require 'fltk'

class WaveWidget < FLTK::Widget
  include FLTK::Drawable

  SIZEX = 1000
  SIZEY = 400
  def initialize
    size(SIZEX,SIZEY)
  end
  
  def draw
    clear
    SIZEX.times do | i |
      x = i * 2 * 3.1415927 / SIZEX
      y = Math.sin(x)
      color(FLTK::BLACK)
      point(i,y*SIZEY/2+SIZEY/2)
    end
  end
end

class MyWindow < FLTK::DoubleWindow
  def initialize
    super(300, 300, 'Scrolling'){|win|
      pack = FLTK::Pack.new(w,h)
      title = FLTK::Box.new(80, 20, 'Sine Wave')
      title.box(FLTK::BORDER_BOX)
      pane = FLTK::Scroll.new(w,h-20)
      pack.resizable(pane)
      wave = WaveWidget.new
      resizable(pack)
      yield(win)
    }
  end
end

MyWindow.new{|win|
  win.show()
}
FLTK::run()