https://tinypng.com/

tinypng.rb

# -*- coding: utf-8 -*-
# $ ruby tinypng.rb drawable/

require 'fileutils'
require 'net/https'
require 'uri'

API_KEY = '***'

i_dir = ARGV[0]
o_dir_prefix = 'tinypng_'
FileUtils.mkdir_p(o_dir_prefix + i_dir)

Dir.glob(i_dir + '*.png').each do |image|

  uri  = URI.parse('https://api.tinypng.com/shrink')
  http = Net::HTTP.new(uri.host, uri.port)
  http.use_ssl = true

  request = Net::HTTP::Post.new(uri.request_uri)
  request.basic_auth("api", API_KEY)
  response = http.request(request, File.binread(image))

  if response.code == "201"
    puts "Compression OK: " + image + " => " + o_dir_prefix + image
    File.binwrite(o_dir_prefix + image, http.get(response["location"]).body)
  else
    puts "Compression NG: " + image
  end

end

    gist/
    ├── tinypng.rb
    ├── ARGV[0]/
    └── tinypng_ + ARGV[0]/