//=========================

// ypChaser class definition

//===========================================================

// sLayerId   : the ID attribute from the chaser div element

// iTopOffset : the amount of space the chaser will maintain 

//              from the top of the page

// iSlideTime : the amount of time the chaser should take to

//              perform the slide animation.

// iCeiling   : optional parameter which specifies a space

//              at the top of the document which the chaser

//              will not animate over.

// iFloor     : optional parameter which specifies a space

//              at the bottom of the document which the 

//              chaser will not animate over.

//

//

// Note:

// the floor feature does not yet work under Opera, as there

// is no way under Opera's DOM to query the pixel height

// of a document. If the floor feature is used in an Opera

// browser, it will be ignored - but otherwise the script

// will function.

//===========================================================

var CurrentDomain = 'eggs.de';

function ypChaser(sLayerId, iTopOffset, iSlideTime, iCeiling, iFloor) {

	this.chaserDiv = null

	this.layerId   = sLayerId

	this.topOffset = iTopOffset

	this.slideTime = iSlideTime

	this.ceiling   = iCeiling

	this.floor     = iFloor

	

	ypChaser.registry[ypChaser.registry.length] = this

}







ypChaser.isIE = window.clientInformation ? true : false

ypChaser.isN4 = document.layers ? true : false

ypChaser.isN6	= navigator.appName == "Netscape" && parseInt(navigator.appVersion) >= 5

ypChaser.isO5 = navigator.userAgent.indexOf("Opera") != -1 && parseInt(navigator.appVersion) >= 4

ypChaser.registry = new Array( )

ypChaser.callRate = 10



window.setInterval("ypChaser.timer( )", ypChaser.callRate)







// this is the main loop of the program. To avoid having multiple timers

// running concurrently (CPU-intensive) this goes through ypChaser.registry[ ]

// and calls the .main( ) method of each instance of ypChaser in turn.

ypChaser.timer = function() {

	for (var i = 0; chObj = this.registry[i]; i++) {

		if (!chObj.chaserDiv) chObj.attemptLoad()

		if (chObj.chaserDiv)  chObj.main()

	}

}





// attempts to find the target layer.

// sets the chaserDiv property of the parent object to

// found layer, or null if none is found.

ypChaser.prototype.attemptLoad = function() {

	var chDiv = null



	if (ypChaser.isN6 || ypChaser.isO5)	chDiv = document.getElementById(this.layerId)

	else if (ypChaser.isIE)			chDiv = document.all[this.layerId]

	else if (ypChaser.isN4)			chDiv = document.layers[this.layerId]



	if (chDiv && chDiv != null) {

		this.chaserDiv = chDiv

	}

}

	





// Main function. gets called very often by ypChaser.timer().

// Updates targetY, and decides whether to start

// the animation over again, continue an existing animation,

// or do nothing at all.

ypChaser.prototype.main = function( )

{

	this.currentY	= this.getCurrentY()

	var scrollTop	= ypChaser.getWindowScroll() 

	var newTargetY	= scrollTop + this.topOffset

	var floor		= ypChaser.getDocumentHeight() - this.floor



	newTargetY = Math.max( newTargetY, this.ceiling)

	if (!ypChaser.isO5) newTargetY = Math.min(newTargetY, floor)



	if ( this.currentY != newTargetY ) {



		if ( newTargetY != this.targetY ) {

			this.targetY = newTargetY

			this.slideInit( )

	

		}



		this.slide( )

		

	}

}





// .slideInit( ). Initializes the slide animation.

ypChaser.prototype.slideInit = function( )

{

	this.A		= (this.targetY - this.currentY) / this.slideTime / this.slideTime

	this.startT	= (new Date()).getTime()

	this.startP	= this.getCurrentY()

	this.D		= this.targetY - this.startP

}





// .slide( ). Moves the Chaser one frame. Its rate decreases and

// is defined by a sine wave.

ypChaser.prototype.slide = function( )

{

	var elapsed	= (new Date()).getTime() - this.startT

	if (elapsed < this.slideTime) {

		this.moveTo(this.D - (Math.round(Math.pow(this.slideTime - elapsed, 2) * this.A)) + this.startP)

	}

}





ypChaser.prototype.moveTo = function(ny) {

	if (ypChaser.isN4)	this.chaserDiv.top = ny

	else				this.chaserDiv.style.top = ny

}

	

ypChaser.prototype.getCurrentY = function() {

	var n = ypChaser.isN4 ? this.chaserDiv.top : parseInt(this.chaserDiv.style.top)

	return isNaN(n) ? 0 : n

}



ypChaser.getWindowScroll = function() {

	if (ypChaser.isIE)	return document.body.scrollTop

	else				return window.pageYOffset

}



ypChaser.getDocumentHeight = function() {

	if (ypChaser.isO5)		return 0 // opera can't retreive this property.

	else if (ypChaser.isIE)	return Math.max(document.body.scrollHeight, document.body.offsetHeight)

	else					return window.document.height

}

function toggleObjectDisplay(objId)
	{
	obj = document.getElementById(objId);
	if (obj)
		{
		if (obj.style.display == "block") obj.style.display = "none";
		else obj.style.display = "block";
		}
	
	}