implement Affection.Property dsl

affection.cabal

@@ -41,6 +41,7 @@ library
                      , Affection.Types
                      , Affection.StateMachine
                      , Affection.MouseInteractable
+                     , Affection.Property
   default-extensions:  OverloadedStrings
 
   -- Modules included in this library but not exported.

examples/example00.hs

@@ -46,18 +46,18 @@ load _ = do
   traceM "loading"
   root <- G.gegl_node_new
   traceM "new root node"
-  checkerboard <- G.gegl_node_new_child root $ G.checkerboardOperation
-    [ G.Property "color1" $ G.PropertyColor $ G.RGBA 0.4 0.4 0.4 1
-    , G.Property "color2" $ G.PropertyColor $ G.RGBA 0.6 0.6 0.6 1
-    ]
+  checkerboard <- G.gegl_node_new_child root $ G.checkerboardOperation $
+    props $ do
+        prop "color1" $ G.RGBA 0.4 0.4 0.4 1
+        prop "color2" $ G.RGBA 0.6 0.6 0.6 1
   traceM "checkerboard"
   over <- G.gegl_node_new_child root G.defaultOverOperation
   traceM "over"
-  text <- G.gegl_node_new_child root $ G.textOperation
-    [ G.Property "string" $ G.PropertyString "Hello world!"
-    , G.Property "color"  $ G.PropertyColor $ G.RGBA 0 0 1 0.5
-    , G.Property "size"   $ G.PropertyDouble 40
-    ]
+  text <- G.gegl_node_new_child root $ G.textOperation $
+    props $ do
+        prop "string" ("Hello world!"::String)
+        prop "color" $ G.RGBA 0 0 1 0.5
+        prop "size" (40::Int)
   traceM "text"
   G.gegl_node_link checkerboard over
   G.gegl_node_connect_to text "output" over "aux"

examples/example01.hs

@@ -48,25 +48,25 @@ load _ = do
   traceM "loading"
   root <- G.gegl_node_new
   traceM "new root node"
-  checkerboard <- G.gegl_node_new_child root $ G.checkerboardOperation
-    [ G.Property "color1" $ G.PropertyColor $ G.RGBA 0.4 0.4 0.4 1
-    , G.Property "color2" $ G.PropertyColor $ G.RGBA 0.6 0.6 0.6 1
-    ]
+  checkerboard <- G.gegl_node_new_child root $ G.checkerboardOperation $
+    props $ do
+        prop "color1" $ G.RGBA 0.4 0.4 0.4 1
+        prop "color2" $ G.RGBA 0.6 0.6 0.6 1
   traceM "checkerboard"
   over <- G.gegl_node_new_child root G.defaultOverOperation
   traceM "over"
   buffer <- G.gegl_buffer_new (Just $ G.GeglRectangle 0 0 800 600) =<<
     B.babl_format (B.PixelFormat B.RGBA B.CFfloat)
-  sink <- G.gegl_node_new_child root $ G.Operation "gegl:copy-buffer"
-    [ G.Property "buffer" $ G.PropertyBuffer buffer
-    ]
+  sink <- G.gegl_node_new_child root $ G.Operation "gegl:copy-buffer" $
+    props $
+    prop "buffer" buffer
   traceM "buffer-source"
   nop <- G.gegl_node_new_child root $ G.Operation "gegl:nop" []
   traceM "nop"
-  crop <- G.gegl_node_new_child root $ G.Operation "gegl:crop"
-    [ G.Property "width" $ G.PropertyDouble 800
-    , G.Property "height" $ G.PropertyDouble 600
-    ]
+  crop <- G.gegl_node_new_child root $ G.Operation "gegl:crop" $
+    props $ do
+        prop "width" (800::Double)
+        prop "height" (600.0::Double)
   G.gegl_node_link_many [checkerboard, over, crop, sink]
   G.gegl_node_connect_to nop "output" over "aux"
   traceM "connections made"

src/Affection.hs

@@ -13,6 +13,7 @@ module Affection
     , getDelta
     , quit
     , module A
+    , module Affection.Property
     ) where
 
 import qualified SDL
@@ -38,6 +39,7 @@ import Affection.Draw as A
 import Affection.Particle as A
 import Affection.StateMachine as A
 import Affection.MouseInteractable as A
+import Affection.Property
 
 import qualified BABL as B
 

src/Affection/Property.hs

@@ -0,0 +1,42 @@
+{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE FlexibleInstances #-}
+module Affection.Property where
+
+import Control.Monad.State.Lazy
+import qualified GEGL as G
+import qualified BABL as B
+import GHC.Ptr (Ptr)
+
+type Props a = State [G.Property] a
+
+props :: Props a -> [G.Property]
+props = flip execState []
+
+prop :: IsPropertyValue v => String -> v -> Props ()
+prop k v = do
+  ps <- get
+  put $ (G.Property k (toPropertyValue v)) : ps
+
+class IsPropertyValue v where
+  toPropertyValue :: v -> G.PropertyValue
+
+instance IsPropertyValue Int where
+  toPropertyValue = G.PropertyInt
+
+instance IsPropertyValue String where
+  toPropertyValue = G.PropertyString
+
+instance IsPropertyValue Double where
+  toPropertyValue = G.PropertyDouble
+
+instance IsPropertyValue G.Color where
+  toPropertyValue = G.PropertyColor
+
+instance IsPropertyValue B.PixelFormat where
+  toPropertyValue = G.PropertyFormat
+
+instance IsPropertyValue G.GeglBuffer where
+  toPropertyValue = G.PropertyBuffer
+
+instance IsPropertyValue (Ptr ()) where
+  toPropertyValue = G.PropertyPointer