//========================================================
// ypSimpleScroll
// 3/11/2001
// 
// youngpup.net's answer to those silly little scroll
// boxes that are so popular these days. features
// the same sooper-smooth animation in all yp-
// comonents.
//
// 3/25/2001
// added scrolling in any direction and initTop, initLeft
// constructor parameters - with only 1k...
//
//
// --youngpup--
//
//========================================================
// 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.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() {
	this.aniTimer = window.clearTimeout(this.aniTimer)
	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) {
	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) {
	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.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) { 
	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
		this.content.style.top = -ny
	}
}



// =========================================================================
// =============================== 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)
	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; z-index:80}')
		d.write('#' + this.id + 'Content { left:' + (-initLeft) + 'px; top:' + (-initTop) + 'px; width:' + contentWidth + 'px; }')
		d.write('</style>')

		//this.load()
	}
}

// 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	= 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)
}