/* =======================================================
 * ypSimpleScroll
 * 3/11/2001
 * 
// dhtml scrolling panel featuring scrolling in any
// direction, smooth frame-dropping animation, and a
// few other goodies.
//
// 3/25/2001
// added scrolling in any direction and initTop, initLeft
// constructor parameters - with only 1k...
//
// 3/30/2001
// fixed bug that occured when if you called scrollTo( )
// and the new position was the same as the current
// position. that was stupid.
//
// 4/02/2001
// small bug fix - on some browsers, on slow connections
// the script would not run at all. to be sure the doc
// is done loading before .load() is called, the author
// must now call the .load() method in the onload handler
// for the page.
//
// 8/22/2001
// if you tried to scroll before page was loaded it threw
// an error. this should be fixed now.
// 
//
 * http://www.youngpup.net/
//
// =======================================================
// ypSimpleScroll(	id, left, top, width, height, speed, 
//					contentWidth, initScrollLeft, 
//					initScrollTop	)
//
// last three parameters are optional.
 * ======================================================= */


// basic methods.
ypSimpleScroll.prototype.scrollNorth = function() { this.startScroll(90) }
ypSimpleScroll.prototype.scrollSouth = function() { this.startScroll(270)  }
ypSimpleScroll.prototype.scrollWest  = function() { this.startScroll(180) }
ypSimpleScroll.prototype.scrollEast  = function() { this.startScroll(0)   }


// start scrolling in an arbitrary direction, with an optional arbitrary speed.
// if no speed is provided, the default speed from the constructor parameter is used.
ypSimpleScroll.prototype.startScroll = function(deg, speed) {
	if (this.loaded)
	{
		if (this.aniTimer) window.clearTimeout(this.aniTimer)
		this.overrideScrollAngle(deg)

		this.speed    = speed ? speed : this.origSpeed
		this.lastTime = (new Date()).getTime() - this.y.minRes
		this.aniTimer = window.setTimeout(this.gRef + ".scroll()", this.y.minRes)
	}
}

// kills pending calls to .scroll(), resets speed
ypSimpleScroll.prototype.endScroll = function() {
	if (this.loaded)
	{
		window.clearTimeout(this.aniTimer)
		this.aniTimer = 0;
		this.speed = this.origSpeed
	}
}

// override the current angle from startScroll() with a new angle
// this method should not be used with scrollTo() because it will
// override the angle created by the first two params to scrollTo().
ypSimpleScroll.prototype.overrideScrollAngle = function(deg) {
	if (this.loaded)
	{
		deg = deg % 360
		if (deg % 90 == 0) {
			var cos = deg == 0  ? 1 : deg == 180 ? -1 : 0
			var sin = deg == 90 ? -1 : deg == 270 ? 1 : 0
		} else {
			var angle = deg * Math.PI / 180
			var cos   = Math.cos(angle)
			var sin   = Math.sin(angle)
			sin = -sin
		}
		this.fx = cos / (Math.abs(cos) + Math.abs(sin))
		this.fy = sin / (Math.abs(cos) + Math.abs(sin))
		this.stopH = deg == 90 || deg == 270 ? this.scrollLeft : deg < 90 || deg > 270 ? this.scrollW : 0
		this.stopV = deg == 0 || deg == 180 ? this.scrollTop : deg < 180 ? 0 : this.scrollH
	}
}

// override the speed for the current scroll.
// should not be used with scrollTo, unless you want to 
// override the speed computed from the aniLen param of scrollTo()
ypSimpleScroll.prototype.overrideScrollSpeed = function(speed) {
	if (this.loaded) this.speed = speed
}

// scroll to an arbitrary position in two dimensions over in
// an arbitrary lenth of time.
ypSimpleScroll.prototype.scrollTo = function(stopH, stopV, aniLen) {
	if (this.loaded)
	{
		if (stopH != this.scrollLeft || stopV != this.scrollTop) {
			if (this.aniTimer) window.clearTimeout(this.aniTimer)
			this.lastTime = (new Date()).getTime()
			var dx = Math.abs(stopH - this.scrollLeft)
			var dy = Math.abs(stopV - this.scrollTop)
			var d = Math.sqrt(Math.pow(dx,2) + Math.pow(dy,2))
			this.fx = (stopH - this.scrollLeft) / (dx + dy)
			this.fy = (stopV - this.scrollTop) / (dx + dy)
			this.stopH = stopH
			this.stopV = stopV
			this.speed = d / aniLen * 1000
			window.setTimeout(this.gRef + ".scroll()", this.y.minRes)
		}
	}
}

