From a0c7989fdfcbe3a1238e48fa4d3a10fa05fc8098 Mon Sep 17 00:00:00 2001
From: Adam Vogt <vogt.adam@gmail.com>
Date: Fri, 19 Jun 2009 07:27:31 +0200
Subject: Add L.LimitWindows layout modifier

Ignore-this: e91c07885f0ab662f70e0ebd82fb7a5d

darcs-hash:20090619052731-1499c-b68f6df5d8d5c750be9cc68c67a9b7e50c51e7dc.gz
---
 XMonad/Layout/LimitWindows.hs | 55 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 XMonad/Layout/LimitWindows.hs

(limited to 'XMonad')

diff --git a/XMonad/Layout/LimitWindows.hs b/XMonad/Layout/LimitWindows.hs
new file mode 100644
index 0000000..9feb462
--- /dev/null
+++ b/XMonad/Layout/LimitWindows.hs
@@ -0,0 +1,55 @@
+{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses #-}
+-----------------------------------------------------------------------------
+-- |
+-- Module      :  XMonad.Layout.LimitWindows
+-- Copyright   :  (c) 2009 Adam Vogt
+-- License     :  BSD-style (see xmonad/LICENSE)
+--
+-- Maintainer  :  vogt.adam@gmail.com
+-- Stability   :  unstable
+-- Portability :  unportable
+--
+-- A layout modifier that limits the number of windows that can be shown.
+--
+-----------------------------------------------------------------------------
+
+module XMonad.Layout.LimitWindows (limitWindows,limitSlice) where
+
+import XMonad.Layout.LayoutModifier
+import XMonad
+import qualified XMonad.StackSet as W
+
+-- | Only display the first @n@ windows.
+limitWindows :: Int -> l a -> ModifiedLayout LimitWindows l a
+limitWindows n = ModifiedLayout (LimitWindows FirstN n)
+
+-- | Only display @n@ windows around the focused window. This makes sense with
+-- layouts that arrange windows linearily, like 'XMonad.Layout.Layout.Accordion'.
+limitSlice :: Int -> l a -> ModifiedLayout LimitWindows l a
+limitSlice n = ModifiedLayout (LimitWindows Slice n)
+
+data LimitWindows a = LimitWindows SliceStyle Int deriving (Read,Show)
+
+data SliceStyle = FirstN | Slice deriving (Read,Show)
+
+-- do the runLayout call in an environment with only the windows chosen by f ... ?
+instance LayoutModifier LimitWindows a where
+     modifyLayout (LimitWindows style n) ws r =
+        runLayout ws { W.stack = f n `fmap` W.stack ws } r
+      where f = case style of
+                    FirstN -> firstN
+                    Slice -> slice
+
+firstN ::  Int -> W.Stack a -> W.Stack a
+firstN n st = W.Stack f (reverse u) d
+    where (u,f:d) = splitAt (min (n-1) $ length $ W.up st)
+                    $ take n $ W.integrate st
+
+slice ::  Int -> W.Stack t -> W.Stack t
+slice n (W.Stack f u d) =
+        W.Stack f (take (nu + unusedD) u)
+                  (take (nd + unusedU) d)
+    where unusedD = max 0 $ nd - length d
+          unusedU = max 0 $ nu - length u
+          nd = div (n - 1) 2
+          nu = uncurry (+) $ divMod (n - 1) 2
-- 
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