{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, TypeSynonymInstances #-}

-----------------------------------------------------------------------------
-- |
-- Module       : XMonad.Layout.LayoutHints
-- Copyright    : (c) David Roundy <droundy@darcs.net>
-- License      : BSD
--
-- Maintainer   : David Roundy <droundy@darcs.net>
-- Stability    : unstable
-- Portability  : portable
--
-- Make layouts respect size hints.
-----------------------------------------------------------------------------

module XMonad.Layout.LayoutHints (
    -- * usage
    -- $usage
    layoutHints,
    LayoutHints) where

import XMonad hiding ( trace )
import XMonad.Layout.LayoutModifier

-- $usage
-- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
--
-- > import XMonad.Layout.LayoutHints
--
-- Then edit your @layoutHook@ by adding the LayoutHints layout modifier
-- to some layout:
--
-- > myLayouts = layoutHints (Tall 1 (3/100) (1/2))  ||| Full ||| etc..
-- > main = xmonad defaultConfig { layoutHook = myLayouts }
--
-- For more detailed instructions on editing the layoutHook see:
--
-- "XMonad.Doc.Extending#Editing_the_layout_hook"

layoutHints :: (LayoutClass l a) => l a -> ModifiedLayout LayoutHints l a
layoutHints = ModifiedLayout LayoutHints

-- | Expand a size by the given multiple of the border width.  The
-- multiple is most commonly 1 or -1.
adjBorders                :: Dimension -> Dimension -> D -> D
adjBorders bW mult (w,h)  = (w+2*mult*bW, h+2*mult*bW)

data LayoutHints a = LayoutHints deriving (Read, Show)

instance LayoutModifier LayoutHints Window where
    modifierDescription _ = "Hinted"
    redoLayout _ _ _ xs = do
                            bW <- asks (borderWidth . config)
                            xs' <- mapM (applyHint bW) xs
                            return (xs', Nothing)
     where
        applyHint bW (w,Rectangle a b c d) =
            withDisplay $ \disp -> do
                sh <- io $ getWMNormalHints disp w
                let (c',d') = adjBorders 1 bW . applySizeHints sh . adjBorders bW (-1) $ (c,d)
                return (w, Rectangle a b c' d')