function confirmDelete(message) {
	var agree=confirm(message);
	if (agree)
		return true ;
	else
		return false ;
}

function popup(url, title){
	window.open(url,title,'toolbar=0,scrollbars=1,resizable=1,directories=0,width=600,height=500,left=200,top=100,screenX=200,screenY=100');
	return;
}

function popupWindow(url, title){
	return window.open(url,title,'toolbar=0,scrollbars=1,resizable=1,directories=0,width=600,height=500,left=200,top=100,screenX=200,screenY=100');
}

function showPosition(objId) {
	var obj = document.getElementById(objId);
	var centroid = calculateCentroid(obj);
	alert("x: " + centroid[0] + "   y: " + centroid[1] );
}

function showMessage(message) {
	alert(message);
}

function isInside(objId1, objId2){
	var obj1 = document.getElementById(objId1);
	var obj2 = document.getElementById(objId2);	
	var centroid = calculateCentroid(obj1);
	if (centroid[0]>=obj2.offsetLeft && centroid[0]<=(obj2.offsetLeft+obj2.offsetWidth) &&
		centroid[1]>=obj2.offsetTop && centroid[1]<=(obj2.offsetTop+obj2.offsetHeight)) {
		return true;
	}
	else {
		return false;
	}
}

function calculateCentroid(obj){
	var x = obj.offsetLeft;
	var y = obj.offsetTop;
	var w = obj.offsetWidth;
	var h = obj.offsetHeight;
	var cX = (2*x + w)/2;
	var cY = (2*y + h)/2;
	var centroid = new Array(2);
	centroid[0] = cX;
	centroid[1] = cY;
	return centroid;
}

function alignToSlots(objId, objIdArr, x, y){
	// set slot to empty when drag an obj out
	for (var i=0; i<objIdArr.length;i++){
		if (objIdArr[i][1]==objId){
			objIdArr[i][1]="none";
			break;
		}
	}

	for (var i=0; i<objIdArr.length;i++){
		var inside = isInside(objId,objIdArr[i][0]);
		if (inside && objIdArr[i][1]=="none"){
			fitSlot(objId, objIdArr[i][0]);
			objIdArr[i][1]=objId;
			return;
		}
	}
	moveObj(objId, x,y);
}

function moveObj(objId, x,y) {
	var obj = document.getElementById(objId);
	obj.ddObj.moveTo(x,y);
}


function fitSlot(objId1, objId2) {
	var obj1 = document.getElementById(objId1);
	var obj2 = document.getElementById(objId2);	
	obj1.ddObj.moveTo(obj2.offsetLeft,obj2.offsetTop);
}