/*
Script: Fx.Base.js
	Contains <Fx.Base> and two Transitions.

Author:
	Valerio Proietti, <http://mad4milk.net>

License:
	MIT-style license.
*/

var Fx = {};

/*
Class: Fx.Base
	Base class for the Mootools Effects (Moo.Fx) library.

Options:
	onStart - the function to execute as the effect begins; nothing (<Class.empty>) by default.
	onComplete - the function to execute after the effect has processed; nothing (<Class.empty>) by default.
	transition - the equation to use for the effect see <Fx.Transitions>; default is <Fx.Transitions.sineInOut>
	duration - the duration of the effect in ms; 500 is the default.
	unit - the unit is 'px' by default (other values include things like 'em' for fonts or '%').
	wait - boolean: to wait or not to wait for a current transition to end before running another of the same instance. defaults to true.
	fps - the frames per second for the transition; default is 30
*/

Fx.Base = new Class({

	getOptions: function(){
		return {
			onStart: Class.empty,
			onComplete: Class.empty,
			onCancel: Class.empty,
			transition: Fx.Transitions.sineInOut,
			duration: 500,
			unit: 'px',
			wait: true,
			fps: 50
		};
	},

	initialize: function(options){
		this.element = this.element || null;
		this.setOptions(this.getOptions(), options);
		if (this.options.initialize) this.options.initialize.call(this);
	},

	step: function(){
		var time = new Date().getTime();
		if (time < this.time + this.options.duration){
			this.cTime = time - this.time;
			this.setNow();
			this.increase();
		} else {
			this.stop(true);
			this.now = this.to;
			this.increase();
			this.fireEvent('onComplete', this.element, 10);
			this.callChain();
		}
	},

	/*
	Property: set
		Immediately sets the value with no transition.

	Arguments:
		to - the point to jump to

	Example:
		>var myFx = new Fx.Style('myElement', 'opacity').set(0); //will make it immediately transparent
	*/

	set: function(to){
		this.now = to;
		this.increase();
		return this;
	},

	setNow: function(){
		this.now = this.compute(this.from, this.to);
	},

	compute: function(from, to){
		return this.options.transition(this.cTime, from, (to - from), this.options.duration);
	},

	/*
	Property: start
		Executes an effect from one position to the other.

	Arguments:
		from - integer: staring value
		to - integer: the ending value

	Examples:
		>var myFx = new Fx.Style('myElement', 'opacity').start(0,1); //display a transition from transparent to opaque.
	*/

	start: function(from, to){
		if (!this.options.wait) this.stop();
		else if (this.timer) return this;
		this.from = from;
		this.to = to;
		this.time = new Date().getTime();
		this.timer = this.step.periodical(Math.round(1000/this.options.fps), this);
		this.fireEvent('onStart', this.element);
		return this;
	},

	/*
	Property: stop
		Stops the transition.
	*/

	stop: function(end){
		if (!this.timer) return this;
		this.timer = $clear(this.timer);
		if (!end) this.fireEvent('onCancel', this.element);
		return this;
	},

	//compat
	custom: function(from, to){return this.start(from, to)},
	clearTimer: function(end){return this.stop(end)}

});

Fx.Base.implement(new Chain);
Fx.Base.implement(new Events);
Fx.Base.implement(new Options);

/*
Class: Fx.Transitions
	A collection of transition equations for use with the <Fx> Class.

See Also:
	<Fxtransitions.js> for a whole bunch of transitions.

Credits:
	Easing Equations, (c) 2003 Robert Penner (http://www.robertpenner.com/easing/), Open Source BSD License.
*/

Fx.Transitions = {

	/* Property: linear */
	linear: function(t, b, c, d){
		return c*t/d + b;
	},

	/* Property: sineInOut */
	sineInOut: function(t, b, c, d){
		return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
	}

};