New Module: XMonad.Hooks.WorkspaceScreen

In a multi-head setup, it might be useful to have screen information of the
visible workspaces combined with the workspace name, for example in a status
bar. This module provides utility functions to do just that.

CHANGES.md

@@ -40,6 +40,12 @@
     A wrapper around the 'ReadP' parser combinator, providing behaviour
     that's closer to the more popular parser combinator libraries.
 
+  * `XMonad.Hooks.StatusBar.WorkspaceScreen`
+
+    In multi-head setup, it might be useful to have screen information of the
+    visible workspaces combined with the workspace name, for example in a status
+    bar. This module provides utility functions to do just that.
+
 ### Bug Fixes and Minor Changes
 
   * `XMonad.Prompt.OrgMode`

XMonad/Hooks/StatusBar/WorkspaceScreen.hs

@@ -0,0 +1,105 @@
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE TypeApplications #-}
+
+{- |
+ Module      :  XMonad.Hooks.StatusBar.WorkspaceScreen
+ Description :  Combine workspace names with screen information
+ Copyright   :  (c) Yecine Megdiche <yecine.megdiche@gmail.com>
+ License     :  BSD3-style (see LICENSE)
+
+ Maintainer  :  Yecine Megdiche <yecine.megdiche@gmail.com>
+ Stability   :  unstable
+ Portability :  unportable
+
+ In multi-head setup, it might be useful to have screen information of the
+ visible workspaces combined with the workspace name, for example in a status
+ bar. This module provides utility functions to do just that.
+-}
+module XMonad.Hooks.StatusBar.WorkspaceScreen
+    (
+    -- * Usage
+    -- $usage
+      combineWithScreen
+    , combineWithScreenName
+    , combineWithScreenNumber
+    , WorkspaceScreenCombiner
+    -- * Limitations
+    -- $limitations
+    ) where
+
+import           Graphics.X11.Xrandr
+import           XMonad
+import           XMonad.Hooks.StatusBar.PP
+import           XMonad.Prelude
+import qualified XMonad.StackSet               as W
+
+{- $usage
+ You can use this module with the following in your @~\/.xmonad\/xmonad.hs@:
+
+ > import XMonad
+ > import XMonad.Hooks.StatusBar
+ > import XMonad.Hooks.StatusBar.PP
+ > import XMonad.Hooks.StatusBar.WorkspaceScreen
+
+ For example, to add the screen number in parentheses to each visible
+ workspace number, you can use 'combineWithScreenNumber':
+
+ > myWorkspaceScreenCombiner :: WorkspaceId -> String -> String
+ > myWorkspaceScreenCombiner w sc = w <> wrap "(" ")" sc
+ >
+ > mySB = statusBarProp "xmobar" (combineWithScreenNumber myWorkspaceScreenCombiner xmobarPP)
+ > main = xmonad $ withEasySB mySB defToggleStrutsKey def
+
+ This will annotate the workspace names as following:
+
+ > [1(0)] 2 3 4 <5(1)> 6 7 8 9
+
+ To use the screen's name instead, checkout 'combineWithScreenName':
+
+ > [1(eDP-1)] 2 3 4 <5(HDMI-1)> 6 7 8 9
+
+ For advanced cases, use 'combineWithScreen'.
+-}
+
+{- $limitations
+ For simplicity, this module assumes xmonad screen ids match screen/monitor
+ numbers as managed by the X server (for example, as given by @xrandr
+ --listactivemonitors@). Thus, it may not work well when screens show an
+ overlapping range of the framebuffer, e.g. when using a projector. This also
+ means that it doesn't work with "XMonad.Layout.LayoutScreens".
+ (This isn't difficult to fix, PRs welcome.)
+-}
+
+-- | Type synonym for a function that combines a workspace name with a screen.
+type WorkspaceScreenCombiner = WorkspaceId -> WindowScreen -> String
+
+-- | A helper function that returns a list of screen names.
+screenNames :: X [Maybe String]
+screenNames = do
+    XConf { display, theRoot } <- ask
+    let getName mi = getAtomName display (xrr_moninf_name mi)
+    io
+        $   maybe (pure []) (traverse getName)
+        =<< xrrGetMonitors display theRoot True
+
+-- | Combine a workspace name with the screen name it's visible on.
+combineWithScreenName :: (WorkspaceId -> String -> String) -> PP -> X PP
+combineWithScreenName c = combineWithScreen $ do
+    screens <- screenNames
+    return $ \w sc -> maybe w (c w) $ join (screens !? fi (W.screen sc))
+
+-- | Combine a workspace name with the screen number it's visible on.
+combineWithScreenNumber :: (WorkspaceId -> String -> String) -> PP -> X PP
+combineWithScreenNumber c =
+    combineWithScreen . return $ \w sc -> c w (show @Int . fi . W.screen $ sc)
+
+-- | Combine a workspace name with a screen according to the given
+-- 'WorkspaceScreenCombiner'.
+combineWithScreen :: X WorkspaceScreenCombiner -> PP -> X PP
+combineWithScreen xCombiner pp = do
+    combiner <- xCombiner
+    ss       <- withWindowSet (return . W.screens)
+    return $ pp
+        { ppRename = ppRename pp <=< \s w ->
+            maybe s (combiner s) (find ((== W.tag w) . W.tag . W.workspace) ss)
+        }

xmonad-contrib.cabal

@@ -200,6 +200,7 @@ library
                         XMonad.Hooks.SetWMName
                         XMonad.Hooks.StatusBar
                         XMonad.Hooks.StatusBar.PP
+                        XMonad.Hooks.StatusBar.WorkspaceScreen
                         XMonad.Hooks.TaffybarPagerHints
                         XMonad.Hooks.ToggleHook
                         XMonad.Hooks.UrgencyHook