A Mouse Wheel Listener in Ruby Processing

For my 3D context free application/library, I would like to be able to zoom using the mouse wheel, I had vaguely thought about using peasycam or proscene to provide that, and other functionality. In the first instance I wanted to create it myself. After a bit of research, this the sort of implementation I would do using the java classes/interfaces in ruby:-

# mouse_listener.rb

class JWheelListener
  include java.awt.event.MouseWheelListener

  attr_reader :zoom

  def initialize(zoom)
    @zoom = zoom
  end

  def mouse_wheel_moved(e)
    @zoom += e.get_wheel_rotation * 10
  end

end

class Mouse < Processing::App

  attr_reader :wheel

  def setup
    size(1000, 1000)
    @wheel = JWheelListener.new(10)
    self.add_mouse_wheel_listener(@wheel)  
  end

  def draw
    background 0
    fill 255, 0, 0
    ellipse(width/2, height/2, wheel.zoom, wheel.zoom)

  end

end

Mouse.new :title => "Mouse Wheel Listener"