// Drag'n'drop funcionality
var dX = 0;
var dY = 0;

var ob;	// the object's style (IE)
var obObj; // the real object (IE)

var linked_obs; // list of linked objects

function MD(e) 
{
	if(e)
	{
		// NN6
		tObj = e.target;
		obObj = e.target.parentNode;
		X = obObj.offsetLeft + obObj.offsetParent.offsetLeft;
		Y = obObj.offsetTop + obObj.offsetParent.offsetTop;
		// for NN7: difference between mouseposition and puzzleitem.position at mousedown
		dX = e.clientX - X;
		dY = e.clientY - Y;
	}
	else
	{
		obObj = event.srcElement.parentElement;
		X=event.offsetX;
		Y=event.offsetY;
	}

	ob = obObj.style;
	if(obObj.tagName.toLowerCase() != "div") 
	{
		obObj = null; // only take divs.
	}
	else
	{	
	//alert("div"+obObj.tagName.toLowerCase());
		oxp = getPosFromId(obObj.id,"x");
		oyp = getPosFromId(obObj.id,"y");
		chunknr = pieces_inchunk[oyp][oxp];
		if (chunknr != null)
		{
			linked_obs = new Array();
			for(i=0;i<chunks[chunknr].length;++i)
			{
				// window.status="object "+obObj.id+" is linked to "+chunks[chunknr][i];
				linked_obs[i] = new Array();
				linked_obs[i]["id"] = chunks[chunknr][i];
								linked_obs[i]["xdiff"] = convertNum(eval(getObjXS(obObj.id)+".style.left")) - convertNum(eval(getObjXS(chunks[chunknr][i])+".style.left"));
				linked_obs[i]["ydiff"] = convertNum(eval(getObjXS(obObj.id)+".style.top")) - convertNum(eval(getObjXS(chunks[chunknr][i])+".style.top"));
							}
		}
	}
	// disable further default browser event handling (important for NN7)
	return false;
}

function MM(e) 
{
	if (ob) 
	{
			if (!e) 
			{ 
				e = event; 
				ob.pixelLeft = e.clientX-X + document.body.scrollLeft;
				ob.pixelTop = e.clientY-Y + document.body.scrollTop;
			}
			else
			{
				ob.left = e.clientX - dX;
				ob.top = e.clientY - dY;
			}
			
			// do rest of group
			if (!(linked_obs == null))
			{
				for(i=0;i<linked_obs.length;++i)
				{
					tmpobj = eval(getObjXS(linked_obs[i]["id"])+".style");
											tmpobj.left = convertNum(ob.left) - linked_obs[i]["xdiff"];
						tmpobj.top = convertNum(ob.top) - linked_obs[i]["ydiff"];
								}
			}
			return false;
 	}
}

function MU() 
{
	if(obObj != null)
	{
		linkToPartner(obObj.id); // try to find docked partners
		obObj = null;
		linked_obs = null;
	}
	ob = null;
}

document.onmousedown = MD;
document.onmousemove = MM;
document.onmouseup = MU;


function getObjXS(id)
{
	return 'document.getElementById("'+id+'")';
}