用边线指定的宽度和颜色绘制轮廓的形状顺序,有: BeveledRectangleBorder 斜面矩形边框CircleBorder 圆形边框ContinuousRectangleBorder 连续矩形边界MaterialStateOutlinedBorderRoundedRectangleBorder 四边形圆角边框StadiumBorder