public IEnumerable <ZoneId> GetAllZoneIds()
{
HashSet <ZoneId> set = new HashSet <ZoneId>();
uint[,] zoneIds = ZoneIds;
int upperBound1 = zoneIds.GetUpperBound(0);
int upperBound2 = zoneIds.GetUpperBound(1);
for (int lowerBound1 = zoneIds.GetLowerBound(0); lowerBound1 <= upperBound1; ++lowerBound1)
{
for (int lowerBound2 = zoneIds.GetLowerBound(1); lowerBound2 <= upperBound2; ++lowerBound2)
{
ZoneId id = (ZoneId)zoneIds[lowerBound1, lowerBound2];
if (id != ZoneId.None && !set.Contains(id))
{
set.Add(id);
yield return(id);
}
}
}
}
