(+) change mode e <-> b

src/Canvas.hs

@@ -1,22 +1,28 @@
 module Canvas where
 
-import Graphics.Gloss.Data.Picture ( Picture, pictures )
-import Graphics.Gloss.Interface.IO.Interact ( Event )
+import Graphics.Gloss.Data.Picture ( Picture (Text), pictures )
+import Graphics.Gloss.Interface.IO.Interact ( Event (EventKey), KeyState (Down), Key (Char) )
 
-newtype Canvas = Canvas {
-    items ::    [Picture]
+data Canvas = Canvas {
+    items   ::  [Picture],
+    mode    ::  Mode   
 }
 
+data Mode = Brush | Eraser deriving (Eq, Show)
+
 initial :: Canvas
 initial = Canvas {
-    items =     []
+    items   =   [] 
+,   mode    =   Brush
 }
 
 render :: Canvas -> Picture
-render canvas = pictures ( items canvas ) 
+render canvas = pictures ( Text ( show (mode canvas)) : items canvas ) 
 
 handle :: Event -> Canvas -> Canvas
-handle _ _ = initial
+handle (EventKey (Char 'b') Down _ _ ) canv = canv { mode = Brush }
+handle (EventKey (Char 'e') Down _ _ ) canv = canv { mode = Eraser }
+handle _ canv = canv
 
 update :: Float -> Canvas -> Canvas
-update _ _ = initial 
+update _ canv = canv