(+) at least it's drawing

src/Canvas.hs

@@ -1,11 +1,11 @@
 module Canvas where
 
-import Graphics.Gloss.Data.Picture ( Picture (Text), pictures, scale, translate )
+import Graphics.Gloss.Data.Picture ( Picture (Text, Blank), pictures, scale, translate, rectangleSolid, circle )
 import Graphics.Gloss.Interface.IO.Interact ( Event (EventKey, EventMotion), KeyState (Down, Up), Key (Char, MouseButton), MouseButton (LeftButton) )
 
 type Dimension  = (Int, Int)
 type Position   = (Float, Float)
-type TipSize    = Float 
+type TipSize    = Float
 
 data Canvas = Canvas {
     items   ::  [Picture]
@@ -17,28 +17,36 @@ data Canvas = Canvas {
 
 data Mode = Brush | Eraser deriving (Eq, Show)
 
-newtype Tip = Shape TipSize 
+data Tip = Tip {
+    shape   :: Shape
+,   size    :: TipSize
+}
 
-data Shape = Rectangular | Circular 
+data Shape = Rectangular | Circular
+
+nextPicture :: Canvas -> Picture
+nextPicture (Canvas _ Brush True position (Tip Rectangular size)) = uncurry translate position $ rectangleSolid size size
+nextPicture (Canvas _ Brush True position (Tip Circular size)) = uncurry translate position $ circle size
+nextPicture _ = Blank
 
 windowSize :: Dimension
 windowSize = (500, 500)
 
-leftCornerize :: Picture -> Picture 
-leftCornerize = translate (fromIntegral $ (-(fst windowSize)) `div` 2 + (fst windowSize `div` 10)) 
+leftCornerize :: Picture -> Picture
+leftCornerize = translate (fromIntegral $ (-(fst windowSize)) `div` 2 + (fst windowSize `div` 10))
                           (fromIntegral $ (snd windowSize)    `div` 2 - (snd windowSize `div` 10))
 
-rightCornerize :: Picture -> Picture 
-rightCornerize = translate (fromIntegral $ (fst windowSize)    `div` 2 - (fst windowSize `div` 5)) 
+rightCornerize :: Picture -> Picture
+rightCornerize = translate (fromIntegral $ (fst windowSize)    `div` 2 - (fst windowSize `div` 5))
                            (fromIntegral $ (snd windowSize)    `div` 2 - (snd windowSize `div` 10))
 
 showInfo :: Canvas -> Picture
 showInfo canv = leftCornerize
-                $ scale 0.15 0.15 
+                $ scale 0.15 0.15
                 $ Text ( show (mode canv) ++ " - " ++ show (pos canv))
 
 render :: Canvas -> Picture
-render canv = pictures ( showInfo canv : items canv ) 
+render canv = pictures ( showInfo canv : items canv )
 
 handle :: Event -> Canvas -> Canvas
 handle (EventKey (Char 'b') Down _ _ ) canv               = canv { mode = Brush }
@@ -49,5 +57,5 @@ handle (EventMotion (x, y)) canv                          = canv { pos = (x, y)}
 handle _ canv = canv
 
 update :: Float -> Canvas -> Canvas
-update _ canv = canv
+update _ canv = canv { items = nextPicture canv : items canv }
 

src/Costants.hs

@@ -16,5 +16,5 @@ initial = Canvas {
 ,   mode    =   Brush
 ,   drawing =   False
 ,   pos     =   (0, 0)
-,   tip     = Rectangular 3
+,   tip     =   Tip Rectangular 3
 }