public void SearchRiver(RiverSearchDelegate call)
 {
     kRecord.Clear();
     for (Direction dir = Direction.Begin; dir <= Direction.End; ++dir)
     {
         SearchRiver(call, dir, kOrigin);
     }
 }
    public void SearchRiver(RiverSearchDelegate call, Direction kDir, Bounds b)
    {
        if (b != null)
        {
            if (!kRecord.ContainsKey(b))
            {
                call(b);
                kRecord.Add(b, 1);
            }

            for (Direction dir = Direction.Begin; dir <= Direction.End; ++dir)
            {
                if (kDir != ExDir(dir))
                {
                    Bounds next = b.GetLink(dir);
                    SearchRiver(call, dir, next);
                }
            }
        }
    }