code: def on_draw(self, event):
      # clear the color buffer
      gloo.clear(color=colormap[0.0])
  
      self.image.draw()
  
      # render the horizontal and vertical bar
      # with the TransformSystem we had created before
      # self.horizontal_bar.draw(self.colorbar_transform_sys)
      self.vertical_bar.draw()
  
file_path: vispy/examples/basics/visuals/colorbar_visual.py
imports: from vispy import app
  from vispy import gloo
  from vispy.visuals.transforms import STTransform
  from vispy.visuals import ColorBarVisual, ImageVisual
  from vispy.color import Color, get_colormap
  import numpy
label_desc: Use image node_id 3 for calling the Canvas obj's underlying member method code with example usage: obj.on_draw(event) without return types