code: def update(self):
      l = len(self.polyline.points)
      # print("up L:", l, " is_added:", self.is_added)
      if l < 3:
          if self.is_added:
              self.remove_from_scene()
      else:  # 大于三个点就可以更新，小于三个点删除多边形
          if self.is_added:
              self.add_to_scene()
          else:
              path_geo = QtGui.QPainterPath()
              self.create_corners()
              path_geo.moveTo(self.corner_points[0])
              for i in range(4):
                  path_geo.lineTo(self.corner_points[(i + 1) % 4])
              self.setPath(QtGui.QPainterPath(path_geo))
              pass
          pass
      pass
  
file_path: PaddleSeg/EISeg/eiseg/widget/bbox.py
imports: from qtpy import QtWidgets, QtGui, QtCore
  from qtpy.QtCore import Qt
label_desc: Use image node_id 7 for calling the BBoxAnnotation obj's underlying member method code with example usage: obj.update() without return types