# File gtk/sample/gtk-demo/cairo-operator.rb, line 40
    def draw(cr)
      cr.save do
        image = Cairo::ImageSurface.from_png("ruby-gnome2-logo.png")
        cr.translate(0.5, 0.5)
        cr.rotate(-45 * Math::PI / 180)
        cr.scale(0.8 / image.width, 0.8 / image.height)
        cr.translate(-0.5 * image.width, -0.5 * image.height)
        cr.set_source(image, 0.0, 0.0)
        cr.paint
      end
      
      cr.set_operator(@operator)
      
      cr.set_source_rgba(1, 0, 0, 0.5)
      cr.rectangle(0.2, 0.2, 0.5, 0.5)
      cr.fill
      cr.set_source_rgba(0, 1, 0)
      cr.rectangle(0.4, 0.4, 0.4, 0.4)
      cr.fill
      cr.set_source_rgba(0, 0, 1)
      cr.rectangle(0.6, 0.6, 0.3, 0.3)
      cr.fill
    end