1 files changed, 155 insertions, 0 deletions
diff --git a/src/Rahm/Desktop/LayoutDraw.hs b/src/Rahm/Desktop/LayoutDraw.hs
new file mode 100644
index 0000000..c3d8c9e
--- /dev/null
+++ b/src/Rahm/Desktop/LayoutDraw.hs
@@ -0,0 +1,155 @@
+{-# LANGUAGE FlexibleInstances, FlexibleContexts, MultiParamTypeClasses,
+ScopedTypeVariables, BangPatterns #-}
+module Rahm.Desktop.LayoutDraw (drawLayout) where
+
+import Control.Monad
+
+import Control.Arrow (second)
+import Control.Concurrent (threadDelay)
+import Control.Exception (handle)
+import Control.Monad.Writer (execWriter, tell)
+import Data.Foldable (find)
+import Data.Maybe (fromMaybe)
+import Rahm.Desktop.Hash (quickHash)
+import Rahm.Desktop.Layout (ZoomModifier(..))
+import System.Directory (createDirectoryIfMissing, doesFileExist)
+import System.FilePath ((</>))
+import Text.Printf (printf)
+import XMonad.Layout.Spacing (SpacingModifier(..), Border(..))
+
+import XMonad (X,
+               Rectangle(..),
+               Dimension,
+               LayoutClass,
+               Message,
+               Window,
+               SomeMessage(..))
+
+import qualified XMonad as X
+import qualified XMonad.StackSet as S
+
+-- Draws and returns an XPM for the current layout.
+--
+-- Returns
+--  - Bool   - true if the xpm has already been written, and is thus cached.
+--  - String - description of the current layout
+--  - String - the text to send to XMobar
+--
+-- This function actually runs the current layout's doLayout function to
+-- generate the XPM, so it's completely portable to all layouts.
+--
+-- Note this function is impure and running the layout to create the XPM is also
+-- impure. While in-practice most layouts are pure, it should be kept in mind.
+drawLayout :: X (Bool, String, String)
+drawLayout = do
+    winset <- X.gets X.windowset
+    let layout = S.layout $ S.workspace $ S.current winset
+
+    -- Gotta reset the layout to a consistent state.
+    layout' <- foldM (flip ($)) layout [
+         handleMessage' $ ModifyWindowBorder $ const $ Border 0 0 0 0,
+         handleMessage' Unzoom
+       ]
+
+    (cached, xpm) <- drawXpmIO layout'
+
+    return (cached , X.description layout, printf "<icon=%s/>" xpm)
+
+-- Returns true if a point is inside a rectangle (inclusive).
+pointInRect :: (Dimension, Dimension) -> Rectangle -> Bool
+pointInRect (x, y) (Rectangle x' y' w h) =
+  x <= (fi x' + fi w) && x >= fi x' && y <= (fi y' + fi h) && y >= fi y'
+  where
+    fi :: (Integral a, Num b) => a -> b
+    fi = fromIntegral
+
+-- Scale factory. Scaling the rectangles before writing the XPM helps to reduce
+-- noise from things like AvoidStruts, as there is unfortunately no way to force
+-- avoid struts to be off, one can only toggle it.
+sf :: (Integral a) => a
+sf = 1024
+
+handleMessage' ::
+    (LayoutClass layout a, Message m) => m -> layout a -> X (layout a)
+handleMessage' message layout  = do
+  fromMaybe layout <$> X.handleMessage layout (SomeMessage message)
+
+-- Creates the XPM for the given layout and returns the path to it.
+--
+-- This function does run doLayout on the given layout, and that should be
+-- accounted for.
+drawXpmIO :: (LayoutClass layout Window) => layout Window -> X (Bool, String)
+drawXpmIO l = do
+  dir <- X.getXMonadDir
+
+  let shrinkAmt = 5 -- amount to shrink the windows by to make pretty gaps.
+
+  let (w, h) = (56, 24)
+  let descr = X.description l
+  let iconCacheDir = dir </> "icons" </> "cache"
+  let iconPath = iconCacheDir </> (quickHash descr ++ ".xpm")
+
+  let colors = [
+        "#cc9a9a", "#cc9999", "#cc8080", "#cc6666",
+        "#cc4c4c", "#cc3232", "#cc1818", "#cc0000" ]
+
+  (rects', _) <-
+    X.runLayout
+      (S.Workspace "0" l (S.differentiate [1 .. 5]))
+      (Rectangle 0 0 ((w + shrinkAmt) * sf) ((h + shrinkAmt) * sf))
+
+  let rects = flip map rects' $ \(_, Rectangle x y w h) ->
+                Rectangle (x `div` sf) (y `div` sf) (w `div` sf) (h `div` sf)
+
+  X.liftIO $ do
+    exists <- doesFileExist iconPath
+    createDirectoryIfMissing True iconCacheDir
+
+    unless exists $ do
+      let xpmText = drawXpm (w, h) (zip (cycle colors) rects) 4
+      writeFile iconPath xpmText
+
+    return (exists, iconPath)
+
+--
+-- Create's an XPM, purely. Returns a string with the XPM contents.
+-- Takes as arguments
+--
+--   - dimensions of the icon.
+--   - list of (color, rectangle) pairs.
+--   - The amount to shrink the windows by for those pretty gaps.
+--
+drawXpm ::
+    (Dimension, Dimension) -> [(String, Rectangle)] -> Dimension -> String
+drawXpm (w, h) rects' shrinkAmt = execWriter $ do
+    tell "/* XPM */\n"
+    tell "static char *out[] = {\n"
+    tell $ printf "\"%d %d %d 1 \",\n" w h (length rects + 1)
+
+    let zipRects = zip ['A' .. 'Z'] rects
+
+    forM_ zipRects $ \(char, (color, _)) -> do
+      tell $ printf "\"%c c %s\",\n" char color
+    tell "\"% c None\"a,\n"
+
+    forM_ [0 .. h - 1] $ \y -> do
+      tell "\""
+      forM_ [0 .. w - 1] $ \x ->
+        (case find (matches x y) zipRects of
+          Nothing -> tell "%"
+          Just (chr, _) -> tell [chr])
+      tell "\""
+      when (y /= h - 1 - shrinkAmt) (tell ",")
+      tell "\n"
+    tell "};\n"
+
+  where
+    matches x y (_, (_, r)) = pointInRect (x, y) r
+    rects = map (second (shrink shrinkAmt)) rects'
+    guard a b = if a <= shrinkAmt then 1 else b
+    shrink amt (Rectangle x y w h) =
+      Rectangle
+        x
+        y
+        (guard w $ w - fromIntegral amt)
+        (guard h $ h - fromIntegral amt)