xmonad-config/lib/SendXMsg.hs

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module SendXMsg (sendXMsg, splitXMsg) where
import Data.Char
import Graphics.X11.Types
import Graphics.X11.Xlib.Atom
import Graphics.X11.Xlib.Display
import Graphics.X11.Xlib.Event
import Graphics.X11.Xlib.Extras
sendXMsg :: String -> String -> IO ()
sendXMsg magic tag = do
dpy <- openDisplay ""
root <- rootWindow dpy $ defaultScreen dpy
allocaXEvent $ \e -> do
setEventType e clientMessage
-- NOTE: This function is written such that the penultimate
-- argument represents the first 40 bits of the 160 bit data
-- field, and it also only takes a decimal digit, which means the
-- string to be stored in the data field needs to be converted to
-- its decimal equivalent. The penultimate argument will be used
-- for the magic string and the last will be used for the tag.
setClientMessageEvent e root bITMAP 8 m t
sendEvent dpy root False substructureNotifyMask e
flush dpy
where
m = str2digit magic
t = str2digit $ tag ++ [garbageDelim]
-- WORKAROUND: setClientMessageEvent seems to put garbage on the end
-- of the data field (which is probably some yucky c problem I don't
-- understand). Easy solution, put something at the end of the tag to
-- separate the tag from the garbage
garbageDelim :: Char
garbageDelim = '~'
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splitXMsg :: (Integral a) => [a] -> (String, String)
splitXMsg s = (magic, filter isAlphaNum . takeWhile (/= garbageDelim) $ tag)
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where
(magic, tag) = splitAt 5 $ map (chr . fromInteger . toInteger) s
str2digit :: (Num a) => String -> a
str2digit = fromIntegral
. sum
. map (\(p, n) -> n * 256 ^ p)
. zip [0 :: Int ..]
. map fromEnum