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243 lines
11 KiB
Haskell
243 lines
11 KiB
Haskell
{-# LANGUAGE NamedFieldPuns #-}
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-----------------------------------------------------------------------------
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-- |
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-- Module : XMonad.Hooks.WindowSwallowing
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-- Copyright : (c) 2020 Leon Kowarschick
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-- License : BSD3-style (see LICENSE)
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--
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-- Maintainer : Leon Kowarschick. <thereal.elkowar@gmail.com>
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-- Stability : unstable
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-- Portability : unportable
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--
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-- Provides a handleEventHook that implements window swallowing.
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--
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-- If you open a GUI-window (i.e. feh) from the terminal,
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-- the terminal will normally still be shown on screen, unnecessarily
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-- taking up space on the screen.
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-- With window swallowing, can detect that you opened a window from within another
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-- window, and allows you "swallow" that parent window for the time the new
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-- window is running.
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--
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-- __NOTE__: This module depends on @pstree@ to analyze the process hierarchy, so make
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-- sure that is on your @$PATH@.
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--
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-- __NOTE__ that this does not always work perfectly:
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--
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-- - Because window swallowing needs to check the process hierarchy, it requires
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-- both the child and the parent to be distinct processes. This means that
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-- applications which implement instance sharing cannot be supported by window swallowing.
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-- Most notably, this excludes some terminal emulators as well as tmux
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-- from functioning as the parent process. It also excludes a good amount of
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-- child programs, because many graphical applications do implement instance sharing.
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-- For example, window swallowing will probably not work with your browser.
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--
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-- - To check the process hierarchy, we need to be able to get the process ID
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-- by looking at the window. This requires the @_NET_WM_PID@ X-property to be set.
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-- If any application you want to use this with does not provide the @_NET_WM_PID@,
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-- there is not much you can do except for reaching out to the author of that
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-- application and asking them to set that property.
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-----------------------------------------------------------------------------
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module WindowSwallowing
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( swallowEventHook
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)
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where
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import XMonad
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import qualified XMonad.StackSet as W
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import qualified XMonad.Util.ExtensibleState as XS
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import XMonad.Util.WindowProperties
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import XMonad.Util.Run ( runProcessWithInput )
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import Data.Semigroup ( All(..) )
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import qualified Data.Map.Strict as M
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import Data.List ( isInfixOf )
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import Control.Monad ( when )
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-- $usage
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-- You can use this module by including the following in your @~\/.xmonad/xmonad.hs@:
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--
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-- > import XMonad.Hooks.WindowSwallowing
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--
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-- and using 'swallowEventHook' somewhere in your 'handleEventHook', for example:
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--
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-- > myHandleEventHook = swallowEventHook (className =? "Alacritty" <||> className =? "Termite") (return True)
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--
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-- For more information on editing your handleEventHook and key bindings,
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-- see "XMonad.Doc.Extending".
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-- | handleEventHook that will swallow child windows when they are
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-- opened from another window.
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swallowEventHook
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:: Query Bool -- ^ query the parent window has to match for window swallowing to occur.
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-- Set this to @return True@ to run swallowing for every parent.
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-> Query Bool -- ^ query the child window has to match for window swallowing to occur.
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-- Set this to @return True@ to run swallowing for every child
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-> Event -- ^ The event to handle.
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-> X All
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swallowEventHook parentQueries childQueries event = do
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case event of
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-- This is called right before a window gets opened. We intercept that
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-- call to possibly open the window ourselves, swapping out
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-- it's parent processes window for the new window in the stack.
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MapRequestEvent { ev_window = childWindow } ->
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-- For a window to be opened from within another window, that other window
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-- must be focused. Thus the parent window that would be swallowed has to be
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-- the currently focused window.
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withFocused $ \parentWindow -> do
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-- First verify that both windows match the given queries
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parentMatches <- runQuery parentQueries parentWindow
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childMatches <- runQuery childQueries childWindow
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when (parentMatches && childMatches) $ do
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-- read the windows _NET_WM_PID properties
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childWindowPid <- getProp32s "_NET_WM_PID" childWindow
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parentWindowPid <- getProp32s "_NET_WM_PID" parentWindow
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case (parentWindowPid, childWindowPid) of
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(Just (parentPid : _), Just (childPid : _)) -> do
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-- check if the new window is a child process of the last focused window
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-- using the process ids.
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isChild <- liftIO $ fi childPid `isChildOf` fi parentPid
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when isChild $ do
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-- We set the newly opened window as the focused window, replacing the parent window.
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-- If the parent window was floating, we transfer that data to the child,
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-- such that it shows up at the same position, with the same dimensions.
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windows
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( W.modify' (\x -> x { W.focus = childWindow })
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. moveFloatingState parentWindow childWindow
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)
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XS.modify (addSwallowedParent parentWindow childWindow)
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_ -> return ()
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return ()
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-- This is called in many circumstances, most notably for us:
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-- right before a window gets closed. We store the current
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-- state of the window stack here, such that we know where the
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-- child window was on the screen when restoring the swallowed parent process.
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ConfigureEvent{} -> withWindowSet $ \ws -> do
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XS.modify . setStackBeforeWindowClosing . currentStack $ ws
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XS.modify . setFloatingBeforeWindowClosing . W.floating $ ws
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-- This is called right after any window closes.