// jump to an arbitrary position in two dimensions.
ypSimpleScroll.prototype.jumpTo = function(nx, ny) { 
	if (this.loaded)
	{
		nx = Math.min(Math.max(nx, 0), this.scrollW)
		ny = Math.min(Math.max(ny, 0), this.scrollH)
		this.scrollLeft = nx
		this.scrollTop = ny
		if (this.y.ns4)this.content.moveTo(-nx, -ny)
		else {
			this.content.style.left = -nx + "px"
			this.content.style.top = -ny + "px"
		}
	}
}



// =========================================================================
// =============================== private =================================
// =========================================================================

ypSimpleScroll.minRes = 10
ypSimpleScroll.ie  = document.all ? 1 : 0
ypSimpleScroll.ns4 = document.layers ? 1 : 0
ypSimpleScroll.dom = document.getElementById ? 1 : 0
ypSimpleScroll.mac = navigator.platform == "MacPPC"
ypSimpleScroll.mo5 = document.getElementById && !document.all ? 1 : 0

// recursively calls itself to animate
ypSimpleScroll.prototype.scroll = function() {
	this.aniTimer = window.setTimeout(this.gRef + ".scroll()", this.y.minRes)
	var nt = (new Date()).getTime()
	var d = Math.round((nt - this.lastTime) / 1000 * this.speed)
	if (d > 0)
	{
		var nx = d * this.fx + this.scrollLeft
		var ny = d * this.fy + this.scrollTop

		var xOut = (nx >= this.scrollLeft && nx >= this.stopH) || (nx <= this.scrollLeft && nx <= this.stopH)
		var yOut = (ny >= this.scrollTop && ny >= this.stopV)  || (ny <= this.scrollTop && ny <= this.stopV)
		//window.status = nx + " " + this.fx + " " + this.scrollLeft + " " + this.stopH + " | " + ny + " " + this.fy + " " + this.scrollTop + " " + this.stopV + " : " + d
		if (nt - this.lastTime != 0 &&
			((this.fx == 0 && this.fy == 0) ||
			 (this.fy == 0 && xOut) ||
			 (this.fx == 0 && yOut) ||
			 (this.fx != 0 && this.fy != 0 && xOut && yOut)))
		{
			this.jumpTo(this.stopH, this.stopV)
			this.endScroll()
		}
		else {
			this.jumpTo(nx, ny)
			this.lastTime = nt
		}
	}
}

// constructor
function ypSimpleScroll(id, left, top, width, height, speed, contentWidth, initLeft, initTop)
{
	var y = this.y = ypSimpleScroll
	if (!initLeft)     initLeft     = 0
	if (!initTop)      initTop      = 0
	if (!contentWidth) contentWidth = width

	// fix for netscape4 first-page bug.
	if (document.layers && !y.ns4) history.go(0)

	if (y.ie || y.ns4 || y.dom) {
		this.loaded		= false
		this.id			= id
		this.origSpeed	= speed
		this.aniTimer	= false
		this.op			= ""
		this.lastTime	= 0
		this.clipH		= height
		this.clipW		= width
		this.scrollTop	= initTop
		this.scrollLeft	= initLeft

		// global reference to this object
		this.gRef = "ypSimpleScroll_"+id
		eval(this.gRef+"=this")

		var d = document
		d.write('<style type="text/css">')
		d.write('#' + this.id + 'Container { left:' + left + 'px; top:' + top + 'px; width:' + width + 'px; height:' + height + 'px; clip:rect(0 ' + width + ' ' + height + ' 0); overflow:hidden; }')
		d.write('#' + this.id + 'Container, #' + this.id + 'Content { position:absolute; }')
		d.write('#' + this.id + 'Content { left:' + (-initLeft) + 'px; top:' + (-initTop) + 'px; width:' + contentWidth + 'px; }')
		d.write('</style>')
	}
}

// once the nceesary objects are present in the DOM, this gathers some info about them.
ypSimpleScroll.prototype.load = function() {
	var d, lyrId1, lyrId2

	d = document
	lyrId1 = this.id + "Container"
	lyrId2 = this.id + "Content"

	this.container	= this.y.dom ? d.getElementById(lyrId1) : this.y.ie ? d.all[lyrId1] : d.layers[lyrId1]
	this.content	= obj2 = this.y.ns4 ? this.container.layers[lyrId2] : this.y.ie ? d.all[lyrId2] : d.getElementById(lyrId2)
	this.docH		= Math.max(this.y.ns4 ? this.content.document.height : this.content.offsetHeight, this.clipH)
	this.docW		= Math.max(this.y.ns4 ? this.content.document.width  : this.content.offsetWidth,  this.clipW)
	this.scrollH	= this.docH - this.clipH
	this.scrollW	= this.docW - this.clipW
	this.loaded		= true
	this.scrollLeft = Math.max(Math.min(this.scrollLeft, this.scrollW),0)
	this.scrollTop  = Math.max(Math.min(this.scrollTop, this.scrollH),0)
	this.jumpTo(this.scrollLeft, this.scrollTop)
}