PositionStore utility to store information about position and size of a window

XMonad/Util/PositionStore.hs

@@ -0,0 +1,81 @@
+{-# LANGUAGE DeriveDataTypeable #-}
+
+----------------------------------------------------------------------------
+-- |
+-- Module      :  XMonad.Util.PositionStore
+-- Copyright   :  (c) Jan Vornberger 2009
+-- License     :  BSD3-style (see LICENSE)
+--
+-- Maintainer  :  jan.vornberger@informatik.uni-oldenburg.de
+-- Stability   :  unstable
+-- Portability :  not portable
+--
+-- A utility module to store information about position and size of a window.
+--
+-----------------------------------------------------------------------------
+
+module XMonad.Util.PositionStore (
+        getPosStore,
+        modifyPosStore,
+
+        posStoreInsert,
+        posStoreMove,
+        posStoreQuery,
+        posStoreRemove
+    ) where
+
+import XMonad
+import XMonad.Util.ExtensibleState
+import Graphics.X11.Xlib
+import Graphics.X11.Types
+import Data.Typeable
+import qualified Data.Map as M
+
+-- Store window positions relative to the upper left screen edge
+-- and windows sizes as well as positions as fractions of the screen size.
+-- This way windows can be easily relocated and scaled when switching screens.
+
+data PositionStore = PS (M.Map Window PosStoreRectangle)
+                            deriving (Read,Show,Typeable)
+data PosStoreRectangle = PSRectangle Double Double Double Double
+                            deriving (Read,Show,Typeable)
+
+instance ExtensionClass PositionStore where
+  initialValue = PS M.empty
+  extensionType = PersistentExtension
+
+getPosStore :: X (PositionStore)
+getPosStore = getState
+
+modifyPosStore :: (PositionStore -> PositionStore) -> X ()
+modifyPosStore f = do
+    posStore <- getState
+    putState (f posStore)
+
+posStoreInsert :: PositionStore -> Window -> Rectangle -> Rectangle -> PositionStore
+posStoreInsert (PS posStoreMap) w (Rectangle x y wh ht) (Rectangle srX srY srWh srHt) =
+    let offsetX = x - srX
+        offsetY = y - srY
+    in PS $ M.insert w (PSRectangle (fromIntegral offsetX / fromIntegral srWh)
+                                               (fromIntegral offsetY / fromIntegral srHt)
+                                               (fromIntegral wh / fromIntegral srWh)
+                                               (fromIntegral ht / fromIntegral srHt)) posStoreMap
+
+posStoreRemove :: PositionStore -> Window -> PositionStore
+posStoreRemove (PS posStoreMap) w = PS $ M.delete w posStoreMap
+
+posStoreQuery :: PositionStore -> Window -> Rectangle -> Maybe Rectangle
+posStoreQuery (PS posStoreMap) w (Rectangle srX srY srWh srHt) = do
+    (PSRectangle x y wh ht) <- M.lookup w posStoreMap
+    let realWh = fromIntegral srWh * wh
+        realHt = fromIntegral srHt * ht
+        realOffsetX = fromIntegral srWh * x
+        realOffsetY = fromIntegral srHt * y
+    return (Rectangle (srX + round realOffsetX) (srY + round realOffsetY)
+                        (round realWh) (round realHt))
+
+posStoreMove :: PositionStore -> Window -> Position -> Position -> Rectangle -> Rectangle -> PositionStore
+posStoreMove posStore w x y oldSr newSr =
+    case (posStoreQuery posStore w oldSr) of
+        Nothing -> posStore     -- not in store, can't move -> do nothing
+        Just (Rectangle _ _ wh ht) -> posStoreInsert posStore w (Rectangle x y wh ht) newSr

xmonad-contrib.cabal

@@ -230,6 +230,7 @@ library
                         XMonad.Util.NamedScratchpad
                         XMonad.Util.NamedWindows
                         XMonad.Util.Paste
+                        XMonad.Util.PositionStore
                         XMonad.Util.Replace
                         XMonad.Util.Run
                         XMonad.Util.Scratchpad