{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, DeriveDataTypeable, ExistentialQuantification #-}
-----------------------------------------------------------------------------
-- |
-- Module : XMonad.Layout.BinarySpacePartition
-- Copyright : (c) 2013 Ben Weitzman <benweitzman@gmail.com>
-- License : BSD3-style (see LICENSE)
--
-- Maintainer : Ben Weitzman <benweitzman@gmail.com>
-- Stability : unstable
-- Portability : unportable
--
-- Layout where new windows will split the focused window in half, based off of BSPWM
--
-----------------------------------------------------------------------------
module XMonad.Layout.BinarySpacePartition (
-- * Usage
-- $usage
emptyBSP
, Rotate(..)
, Swap(..)
, ResizeDirectional(..)
, Bound(..)
) where
import XMonad
import qualified XMonad.StackSet as W
import XMonad.Util.Stack hiding (Zipper)
import qualified Data.Map as M
import Data.List ((\\))
import Control.Monad
-- $usage
-- You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
--
-- > import XMonad.Layout.BinarySpacePartition
--
-- Then add the layout, using the default BSP (BinarySpacePartition)
--
-- > myLayout = emptyBSP ||| etc ..
--
-- It will be helpful to add the following key bindings
--
-- > , ((modm .|. altMask, xK_l ), sendMessage $ ExpandTowards East)
-- > , ((modm .|. altMask, xK_h ), sendMessage $ ExpandTowards West)
-- > , ((modm .|. altMask, xK_j ), sendMessage $ ExpandTowards South)
-- > , ((modm .|. altMask, xK_k ), sendMessage $ ExpandTowards North)
-- > , ((modm .|. altMask .|. ctrlMask , xK_l ), sendMessage $ ShrinkFrom East)
-- > , ((modm .|. altMask .|. ctrlMask , xK_h ), sendMessage $ ShrinkFrom West)
-- > , ((modm .|. altMask .|. ctrlMask , xK_j ), sendMessage $ ShrinkFrom South)
-- > , ((modm .|. altMask .|. ctrlMask , xK_k ), sendMessage $ ShrinkFrom North)
-- > , ((modm, xK_r ), sendMessage Rotate)
-- > , ((modm, xK_s ), sendMessage Swap)
--
-- |Message for rotating a split in the BSP. Keep in mind that this does not change the order
-- of the windows, it will just turn a horizontal split into a verticial one and vice versa
data Rotate = Rotate deriving Typeable
instance Message Rotate
-- |Message for resizing one of the cells in the BSP
data ResizeDirectional = ExpandTowards Bound | ShrinkFrom Bound deriving Typeable
instance Message ResizeDirectional
-- |Message for swapping the left child of a split with the right child of split.
-- Keep in mind that it does not change the order of windows and will seem to have bizarre effects
-- if you are not expecting them.
data Swap = Swap deriving Typeable
instance Message Swap
data Bound = East | West | North | South deriving Typeable
data Direction = Horizontal | Vertical deriving (Show, Read, Eq)
oppositeDirection :: Direction -> Direction
oppositeDirection Vertical = Horizontal
oppositeDirection Horizontal = Vertical
split :: Direction -> Rational -> Rectangle -> (Rectangle, Rectangle)
split Horizontal r (Rectangle sx sy sw sh) = (r1, r2) where
r1 = Rectangle sx sy sw sh'
r2 = Rectangle sx (sy + fromIntegral sh') sw (sh - sh')
sh' = floor $ fromIntegral sh * r
split Vertical r (Rectangle sx sy sw sh) = (r1, r2) where
r1 = Rectangle sx sy sw' sh
r2 = Rectangle (sx + fromIntegral sw') sy (sw - sw') sh
sw' = floor $ fromIntegral sw * r
data Split = Split { direction :: Direction
, ratio :: Rational
} deriving (Show, Read, Eq)
oppositeSplit :: Split -> Split
oppositeSplit (Split d r) = Split (oppositeDirection d) r
increaseRatio :: Split -> Rational -> Split
increaseRatio (Split d r) delta = Split d (min 0.9 (max 0.1 (r + delta)))
data Tree a = Leaf | Node { value :: a
, left :: Tree a
, right :: Tree a
} deriving (Show, Read, Eq)
numLeaves :: Tree a -> Int
numLeaves Leaf = 1
numLeaves (Node _ l r) = numLeaves l + numLeaves r
data Crumb a = LeftCrumb a (Tree a) | RightCrumb a (Tree a) deriving (Show, Read, Eq)
swapCrumb :: Crumb a -> Crumb a
