public POSLineItem AddItem(POSItem i, int quantity)
{
bool exists = false;
POSLineItem targetItem = null;
foreach(POSLineItem lineI in Items)
{
if(lineI.Item.ID == i.ID)
{
exists = true;
lineI.Quantity += quantity;
targetItem = lineI;
break;
}
}
if(!exists)
{
POSLineItem li = new POSLineItem();
li.Quantity = quantity;
li.Item = i;
targetItem = li;
Items.Add(li);
}
onOrderChange(this, OrderChangeTarget.ITEM);
return targetItem;
}