aboutsummaryrefslogtreecommitdiffstats
path: root/XMonad/Layout/MultiToggle.hs
blob: ebf41b0af148027b5e7dd7086e6493762158e6b5 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
{-# LANGUAGE DeriveDataTypeable, ExistentialQuantification, Rank2Types, MultiParamTypeClasses, FunctionalDependencies, FlexibleInstances, FlexibleContexts, PatternGuards #-}

-----------------------------------------------------------------------------
-- |
-- Module      :  XMonad.Layout.MultiToggle
-- Copyright   :  (c) Lukas Mai
-- License     :  BSD-style (see LICENSE)
--
-- Maintainer  :  <l.mai@web.de>
-- Stability   :  unstable
-- Portability :  unportable
--
-- Dynamically apply and unapply transformers to your window layout. This can
-- be used to rotate your window layout by 90 degrees, or to make the
-- currently focused window occupy the whole screen (\"zoom in\") then undo
-- the transformation (\"zoom out\").

module XMonad.Layout.MultiToggle (
    -- * Usage
    -- $usage
    Transformer(..),
    Toggle(..),
    (??),
    EOT(..),
    single,
    mkToggle,
    mkToggle1
) where

import XMonad

import XMonad.StackSet (Workspace(..))

import Control.Arrow
import Data.Typeable
import Data.Maybe

-- $usage
-- The basic idea is to have a base layout and a set of layout transformers,
-- of which at most one is active at any time. Enabling another transformer
-- first disables any currently active transformer; i.e. it works like a
-- group of radio buttons.
--
-- A side effect of this meta-layout is that layout transformers no longer
-- receive any messages; any message not handled by MultiToggle itself will
-- undo the current layout transformer, pass the message on to the base
-- layout, then reapply the transformer.
--
-- To use this module, you need some data types which represent
-- transformers; for some commonly used transformers (including
-- MIRROR, NOBORDERS, and FULL used in the examples below) you can
-- simply import "XMonad.Layout.MultiToggle.Instances".
--
-- Somewhere else in your file you probably have a definition of @layout@;
-- the default looks like this:
--
-- > layout = tiled ||| Mirror tiled ||| Full
--
-- After changing this to
--
-- > layout = mkToggle (single MIRROR) (tiled ||| Full)
--
-- you can now dynamically apply the 'XMonad.Layout.Mirror' transformation:
--
-- > ...
-- >   , ((modm,               xK_x     ), sendMessage $ Toggle MIRROR)
-- > ...
--
-- (That should be part of your key bindings.) When you press @mod-x@, the
-- active layout is mirrored. Another @mod-x@ and it's back to normal.
--
-- It's also possible to stack @MultiToggle@s.  For example:
--
-- @
-- layout = id
--     . 'XMonad.Layout.NoBorders.smartBorders'
--     . mkToggle (NOBORDERS ?? FULL ?? EOT)
--     . mkToggle (single MIRROR)
--     $ tiled ||| 'XMonad.Layout.Grid.Grid' ||| 'XMonad.Layout.Circle.Circle'
-- @
--
-- By binding a key to @(sendMessage $ Toggle FULL)@ you can temporarily
-- maximize windows, in addition to being able to rotate layouts and remove
-- window borders.
--
-- You can also define your own transformers by creating a data type
-- which is an instance of the 'Transformer' class.  For example, here
-- is the definition of @MIRROR@:
--
-- > data MIRROR = MIRROR deriving (Read, Show, Eq, Typeable)
-- > instance Transformer MIRROR Window where
-- >     transform _ x k = k (Mirror x)
--
-- Note, you need to put @{-\# LANGUAGE DeriveDataTypeable \#-}@ at the
-- beginning of your file.

-- | A class to identify custom transformers (and look up transforming
-- functions by type).
class (Eq t, Typeable t) => Transformer t a | t -> a where
    transform :: (LayoutClass l a) => t -> l a -> (forall l'. (LayoutClass l' a) => l' a -> b) -> b

data EL a = forall l. (LayoutClass l a) => EL (l a)

unEL :: EL a -> (forall l. (LayoutClass l a) => l a -> b) -> b
unEL (EL x) k = k x

transform' :: (Transformer t a) => t -> EL a -> EL a
transform' t el = el `unEL` \l -> transform t l EL

