class_docstr: Camera implementing a MagnifyTransform combined with PanZoomCamera.
  
  Parameters
  ----------
  size_factor : float
      The size factor to use.
  radius_ratio : float
      The radius ratio to use.
  **kwargs : dict
      Keyword arguments to pass to `PanZoomCamera` and create a transform.
  
  Notes
  -----
  This Camera uses the mouse cursor position to set the center position of
  the MagnifyTransform, and uses mouse wheel events to adjust the 
  magnification factor.
  
  At high magnification, very small mouse movements can result in large
  changes, so we use a timer to animate transitions in the transform 
  properties.
  
  The camera also adjusts the size of its "lens" area when the view is
  resized.
docstr: The ViewBox mouse event handler
  
  Parameters
  ----------
  event : instance of Event
      The mouse event.
docstr_tok: ["The","ViewBox","mouse","event","handler","Parameters","--","--","--","--","--","event",":","instance","of","Event","The","mouse","event","."]
code: def viewbox_mouse_event(self, event):
      """The ViewBox mouse event handler
  
      Parameters
      ----------
      event : instance of Event
          The mouse event.
      """
      # When the attached ViewBox reseives a mouse event, it is sent to the
      # camera here.
  
      self.mouse_pos = event.pos[:2]
      if event.type == "mouse_wheel":
          # wheel rolled; adjust the magnification factor and hide the
          # event from the superclass
          m = self.mag_target
          m *= 1.2 ** event.delta[1]
          m = m if m > 1 else 1
          self.mag_target = m
      else:
          # send everything _except_ wheel events to the superclass
          super(MagnifyCamera, self).viewbox_mouse_event(event)
  
      # start the timer to smoothly modify the transform properties.
      if not self.timer.running:
          self.timer.start()
  
      self._update_transform()
  
file_path: vispy/vispy/scene/cameras/magnify.py
imports: from __future__ import division
  import numpy
  from .panzoom import PanZoomCamera
  from ...visuals.transforms.nonlinear import MagnifyTransform, Magnify1DTransform
  from ...app import Timer
label_desc: Use image node_id 4 for calling the MagnifyCamera obj's underlying member method code with example usage: obj.viewbox_mouse_event(event) without return types