Raspberry Pi Device Prototyping

config.toml

[config]
  root = "./"
[screens."pic1.png"]
  right = 'pic2.png'
  left = 'pic4.png'
  up = 'pic1.png'
  down = 'pic3.png'

[screens."pic2.png"]
  right = 'pic2.png'
  left = 'pic4.png'
  up = 'pic1.png'
  down = 'pic3.png'

[screens."pic3.png"]
  right = 'pic2.png'
  left = 'pic4.png'
  up = 'pic1.png'
  down = 'pic3.png'

[screens."pic4.png"]
  right = 'pic2.png'
  left = 'pic4.png'
  up = 'pic1.png'
  down = 'pic3.png'

[screens.default]
  r = 'pic1.png'

input_manager.rb

require 'io/console'
require 'tomlrb'
require 'socket'

# Taken from https://github.com/jkraemer/pi-slideshow/blob/master/lib/pi_slides/fim.rb
class Fim

  def initialize(options = {})
    @mutex = Mutex.new
    options = {
      :host => 'localhost', :port => 9999
    }.merge options
    @host = options[:host]
    @port = options[:port]
  end

  # pushes the file, displays it and removes it from the list immediately
  # shows and pops the next file from the list if path.nil?
  def show(path=nil)
    exec %{#{"push '#{path}';" if path}next;pop;}
  end

  # turn status line on/off
  def status_line(switch_on = true)
    if switch_on
      set_vars :_display_busy => 1, :_display_status => 1
    else # switch off
      set_vars :_display_busy => 0, :_display_status => 0
    end
  end

  def disable_autowidth
    exec 'set autowidth 0;'
  end

  def toggle_autowidth
    exec 'autowidth=1-autowidth;'
  end

  def push(*files)
    exec files.map{|f| "push '#{f}';"}.join + "prefetch;"
  end

  def set_vars(vars = {})
    exec vars.to_a.map{|name, value| %{#{name}=#{value};}}.join
  end

  def exec(cmd)
    @mutex.synchronize do
      TCPSocket.open(@host, @port).tap do |s|
        s << cmd
        s.close
      end
    end
  rescue
    sleep 1
    retry
  end
end


$file_tree = Tomlrb.load_file('config.toml')
$config = $file_tree['config']
$screens = $file_tree['screens']
$current_screen_key = $screens.first[0]
$default_actions = $screens['default']

$fim = Fim.new(host: '192.168.1.1', port: 9999)
$fim.status_line(false)
$fim.exec('v:auto_scale_v=0;autowidth=0;reload;')
 
# Reads keypresses from the user including 2 and 3 escape character sequences.
def read_char
  STDIN.echo = false
  STDIN.raw!
 
  input = STDIN.getc.chr
  if input == "\e" then
    input << STDIN.read_nonblock(3) rescue nil
    input << STDIN.read_nonblock(2) rescue nil
  end
ensure
  STDIN.echo = true
  STDIN.cooked!
 
  return input
end
 
# oringal case statement from:
# http://www.alecjacobson.com/weblog/?p=75
def show_single_key
  c = read_char
  aliased_char = case c
                 when " "
                   "space"
                 when "\t"
                   "tab"
                 when "\r"
                   "enter"
                 when "\n"
                   "enter"
                 when "\e"
                   "esc"
                 when "\e[A"
                   "up"
                 when "\e[B"
                   "down"
                 when "\e[C"
                   "right"
                 when "\e[D"
                   "left"
                 when "\177"
                   "backspace"
                 when "\004"
                   "delete"
                 when "\u0003"
                   puts "CONTROL-C - exiting"
                   exit 0
                 else
                   c
                 end

  current_screen = $screens[$current_screen_key] || {}
  target_screen = current_screen[aliased_char] || $default_actions[aliased_char]
  if (target_screen)
    puts "Moving to target screen: #{target_screen}"
    $fim.show($config['root'] + target_screen)
    $current_screen_key = target_screen
  else
    puts "No action found for key: #{aliased_char} from screen: #{current_screen}"
  end
end
 
show_single_key while(true)

server.sh

#!/bin/sh
fim -c 'while(1){popen "nc -l 9999";}'