Small ruby script to encode screen setups.

extscreen.rb

[maarten@maarten-laptop:~]$ cat `which extscreen`
#!/usr/bin/env ruby
require 'pathname'
require 'digest'

BASE_CARD_PATH = "/sys/class/drm/card0-"

SETUPS = {
  "desktop" => {
    screens: {
        "HDMI-A-1" => "d17e9077f6e649495c6351b380ff5feeeb2076d49a5a8dcf7825733a0bfe5e03",
        "DP-2" => "4608940ef02fd1627b7425047b7cf1ad51038d52bbf7bd76b23a5a0769768811"
    },
    command: "xrandr --output LVDS1 --off --output HDMI1 --auto --rotate right --output DP2 --auto --rotate right --right-of HDMI1"
  },
  "woonkamer" => {
    screens: {
      "LVDS-1" => "413edd161b6a0af2afb86570904f67240e4586eab8d29f0facb440055d39a9af",
      "DP-2" => "53453c918410de8e0ef2191c876eb30d7782cade67515fde9cedc971339b290d",
    },
    command: "xrandr --output LVDS1 --auto --output HDMI1 --off --output DP2 --auto --rotate left --right-of LVDS1"
  },
  "laptop" => {
    screens: {
      "LVDS-1" =>"413edd161b6a0af2afb86570904f67240e4586eab8d29f0facb440055d39a9af"
    },
    command: "xrandr --output DP2 --off --output HDMI1 --off --output LVDS1 --auto"
  },

}

class Device
  def initialize(path)
    @path = Pathname.new(path)
  end

  def name
    @path.to_s.sub(BASE_CARD_PATH,"")
  end

  def connected?
    File.read(@path.join("status")).chomp == "connected"
  end

  def raw_edid
    File.read(@path.join("edid")).chomp
  end

  def hex_edid
    Digest::SHA256.hexdigest(self.raw_edid)
  end
end

DEVICES = Dir[BASE_CARD_PATH+"*"].map do |dir|
  Device.new(dir)
end

def find_dev_by_name(name)
  DEVICES.find { |d| d.name == name }
end

def main
  verb = ARGV.shift

  verb = "help" if verb.nil?

  case verb
    when "help"
      puts "USAGE: #{$PROGRAM_NAME} [apply <configuration name> | list | connected]"
    when "list" 
      verb_list
    when "apply" 
      verb_apply
    when "connected" 
      verb_connected
    else
      $stderr.puts "Unknown verb #{verb}"
      exit 1
  end
end

def verb_list
  require 'pp'
  pp SETUPS
end

def verb_connected
  connected = DEVICES.select { |d| d.connected? }
  connected.each do |device|
    p [device.name, device.hex_edid]
  end
end

def verb_apply
  config = ARGV.shift

  if config.nil?
    config = find_matching_setup
  end

  matching_setup = SETUPS[config]
  if matching_setup.nil?
    $stderr.puts("Wrong setup name '#{config}'!")
    exit 1
  end

  # Apply configuration
  puts "Applying '#{config}'"
  system(matching_setup[:command])
end

# Detect top down the first matching setup.
def find_matching_setup
  found = SETUPS.find do |setup_name, setup|
    ok = true

    setup[:screens].each do |screen_name, edid|
      if find_dev_by_name(screen_name).hex_edid != edid
        ok = false
      end
    end

    ok
  end

  if found.nil?
    raise("Could not find a suitable setup!")
  else
    found[0]
  end
end

main