ターミナルで Gif アニメを表示する。

pictan.rb

#!/usr/bin/env ruby

require 'curses'
require 'rmagick'

require 'pry'
require 'pry-debugger' 

def clear_screen
  puts "\e[H\e[2J"
end

def pixel2color(pixel)
  color = [pixel.red, pixel.green, pixel.blue].map { |n| (n * 5) / (255 * 255) }
  "\x1b[48;5;#{16 + color[0] * 36 + color[1] * 6 + color[2]}m  \x1b[0m"
end

def screen_columns
  Curses.init_screen
  columns = Curses.cols / 2
  Curses.close_screen
  columns
end

def draw(image)
  image = image.sample(1.0 * screen_columns / image.columns)
  rows = (0...image.rows).map do |row|
    image.get_pixels(0, row, image.columns, 1).map { |pixel| pixel2color(pixel) }.join
  end
  picture = rows.join("\n")

  puts picture
end

def animate(image_path)
  image_list = Magick::ImageList.new(image_path)
  interval = (1.0 * image_list.delay) / 100

  image_list.each do |image|
    draw(image)
    sleep(interval)
  end
end

def main
  interrupted = false
  Signal.trap("INT") { interrupted = true } # traps Ctrl-C

  until interrupted do
    animate(ARGV[0])
  end

  clear_screen
end

main