code: def activate_zoom(self):
      width, height = self.size
      gloo.set_viewport(0, 0, *self.physical_size)
      far = SIZE * (NBLOCKS - 2)
      self.projection = perspective(
          25.0, width / float(height), 1.0, far
      )
      self.program["u_projection"] = self.projection
  
file_path: vispy/examples/demo/gloo/spacy.py
imports: import time
  import numpy
  from vispy import gloo
  from vispy import app
  from vispy.util.transforms import perspective
label_desc: Use image node_id 4 for calling the Canvas obj's underlying member method code with example usage: obj.activate_zoom() without return types