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;
	}
};



/**
<script type="text/javascript" src="dom-drag.js"></script>

Creating a draggable handle

Sometimes you want to set only a special area within a complex object to be draggable - aka a handle. To do this, pass two references to the method Drag.init(): the handle and the root.

<div id="root" style="left:50px; top:50px;">
<div id="handle">Handle</div>
Some text
</div>

<script type="text/javascript">
var theHandle = document.getElementById("handle");
var theRoot = document.getElementById("root");
Drag.init(theHandle, theRoot);
</script>

Limiting the range of the drag

You can also set up the drag behavior in a way so the dragging is limited by range, whether vertically or horizontally. This is useful, for example, when you're creating an artificial scrollbar, and it should only be allowed to be dragged vertically or horizontally a certain distance.

<div id="thumb" style="position: relative; left:0; top:0;"></div>

<script language="javascript">
var aThumb = document.getElementById("thumb");
Drag.init(aThumb, null, 0, 300, 0, 0);
</script>

Drag and react

What good is dragging if it your page cant be aware of and react to this action? DOM-Drag fires three events into the environment that you can tap into:

.onDragStart(x,y)
.onDragEnd(x,y)
.onDrag(x,y).

These custom event handlers allow your page to react to the dragging in any fashion your creativity takes you. Take a look at this script to see how to use some of these event handlers:

<script language="javascript">
var aThumbv = document.getElementById("thumbv");
var scrolldiv=document.getElementById("scrollcontent");
Drag.init(aThumbv, null, 0, 0, 0, 150);
aThumbv.onDrag = function(x, y) {// x, y contains current offset coords of drag
scrolldiv.style.top=y * (-1) +"px";
}
</script>
**/