class_docstr: A simple test canvas for drawing demo 
class_docstr_tok: ["A","simple","test","canvas","for","drawing","demo"]
code: def on_mouse_move(self, event):
      if event.button == 1:
          if self.selected_object is not None:
              self.view.camera._viewbox.events.mouse_move.disconnect(
                  self.view.camera.viewbox_mouse_event
              )
              # update transform to selected object
              tr = self.scene.node_transform(self.selected_object)
              pos = tr.map(event.pos)
  
              self.selected_object.move(pos[0:2])
          else:
              self.view.camera._viewbox.events.mouse_move.connect(
                  self.view.camera.viewbox_mouse_event
              )
      else:
          None
  
imports: import numpy
  from vispy import app, scene
  from vispy.color import Color
label_desc: Use image node_id 4 for calling the Canvas obj's underlying member method code with example usage: obj.on_mouse_move(event) without return types