Add setNextWindow functions, pushColor, pushStyle, indent-related functions (#27)

src/DearImGui/Context.hs

@@ -19,14 +19,15 @@ import Language.C.Types
 
 -- dear-imgui
 import DearImGui.Structs
-  ( ImVec3, ImVec4 )
+  ( ImVec2, ImVec3, ImVec4 )
 
 --------------------------------------------------------------------------------
 
 imguiContext :: Context
 imguiContext = mempty
   { ctxTypesTable = Map.fromList
-      [ ( TypeName "ImVec3", [t| ImVec3 |] )
+      [ ( TypeName "ImVec2", [t| ImVec2 |] )
+      , ( TypeName "ImVec3", [t| ImVec3 |] )
       , ( TypeName "ImVec4", [t| ImVec4 |] )
       ]
   }

src/DearImGui/Structs.hs

@@ -8,6 +8,23 @@ import Foreign
   ( Storable(..), castPtr, plusPtr )
 
 --------------------------------------------------------------------------------
+data ImVec2 = ImVec2 { x, y :: {-# unpack #-} !Float }
+
+
+instance Storable ImVec2 where
+  sizeOf ~ImVec2{x, y} = sizeOf x + sizeOf y
+
+  alignment _ = 0
+
+  poke ptr ImVec2{ x, y } = do
+    poke (castPtr ptr `plusPtr` (sizeOf x * 0)) x
+    poke (castPtr ptr `plusPtr` (sizeOf x * 1)) y
+
+  peek ptr = do
+    x <- peek (castPtr ptr                         )
+    y <- peek (castPtr ptr `plusPtr` (sizeOf x * 1))
+    return ImVec2{ x, y  }
+
 
 data ImVec3 = ImVec3 { x, y, z :: {-# unpack #-} !Float }