From 5efa7f8b67ba0ac86346e0703b9034a2c75e486a Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Tue, 1 Dec 2015 01:23:00 +0000
Subject: Change keyboard layout via keybinding

---
 .xmonad/xmonad.hs | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/.xmonad/xmonad.hs b/.xmonad/xmonad.hs
index 7594cd0..9bd67b2 100644
--- a/.xmonad/xmonad.hs
+++ b/.xmonad/xmonad.hs
@@ -66,6 +66,7 @@ data Host = Host
             , hCoWsp :: String -> Maybe WorkspaceId
             , hKeysMod :: XConfig Layout -> (KeyMap -> KeyMap)
             , hScreens :: [ScreenId]
+            , hKbLayouts :: [(String, Maybe String)]
             }
 
 defaultHost = Host { hName = "unkown"
@@ -74,6 +75,10 @@ defaultHost = Host { hName = "unkown"
                    , hCoWsp = const Nothing
                    , hKeysMod = const id
                    , hScreens = [0,1..]
+                   , hKbLayouts = [ ("us", Nothing)
+                                  , ("us", Just "dvp")
+                                  , ("de", Nothing)
+                                  ]
                    }
 
 hostFromName :: HostName -> Host
@@ -243,6 +248,28 @@ sshOverrides = map (\h -> mkOverride { oHost = h, oCommand = moshCmd . inTmux }
                [ "galois", "galois.praseodym.org"
                ]
 
+cycleKbLayout :: [(String, Maybe String)] -> X ()
+cycleKbLayout [] = return ()
+cycleKbLayout layouts = liftIO $ do
+  next <- (getNext . extract) `liftM` runProcessWithInput "setxkbmap" ["-query"] ""
+  let
+    args = case next of
+      (l, Just v) -> [l, v]
+      (l, Nothing) -> [l]
+  safeSpawn "setxkbmap" args
+  where
+    extract :: String -> Maybe (String, Maybe String)
+    extract str = listToMaybe $ do
+      ["layout:", l] <- str'
+      [(l, Just v) | ["variant:", v] <- str'] ++ pure (l, Nothing)
+      where
+        str' = map words $ lines str
+    getNext :: Maybe (String, Maybe String) -> (String, Maybe String)
+    getNext = maybe (head layouts) getNext'
+    getNext' x = case elemIndex x layouts of
+      Nothing -> getNext Nothing
+      Just i -> layouts !! ((i + 1) `mod` length layouts)
+
 myKeys' conf host = Map.fromList $
     -- launch a terminal
     [ ((modm,               xK_Return), spawn $ (XMonad.terminal conf) ++ " -e tmux")
@@ -309,6 +336,8 @@ myKeys' conf host = Map.fromList $
 
     , ((0, xF86XK_AudioRaiseVolume), safeSpawn "amixer" ["sset", "Master", "Playback", "5+"])
     , ((0, xF86XK_AudioLowerVolume), safeSpawn "amixer" ["sset", "Master", "Playback", "5-"])
+
+    , ((modm              , xK_Escape), cycleKbLayout (hKbLayouts host))
  
     -- Toggle the status bar gap
     -- Use this binding with avoidStruts from Hooks.ManageDocks.
-- 
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