code: def apply_zoom(self):
      width, height = self.physical_size
      gloo.set_viewport(0, 0, width, height)
      self.program["inv_resolution_x"] = set_emulated_double(1 / width)
      self.program["inv_resolution_y"] = set_emulated_double(1 / height)
  
file_path: vispy/examples/demo/gloo/mandelbrot_double.py
imports: from __future__ import division
  import numpy
  from vispy import app, gloo
label_desc: Use image node_id 4 for calling the Canvas obj's underlying member method code with example usage: obj.apply_zoom() without return types