code: def on_draw(self, ev):
      # Stolen from previous - just clears the screen and redraws stuff
      self.context.set_clear_color((0, 0, 0, 1))
      self.context.set_viewport(0, 0, *self.physical_size)
      self.context.clear()
      for vis in self.visuals:
          if vis is self.center_point and not self.show_pivot:
              continue
          else:
              vis.draw()
  
imports: from __future__ import division, print_function, absolute_import
  from vispy import app, visuals
  from vispy.visuals import transforms
  from vispy.io import load_data_file
  import sys
  import numpy
  import string
  import logging
  import traceback
  from PyQt5 import QtCore, QtGui, QtWidgets
label_desc: Use image node_id 2 for calling the WigglyBar obj's underlying member method code with example usage: obj.on_draw(ev) without return types