swapCrumb (LeftCrumb s t) = RightCrumb s t
swapCrumb (RightCrumb s t) = LeftCrumb s t
parentVal :: Crumb a -> a
parentVal (LeftCrumb s _) = s
parentVal (RightCrumb s _) = s
modifyParentVal :: (a -> a) -> Crumb a -> Crumb a
modifyParentVal f (LeftCrumb s t) = LeftCrumb (f s) t
modifyParentVal f (RightCrumb s t) = RightCrumb (f s) t
type Zipper a = (Tree a, [Crumb a])
toZipper :: Tree a -> Zipper a
toZipper t = (t, [])
goLeft :: Zipper a -> Maybe (Zipper a)
goLeft (Leaf, _) = Nothing
goLeft (Node x l r, bs) = Just (l, LeftCrumb x r:bs)
goRight :: Zipper a -> Maybe (Zipper a)
goRight (Leaf, _) = Nothing
goRight (Node x l r, bs) = Just (r, RightCrumb x l:bs)
goUp :: Zipper a -> Maybe (Zipper a)
goUp (_, []) = Nothing
goUp (t, LeftCrumb x r:cs) = Just (Node x t r, cs)
goUp (t, RightCrumb x l:cs) = Just (Node x l t, cs)
goSibling :: Zipper a -> Maybe (Zipper a)
goSibling (_, []) = Nothing
goSibling z@(_, LeftCrumb _ _:_) = Just z >>= goUp >>= goRight
goSibling z@(_, RightCrumb _ _:_) = Just z >>= goUp >>= goLeft
goToNthLeaf :: Int -> Zipper a -> Maybe (Zipper a)
goToNthLeaf _ z@(Leaf, _) = Just z
goToNthLeaf n z@(t, _) =
if numLeaves (left t) > n
then do z' <- goLeft z
goToNthLeaf n z'
else do z' <- goRight z
goToNthLeaf (n - (numLeaves . left $ t)) z'
splitCurrentLeaf :: Zipper Split -> Maybe (Zipper Split)
splitCurrentLeaf (Leaf, []) = Just (Node (Split Vertical 0.5) Leaf Leaf, [])
splitCurrentLeaf (Leaf, crumb:cs) = Just (Node (Split (oppositeDirection . direction . parentVal $ crumb) 0.5) Leaf Leaf, crumb:cs)
splitCurrentLeaf _ = Nothing
removeCurrentLeaf :: Zipper a -> Maybe (Zipper a)
removeCurrentLeaf (Leaf, []) = Nothing
removeCurrentLeaf (Leaf, LeftCrumb _ r:cs) = Just (r, cs)
removeCurrentLeaf (Leaf, RightCrumb _ l:cs) = Just (l, cs)
removeCurrentLeaf _ = Nothing
rotateCurrentLeaf :: Zipper Split -> Maybe (Zipper Split)
rotateCurrentLeaf (Leaf, []) = Just (Leaf, [])
rotateCurrentLeaf (Leaf, c:cs) = Just (Leaf, modifyParentVal oppositeSplit c:cs)
rotateCurrentLeaf _ = Nothing
swapCurrentLeaf :: Zipper a -> Maybe (Zipper a)
swapCurrentLeaf (Leaf, []) = Just (Leaf, [])
swapCurrentLeaf (Leaf, c:cs) = Just (Leaf, swapCrumb c:cs)
swapCurrentLeaf _ = Nothing
expandTreeTowards :: Bound -> Zipper Split -> Maybe (Zipper Split)
expandTreeTowards _ z@(_, []) = Just z
expandTreeTowards East (t, LeftCrumb s r:cs)
| direction s == Vertical = Just (t, LeftCrumb (increaseRatio s 0.1) r:cs)
expandTreeTowards West (t, RightCrumb s l:cs)
| direction s == Vertical = Just (t, RightCrumb (increaseRatio s (-0.1)) l:cs)
expandTreeTowards South (t, LeftCrumb s r:cs)
| direction s == Horizontal = Just (t, LeftCrumb (increaseRatio s 0.1) r:cs)
expandTreeTowards North (t, RightCrumb s l:cs)
| direction s == Horizontal = Just (t, RightCrumb (increaseRatio s (-0.1)) l:cs)
expandTreeTowards dir z = goUp z >>= expandTreeTowards dir
shrinkTreeFrom :: Bound -> Zipper Split -> Maybe (Zipper Split)
shrinkTreeFrom _ z@(_, []) = Just z
shrinkTreeFrom East z@(_, LeftCrumb s _:_)
| direction s == Vertical = Just z >>= goSibling >>= expandTreeTowards West
shrinkTreeFrom West z@(_, RightCrumb s _:_)
| direction s == Vertical = Just z >>= goSibling >>= expandTreeTowards East
shrinkTreeFrom South z@(_, LeftCrumb s _:_)
| direction s == Horizontal = Just z >>= goSibling >>= expandTreeTowards North
shrinkTreeFrom North z@(_, RightCrumb s _:_)
| direction s == Horizontal = Just z >>= goSibling >>= expandTreeTowards South
shrinkTreeFrom dir z = goUp z >>= shrinkTreeFrom dir
top :: Zipper a -> Zipper a
top z = case goUp z of
Nothing -> z
Just z' -> top z'
toTree :: Zipper a -> Tree a
toTree = fst . top
index :: W.Stack a -> Int
index s = case toIndex (Just s) of
(_, Nothing) -> 0
(_, Just int) -> int
data BinarySpacePartition a = BinarySpacePartition { getTree :: Maybe (Tree Split) } deriving (Show, Read)
-- | an empty BinarySpacePartition to use as a default for adding windows to.
