IfMax-Layout

This adds a new ("conditional") layout, IfMax, which simply runs one layout, if there are <= N windows, and else runs another layout.

XMonad/Layout/IfMax.hs

@@ -0,0 +1,77 @@
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  XMonad.Layout.IfMax
+-- Copyright   :  (c) 2013 Ilya Portnov
+-- License     :  BSD3-style (see LICENSE)
+--
+-- Maintainer  :  Ilya Portnov <portnov84@rambler.ru>
+-- Stability   :  unstable
+-- Portability :  unportable
+--
+-- Provides IfMax layout, which will run one layout if there are maximum N 
+-- windows on workspace, and another layout, when number of windows is greater
+-- than N.
+--
+-----------------------------------------------------------------------------
+
+{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses #-}
+
+module XMonad.Layout.IfMax
+    ( -- * Usage
+      -- $usage
+      IfMax (..)
+    , ifMax
+    ) where
+
+import Data.Maybe
+
+import XMonad
+import qualified XMonad.StackSet as W
+
+-- $usage
+-- IfMax layout will run one layout if number of windows on workspace is as 
+-- maximum N, and else will run another layout.
+--
+-- You can use this module by adding folowing in your @xmonad.hs@:
+--
+-- > import XMonad.Layout.IfMax
+--
+-- Then add layouts to your layoutHook:
+--
+-- > myLayoutHook = IfMax 2 Full (Tall ...) ||| ...
+--
+-- In this example, if there are 1 or 2 windows, Full layout will be used;
+-- otherwise, Tall layout will be used.
+--
+
+data IfMax l1 l2 w = IfMax Int (l1 w) (l2 w)
+  deriving (Read, Show)
+
+instance (LayoutClass l1 a, LayoutClass l2 a, Read a, Show a, Eq a, Typeable a)
+    => LayoutClass (IfMax l1 l2) a where
+
+  runLayout (W.Workspace _ (IfMax n l1 l2) s) rect = arrange (W.integrate' s)
+    where
+      arrange [] = do l1' <- maybe l1 id `fmap` handleMessage l1 (SomeMessage ReleaseResources)
+                      l2' <- maybe l2 id `fmap` handleMessage l2 (SomeMessage ReleaseResources)
+                      return ([], Just $ IfMax n l1' l2')
+      arrange ws | length ws <= n = do
+                                    (wrs, ml1') <- runLayout (W.Workspace "" l1 s) rect
+                                    let l1' = fromMaybe l1 ml1'
+                                    return (wrs, Just $ IfMax n l1' l2)
+                 | otherwise      = do
+                                    (wrs, ml2') <- runLayout (W.Workspace "" l2 s) rect
+                                    let l2' = fromMaybe l2 ml2'
+                                    return (wrs, Just $ IfMax n l1 l2')
+
+  description (IfMax n l1 l2) = "If number of windows is <= " ++ show n ++ ", then " ++
+                                description l1 ++ ", else " ++ description l2
+
+-- | Layout itself
+ifMax :: (LayoutClass l1 w, LayoutClass l2 w)
+      => Int            -- ^ Maximum number of windows for the first layout
+      -> l1 w           -- ^ First layout
+      -> l2 w           -- ^ Second layout
+      -> IfMax l1 l2 w
+ifMax n l1 l2 = IfMax n l1 l2
+

xmonad-contrib.cabal

@@ -217,6 +217,7 @@ library
                         XMonad.Layout.Groups.Wmii
                         XMonad.Layout.HintedGrid
                         XMonad.Layout.HintedTile
+                        XMonad.Layout.IfMax
                         XMonad.Layout.IM
                         XMonad.Layout.ImageButtonDecoration
                         XMonad.Layout.IndependentScreens