Restructured widget state

1 files changed, 67 insertions, 0 deletions

diff --git a/lib/Phi/Widget.hs b/lib/Phi/Widget.hs
new file mode 100644
index 0000000..a4850e7
--- /dev/null
+++ b/lib/Phi/Widget.hs
@@ -0,0 +1,67 @@
+{-# LANGUAGE ExistentialQuantification, TypeFamilies #-}
+
+module Phi.Widget ( Widget(..)
+                  , WidgetClass(..)
+                  , WidgetState(..)
+                  , separator
+                  , createWidgetState
+                  , layoutWidgets
+                  , renderWidgets
+                  ) where
+
+import Control.Monad
+
+import Graphics.Rendering.Cairo
+
+
+class WidgetClass a where
+  type WidgetData a :: *
+  
+  initialState :: a -> WidgetData a
+  
+  minSize :: a -> Int
+  
+  weight :: a -> Float
+  weight _ = 0
+
+  layout :: a -> Int -> Int -> WidgetData a
+  layout widget _ _ = initialState widget
+  
+  render :: a -> WidgetData a -> Int -> Int -> Render ()
+
+data Widget = forall a. WidgetClass a => Widget a
+
+data WidgetState = forall a. WidgetClass a => WidgetState { stateWidget      :: a
+                                                          , stateWidth       :: Int 
+                                                          , stateHeight      :: Int
+                                                          , statePrivateData :: WidgetData a
+                                                          }
+
+createWidgetState :: Widget -> WidgetState
+createWidgetState (Widget w) = WidgetState { stateWidget = w
+                                           , stateWidth = 0
+                                           , stateHeight = 0
+                                           , statePrivateData = initialState w
+                                           }
+
+layoutWidgets :: [WidgetState] -> Int -> Int -> [WidgetState]
+layoutWidgets widgets w h = map layoutWidget widgets
+  where
+    layoutWidget state = state { stateWidth = w, stateHeight = h }
+
+renderWidgets :: [WidgetState] -> Render ()
+renderWidgets widgets = forM_ widgets $ \WidgetState { stateWidget = widget, stateWidth = w, stateHeight = h, statePrivateData = priv } -> render widget priv w h 
+
+
+data Separator = Separator Int Float
+
+instance WidgetClass Separator where
+  type WidgetData Separator = ()
+  initialState _ = ()
+  
+  minSize (Separator s _) = s
+  weight (Separator _ w) = w
+  render _ _ _ _ = return ()
+
+separator :: Int -> Float -> Widget
+separator s w = Widget $ Separator s w