Add remaining BeginChild arguments as required (#93)

Old behaviour with all default arguments is a special case to run
some action scoped to a different child window.

This now handled by `beginChildContext`/`withChildContext`.

Main.hs

@@ -120,7 +120,7 @@ loop window checked color slider r pos size' selected tab1Ref tab2Ref = do
 
   progressBar 0.314 (Just "Pi")
 
-  beginChild "Child"
+  beginChild "Child" (ImVec2 0 0) True ImGuiWindowFlags_None
 
   beginCombo "Label" "Preview" >>= whenTrue do
     selectable "Testing 1"

src/DearImGui.hs

@@ -71,6 +71,7 @@ module DearImGui
     -- ** Child Windows
   , withChild
   , withChildOpen
+  , withChildContext
   , beginChild
   , Raw.endChild
 
@@ -350,25 +351,52 @@ fullscreenFlags = foldl' (.|.) zeroBits
   , ImGuiWindowFlags_NoTitleBar
   ]
 
--- | Wraps @ImGui::BeginChild()@.
-beginChild :: MonadIO m => String -> m Bool
-beginChild name = liftIO do
-  withCString name Raw.beginChild
 
--- | Child windows used for self-contained independent scrolling/clipping regions
+-- | Begin a self-contained independent scrolling/clipping regions within a host window.
--- within a host window. Child windows can embed their own child.
+--
+-- Child windows can embed their own child.
+--
+-- For each independent axis of @size@:
+--   * ==0.0f: use remaining host window size
+--   * >0.0f: fixed size
+--   * <0.0f: use remaining window size minus abs(size)
+--
+-- Each axis can use a different mode, e.g. @ImVec2 0 400@.
+--
+-- @BeginChild()@ returns `False` to indicate the window is collapsed or fully clipped, so you may early out and omit submitting anything to the window.
+--
+-- Always call a matching `endChild` for each `beginChild` call, regardless of its return value.
+--
+-- Wraps @ImGui::BeginChild()@.
+beginChild :: MonadIO m => String -> ImVec2 -> Bool -> ImGuiWindowFlags -> m Bool
+beginChild name size border flags = liftIO do
+  withCString name \namePtr ->
+    with size \sizePtr ->
+      Raw.beginChild namePtr sizePtr (bool 0 1 border) flags
+
+-- | Action wrapper for child windows.
 --
 -- Action will get 'False' if the child region is collapsed or fully clipped.
-withChild :: MonadUnliftIO m => String -> (Bool -> m a) -> m a
+withChild :: MonadUnliftIO m => String -> ImVec2 -> Bool -> ImGuiWindowFlags -> (Bool -> m a) -> m a
-withChild name = bracket (beginChild name) (const Raw.endChild)
+withChild name size border flags = bracket (beginChild name size border flags) (const Raw.endChild)
 
--- | Child windows used for self-contained independent scrolling/clipping regions
+-- | Action-skipping wrapper for child windows.
--- within a host window. Child windows can embed their own child.
 --
 -- Action will be skipped if the child region is collapsed or fully clipped.
-withChildOpen :: MonadUnliftIO m => String -> m () -> m ()
+withChildOpen :: MonadUnliftIO m => String -> ImVec2 -> Bool -> ImGuiWindowFlags -> m () -> m ()
-withChildOpen name action =
+withChildOpen name size border flags action =
-  withChild name (`when` action)
+  withChild name size border flags (`when` action)
+
+-- | Action wrapper to run in a context of another child window addressed by its name.
+--
+-- Action will get 'False' if the child region is collapsed or fully clipped.
+withChildContext :: MonadUnliftIO m => String -> (Bool -> m a) -> m a
+withChildContext name action =
+  bracket
+    (liftIO $ withCString name Raw.beginChildContext)
+    (const Raw.endChild)
+    action
+
 
 -- | Plain text.
 text :: MonadIO m => String -> m ()

src/DearImGui/Raw.hs

@@ -66,6 +66,7 @@ module DearImGui.Raw
 
     -- ** Child Windows
   , beginChild
+  , beginChildContext
   , endChild
 
     -- * Parameter stacks
@@ -390,11 +391,47 @@ end = liftIO do
   [C.exp| void { End(); } |]
 
 
--- | Wraps @ImGui::BeginChild()@.
+-- | Begin a self-contained independent scrolling/clipping regions within a host window.
-beginChild :: (MonadIO m) => CString -> m Bool
+--
-beginChild namePtr = liftIO do
+-- Child windows can embed their own child.
-  (0 /=) <$> [C.exp| bool { BeginChild($(char* namePtr)) } |]
+--
+-- For each independent axis of @size@:
+--   * ==0.0f: use remaining host window size
+--   * >0.0f: fixed size
+--   * <0.0f: use remaining window size minus abs(size)
+--
+-- Each axis can use a different mode, e.g. @ImVec2 0 400@.
+--
+-- @BeginChild()@ returns `False` to indicate the window is collapsed or fully clipped, so you may early out and omit submitting anything to the window.
+--
+-- Always call a matching `endChild` for each `beginChild` call, regardless of its return value.
+--
+-- Wraps @ImGui::BeginChild()@.
+beginChild :: (MonadIO m) => CString -> Ptr ImVec2 -> CBool -> ImGuiWindowFlags -> m Bool
+beginChild namePtr sizePtr border flags = liftIO do
+  (0 /=) <$> [C.exp|
+    bool {
+      BeginChild(
+        $(char* namePtr),
+        *$(ImVec2* sizePtr),
+        $(bool border),
+        $(ImGuiWindowFlags flags)
+      )
+    }
+  |]
 
+-- | Switch context to another child window by its ID
+--
+-- Wraps @ImGui::BeginChild()@.
+beginChildContext :: (MonadIO m) => CString -> m Bool
+beginChildContext namePtr = liftIO do
+  (0 /=) <$> [C.exp|
+    bool {
+      BeginChild(
+        $(char* namePtr)
+      )
+    }
+  |]
 
 -- | Wraps @ImGui::EndChild()@.
 endChild :: (MonadIO m) => m ()