Merge pull request #77 from LSLeary/master

A very simple extension to Navigation2D so it plays better with gaps

XMonad/Actions/Navigation2D.hs

@@ -43,6 +43,7 @@ module XMonad.Actions.Navigation2D ( -- * Usage
                                    , Navigation2D
                                    , lineNavigation
                                    , centerNavigation
+                                   , hybridNavigation
                                    , fullScreenRect
                                    , singleWindowRect
                                    , switchLayer
@@ -74,10 +75,11 @@ import XMonad.Util.Types
 -- natural but may make it impossible to navigate to a given window from the
 -- current window, particularly in the floating layer.  /Center navigation/
 -- feels less natural in certain situations but ensures that all windows can be
--- reached without the need to involve the mouse.  Navigation2D allows different
--- navigation strategies to be used in the two layers and allows customization
--- of the navigation strategy for the tiled layer based on the layout currently
--- in effect.
+-- reached without the need to involve the mouse. A third option is to use
+-- /Hybrid navigation/, which automatically chooses between the two whenever
+-- navigation is attempted.  Navigation2D allows different navigation strategies
+-- to be used in the two layers and allows customization of the navigation strategy
+-- for the tiled layer based on the layout currently in effect.
 --
 -- You can use this module with (a subset of) the following in your @~\/.xmonad\/xmonad.hs@:
 --
@@ -316,6 +318,13 @@ lineNavigation = N 1 doLineNavigation
 centerNavigation :: Navigation2D
 centerNavigation = N 2 doCenterNavigation
 
+-- | Hybrid navigation. This attempts Line navigation, then falls back on Center
+-- navigation if it does not find any suitable target windows. This is useful since
+-- Line navigation tends to fail on gaps, but provides more intuitive motions
+-- when it succeeds—provided there are no floating windows.
+hybridNavigation :: Navigation2D
+hybridNavigation = N 2 doHybridNavigation
+
 -- | Stores the configuration of directional navigation. The 'Default' instance
 -- uses line navigation for the tiled layer and for navigation between screens,
 -- and center navigation for the float layer.  No custom navigation strategies
@@ -758,6 +767,13 @@ doCenterNavigation dir (cur, rect) winrects
                                              -- or it has the same distance but comes later
                                              -- in the window stack
 
+-- | Implements Hybrid navigation. This attempts Line navigation first,
+-- then falls back on Center navigation if it finds no suitable target window.
+doHybridNavigation :: Eq a => Direction2D -> Rect a -> [Rect a] -> Maybe a
+doHybridNavigation = applyToBoth (<|>) doLineNavigation doCenterNavigation
+    where
+        applyToBoth f g h a b c = f (g a b c) (h a b c)
+
 -- | Swaps the current window with the window given as argument
 swap :: Window -> WindowSet -> WindowSet
 swap win winset = W.focusWindow cur