Hello there all,
i have a simple function to draw an image, but i cannot for the life
of me figgure out from the docs how to make it about 20% transparent.

 def circle_image(zoom)
    site = self.site
     zoomhash = {13 => 0.5, 14 => 1, 15 => 2, 16 => 4}
    r = (self.radius.to_f * zoomhash[zoom.to_i].to_f)
    canvas = Magick::Image.new((2 * r), (2*r),
Magick::HatchFill.new('transparent', 'transparent'))
    gc = Magick::Draw.new
    # for the outside perimeter of the circle
    gc.stroke('black')
    gc.stroke_width(1)
    # fill in the inside
    color = KeyWord.stat_description(site.status_sensor.last_value)[1]
    gc.fill(color)
    gc.circle(r, r, 0, r)
    image = gc.draw(canvas)
    canvas.write("public/images/tmp/#{site.id}.png")
  end

please help, thanks

shawn