/*
	EXAMPLE:
	<script type="text/javascript" src="slider.js"></script>
	<a href="javascript:Slide('mydiv').down();">Slide Down</a>
	<a href="javascript:Slide('mydiv').up();">Slide Up</a>
	<div id="mydiv" style="display:none; overflow:hidden; height:100px; background-color:black; color:white;"><h2>Hello world!</h2></div>
	
	You can also pass variables to the script
	Slide('mydiv',{duration:5,onComplete: function() {alert('Hello World!');} }).down();
*/

var slideInUse = new Array();

function Slide(objId, options) {
	this.obj = document.getElementById(objId);
	this.duration = 0.5;
	this.height = parseInt(this.obj.style.height);

	if(typeof options != 'undefined') { this.options = options; } else { this.options = {}; }
	if(this.options.duration) { this.duration = this.options.duration; }
		
	this.up = function() {
		this.curHeight = this.height;
		this.newHeight = '1';
		if(slideInUse[objId] != true) {
			var finishTime = this.slide();
			window.setTimeout("Slide('"+objId+"').finishup("+this.height+");",finishTime);
		}
	}
	
	this.down = function() {
		this.newHeight = this.height;
		this.curHeight = '1';
		if(slideInUse[objId] != true) {
			this.obj.style.height = '1px';
			this.obj.style.display = 'block';
			this.slide();
		}
	}
	
	this.slide = function() {
		slideInUse[objId] = true;
		var frames = 30 * duration; // Running at 30 fps

		var tIncrement = (duration*1000) / frames;
		tIncrement = Math.round(tIncrement);
		var sIncrement = (this.curHeight-this.newHeight) / frames;

		var frameSizes = new Array();
		for(var i=0; i < frames; i++) {
			if(i < frames/2) {
				frameSizes[i] = (sIncrement * (i/frames))*4;
			} else {
				frameSizes[i] = (sIncrement * (1-(i/frames)))*4;
			}
		}
		
		for(var i=0; i < frames; i++) {
			this.curHeight = this.curHeight - frameSizes[i];
			window.setTimeout("document.getElementById('"+objId+"').style.height='"+Math.round(this.curHeight)+"px';",tIncrement * i);
		}
		
		window.setTimeout("delete(slideInUse['"+objId+"']);",tIncrement * i);
		
		if(this.options.onComplete) {
			window.setTimeout(this.options.onComplete, tIncrement * (i-2));
		}
		
		return tIncrement * i;
	}
	
	this.finishup = function(height) {
		this.obj.style.display = 'none';
		this.obj.style.height = height + 'px';
	}
	
	return this;
}