UpdatePointer: Make pointer position configurable.

XMonad/Actions/UpdatePointer.hs

@@ -19,6 +19,7 @@ module XMonad.Actions.UpdatePointer
      -- * Usage
      -- $usage
      updatePointer
+     , PointerPosition (..)
     )
     where
 
@@ -33,24 +34,42 @@ import Control.Monad
 --
 -- Enable it by including it in your logHook definition. Eg:
 -- 
--- > logHook = updatePointer
+-- > logHook = updatePointer Nearest
 -- 
--- which will move the pointer to the nearest point of a newly focused window
+-- which will move the pointer to the nearest point of a newly focused window, or
+--
+-- > logHook = updatePointer (Relative 0.5 0.5)
+--
+-- which will move the pointer to the center of a newly focused window.
+--
+-- To use this with an existing logHook, use >> :
+--
+-- > logHook = dynamicLog
+-- >           >> updatePointer (RelativePosition 1 1)
+--
+-- which moves the pointer to the bottom-right corner of the focused window.
 
+data PointerPosition = Nearest | Relative Rational Rational
 
--- | Update the pointer's location to the nearest point of the currently focused
+-- | Update the pointer's location to the currently focused
 -- window unless it's already there
-updatePointer ::  X ()
-updatePointer = withFocused $ \w -> do
+updatePointer :: PointerPosition -> X ()
+updatePointer p = withFocused $ \w -> do
   dpy <- asks display
   root <- asks theRoot
   wa <- io $ getWindowAttributes dpy w
   (_sameRoot,_,w',rootx,rooty,_,_,_) <- io $ queryPointer dpy root
   -- Can sameRoot ever be false in this case? I'm going to assume not
-  unless (w == w') $ do
+  unless (w == w') $
+    case p of
+    Nearest -> do
       let x = moveWithin rootx (wa_x wa) ((wa_x wa) + (wa_width  wa))
       let y = moveWithin rooty (wa_y wa) ((wa_y wa) + (wa_height wa))
       io $ warpPointer dpy none root 0 0 0 0 (fromIntegral x) (fromIntegral y)
+    Relative h v ->
+      io $ warpPointer dpy none w 0 0 0 0
+           (fraction h (wa_width wa)) (fraction v (wa_height wa))
+        where fraction x y = floor (x * fromIntegral y)
 
 moveWithin :: Integral a => a -> a -> a -> a
 moveWithin current lower upper =