FlexibleResize - Resize from edge, don't move adjust at opposite edge

When resizing other corners than bottom-right, instead of adjusting to even columns/rows on the opposite side to it the same way as if resizing was made from the bottom right.

Also add the possibility to add an area in the middle of an edge where only that edge is resized, not the closest corner.

XMonad/Actions/FlexibleResize.hs

@@ -15,7 +15,8 @@
 module XMonad.Actions.FlexibleResize (
         -- * Usage
         -- $usage
-        XMonad.Actions.FlexibleResize.mouseResizeWindow
+        XMonad.Actions.FlexibleResize.mouseResizeWindow,
+        XMonad.Actions.FlexibleResize.mouseResizeEdgeWindow
 ) where
 
 import XMonad
@@ -35,33 +36,46 @@ import Foreign.C.Types
 
 -- | Resize a floating window from whichever corner the mouse is
 --   closest to.
-mouseResizeWindow :: Window -> X ()
-mouseResizeWindow w = whenX (isClient w) $ withDisplay $ \d -> do
+mouseResizeWindow
+  :: Window -- ^ The window to resize.
+  -> X ()
+mouseResizeWindow = mouseResizeEdgeWindow 0
+
+
+-- | Resize a floating window from whichever corner or edge the mouse is
+--   closest to.
+mouseResizeEdgeWindow
+  :: Rational -- ^ The size of the area where only one edge is resized.
+  -> Window   -- ^ The window to resize.
+  -> X ()
+mouseResizeEdgeWindow edge w = whenX (isClient w) $ withDisplay $ \d -> do
     io $ raiseWindow d w
     wa <- io $ getWindowAttributes d w
     sh <- io $ getWMNormalHints d w
     (_, _, _, _, _, ix, iy, _) <- io $ queryPointer d w
     let
-        [pos_x, pos_y, width, height] = map (fromIntegral . ($ wa)) [wa_x, wa_y, wa_width, wa_height]
-        west  = firstHalf ix width
-        north = firstHalf iy height
+        [pos_x, pos_y, width, height] = map (fi . ($ wa)) [wa_x, wa_y, wa_width, wa_height]
+        west  = findPos ix width
+        north = findPos iy height
         (cx, fx, gx) = mkSel west  width  pos_x
         (cy, fy, gy) = mkSel north height pos_y
     io $ warpPointer d none w 0 0 0 0 cx cy
-    mouseDrag (\ex ey -> do
-                 wa' <- io $ getWindowAttributes d w
-                 let [px, py] = map (fromIntegral . ($ wa')) [wa_x, wa_y]
-                 io $ moveResizeWindow d w (fx px (fromIntegral ex))
-                                           (fy py (fromIntegral ey))
-                            `uncurry` applySizeHintsContents sh (gx $ fromIntegral ex, gy $ fromIntegral ey))
+    mouseDrag (\ex ey -> do let (nw,nh) = applySizeHintsContents sh (gx ex, gy ey)
+                            io $ moveResizeWindow d w (fx nw) (fy nh) nw nh)
               (float w)
     where
-    firstHalf :: CInt -> Position -> Bool
-    firstHalf a b = fromIntegral a * 2 <= b
-    cfst = curry fst
-    csnd = curry snd
-    mkSel :: Bool -> Position -> Position -> (Position, a -> a -> a, CInt -> Position)
-    mkSel b k p =
-        if b
-            then (0, csnd, ((k + p) -) . fromIntegral)
-            else (k, cfst, subtract p  . fromIntegral)
+    findPos :: CInt -> Position -> Maybe Bool
+    findPos m s = if p < 0.5 - edge/2
+                  then Just True
+                  else if p < 0.5 + edge/2
+                       then Nothing
+                       else Just False
+                  where p = fi m / fi s
+    mkSel :: Maybe Bool -> Position -> Position -> (Position, Dimension -> Position, Position -> Dimension)
+    mkSel b k p = case b of
+                      Just True ->  (0, (fi k + fi p -).fi, (fi k + fi p -).fi)
+                      Nothing ->    (k `div` 2, const p, const $ fi k)
+                      Just False -> (k, const p, subtract (fi p) . fi)
+
+fi :: (Num b, Integral a) => a -> b
+fi = fromIntegral