var Drag = {

	obj : null,

	init : function(o, oRoot, minX, maxX, minY, maxY, bSwapHorzRef, bSwapVertRef, fXMapper, fYMapper)
	{
		o.onmousedown	= Drag.start;

		o.hmode			= bSwapHorzRef ? false : true ;
		o.vmode			= bSwapVertRef ? false : true ;

		o.root = oRoot && oRoot != null ? oRoot : o ;

		if (o.hmode  && isNaN(parseInt(o.root.style.left  ))) o.root.style.left   = "0px";
		if (o.vmode  && isNaN(parseInt(o.root.style.top   ))) o.root.style.top    = "0px";
		if (!o.hmode && isNaN(parseInt(o.root.style.right ))) o.root.style.right  = "0px";
		if (!o.vmode && isNaN(parseInt(o.root.style.bottom))) o.root.style.bottom = "0px";

		o.minX	= typeof minX != 'undefined' ? minX : null;
		o.minY	= typeof minY != 'undefined' ? minY : null;
		o.maxX	= typeof maxX != 'undefined' ? maxX : null;
		o.maxY	= typeof maxY != 'undefined' ? maxY : null;

		o.xMapper = fXMapper ? fXMapper : null;
		o.yMapper = fYMapper ? fYMapper : null;

		o.root.onDragStart	= new Function();
		o.root.onDragEnd	= new Function();
		o.root.onDrag		= new Function();
	},

	start : function(e)
	{
		var o = Drag.obj = this;
		e = Drag.fixE(e);
		var y = parseInt(o.vmode ? o.root.style.top  : o.root.style.bottom);
		var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );
		o.root.onDragStart(x, y);

		o.lastMouseX	= e.clientX;
		o.lastMouseY	= e.clientY;

		if (o.hmode) {
			if (o.minX != null)	o.minMouseX	= e.clientX - x + o.minX;
			if (o.maxX != null)	o.maxMouseX	= o.minMouseX + o.maxX - o.minX;
		} else {
			if (o.minX != null) o.maxMouseX = -o.minX + e.clientX + x;
			if (o.maxX != null) o.minMouseX = -o.maxX + e.clientX + x;
		}

		if (o.vmode) {
			if (o.minY != null)	o.minMouseY	= e.clientY - y + o.minY;
			if (o.maxY != null)	o.maxMouseY	= o.minMouseY + o.maxY - o.minY;
		} else {
			if (o.minY != null) o.maxMouseY = -o.minY + e.clientY + y;
			if (o.maxY != null) o.minMouseY = -o.maxY + e.clientY + y;
		}

		document.onmousemove	= Drag.drag;
		document.onmouseup		= Drag.end;

		return false;
	},

	drag : function(e)
	{
		e = Drag.fixE(e);
		var o = Drag.obj;

		var ey	= e.clientY;
		var ex	= e.clientX;
		var y = parseInt(o.vmode ? o.root.style.top  : o.root.style.bottom);
		var x = parseInt(o.hmode ? o.root.style.left : o.root.style.right );
		var nx, ny;

		if (o.minX != null) ex = o.hmode ? Math.max(ex, o.minMouseX) : Math.min(ex, o.maxMouseX);
		if (o.maxX != null) ex = o.hmode ? Math.min(ex, o.maxMouseX) : Math.max(ex, o.minMouseX);
		if (o.minY != null) ey = o.vmode ? Math.max(ey, o.minMouseY) : Math.min(ey, o.maxMouseY);
		if (o.maxY != null) ey = o.vmode ? Math.min(ey, o.maxMouseY) : Math.max(ey, o.minMouseY);

		nx = x + ((ex - o.lastMouseX) * (o.hmode ? 1 : -1));
		ny = y + ((ey - o.lastMouseY) * (o.vmode ? 1 : -1));

		if (o.xMapper)		nx = o.xMapper(y)
		else if (o.yMapper)	ny = o.yMapper(x)

		Drag.obj.root.style[o.hmode ? "left" : "right"] = nx + "px";
		Drag.obj.root.style[o.vmode ? "top" : "bottom"] = ny + "px";
		Drag.obj.lastMouseX	= ex;
		Drag.obj.lastMouseY	= ey;

