Box bbox = tantrix.getBoundingBox();
Set<Location> empties = new HashSet<Location>();
for (int i = bbox.getMinCol(); i <= bbox.getMaxCol(); i++) {
Location loc = new ByteLocation(bbox.getMinRow(), i);
if (tantrix.get(loc) == null) {
empties.add(loc);
}
loc = new ByteLocation(bbox.getMaxRow(), i);
if (tantrix.get(loc) == null) {
empties.add(loc);
}
}
for (int i = bbox.getMinRow() + 1; i < bbox.getMaxRow(); i++) {
Location loc = new ByteLocation(i, bbox.getMinCol());
if (tantrix.get(loc) == null) {
empties.add(loc);
}
loc = new ByteLocation(i, bbox.getMaxCol());
if (tantrix.get(loc) == null) {
empties.add(loc);
}
}