code: def _prepare_draw(self, view):
      if self._need_vertex_update:
          self._build_vertex_data()
  
      if view._need_method_update:
          self._update_method(view)
  
file_path: vispy/examples/demo/scene/oscilloscope.py
imports: from __future__ import division
  import threading
  import atexit
  import numpy
  from vispy import app, scene, gloo, visuals
  from vispy.util.filter import gaussian_filter
label_desc: Use image node_id 4 for calling the ScrollingImage obj's underlying member method code with example usage: obj._prepare_draw(view) without return types