Circle layout

Windows are arranged in a circle around the master window. Rather nice to use
with a mouse, if you got many windows open.

Screenshot: http://caladan.rave.org/circle.png

Circle.hs

@@ -0,0 +1,30 @@
+module XMonadContrib.Circle (circle) where -- actually it's an ellipse
+
+import Graphics.X11.Xlib
+import XMonad
+
+circle :: Layout
+circle = Layout { doLayout = circleLayout,
+                  modifyLayout = const Nothing }
+
+circleLayout :: Rectangle -> [Window] -> X [(Window, Rectangle)]
+circleLayout _ []     = return []
+circleLayout r (w:ws) = return $ (w, center r) : (zip ws sats)
+    where sats = map (satellite r) $ take (length ws) [0, pi * 2 / fromIntegral (length ws) ..]
+
+center :: Rectangle -> Rectangle
+center (Rectangle sx sy sw sh) = Rectangle x y w h
+    where w = round ((fromIntegral sw / sqrt 2) :: Double)
+          h = round ((fromIntegral sh / sqrt 2) :: Double)
+          x = sx + fromIntegral (sw - w) `div` 2
+          y = sy + fromIntegral (sh - h) `div` 2
+
+satellite :: Rectangle -> Double -> Rectangle
+satellite (Rectangle sx sy sw sh) a = Rectangle (sx + round (rx + rx * cos a))
+                                                (sy + round (ry + ry * sin a))
+                                                w h
+    where rx = fromIntegral (sw - w) / 2
+          ry = fromIntegral (sh - h) / 2
+          w = sw * 10 `div` 25
+          h = sh * 10 `div` 25
+