/*
	durgle.draganddrop.1.9.4.js
	version 1.9.4
	first created: 10/27/03
	last revised: 01/01/07
	http://www.durgle.com
	talk@durgle.com
*/


// -------- BEGIN DRAG AND DROP FUNCTIONS ----------


var _startX = 0;			// mouse starting positions
var _startY = 0;
var _offsetX = 0;			// current element offset
var _offsetY = 0;
var _dragElement;			// needs to be passed from OnMouseDown to OnMouseMove
var _oldZIndex = 0;			// we temporarily increase the z-index during drag


InitDragDrop();

function InitDragDrop()
{
	document.onmousedown = OnMouseDown;
	document.onmouseup = OnMouseUp;
}

function OnMouseDown(e) {
	// IE is retarded and doesn't pass the event object
	if (e == null) 
		e = window.event; 
	// IE uses srcElement, others use target
	var target = e.target != null ? e.target : e.srcElement;
	// for IE, left click == 1
	// for Firefox, left click == 0
	if ((e.button == 1 && window.event != null || 
		e.button == 0) && 
		target.className == 'drag')
	{
		// grab the mouse position
		_startX = e.clientX;
		_startY = e.clientY;
		
		// grab the clicked element's position
		_offsetX = ExtractNumber(target.style.left);
		_offsetY = ExtractNumber(target.style.top);
		
		// bring the clicked element to the front while it is being dragged
		_oldZIndex = target.style.zIndex;
		target.style.zIndex = 10000;
		
		// we need to access the element in OnMouseMove
		_dragElement = target;

		// tell our code to start moving the element with the mouse
		document.onmousemove = OnMouseMove;
		
		// cancel out any text selections
		document.body.focus();
		
		// prevent text selection in IE
		document.onselectstart = function () { return false; };
		
		// prevent text selection (except IE)
		return false;
	}
}

function ExtractNumber(value) {
	var n = parseInt(value);
	return n == null || isNaN(n) ? 0 : n;
}

function OnMouseMove(e) {
	if (e == null) 
		var e = window.event; 
	// this is the actual "drag code"
	_dragElement.style.left = (_offsetX + e.clientX - _startX) + 'px';
	_dragElement.style.top = (_offsetY + e.clientY - _startY) + 'px';
}

function OnMouseUp(e)
{
	if (_dragElement != null)
	{
		_dragElement.style.zIndex = _oldZIndex;

		// we're done with these events until the next OnMouseDown
		document.onmousemove = null;
		document.onselectstart = null;

		// this is how we know we're not dragging		
		_dragElement = null;
		
	}
}


// -------- END DRAG AND DROP FUNCTIONS ----------