		Drag.obj.root.onDrag(nx, ny);
		return false;
	},

	end : function()
	{
		document.onmousemove = null;
		document.onmouseup   = null;
		Drag.obj.root.onDragEnd(	parseInt(Drag.obj.root.style[Drag.obj.hmode ? "left" : "right"]), 
									parseInt(Drag.obj.root.style[Drag.obj.vmode ? "top" : "bottom"]));
		Drag.obj = null;
	},

	fixE : function(e)
	{
		if (typeof e == 'undefined') e = window.event;
		if (typeof e.layerX == 'undefined') e.layerX = e.offsetX;
		if (typeof e.layerY == 'undefined') e.layerY = e.offsetY;
		return e;
	}
};


function getObj(objName) {
	if ( document.getElementById ) {
		return document.getElementById(objName);
	}
}

function updateContent(myName, pos) {
  obj = scrollers[myName];
  var scrollY = parseInt(pos)-obj.verticalmargin;
  var docY = 0 - (scrollY * (obj.docH - obj.contH) / obj.scrollDist);

			if(docY)
											document.getElementById(obj.objcontent).style.top = docY + "px";

}

function movedown(myName){
  obj = scrollers[myName];
	target = getObj(obj.objscroller);
	if ( parseInt(target.style.top)<obj.verticalmargin+obj.scrollDist-obj.speed) {
		target.style.top=parseInt(target.style.top)+obj.speed+"px";
	}
	else {
		target.style.top=parseInt(obj.verticalmargin+obj.scrollDist)+"px";
  }
  updateContent(myName, target.style.top);
	obj.moveup=setTimeout("movedown('" + myName + "')",20);
}

function stopmove(myName) {
  obj = scrollers[myName];
  clearTimeout(obj.moveup);
  clearTimeout(obj.movedown);
}

function moveup(myName){

  obj = scrollers[myName];

	target = getObj(obj.objscroller);
	if ( parseInt(target.style.top)-obj.speed>obj.verticalmargin ) {
		target.style.top=parseInt(target.style.top)-obj.speed+"px";
	}
	else {
		target.style.top=obj.verticalmargin+"px";
  }
  updateContent(myName, target.style.top);
	obj.movedown=setTimeout("moveup('" + myName + "')",20);
}


function DHTMLScroller(myName, speed, verticalmargin, hidescroll, blankimg) {

    this.speed          = speed;
    this.verticalmargin = verticalmargin;
    this.objscroller    = "scroller_"+myName;
    this.objcontent     = "content_"+myName;
    this.objcontainer   = "container_"+myName;
    this.objscrollArea  = "scrollArea_"+myName;
    this.imgup          = "imgup_"+myName;
    this.imgdown        = "imgdown_"+myName;
    
    if (document.getElementById(this.objcontent)) {
      getObj(this.objscroller).style.top = verticalmargin;
    	getObj(this.objcontent).content_height = getObj(this.objcontent).offsetHeight;
      //collect the variables
      this.docH = getObj(this.objcontent).offsetHeight;
      this.contH = getObj(this.objcontainer).offsetHeight;
      this.scrollAreaH = getObj(this.objscrollArea).offsetHeight-2*this.verticalmargin;
        
      //calculate height of scroller and resize the scroller div
      //(however, we make sure that it isn't to small for long pages)
      this.scrollH = (this.contH * this.scrollAreaH) / this.docH;
      if(this.scrollH < 15) this.scrollH = 15;
      if(this.scrollH > this.scrollAreaH) this.scrollH = this.scrollAreaH;
      
      getObj(this.objscroller).style.height = Math.round(this.scrollH) + "px";
      
      //what is the effective scroll distance once the scoller's height has been taken into account
      this.scrollDist = Math.round(this.scrollAreaH-this.scrollH);
      //make the scroller div draggable
      Drag.init(getObj(this.objscroller),null,0,0,this.verticalmargin,this.verticalmargin+this.scrollDist);
     
      if (hidescroll) {
        if (this.contH>this.docH) {
            getObj(this.objscrollArea).style.visibility = "hidden";
            getObj(this.imgup).src = blankimg;
            getObj(this.imgdown).src = blankimg;
        }
      }
  
      document.getElementById(this.objscroller).onDrag = function (x,y) {      
        var id_array = this.id.split("_");;
        updateContent(id_array[1], y);
      }
    }
}