{-# OPTIONS -fglasgow-exts #-}
-----------------------------------------------------------------------------
-- |
-- Module : XMonad.hs
-- Copyright : (c) Spencer Janssen 2007
-- License : BSD3-style (see LICENSE)
--
-- Maintainer : sjanssen@cse.unl.edu
-- Stability : unstable
-- Portability : not portable, uses cunning newtype deriving
--
-----------------------------------------------------------------------------
--
-- The X monad, a state monad transformer over IO, for the window
-- manager state, and support routines.
--
module XMonad (
X, WindowSet, WorkspaceId(..), ScreenId(..), XState(..), XConf(..), Layout(..),
Typeable, Message, SomeMessage(..), fromMessage,
runX, io, withDisplay, withWorkspace, isRoot, spawn, restart, trace, whenJust, whenX
) where
import StackSet (StackSet)
import Control.Monad.State
import Control.Monad.Reader
import System.IO
import System.Posix.Process (executeFile, forkProcess, getProcessStatus, createSession)
import System.Exit
import System.Environment
import Graphics.X11.Xlib
import Data.Typeable
import qualified Data.Map as M
-- | XState, the window manager state.
-- Just the display, width, height and a window list
data XState = XState
{ windowset :: !WindowSet -- ^ workspace list
, xineScreens :: ![Rectangle] -- ^ dimensions of each screen
, dimensions :: !(Position,Position) -- ^ dimensions of the screen,
, statusGaps :: ![(Int,Int,Int,Int)] -- ^ width of status bar on each screen
, layouts :: !(M.Map WorkspaceId (Layout, [Layout])) }
-- ^ mapping of workspaces to descriptions of their layouts
data XConf = XConf
{ display :: Display -- ^ the X11 display
, theRoot :: !Window -- ^ the root window
, wmdelete :: !Atom -- ^ window deletion atom
, wmprotocols :: !Atom -- ^ wm protocols atom
, normalBorder :: !Color -- ^ border color of unfocused windows
, focusedBorder :: !Color } -- ^ border color of the focused window
type WindowSet = StackSet WorkspaceId Window ScreenId
-- | Virtual workspace indicies
newtype WorkspaceId = W Int deriving (Eq,Ord,Show,Read,Enum,Num,Integral,Real)
-- | Physical screen indicies
newtype ScreenId = S Int deriving (Eq,Ord,Show,Read,Enum,Num,Integral,Real)
------------------------------------------------------------------------
-- | The X monad, a StateT transformer over IO encapsulating the window
-- manager state
--
-- Dynamic components may be retrieved with 'get', static components
-- with 'ask'. With newtype deriving we get readers and state monads
-- instantiated on XConf and XState automatically.
--
newtype X a = X (ReaderT XConf (StateT XState IO) a)
deriving (Functor, Monad, MonadIO, MonadState XState, MonadReader XConf)
-- | Run the X monad, given a chunk of X monad code, and an initial state
-- Return the result, and final state
runX :: XConf -> XState -> X a -> IO ()
runX c st (X a) = runStateT (runReaderT a c) st >> return ()
-- ---------------------------------------------------------------------
-- Convenient wrappers to state
-- | Run a monad action with the current display settings
withDisplay :: (Display -> X a) -> X a
withDisplay f = asks display >>= f
-- | Run a monadic action with the current workspace
withWorkspace :: (WindowSet -> X a) -> X a
withWorkspace f = gets windowset >>= f
-- | True if the given window is the root window
isRoot :: Window -> X Bool
isRoot w = liftM (w==) (asks theRoot)
------------------------------------------------------------------------
-- Layout handling
-- | The different layout modes
-- 'doLayout', a pure function to layout a Window set 'modifyLayout',
-- 'modifyLayout' can be considered a branch of an exception handler.
--
data Layout = Layout { doLayout :: Rectangle -> [Window] -> X [(Window, Rectangle)]
, modifyLayout :: SomeMessage -> Maybe Layout }
-- Based on ideas in /An Extensible Dynamically-Typed Hierarchy of Exceptions/,
-- Simon Marlow, 2006. Use extensible messages to the modifyLayout handler.
--
-- User-extensible messages must be a member of this class:
--
class Typeable a => Message a
--
-- A wrapped value of some type in the Message class.
--
data SomeMessage = forall a. Message a => SomeMessage a
--
-- And now, unwrap a given, unknown Message type, performing a (dynamic)
-- type check on the result.
--
fromMessage :: Message m => SomeMessage -> Maybe m
fromMessage (SomeMessage m) = cast m
-- ---------------------------------------------------------------------
-- General utilities
-- | Lift an IO action into the X monad
io :: IO a -> X a
io = liftIO
-- | spawn. Launch an external application
spawn :: String -> X ()
spawn x = io $ do
pid <- forkProcess $ do
forkProcess (createSession >> executeFile "/bin/sh" False ["-c", x] Nothing)
exitWith ExitSuccess
getProcessStatus True False pid
return ()
-- | Restart xmonad via exec().
--
-- If the first parameter is 'Just name', restart will attempt to execute the
-- program corresponding to 'name'. Otherwise, xmonad will attempt to execute
-- the name of the current program.
--
-- When the second parameter is 'True', xmonad will attempt to resume with the
-- current window state.
restart :: Maybe String -> Bool -> X ()
restart mprog resume = do
prog <- maybe (io $ getProgName) return mprog
args <- if resume then gets (("--resume":) . return . show . windowset) else return []
io $ catch (executeFile prog True args Nothing)
(const $ return ()) -- ignore executable not found exception
-- | Run a side effecting action with the current workspace. Like 'when' but
whenJust :: Maybe a -> (a -> X ()) -> X ()
whenJust mg f = maybe (return ()) f mg
-- | Conditionally run an action, using a X event to decide
whenX :: X Bool -> X () -> X ()
whenX a f = a >>= \b -> when b f
-- | Grab the X server (lock it) from the X monad
-- withServerX :: X () -> X ()
-- withServerX f = withDisplay $ \dpy -> do
-- io $ grabServer dpy
-- f
-- io $ ungrabServer dpy
-- | A 'trace' for the X monad. Logs a string to stderr. The result may
-- be found in your .xsession-errors file
trace :: String -> X ()
trace msg = io $! do hPutStrLn stderr msg; hFlush stderr
