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{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, DeriveDataTypeable #-}
-----------------------------------------------------------------------------
-- |
-- 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 (
-- * Usage
-- $usage
-- Layout Modifiers
limitWindows,limitSlice,
-- Change the number of windows
increaseLimit,decreaseLimit,setLimit
) where
import XMonad.Layout.LayoutModifier
import XMonad
import qualified XMonad.StackSet as W
import Control.Monad((<=<),guard)
import Data.Maybe(fromJust)
-- $usage
-- To use this module, add the following import to @~\/.xmonad\/xmonad.hs@:
--
-- > import XMonad.Layout.LimitWindows
--
-- > myLayout = limitWindows 6 $ Tall 1 0.03 0.5 ||| Full ||| RandomOtherLayout...
-- > main = xmonad defaultConfig { layoutHook = myLayout }
--
-- You may also be interested in dynamically changing the number dynamically,
-- by binding keys to the 'increaseLimit', 'decreaseLimit', or 'setLimit'
-- actions.
--
-- For detailed instructions on editing your key bindings, see
-- "XMonad.Doc.Extending#Editing_key_bindings".
--
-- See also 'XMonad.Layout.BoringWindows.boringAuto' for keybindings that skip
-- the hidden windows.
increaseLimit :: X ()
increaseLimit = sendMessage $ LimitChange succ
decreaseLimit :: X ()
decreaseLimit = sendMessage . LimitChange $ max 1 . pred
setLimit :: Int -> X ()
setLimit tgt = sendMessage . LimitChange $ const tgt
-- | 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)
data LimitChange = LimitChange { unLC :: (Int -> Int) } deriving (Typeable)
instance Message LimitChange
instance LayoutModifier LimitWindows a where
pureMess (LimitWindows s n) =
fmap (LimitWindows s) . pos <=< (`app` n) . unLC <=< fromMessage
where pos x = guard (x>=1) >> return x
app f x = guard (f x /= x) >> return (f x)
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 = upfocus $ fromJust $ W.differentiate $ take (max 1 n) $ W.integrate st
where upfocus = foldr (.) id $ replicate (length (W.up st)) W.focusDown'
-- | A non-wrapping, fixed-size slice of a stack around the focused element
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
|