Keeping it Small and Simple


Simple wallpaper tool in Ruby

Filed under: Ruby Programming — Tags: , , , , — Lorenzo E. Danielsson @ 15:39

Ben is constantly on the look-out for small applications that he can write in order to practice his Ruby skills. This morning he told me he wants to write a “wallpaper switcher” (or whatever you call those things). It seemed like an interesting little program, so I hastily put this together.

 1 #! /usr/bin/ruby
 3 # A wallpaper tool.
 5 require optparse
 7 def parsedir(path)
 8   a = []
10 do |file|
11     next if file =~ /^\./
13     fp = "#{path}/#{file}"
14 ? a.concat(parsedir(fp)) : a << fp
15   end
16   a
17 end
19 options = {
20   :dir => nil,
21   :file => nil,
22   :interval => 60,
23   :random => false,
24   :use => wmsetbg
25 }
27 begin
28 do |opts|
29     opts.banner = "usage: #{$0} [options]"
31     opts.on("-d", "–directory=DIR", String, "scan directory") do |dir|
32       options[:dir] = dir
33     end
35     opts.on("-f", "–file=FILE", String, "read wallpapers from file") do |file|
36       options[:file] = file
37     end
39     opts.on("-i", "–interval=I", Integer, "set the interval") do |interval|
40       options[:interval] = interval
41     end
43     opts.on("-r", "–[no-]random", "randomize the order") do |r|
44       options[:random] = r
45     end
47     opts.on("-u", "–use=APP", String, "set the utility to use") do |use|
48       options[:use] = use
49     end
50   end.parse!
51 rescue OptionParser::InvalidOption => err
52   $stderr.print err.to_s + "\n"
53   exit
54 rescue OptionParser::MissingArgument => err
55   $stderr.print err.to_s + "\n"
56   exit
57 end
59 wp = []
60 wp.concat(IO.readlines(options[:file])) unless options[:file].nil?
61 wp.concat(parsedir(options[:dir])) unless options[:dir].nil?
62 wp.collect! { |image| image.chomp }.delete_if { |image| !File.exists? image }
63 abort "No wallpapers in list." if wp.empty?
65 %w[TERM INT].each do |sig|
66   trap(sig) {
67     puts "Are you crazy?? What are you doing to me?"
68     exit
69   }
70 end
72 loop do
73   (options[:random] ? wp.sort_by { rand } : wp).each { |image|
74     `#{options[:use]} #{image} > /dev/null 2>&1`
75     sleep options[:interval]
76   }
77 end

Improving it

Several ideas come to mind:

  • Add standard options like –help
  • Handle errors.
  • Make sure all the files added to the wp array actually are images.
  • Add an option to make the program run through the wallpapers once only (or a certain number of times.
  • Currently all the images get scaled by default (using wmsetbg). Add options for centering, tiling etc. images.
  • I’m calling a utility called wmsetbg, which comes with Window Maker. Instead of doing this, you could set the “paint” an image on the root window yourself. Look into Ruby/Xlib, Imlib2-ruby or any other library that you know of that will allow you access to the root window.
  • I’m sure you can think of lots more.

If you really wanted to take this little exercise a bit further you could create a custom format for the wallpapers file. For example, it could look like this


Where options would be something like scale, center, tile, etc. You could take it way too far and create an XML file with all kinds of options, such as display such-and-such image only during a specific time of the day, or on a specific day or interval of days. This way you could have special images for special occasions, such as Yule, Easter and so on. If you do decide to implement this, you may also want to consider a visit to your shrink. You are going waaay overboard and need help. Urgently.

Does it work with JRuby?

I’m glad you asked. Short answer: yes. Long answer: Hell, yeah! 😉

Does it work with Ruby 1.9?

Yes it does. Notice that there are some things you could do to ruby1.9-ify it. For instance, you could initialize the options array as follows:

options = {
  dir: nil,
  file: nil,
  interval: 60,
  random: false,
  use: wmsetbg

Does it work with Rubinius?

Yes, of course it does! 🙂

I did discover one small annoyance. Hitting CTRL+C will display the “Are you..” message alright, but the program will keep running. Not sure why, but I’ll look into that.

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