画像の色を反転させるプロキシ

negaproxy.rb

#!/usr/bin/env ruby

require 'webrick'
require 'webrick/httpproxy'
require 'RMagick'

handler = Proc.new() { |req,res|
  if res['content-type'] =~ /image/
    begin
      img = Magick::Image.from_blob(res.body).first
      body = img.negate.to_blob
      res.body = body
    rescue
    end
  end
}

s = WEBrick::HTTPProxyServer.new(
  :BindAddress => '127.0.0.1',
  :Port => 9090,
  :ProxyContentHandler => handler
  )

Signal.trap('INT') do
  s.shutdown
end

s.start