add Propane.Colour

Propane.hs

@@ -1,11 +1,13 @@
 module Propane
     ( module Propane.Types
+    , module Propane.Helpers
     , module Propane.Raster
     , module Propane.IO
-    , module Propane.Helpers
+    , module Propane.Colour
     ) where
 
 import Propane.Types
+import Propane.Helpers
 import Propane.Raster
 import Propane.IO
-import Propane.Helpers
+import Propane.Colour

Propane/Colour.hs

@@ -0,0 +1,32 @@
+module Propane.Colour
+    ( BaseColour
+    , opaque, transparent, withOpacity
+    , blend, over, darken, dissolve
+    ) where
+
+import qualified Data.Colour as C
+
+import Propane.Types
+
+type BaseColour = C.Colour R
+
+opaque :: BaseColour -> Colour
+opaque = C.opaque
+
+withOpacity :: BaseColour -> R -> Colour
+withOpacity = C.withOpacity
+
+transparent :: Colour
+transparent = C.transparent
+
+blend :: R -> Colour -> Colour -> Colour
+blend = C.blend
+
+over :: Colour -> Colour -> Colour
+over = C.over
+
+darken :: R -> Colour -> Colour
+darken = C.darken
+
+dissolve :: R -> Colour -> Colour
+dissolve = C.darken

examples/green.hs

@@ -1,5 +1,4 @@
 import Propane
-import Data.Colour
 import Data.Colour.Names
 
 main = saveImage "out.png" (Size 400 400) (const (opaque green))

propane.cabal

@@ -18,9 +18,10 @@ library
   exposed-modules:
       Propane
     , Propane.Types
+    , Propane.Helpers
     , Propane.Raster
     , Propane.IO
-    , Propane.Helpers
+    , Propane.Colour
   ghc-options:      -Wall
   build-depends:
       base         >= 3 && < 5