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DestroyWindowEvent { ev_event = eventId, ev_window = childWindow } ->
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-- Because DestroyWindowEvent is emitted a lot more often then you think,
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-- this check verifies that the event is /actually/ about closing a window.
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when (eventId == childWindow) $ do
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-- we get some data from the extensible state, most notably we ask for
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-- the \"parent\" window of the now closed window.
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maybeSwallowedParent <- XS.gets (getSwallowedParent childWindow)
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maybeOldStack <- XS.gets stackBeforeWindowClosing
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oldFloating <- XS.gets floatingBeforeClosing
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case (maybeSwallowedParent, maybeOldStack) of
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(Just parent, Just oldStack) -> do
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-- If there actually is a corresponding swallowed parent window for this window,
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-- we will try to restore it.
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-- because there are some cases where the stack-state is not stored correctly in the ConfigureEvent hook,
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-- we have to first check if the stack-state is valid.
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-- if it is, we can restore the parent exactly where the child window was before being closed
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-- if the stored stack-state is invalid however, we still restore the window
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-- by just inserting it as the focused window in the stack.
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stackStoredCorrectly <- do
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curStack <- withWindowSet (return . currentStack)
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let oldLen = length (W.integrate oldStack)
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let curLen = length (W.integrate' curStack)
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return (oldLen - 1 == curLen && childWindow == W.focus oldStack)
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if stackStoredCorrectly
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then windows
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(\ws ->
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updateCurrentStack
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(const $ Just $ oldStack { W.focus = parent })
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$ moveFloatingState childWindow parent
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$ ws { W.floating = oldFloating }
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)
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else windows (insertIntoStack parent)
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-- after restoring, we remove the information about the swallowing from the state.
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XS.modify $ removeSwallowed childWindow
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XS.modify $ setStackBeforeWindowClosing Nothing
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_ -> return ()
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return ()
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_ -> return ()
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return $ All True
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-- | insert a window as focused into the current stack, moving the previously focused window down the stack
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insertIntoStack :: a -> W.StackSet i l a sid sd -> W.StackSet i l a sid sd
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insertIntoStack win = W.modify
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(Just $ W.Stack win [] [])
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(\s -> Just $ s { W.focus = win, W.down = W.focus s : W.down s })
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-- | run a pure transformation on the Stack of the currently focused workspace.
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updateCurrentStack
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:: (Maybe (W.Stack a) -> Maybe (W.Stack a))
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-> W.StackSet i l a sid sd
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-> W.StackSet i l a sid sd
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updateCurrentStack f = W.modify (f Nothing) (f . Just)
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currentStack :: W.StackSet i l a sid sd -> Maybe (W.Stack a)
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currentStack = W.stack . W.workspace . W.current
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-- | move the floating state from one window to another, sinking the original window
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moveFloatingState
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:: Ord a
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=> a -- ^ window to move from
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-> a -- ^ window to move to
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-> W.StackSet i l a s sd
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-> W.StackSet i l a s sd
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moveFloatingState from to ws = ws
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{ W.floating = M.delete from $ maybe (M.delete to (W.floating ws))
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(\r -> M.insert to r (W.floating ws))
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(M.lookup from (W.floating ws))
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}
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-- | check if a given process is a child of another process. This depends on "pstree" being in the PATH
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-- NOTE: this does not work if the child process does any kind of process-sharing.
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isChildOf
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:: Int -- ^ child PID
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-> Int -- ^ parent PID
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-> IO Bool
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isChildOf child parent = do
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output <- runProcessWithInput "pstree" ["-T", "-p", show parent] ""
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return $ any (show child `isInfixOf`) $ lines output
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data SwallowingState =
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SwallowingState
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{ currentlySwallowed :: M.Map Window Window -- ^ mapping from child window window to the currently swallowed parent window
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, stackBeforeWindowClosing :: Maybe (W.Stack Window) -- ^ current stack state right before DestroyWindowEvent is sent
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, floatingBeforeClosing :: M.Map Window W.RationalRect -- ^ floating map of the stackset right before DestroyWindowEvent is sent
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} deriving (Typeable, Show)
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getSwallowedParent :: Window -> SwallowingState -> Maybe Window
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getSwallowedParent win SwallowingState { currentlySwallowed } =
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M.lookup win currentlySwallowed
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addSwallowedParent :: Window -> Window -> SwallowingState -> SwallowingState
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addSwallowedParent parent child s@SwallowingState { currentlySwallowed } =
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s { currentlySwallowed = M.insert child parent currentlySwallowed }
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removeSwallowed :: Window -> SwallowingState -> SwallowingState
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removeSwallowed child s@SwallowingState { currentlySwallowed } =
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s { currentlySwallowed = M.delete child currentlySwallowed }
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setStackBeforeWindowClosing
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:: Maybe (W.Stack Window) -> SwallowingState -> SwallowingState
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setStackBeforeWindowClosing stack s = s { stackBeforeWindowClosing = stack }
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setFloatingBeforeWindowClosing
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:: M.Map Window W.RationalRect -> SwallowingState -> SwallowingState
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setFloatingBeforeWindowClosing x s = s { floatingBeforeClosing = x }
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instance ExtensionClass SwallowingState where
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initialValue = SwallowingState { currentlySwallowed = mempty
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, stackBeforeWindowClosing = Nothing
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, floatingBeforeClosing = mempty
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}
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fi :: (Integral a, Num b) => a -> b
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fi = fromIntegral
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