枚举成员
BOTTOM_CORNER
BOTTOM_CORNER
BOTTOM_LEFT_CORNER
BOTTOM_LEFT_CORNER
BOTTOM_LEFT_SIDE
BOTTOM_LEFT_SIDE
BOTTOM_RIGHT_CORNER
BOTTOM_RIGHT_CORNER
BOTTOM_RIGHT_SIDE
BOTTOM_RIGHT_SIDE
TOP_LEFT_CORNER
TOP_LEFT_CORNER
TOP_LEFT_SIDE
TOP_LEFT_SIDE
TOP_RIGHT_CORNER
TOP_RIGHT_CORNER
TOP_RIGHT_SIDE
TOP_RIGHT_SIDE