class_docstr:   This is an interactive example of how to display text on app.Canvas.
    The text rendering will respond to standard C escape sequences.
  
    - Scroll for changing text font size
    - Press left and right arrows for changing text anchor positions
    - Press up and down arrows for changing text content
  
    Standard C escape sequences:
        -     ->  alert (beep, bell)
        -     ->  Backspace
        -     ->  Formfeed
        -   
  ->  Newline
        -   
    ->  Carriage Return
        -         ->  Horizontal Tab
        -     ->  Vertical Tab
        -   \  ->  Backslash
        -   '  ->  Single quotation mark
        -   "  ->  Double quotation mark
    
docstr: Use the mouse wheel to zoom.
code: def on_mouse_wheel(self, event):
      """Use the mouse wheel to zoom."""
      self.font_size *= 1.25 if event.delta[1] > 0 else 0.8
      self.font_size = max(min(self.font_size, 160.0), 6.0)
      self.update_text()
  
file_path: vispy/examples/basics/visuals/text_visual.py
imports: from vispy import app, gloo, visuals
  import numpy
label_desc: Use image node_id 3 for calling the Canvas obj's underlying member method code with example usage: obj.on_mouse_wheel(event) without return types