From 90d96ad938253d142a4c4786652fff3c844aaa24 Mon Sep 17 00:00:00 2001
From: Ollie Charles <ollie@ocharles.org.uk>
Date: Sun, 24 Jan 2021 15:56:14 +0000
Subject: [PATCH] Wrap ImGui::Checkbox()

---
 Main.hs             | 15 ++++++++++-----
 hs-dear-imgui.cabal |  2 +-
 src/DearImGui.hs    | 20 +++++++++++++++++++-
 3 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/Main.hs b/Main.hs
index fe81714..305adb0 100644
--- a/Main.hs
+++ b/Main.hs
@@ -5,6 +5,7 @@
 
 module Main (main) where
 
+import Data.IORef
 import DearImGui
 import Control.Exception
 import Graphics.GL
@@ -23,12 +24,12 @@ main = do
       styleColorsLight
       openGL2Init
 
-      loop w
+      newIORef False >>= loop w
 
       openGL2Shutdown
 
-loop :: Window -> IO ()
-loop w = do
+loop :: Window -> IORef Bool -> IO ()
+loop w checked = do
   ev <- pollEventWithImGui
 
   openGL2NewFrame
@@ -53,6 +54,10 @@ loop w = do
 
   arrowButton "Arrow" ImGuiDirUp
 
+  checkbox "Check!" checked >>= \case
+    True  -> readIORef checked >>= print
+    False -> return ()
+
   end
 
   render
@@ -63,7 +68,7 @@ loop w = do
   glSwapWindow w
 
   case ev of
-    Nothing -> loop w
+    Nothing -> loop w checked
     Just Event{ eventPayload } -> case eventPayload of
       QuitEvent -> return ()
-      _         -> loop w
+      _         -> loop w checked
diff --git a/hs-dear-imgui.cabal b/hs-dear-imgui.cabal
index 27f4b32..a6ce3b3 100644
--- a/hs-dear-imgui.cabal
+++ b/hs-dear-imgui.cabal
@@ -20,7 +20,7 @@ library
   extra-libraries: stdc++
   pkgconfig-depends: sdl2
   include-dirs: imgui
-  build-depends: base, inline-c, inline-c-cpp, sdl2
+  build-depends: base, inline-c, inline-c-cpp, sdl2, StateVar
   extra-libraries: GL
 
 
diff --git a/src/DearImGui.hs b/src/DearImGui.hs
index 84a1e23..1c5e202 100644
--- a/src/DearImGui.hs
+++ b/src/DearImGui.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE BlockArguments #-}
+{-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE NamedFieldPuns #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE PatternSynonyms #-}
@@ -55,6 +56,7 @@ module DearImGui
   , button
   , smallButton
   , arrowButton
+  , checkbox
 
     -- * Types
   , ImGuiDir
@@ -65,9 +67,11 @@ module DearImGui
   )
   where
 
+import Data.Bool
+import Data.StateVar
 import Control.Monad ( when )
 import Foreign
-import Foreign.C.String
+import Foreign.C
 import qualified Language.C.Inline as C
 import qualified Language.C.Inline.Cpp as Cpp
 import SDL
@@ -297,6 +301,20 @@ arrowButton strId (ImGuiDir dir) = withCString strId \strIdPtr ->
   (1 ==) <$> [C.exp| bool { ArrowButton($(char* strIdPtr), $(int dir)) } |]
 
 
+-- | Wraps @ImGui::Checkbox()@.
+checkbox :: (HasSetter ref Bool, HasGetter ref Bool) => String -> ref -> IO Bool
+checkbox label ref = do
+  currentValue <- get ref
+  with (bool 0 1 currentValue :: CBool) \boolPtr -> do
+    changed <- withCString label \labelPtr ->
+      (1 ==) <$> [C.exp| bool { Checkbox($(char* labelPtr), $(bool* boolPtr)) } |]
+
+    newValue <- peek boolPtr
+    ref $=! (newValue == 1)
+
+    return changed
+
+
 -- | A cardinal direction.
 newtype ImGuiDir      = ImGuiDir CInt