emptyBSP :: BinarySpacePartition a
emptyBSP = BinarySpacePartition Nothing
makeBSP :: Tree Split -> BinarySpacePartition a
makeBSP = BinarySpacePartition . Just
makeZipper :: BinarySpacePartition a -> Maybe (Zipper Split)
makeZipper (BinarySpacePartition Nothing) = Nothing
makeZipper (BinarySpacePartition (Just t)) = Just . toZipper $ t
size :: BinarySpacePartition a -> Int
size = maybe 0 numLeaves . getTree
zipperToBinarySpacePartition :: Maybe (Zipper Split) -> BinarySpacePartition b
zipperToBinarySpacePartition Nothing = BinarySpacePartition Nothing
zipperToBinarySpacePartition (Just z) = BinarySpacePartition . Just . toTree . top $ z
rectangles :: BinarySpacePartition a -> Rectangle -> [Rectangle]
rectangles (BinarySpacePartition Nothing) _ = []
rectangles (BinarySpacePartition (Just Leaf)) rootRect = [rootRect]
rectangles (BinarySpacePartition (Just node)) rootRect =
rectangles (makeBSP . left $ node) leftBox ++
rectangles (makeBSP . right $ node) rightBox
where (leftBox, rightBox) = split (direction info) (ratio info) rootRect
info = value node
doToNth :: (Zipper Split -> Maybe (Zipper Split)) -> BinarySpacePartition a -> Int -> BinarySpacePartition a
doToNth f b n = zipperToBinarySpacePartition $ makeZipper b >>= goToNthLeaf n >>= f
splitNth :: BinarySpacePartition a -> Int -> BinarySpacePartition a
splitNth (BinarySpacePartition Nothing) _ = makeBSP Leaf
splitNth b n = doToNth splitCurrentLeaf b n
removeNth :: BinarySpacePartition a -> Int -> BinarySpacePartition a
removeNth (BinarySpacePartition Nothing) _ = emptyBSP
removeNth (BinarySpacePartition (Just Leaf)) _ = emptyBSP
removeNth b n = doToNth removeCurrentLeaf b n
rotateNth :: BinarySpacePartition a -> Int -> BinarySpacePartition a
rotateNth (BinarySpacePartition Nothing) _ = emptyBSP
rotateNth b@(BinarySpacePartition (Just Leaf)) _ = b
rotateNth b n = doToNth rotateCurrentLeaf b n
swapNth :: BinarySpacePartition a -> Int -> BinarySpacePartition a
swapNth (BinarySpacePartition Nothing) _ = emptyBSP
swapNth b@(BinarySpacePartition (Just Leaf)) _ = b
swapNth b n = doToNth swapCurrentLeaf b n
growNthTowards :: Bound -> BinarySpacePartition a -> Int -> BinarySpacePartition a
growNthTowards _ (BinarySpacePartition Nothing) _ = emptyBSP
growNthTowards _ b@(BinarySpacePartition (Just Leaf)) _ = b
growNthTowards dir b n = doToNth (expandTreeTowards dir) b n
shrinkNthFrom :: Bound -> BinarySpacePartition a -> Int -> BinarySpacePartition a
shrinkNthFrom _ (BinarySpacePartition Nothing) _ = emptyBSP
shrinkNthFrom _ b@(BinarySpacePartition (Just Leaf)) _ = b
shrinkNthFrom dir b n = doToNth (shrinkTreeFrom dir) b n
instance LayoutClass BinarySpacePartition a where
doLayout b r s = return (zip ws rs, layout b) where
ws = W.integrate s
layout bsp
| l == count = Just bsp
| l > count = layout $ splitNth bsp n
| otherwise = layout $ removeNth bsp n
where count = size bsp
l = length ws
n = index s
rs = case layout b of
Nothing -> rectangles b r
Just bsp' -> rectangles bsp' r
handleMessage b m =
do ms <- (W.stack . W.workspace . W.current) `fmap` gets windowset
fs <- (M.keys . W.floating) `fmap` gets windowset
return $ ms >>= unfloat fs >>= handleMesg
where handleMesg s = msum [fmap (`rotate` s) (fromMessage m)
,fmap (`resize` s) (fromMessage m)
,fmap (`swap` s) (fromMessage m)
]
unfloat fs s = if W.focus s `elem` fs
then Nothing
else Just (s { W.up = W.up s \\ fs
, W.down = W.down s \\ fs })
rotate Rotate s = rotateNth b $ index s
swap Swap s = swapNth b $ index s
resize (ExpandTowards dir) s = growNthTowards dir b $ index s
resize (ShrinkFrom dir) s = shrinkNthFrom dir b $ index s
description _ = "BSP"
