This patch adds support for multiple master windows to X.L.Master

XMonad/Layout/Master.hs

@@ -17,7 +17,8 @@ module XMonad.Layout.Master (
     -- * Usage
     -- $usage
 
-    mastered
+    mastered,
+    multimastered
 ) where
 
 import XMonad
@@ -34,6 +35,10 @@ import XMonad.Layout.LayoutModifier
 --
 -- > mastered (1/100) (1/2) $ Grid
 --
+-- Or if you want multiple (here two) master windows from the beginning:
+--
+-- > multimastered 2 (1/100) (1/2) $ Grid
+--
 -- This will use the left half of your screen for a master window and let
 -- Grid manage the right half.
 --
@@ -45,42 +50,68 @@ import XMonad.Layout.LayoutModifier
 
 -- | Data type for LayoutModifier which converts given layout to a mastered
 -- layout
-data AddMaster a = AddMaster Rational Rational deriving (Show, Read)
+data AddMaster a = AddMaster Int Rational Rational deriving (Show, Read)
 
 -- | Modifier which converts given layout to a mastered one
+multimastered :: (LayoutClass l a) =>
+       Int -- ^ @k@, number of master windows
+    -> Rational -- ^ @delta@, the ratio of the screen to resize by
+    -> Rational -- ^ @frac@, what portion of the screen to use for the master window
+    -> l a      -- ^ the layout to be modified
+    -> ModifiedLayout AddMaster l a
+multimastered k delta frac = ModifiedLayout $ AddMaster k delta frac
+
 mastered :: (LayoutClass l a) =>
        Rational -- ^ @delta@, the ratio of the screen to resize by
     -> Rational -- ^ @frac@, what portion of the screen to use for the master window
     -> l a      -- ^ the layout to be modified
     -> ModifiedLayout AddMaster l a
-mastered delta frac = ModifiedLayout $ AddMaster delta frac
+mastered delta frac = multimastered 1 delta frac
 
 instance LayoutModifier AddMaster Window where
-    modifyLayout (AddMaster delta frac) = applyMaster delta frac
+    modifyLayout (AddMaster k delta frac) = applyMaster k delta frac
     modifierDescription _               = "Mastered"
 
-    pureMess (AddMaster delta frac) m
-        | Just Shrink <- fromMessage m = Just $ AddMaster delta (frac-delta)
-        | Just Expand <- fromMessage m = Just $ AddMaster delta (frac+delta)
+    pureMess (AddMaster k delta frac) m
+        | Just Shrink <- fromMessage m = Just $ AddMaster k delta (frac-delta)
+        | Just Expand <- fromMessage m = Just $ AddMaster k delta (frac+delta)
+        | Just (IncMasterN d) <- fromMessage m = Just $ AddMaster (max 1 (k+d)) delta frac
 
     pureMess _ _ = Nothing
 
 -- | Internal function for adding a master window and let the modified
 -- layout handle the rest of the windows
 applyMaster :: (LayoutClass l Window) =>
-                  Rational
+                  Int
+               -> Rational
                -> Rational
                -> S.Workspace WorkspaceId (l Window) Window
                -> Rectangle
                -> X ([(Window, Rectangle)], Maybe (l Window))
-applyMaster _ frac wksp rect = do
+applyMaster k _ frac wksp rect = do
     let st= S.stack wksp
     let ws = S.integrate' $ st
-    if length ws > 1 then do
-        let m = head ws
-        let (mr, sr) = splitHorizontallyBy frac rect
-        let nst = st>>= S.filter (m/=)
-        wrs <- runLayout (wksp {S.stack = nst}) sr
-        return ((m, mr) : fst wrs, snd wrs)
-
+    let n = length ws
+    if n > 1 then do
+        if(n<=k) then
+             return ((divideCol rect ws), Nothing)
+             else do
+             let m = take k ws
+             let (mr, sr) = splitHorizontallyBy frac rect
+             let nst = st>>= S.filter (\w -> not (w `elem` m))
+             wrs <- runLayout (wksp {S.stack = nst}) sr
+             return ((divideCol mr m) ++ (fst wrs), snd wrs)
         else runLayout wksp rect
+
+-- | Shift rectangle down
+shiftD :: Position -> Rectangle -> Rectangle
+shiftD s (Rectangle x y w h) = Rectangle x (y+s) w h
+
+-- | Divide rectangle between windows
+divideCol :: Rectangle -> [a] -> [(a, Rectangle)]
+divideCol (Rectangle x y w h) ws = zip ws rects
+    where n = length ws
+          oneH = fromIntegral h `div` n
+          oneRect = Rectangle x y w (fromIntegral oneH)
+          rects = take n $ iterate (shiftD (fromIntegral oneH)) oneRect
+