X.A.UpKeys: Init

Original implementation from https://stackoverflow.com/a/11308086

XMonad/Actions/UpKeys.hs

@@ -0,0 +1,169 @@
+{-# LANGUAGE BlockArguments #-}
+{-# LANGUAGE InstanceSigs #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE TypeApplications #-}
+{- |
+   Module      : XMonad.Actions.UpKeys
+   Description : Bind an action to the release of a key
+   Copyright   : (c) Tony Zorman, 2024
+   License     : BSD-3
+   Maintainer  : Tony Zorman <soliditsallgood@mailbox.org>
+
+A combinator for binding an action to the release of a key. This can be
+useful for hold-type buttons, where the press of a key engages some
+functionality, and its release… releases it again.
+-}
+module XMonad.Actions.UpKeys
+  ( -- * Usage
+    -- $usage
+    useUpKeys,
+    UpKeysConfig (..),
+    ezUpKeys,
+  )
+where
+
+import Data.Map.Strict (Map)
+import qualified Data.Map.Strict as Map
+import XMonad
+import XMonad.Prelude
+import XMonad.Util.EZConfig (mkKeymap)
+import qualified XMonad.Util.ExtensibleConf as XC
+
+{- $usage
+You can use this module with the following in your @xmonad.hs@:
+
+> import XMonad.Actions.UpKeys
+
+Next, define the keys and actions you want to have happen on the release
+of a key:
+
+> myUpKeys = ezUpKeys $
+>   [ ("M-z", myAction)
+>   , ("M-a", myAction2)
+>   ]
+
+All that's left is to plug this definition into the 'useUpKeys'
+combinator that this module provides:
+
+> main :: IO ()
+> main = xmonad
+>      . useUpKeys (def{ grabKeys = True, upKeys = myUpKeys })
+>      $ myConfig
+
+Note the presence of @'grabKeys' = True@; this is for situations where
+you don't have any of these keys bound to do something upon pressing
+them; i.e., you use them solely for their release actions. If you want
+something to happen in both cases, remove that part (@'grabKeys' =
+False@ is the default) and bind the keys to actions as you normally
+would.
+
+==== __Examples__
+
+As an extended example, consider the case where you want all of your
+docks (e.g., status bar) to "pop up" when you press the super key, and
+then vanish again once that keys is released.
+
+Since docks are not generally part of XMonad's window-set—otherwise, we
+would have to manage them—we first need a way to access and manipulate
+all docks.
+
+> onAllDocks :: (Display -> Window -> IO ()) -> X ()
+> onAllDocks act = withDisplay \dpy -> do
+>   rootw <- asks theRoot
+>   (_, _, wins) <- io $ queryTree dpy rootw
+>   traverse_ (io . act dpy) =<< filterM (runQuery checkDock) wins
+
+This is also the place where one could filter for just status bar,
+trayer, and so on.
+
+Now we have to decide what kinds of keys we want to watch out for. Since
+you most likely use left super as your modifier key, this is a little
+bit more complicated than for other keys, as you will most likely see
+the key both as a @KeyMask@, as well as a @KeySym@. One could think a
+bit and probably come up with an elegant solution for this—or one could
+grab all possible key combinations by brute-force!
+
+> dockKeys :: X () -> [((KeyMask, KeySym), X ())]
+> dockKeys act = map (actKey . foldr1 (.|.)) . combinations $ keyMasks
+>  where
+>   actKey :: KeyMask -> ((KeyMask, KeySym), X ())
+>   actKey mask = ((mask, xK_Super_L), act)
+>
+>   keyMasks :: [KeyMask]
+>   keyMasks = [ noModMask, shiftMask, lockMask, controlMask, mod1Mask, mod2Mask, mod3Mask, mod4Mask, mod5Mask ]
