var fx = new Object();
//base
fx.Base = function(){};
fx.Base.prototype = {
	setOptions: function(options) {
	this.options = {
		duration: 500,
		onComplete: '',
		transition: fx.sinoidal
	}
	Object.extend(this.options, options || {});
	},

	step: function() {
		var time  = (new Date).getTime();
		if (time >= this.options.duration+this.startTime) {
			this.now = this.to;
			clearInterval (this.timer);
			this.timer = null;
			if (this.options.onComplete) setTimeout(this.options.onComplete.bind(this), 10);
		}
		else {
			var Tpos = (time - this.startTime) / (this.options.duration);
			this.now = this.options.transition(Tpos) * (this.to-this.from) + this.from;
		}
		this.increase();
	},

	custom: function(from, to) {
		if (this.timer != null) return;
		this.from = from;
		this.to = to;
		this.startTime = (new Date).getTime();
		this.timer = setInterval (this.step.bind(this), 13);
	},

	hide: function() {
		this.now = 0;
		this.increase();
	},

	clearTimer: function() {
		clearInterval(this.timer);
		this.timer = null;
	}
}

//stretchers
fx.Layout = Class.create();
fx.Layout.prototype = Object.extend(new fx.Base(), {
	initialize: function(el, options) {
		this.el = $(el);
		this.el.style.overflow = "hidden";
		this.iniWidth = this.el.offsetWidth;
		this.iniHeight = this.el.offsetHeight;
		this.setOptions(options);
	}
});

fx.Height = Class.create();
Object.extend(Object.extend(fx.Height.prototype, fx.Layout.prototype), {	
	increase: function() {
		this.el.style.height = this.now + "px";
	},

	toggle: function() {
		if (this.el.offsetHeight > 0) this.custom(this.el.offsetHeight, 0);
		else this.custom(0, this.el.scrollHeight);
	}
});

fx.Width = Class.create();
Object.extend(Object.extend(fx.Width.prototype, fx.Layout.prototype), {	
	increase: function() {
		this.el.style.width = this.now + "px";
	},

	toggle: function(){
		if (this.el.offsetWidth > 0) this.custom(this.el.offsetWidth, 0);
		else this.custom(0, this.iniWidth);
	}
});

//fader
fx.Opacity = Class.create();
fx.Opacity.prototype = Object.extend(new fx.Base(), {
	initialize: function(el, options) {
		this.el = $(el);
		this.now = 1;
		this.increase();
		this.setOptions(options);
	},

	increase: function() {
		if (this.now == 1 && (/Firefox/.test(navigator.userAgent))) this.now = 0.9999;
		this.setOpacity(this.now);
	},
	
	setOpacity: function(opacity) {
		if (opacity == 0 && this.el.style.visibility != "hidden") this.el.style.visibility = "hidden";
		else if (this.el.style.visibility != "visible") this.el.style.visibility = "visible";
		if (window.ActiveXObject) this.el.style.filter = "alpha(opacity=" + opacity*100 + ")";
		this.el.style.opacity = opacity;
	},

	toggle: function() {
		if (this.now > 0) this.custom(1, 0);
		else this.custom(0, 1);
	}
});

//transitions
fx.sinoidal = function(pos){
	return ((-Math.cos(pos*Math.PI)/2) + 0.5);
	//this transition is from script.aculo.us
}
fx.linear = function(pos){
	return pos;
}
fx.cubic = function(pos){
	return Math.pow(pos, 3);
}
fx.circ = function(pos){
	return Math.sqrt(pos);
}