枚举成员

BOTTOM_CORNER
BOTTOM_LEFT_CORNER
BOTTOM_LEFT_SIDE
BOTTOM_RIGHT_CORNER
BOTTOM_RIGHT_SIDE
BOTTOM_SIDE
LEFT_CORNER
LEFT_SIDE
MAX
RIGHT_CORNER
RIGHT_SIDE
TOP_CORNER
TOP_LEFT_CORNER
TOP_LEFT_SIDE
TOP_RIGHT_CORNER
TOP_RIGHT_SIDE
TOP_SIDE