+>
+>   -- Return all combinations of a sequence of values.
+>   combinations :: [a] -> [[a]]
+>   combinations xs = concat [combs i xs | i <- [1 .. length xs]]
+>    where
+>     combs 0 _      = [[]]
+>     combs _ []     = []
+>     combs n (x:xs) = map (x:) (combs (n-1) xs) <> combs n xs
+
+Given some action, like lowering or raising the window, we generate all
+possible combinations of modifiers that may be pressed with the super
+key. This is a good time to say that this is just for demonstrative
+purposes, btw—please don't actually do this.
+
+All that's left is to plug everything into the machinery of this module,
+and we're done!
+
+> import qualified Data.Map.Strict as Map
+>
+> main :: IO ()
+> main = xmonad
+>      . … -- other combinators
+>      . useUpKeys (def { upKeys = Map.fromList $ dockKeys (onAllDocks lowerWindow) })
+>      $ myConfig `additionalKeys` dockKeys (onAllDocks raiseWindow)
+>
+> myConfig = …
+-}
+
+data UpKeysConfig = UpKeysConfig
+  { -- | Whether to grab all keys that are not already grabbed.
+    grabKeys :: !Bool
+    -- | The keys themselves.
+  , upKeys :: !(Map (KeyMask, KeySym) (X ()))
+  }
+
+-- | The default 'UpKeysConfig'; keys are not grabbed, and no upkeys are
+-- specified.
+instance Default UpKeysConfig where
+  def :: UpKeysConfig
+  def = UpKeysConfig { grabKeys = False, upKeys = mempty }
+
+instance Semigroup UpKeysConfig where
+  (<>) :: UpKeysConfig -> UpKeysConfig -> UpKeysConfig
+  UpKeysConfig g u <> UpKeysConfig g' u' = UpKeysConfig (g && g') (u <> u')
+
+-- | Bind actions to keys upon their release.
+useUpKeys :: UpKeysConfig -> (XConfig l -> XConfig l)
+useUpKeys upKeysConf = flip XC.once upKeysConf \conf -> conf
+  { handleEventHook = handleEventHook conf <> (\e -> handleKeyUp e $> All True)
+  , startupHook     = startupHook     conf <> when (grabKeys upKeysConf) grabUpKeys
+  }
+ where
+  grabUpKeys :: X ()
+  grabUpKeys = do
+    XConf{ display = dpy, theRoot = rootw } <- ask
+    realKeys <- maybe mempty upKeys <$> XC.ask @X @UpKeysConfig
+    let grab :: (KeyMask, KeyCode) -> X ()
+        grab (km, kc) = io $ grabKey dpy kc km rootw True grabModeAsync grabModeAsync
+    traverse_ grab =<< mkGrabs (Map.keys realKeys)
+
+-- | Parse the given EZConfig-style keys into the internal keymap
+-- representation.
+--
+-- This is just 'mkKeymap' with a better name.
+ezUpKeys :: XConfig l -> [(String, X ())] -> Map (KeyMask, KeySym) (X ())
+ezUpKeys = mkKeymap
+
+-- | A handler for key-up events.
+handleKeyUp :: Event -> X ()
+handleKeyUp KeyEvent{ ev_event_type, ev_state, ev_keycode }
+  | ev_event_type == keyRelease = withDisplay \dpy -> do
+      s   <- io $ keycodeToKeysym dpy ev_keycode 0
+      cln <- cleanMask ev_state
+      ks  <- maybe mempty upKeys <$> XC.ask @X @UpKeysConfig
+      userCodeDef () $ whenJust (ks Map.!? (cln, s)) id
+handleKeyUp _ = pure ()

xmonad-contrib.cabal

@@ -154,6 +154,7 @@ library
                         XMonad.Actions.TreeSelect
                         XMonad.Actions.UpdateFocus
                         XMonad.Actions.UpdatePointer
+                        XMonad.Actions.UpKeys
                         XMonad.Actions.Warp
                         XMonad.Actions.WindowBringer
                         XMonad.Actions.WindowGo