1 files changed, 67 insertions, 0 deletions
diff --git a/ToggleLayouts.hs b/ToggleLayouts.hs
new file mode 100644
index 0000000..60b510b
--- /dev/null
+++ b/ToggleLayouts.hs
@@ -0,0 +1,67 @@
+{-# -fglasgow-exts #-} -- For deriving Data/Typeable
+{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, PatternGuards #-}
+
+-----------------------------------------------------------------------------
+-- |
+-- Module       : XMonadContrib.ToggleLayouts
+-- Copyright    : (c) David Roundy <droundy@darcs.net>
+-- License      : BSD
+--
+-- Maintainer   : David Roundy <droundy@darcs.net>
+-- Stability    : unstable
+-- Portability  : portable
+--
+-- A module for writing easy Layouts
+-----------------------------------------------------------------------------
+
+module XMonadContrib.ToggleLayouts (
+    -- * Usage
+    -- $usage
+    toggleLayouts, ToggleLayout(..)
+    ) where
+
+import XMonad
+import Operations ( LayoutMessages(Hide, ReleaseResources) )
+
+-- $usage
+-- Use toggleLayouts to toggle between two layouts.
+-- import XMonadContrib.ToggleLayouts, and add to your layoutHook something like
+-- > layoutHook = Layout $ toggleLayouts (noBorders Full) $ Select layouts
+-- and a key binding like
+-- >    , ((modMask .|. controlMask, xK_space), sendMessage ToggleLayout)
+
+data ToggleLayouts lt lf a = ToggleLayouts Bool (lt a) (lf a) deriving (Read,Show)
+data ToggleLayout = ToggleLayout deriving (Read,Show,Typeable)
+instance Message ToggleLayout
+
+toggleLayouts :: (LayoutClass lt a, LayoutClass lf a) => lt a -> lf a -> ToggleLayouts lt lf a
+toggleLayouts = ToggleLayouts False
+
+instance (LayoutClass lt a, LayoutClass lf a) => LayoutClass (ToggleLayouts lt lf) a where
+    doLayout (ToggleLayouts True lt lf) r s = do (ws,mlt') <- doLayout lt r s
+                                                 return (ws,fmap (\lt' -> ToggleLayouts True lt' lf) mlt')
+    doLayout (ToggleLayouts False lt lf) r s = do (ws,mlf') <- doLayout lf r s
+                                                  return (ws,fmap (\lf' -> ToggleLayouts False lt lf') mlf')
+    description (ToggleLayouts True lt _) = description lt
+    description (ToggleLayouts False _ lf) = description lf
+    handleMessage (ToggleLayouts bool lt lf) m
+        | Just ReleaseResources <- fromMessage m =
+                                   do mlf' <- handleMessage lf m
+                                      mlt' <- handleMessage lt m
+                                      return $ case (mlt',mlf') of
+                                          (Nothing ,Nothing ) -> Nothing
+                                          (Just lt',Nothing ) -> Just $ ToggleLayouts bool lt' lf
+                                          (Nothing ,Just lf') -> Just $ ToggleLayouts bool lt lf'
+                                          (Just lt',Just lf') -> Just $ ToggleLayouts bool lt' lf'
+    handleMessage (ToggleLayouts True lt lf) m
+        | Just ToggleLayout <- fromMessage m = do mlt' <- handleMessage lt (SomeMessage Hide)
+                                                  let lt' = maybe lt id mlt'
+                                                  return $ Just $ ToggleLayouts False lt' lf
+        | otherwise = do mlt' <- handleMessage lt m
+                         return $ fmap (\lt' -> ToggleLayouts True lt' lf) mlt'
+    handleMessage (ToggleLayouts False lt lf) m
+        | Just ToggleLayout <- fromMessage m = do mlf' <- handleMessage lf (SomeMessage Hide)
+                                                  let lf' = maybe lf id mlf'
+                                                  return $ Just $ ToggleLayouts True lt lf'
+        | otherwise = do mlf' <- handleMessage lf m
+                         return $ fmap (\lf' -> ToggleLayouts False lt lf') mlf'