A progressbar in the command line

progressbar.rb

# Usage
#   bar = ProgressBar.new
#   bar.init
#   0.step(100, 0.5) { |i|
#     bar.update(i)
#     sleep(rand*0.1)
#   }
#   bar.finish
# 
# you can update the progress and render independently if you wish. Use
# ProgessBar#progress= for that and don't pass a value to #update.
class ProgressBar
  TopLeft     = "\342\224\214"
  Top         = "\342\224\200"
  TopRight    = "\342\224\220"
  Left        = "\342\224\202"
  Right       = "\342\224\202"
  BottomLeft  = "\342\224\224"
  Bottom      = "\342\224\200"
  BottomRight = "\342\224\230"
  LightCheck  = "\e[32m\342\234\223\e[0m"
  Check       = "\e[32m\342\234\224\e[0m"

  attr_accessor :progress

  def initialize(pad=["","",""], io=$stdout)
    @progress = 0
    @pad      = pad
    @io       = io
  end
  def init
    puts "","",""
  end
  def update(progress=nil)
    @progress = progress if progress
    prog   = @progress
    filled = (0.5*prog).round
    free   = 50-filled
    @io.print "\e[3A",
      @pad[0], TopLeft, Top*50, TopRight, "\n",
      @pad[1], Left, "\e[44m", " "*filled, "\e[46m", " "*free, "\e[0m", Right, " ", prog.round, "%\n",
      @pad[2], BottomLeft, Bottom*50, BottomRight, "\n"
    @io.flush
  end
  def finish
    @io.print "\e[3A",
      @pad[0], TopLeft, Top*50, TopRight, "\n",
      @pad[1], Left, "\e[44m", " "*50, "\e[0m", Right, " ", Check, "    \n",
      @pad[2], BottomLeft, Bottom*50, BottomRight, "\n"
    @io.flush
  end
end