[xmonad] X () with side effects

[Jochen Keil]

Hi,

On 08/14/2011 07:07 PM, Brandon Allbery wrote:
> On Sun, Aug 14, 2011 at 06:05, Jochen Keil <jochen.keil at gmail.com>
> wrote:
>
>> However, if I call foo from a keybinding
>>
>> ((modMask, xK_x), foo)
>>
>> the spawned program will run but not mapped. This means that I can
>> see the console output in xmonad stdout/stderr but the window will
>> not pop up. I think this is because of the internal handling of
>> keyevents in
>>
>
> It's because your function is doing stuff instead of listening for X
> events.  If you want to go off and do something else, forkIO a thread
I've already tried forkIO, xfork, seq, par, etc. all with more or less
the same result: the program's window will be mapped only after the
function returns.

> for the something else.  If your something else requires communication
> with X11, you'll need to think about rewriting around the event
> handler instead.
I can't see how to do this at the moment. Is this even possible? As far
as I understand/stood the xmonad code it's all about grabbing events.

>> code I have written. It's some kind of of vi-mode behaviour for
>> xmonad.
>>
>
> XMonad.Actions.Submap would be a good starting point for this.  Not an
> ideal one, as  it doesn't support timeouts or grabbing an entire
> submap.
Well, at least the timeout issue is solved. :)
Concerning the submap. I currently take my regular keymap and AND the
complemented modMask from the modifier. Then I feed this into my vi-mode
function as keymap.

But maybe you want to take a look for yourself. I've attached the code
inline below.

Regards,

Jochen



defaultConfig { keys = myKeyMap conf etc `Data.Map.union` viKeys conf }


viKeys (XConfig { XMonad.modMask = modMask }) keyMap =
    M.fromList $
    [ ((modMask, xK_z), viMode modMask xK_z (myKeyHandler keyMap)) ]
    where
    cleanMask mod = complement modMask .&. mod
    myKeyHandler km m k =
            M.lookup (cleanMask m, k) $
            M.mapKeys (\(mod, key) -> (cleanMask mod, key)) $
            M.delete (modMask, xK_z) km


module XMonad.Actions.ViMode
    ( viMode
    ) where

import Data.Map as M
import Data.Maybe (fromMaybe)

import XMonad hiding (workspaces)
import qualified XMonad.StackSet as W

keyEvent :: Display -> IO (EventType, ButtonMask, Time, KeySym)
keyEvent d = do
    allocaXEvent $ \p -> do
        maskEvent d (keyPressMask .|. keyReleaseMask) p
        KeyEvent { ev_event_type = e
                 , ev_state = s
                 , ev_time = t
                 , ev_keycode = kc} <- getEvent p
        fmap (\ks -> (e, s, t, ks)) $ keycodeToKeysym d kc 0

grabKeys :: X ()
grabKeys = do
    XConf {theRoot = root, display = d} <- ask
    io $ grabKeyboard d root False grabModeAsync grabModeAsync currentTime
    return ()

releaseKeys :: X ()
releaseKeys = do
    d <- asks display
    io $ ungrabKeyboard d currentTime

viMode :: ButtonMask -> KeySym
       -> (ButtonMask -> KeySym -> Maybe (X ()))
       -> X ()
viMode mod key f = asks display >>= cycleKeys (mod, key, 0, True) f

cycleKeys :: (ButtonMask, KeySym, Time, Bool)
          -> (ButtonMask -> KeySym -> Maybe (X ()))
          -> Display
          -> X ()
cycleKeys (mod, key, last, grab) keyHandler d = do
    if grab
    then grabKeys >> cycleKeys (mod, key, last, False) keyHandler d
    else do
        io $ flush d
        timeout <- io $ waitForEvent d 1000000
        if timeout
        then releaseKeys
        else io (keyEvent d) >>= keyDecision
    where
    keyDecision (e, s, t, ks)
        | e == keyPress && s == mod && ks == key = releaseKeys
        | e == keyPress = do
            case keyHandler s ks of
                Just action -> do
                    action
                    cycleKeys (mod, key, t, False) keyHandler d
                Nothing -> releaseKeys
        | otherwise = cycleKeys (mod, key, t, False) keyHandler d

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