-- | Toggle the specified layout transformer.
data Toggle a = forall t. (Transformer t a) => Toggle t
    deriving (Typeable)

instance (Typeable a) => Message (Toggle a)

data MultiToggleS ts l a = MultiToggleS (l a) (Maybe Int) ts
    deriving (Read, Show)

data MultiToggle ts l a = MultiToggle{
    baseLayout :: l a,
    currLayout :: EL a,
    currIndex :: Maybe Int,
    currTrans :: EL a -> EL a,
    transformers :: ts
}

expand :: (LayoutClass l a, HList ts a) => MultiToggleS ts l a -> MultiToggle ts l a
expand (MultiToggleS b i ts) =
    resolve ts (fromMaybe (-1) i) id
        (\x mt ->
            let g = transform' x in
            mt{
                currLayout = g . EL $ baseLayout mt,
                currTrans = g
            }
        )
        (MultiToggle b (EL b) i id ts)

collapse :: MultiToggle ts l a -> MultiToggleS ts l a
collapse mt = MultiToggleS (baseLayout mt) (currIndex mt) (transformers mt)

instance (LayoutClass l a, Read (l a), HList ts a, Read ts) => Read (MultiToggle ts l a) where
    readsPrec p s = map (first expand) $ readsPrec p s

instance (Show ts, Show (l a)) => Show (MultiToggle ts l a) where
    showsPrec p = showsPrec p . collapse

-- | Construct a @MultiToggle@ layout from a transformer table and a base
-- layout.
mkToggle :: (LayoutClass l a) => ts -> l a -> MultiToggle ts l a
mkToggle ts l = MultiToggle l (EL l) Nothing id ts

-- | Construct a @MultiToggle@ layout from a single transformer and a base
-- layout.
mkToggle1 :: (LayoutClass l a) => t -> l a -> MultiToggle (HCons t EOT) l a
mkToggle1 t = mkToggle (single t)

-- | Marks the end of a transformer list.
data EOT = EOT deriving (Read, Show)
data HCons a b = HCons a b deriving (Read, Show)

infixr 0 ??
-- | Prepend an element to a heterogeneous list. Used to build transformer
-- tables for 'mkToggle'.
(??) :: (HList b w) => a -> b -> HCons a b
(??) = HCons

-- | Construct a singleton transformer table.
single :: a -> HCons a EOT
single = (?? EOT)

class HList c a where
    find :: (Transformer t a) => c -> t -> Maybe Int
    resolve :: c -> Int -> b -> (forall t. (Transformer t a) => t -> b) -> b

instance HList EOT w where
    find EOT _ = Nothing
    resolve EOT _ d _ = d

instance (Transformer a w, HList b w) => HList (HCons a b) w where
    find (HCons x xs) t
        | t `geq` x = Just 0
        | otherwise = fmap succ (find xs t)
    resolve (HCons x xs) n d k =
        case n `compare` 0 of
            LT -> d
            EQ -> k x
            GT -> resolve xs (pred n) d k

geq :: (Typeable a, Eq a, Typeable b) => a -> b -> Bool
geq a b = Just a == cast b

acceptChange :: (LayoutClass l' a) => MultiToggle ts l a -> ((l' a -> MultiToggle ts l a) -> b -> c) -> X b -> X c
acceptChange mt f = fmap (f (\x -> mt{ currLayout = EL x }))

instance (Typeable a, Show ts, HList ts a, LayoutClass l a) => LayoutClass (MultiToggle ts l) a where
    description mt = currLayout mt `unEL` \l -> description l

    runLayout (Workspace i mt s) r
        | isNothing (currIndex mt) =
            acceptChange mt (fmap . fmap . \f x -> (f x){ baseLayout = x }) $ runLayout (Workspace i (baseLayout mt) s) r
        | otherwise = currLayout mt `unEL` \l ->
            acceptChange mt (fmap . fmap) $ runLayout (Workspace i l s) r

    handleMessage mt m
        | Just (Toggle t) <- fromMessage m
        , i@(Just _) <- find (transformers mt) t
            = currLayout mt `unEL` \l ->
            if i == currIndex mt
                then do
                    handleMessage l (SomeMessage ReleaseResources)
                    return . Just $
                        mt{
                            currLayout = EL $ baseLayout mt,
                            currIndex = Nothing,
                            currTrans = id
                        }
                else do
                    handleMessage l (SomeMessage ReleaseResources)
                    let f = transform' t
                    return . Just $
                        mt{
                            currLayout = f . EL $ baseLayout mt,
                            currIndex = i,
                            currTrans = f
                        }
        | fromMessage m == Just ReleaseResources ||
          fromMessage m == Just Hide
            = currLayout mt `unEL` \l -> acceptChange mt fmap (handleMessage l m)
        | otherwise = do
            ml <- handleMessage (baseLayout mt) m
            case ml of
                Nothing -> return Nothing
                Just b' -> currLayout mt `unEL` \l -> do
                    handleMessage l (SomeMessage ReleaseResources)
                    return . Just $
                        mt{ baseLayout = b', currLayout = currTrans mt . EL $ b' }