Add xrandr.lua multiple monitor recipe (#73)

recipes.mdwn

@@ -12,3 +12,6 @@ The recipes section is where you can find useful snippets and tutorials on how t
 
 * [Lain Widget Library](https://github.com/copycat-killer/lain)
 * [[MPD current song|recipes/mpc]]
+
+## Others 
+* [[Swap Monitor Snippet|recipes/xrandr]]

recipes/xrandr.lua

@@ -0,0 +1,147 @@
+--- Separating Multiple Monitor functions as a separeted module (taken from awesome wiki)
+
+local awful     = require("awful")
+local naughty   = require("naughty")
+local beautiful = require("beautiful");
+
+-- A path to a fancy icon
+local icon_path = "";
+
+-- Get active outputs
+local function outputs()
+   local outputs = {}
+   local xrandr = io.popen("xrandr -q --current")
+
+   if xrandr then
+      for line in xrandr:lines() do
+         local output = line:match("^([%w-]+) connected ")
+         if output then
+            outputs[#outputs + 1] = output
+                                   end
+      end
+      xrandr:close()
+   end
+
+   return outputs
+end
+
+local function arrange(out)
+   -- We need to enumerate all permutations of horizontal outputs.
+
+   local choices  = {}
+   local previous = { {} }
+   for i = 1, #out do
+      -- Find all permutation of length `i`: we take the permutation
+      -- of length `i-1` and for each of them, we create new
+      -- permutations by adding each output at the end of it if it is
+      -- not already present.
+      local new = {}
+      for _, p in pairs(previous) do
+         for _, o in pairs(out) do
+            if not awful.util.table.hasitem(p, o) then
+               new[#new + 1] = awful.util.table.join(p, {o})
+            end
+         end
+      end
+      choices = awful.util.table.join(choices, new)
+      previous = new
+   end
+
+   return choices
+end
+
+-- Build available choices
+local function menu()
+   local menu = {}
+   local out = outputs()
+   local choices = arrange(out)
+
+   for _, choice in pairs(choices) do
+      local cmd = "xrandr"
+      -- Enabled outputs
+      for i, o in pairs(choice) do
+         cmd = cmd .. " --output " .. o .. " --auto"
+         if i > 1 then
+            cmd = cmd .. " --right-of " .. choice[i-1]
+         end
+      end
+      -- Disabled outputs
+      for _, o in pairs(out) do
+         if not awful.util.table.hasitem(choice, o) then
+            cmd = cmd .. " --output " .. o .. " --off"
+         end
+      end
+
+      local label = ""
+      if #choice == 1 then
+         label = 'Only <span weight="bold">' .. choice[1] .. '</span>'
+      else
+         for i, o in pairs(choice) do
+            if i > 1 then label = label .. " + " end
+            label = label .. '<span weight="bold">' .. o .. '</span>'
+         end
+      end
+
+      menu[#menu + 1] = { label,
+                          cmd,
+                          icon_path}
+   end
+
+   return menu
+end
+
+-- Display xrandr notifications from choices
+local state = { iterator = nil,
+                timer = nil,
+                cid = nil }
+local function xrandr()
+   -- Stop any previous timer
+   if state.timer then
+      state.timer:stop()
+      state.timer = nil
+   end
+
+   -- Build the list of choices
+   if not state.index then
+      state.menu = menu()
+      state.index = 1
+   end
+
+   -- Select one and display the appropriate notification
+   local label, action, icon
+   local next  = state.menu[state.index]
+   state.index = state.index + 1
+
+   if not next then
+      label, icon = "Keep the current configuration", icon_path
+      state.iterator = nil
+   else
+      label, action, icon = unpack(next)
+   end
+   state.cid = naughty.notify({ text = label,
+                                icon = icon,
+                                timeout = 4,
+                                screen = mouse.screen,
+                                font = beautiful.font,
+                                replaces_id = state.cid }).id
+
+   -- Setup the timer
+   state.timer = timer { timeout = 4 }
+   state.timer:connect_signal("timeout",
+                              function()
+                                 state.timer:stop()
+                                 state.timer = nil
+                                 state.iterator = nil
+                                 if action then
+                                    awful.util.spawn(action, false)
+                                 end
+   end)
+   state.timer:start()
+end
+
+return {
+   outputs = outputs,
+   arrange = arrange,
+   menu = menu,
+   xrandr = xrandr
+}

recipes/xrandr.mdwn

@@ -0,0 +1,23 @@
+# Multiple Monitor Helper
+
+This page is intended to show how to user `xrandr.lua` script to help the way you deal with multiple monitors.
+Using this snippet you can set a keybinding where you swap to all possible arrangements of monitors.
+
+The process of setting up this script goes as follow:
+
+1. Create a file called `xrandr.lua` in your file system (preferably in awesome's folder) with the [script](xrandr.lua) content.
+
+2. Import the script in your `rc.lua`
+
+          local xrandr = require("/path/to/file/xrandr")
+
+3. Create a keybinding to the script in the appropriated globalkeys table
+
+Pressing this key binding will open a popup with a possible screen arrangement.
+Pressing the key again will replace this popup with another possibility, eventually arriving at "keep the current configuration".
+
+If the key is not pressed again within four seconds, the configuration described in the current popup is applied.
+
+
+           awful.key({}, "Some Key", function() xrandr.xrandr() end)
+