTimeout(animateTween, 30);
	}
}