curses_sample.rb

# -*- encoding: utf-8 -*-
require 'curses'

def main
  Curses.init_screen

  begin
    @y = Curses.lines / 2
    @x = Curses.cols / 2
    while true
      draw_cursor
      @input = wait_input
      break unless @input
    end

  ensure
    Curses.close_screen
  end
end

def draw_cursor
  s = "@"
  Curses.clear
  Curses.setpos(@y, @x)
  Curses.addstr(s)

  Curses.setpos(Curses.lines - 1, 0)
  Curses.addstr("Y:#{@y} X:#{@x} input:#{@input}")

  Curses.refresh
end

def wait_input
  input = Curses.getch
  return nil if input == 27 || input == 'q' # <ESC> key

  case input
  when 'h' then move_left(1)
  when 'j' then move_down(1)
  when 'k' then move_up(1)
  when 'l' then move_right(1)
  end

  input
end

def move_left(n)
  @x = [@x - n, 0].max
end

def move_right(n)
  @x = [@x + n, Curses.cols - 1].min
end

def move_up(n)
  @y = [@y - n, 0].max
end

def move_down(n)
  @y = [@y + n, Curses.lines - 2].min
end

case $PROGRAM_NAME
when __FILE__
  main
when /spec[^\/]*$/
  # {spec of the implementation}
end