public override void Remove(UnSafeGraphics g)
 {
     complexGraphics.Remove(g);
 }
 public override void Add(UnSafeGraphics g)
 {
     complexGraphics.Add(g);
 }
 public override void Remove(UnSafeGraphics g)
 {
     throw new Exception("不能向简单图形Circle移除其他图形");
 }
 public override void Add(UnSafeGraphics g)
 {
     throw new Exception("不能向简单图形Circle添加其他图形");
 }
 public abstract void Remove(UnSafeGraphics g);
 public abstract void Add(UnSafeGraphics g);