set Max Height and Max Width

function setMaxSizes(obj:*, maxWidth:Number, maxHeight:Number):void {
	if (obj.height > obj.width) {
		obj.width = (maxHeight * obj.width) / obj.height;
		obj.height = maxHeight;
	} else if (obj.width>obj.height) {
		obj.height = (maxWidth * obj.height) / obj.width;
		obj.width = maxWidth;
	} else {
		obj.width = maxWidth;
		obj.height = maxHeight;
	}
	return;
}

This is also usefull for flex

function getFlashVars():Object {
    return Object( LoaderInfo(root.loaderInfo ).parameters );
}

var flvars1:Object = getFlashVars().var1;
var flvars2:Object = getFlashVars().var2;