/// <summary>
 /// 下落时检查方块碰撞
 /// </summary>
 /// <returns></returns>
 public static bool CheckBoxByBottom(DropBox box, DropedBox[,] stageBoxs)
 {
     /* 检测方块碰撞 */
     for (int i = 0, c = 0; i < box.boxData.GetLength(0) && c < 4; i++) {
         for (int j = box.boxData.GetLength(1) - 1; j >= 0; j--) {
             if (box.boxData[j, i] == 1) {
                 c++;
                 if ((int)box.position.Y / DropBox.size + j + 1 < stageBoxs.GetLength(0)) {
                     if (stageBoxs[(int)box.position.Y / DropBox.size + j + 1,
                                 (int)box.position.X / DropBox.size + i] != null) {
                         return false;
                     }
                 }
             }
         }
     }
     return true;
 }