rofi-extras/app/current-output.hs

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module Main (main) where
--------------------------------------------------------------------------------
-- | Return current xrandr output name
--
-- Since this seems random, the reason for this is that I want rofi to appear
-- over the current xmonad workspace, and rofi has no concept of what an
-- xmonad workspace is (not that it is supposed to, xmonad is weird...). Rofi
-- accepts the name of an xrandr output onto which it should appear, so this
-- script provides a way to determine which xmonad workspace is in focus and
-- provide the name of the output displaying said workspace.
--
-- Assumptions: xmonad sets the _NET_DESKTOP_VIEWPORT atom with the positions of
-- the active workspace (actually an array of the positions of all workspaces
-- but the rest don't matter if I only care about the active one). This is not
-- default behavior and not in any contrib modules (yet) so I added this myself
-- using a custom loghook.
--
-- Steps:
-- 1) Get _NET_CURRENT_DESKTOP to find index of active workspace
-- 2) Use index from (1) and to get the position of the active workspace from
-- _NET_DESKTOP_VIEWPORT
-- 3) Find the name of the xrandr output whose position matches that from (2)
import Data.Maybe (catMaybes, maybe)
import Graphics.X11.Types
import Graphics.X11.Xlib
import Graphics.X11.Xlib.Extras
import Graphics.X11.Xrandr
import System.Exit
main :: IO ()
main = getMonitorName >>= maybe exitFailure (\n -> putStrLn n >> exitSuccess)
data Coord = Coord Int Int
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deriving (Eq, Show)
getMonitorName :: IO (Maybe String)
getMonitorName = do
dpy <- openDisplay ""
root <- rootWindow dpy $ defaultScreen dpy
index <- getCurrentDesktopIndex dpy root
viewports <- getDesktopViewports dpy root
outputs <- getOutputs dpy root
return $ flip lookup outputs =<< (viewports !!?) =<< index
getCurrentDesktopIndex :: Display -> Window -> IO (Maybe Int)
getCurrentDesktopIndex dpy root =
(!!? 0) <$> getAtom32 dpy root "_NET_CURRENT_DESKTOP"
getDesktopViewports :: Display -> Window -> IO [Coord]
getDesktopViewports dpy root =
pairs <$> getAtom32 dpy root "_NET_DESKTOP_VIEWPORT"
where
pairs = reverse . pairs' []
pairs' acc [] = acc
pairs' acc [_] = acc
pairs' acc (x1:x2:xs) = pairs' (Coord x1 x2 : acc) xs
getOutputs :: Display -> Window -> IO [(Coord, String)]
getOutputs dpy root = xrrGetScreenResourcesCurrent dpy root >>=
maybe (return []) resourcesToCells
where
resourcesToCells r = catMaybes <$> mapM (outputToCell r) (xrr_sr_outputs r)
outputToCell r o = xrrGetOutputInfo dpy r o >>= infoToCell r
-- connection: 0 == connected, 1 == disconnected
infoToCell r (Just XRROutputInfo { xrr_oi_connection = 0
, xrr_oi_name = n
, xrr_oi_crtc = c
}) = do
cinfo <- xrrGetCrtcInfo dpy r c
return $ fmap (\i -> (toCoord i, n)) cinfo
infoToCell _ _ = return Nothing
toCoord c = Coord (fromIntegral $ xrr_ci_x c) (fromIntegral $ xrr_ci_y c)
infix 9 !!?
(!!?) :: [a] -> Int -> Maybe a
(!!?) xs i
| i < 0 = Nothing
| otherwise = go i xs
where
go :: Int -> [a] -> Maybe a
go 0 (x:_) = Just x
go j (_:ys) = go (j - 1) ys
go _ [] = Nothing
getAtom32 :: Display -> Window -> String -> IO [Int]
getAtom32 dpy root str = do
a <- internAtom dpy str False
p <- getWindowProperty32 dpy a root
return $ maybe [] (fmap fromIntegral) p