Nav: TreeNode: Added ImGuiTreeNodeFlags_NavCloseFromChild flag, allow closing a TreeNode() from any of child. The explicit flag is not great, perhaps allowing some form of inheritance would help. (#787, #1079)

imgui.cpp

@@ -5924,6 +5924,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         window->DC.TextWrapPosStack.resize(0);
         window->DC.ColumnsSet = NULL;
         window->DC.TreeDepth = 0;
+        window->DC.TreeDepthMayCloseOnPop = 0x00;
         window->DC.StateStorage = &window->StateStorage;
         window->DC.GroupStack.resize(0);
         window->MenuColumns.Update(3, style.ItemSpacing.x, window_just_activated_by_user);
@@ -7883,6 +7884,13 @@ bool ImGui::TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* l
     // (Ideally we'd want to add a flag for the user to specify if we want the hit test to be done up to the right side of the content or not)
     const ImRect interact_bb = display_frame ? bb : ImRect(bb.Min.x, bb.Min.y, bb.Min.x + text_width + style.ItemSpacing.x*2, bb.Max.y);
     bool is_open = TreeNodeBehaviorIsOpen(id, flags);
+
+    // Store a flag for the current depth to tell if we will allow closing this node when navigating one of its child. 
+    // For this purpose we essentially compare if g.NavIdIsAlive went from 0 to 1 between TreeNode() and TreePop().
+    // This is currently only support 32 level deep and we are fine with (1 << Depth) overflowing into a zero.
+    if (is_open && !g.NavIdIsAlive && (flags & ImGuiTreeNodeFlags_NavCloseFromChild) && !(flags & ImGuiTreeNodeFlags_NoTreePushOnOpen))
+        window->DC.TreeDepthMayCloseOnPop |= (1 << window->DC.TreeDepth);
+
     if (!ItemAdd(interact_bb, id))
     {
         if (is_open && !(flags & ImGuiTreeNodeFlags_NoTreePushOnOpen))
@@ -12529,9 +12537,21 @@ void ImGui::TreePushRawID(ImGuiID id)
 
 void ImGui::TreePop()
 {
-    ImGuiWindow* window = GetCurrentWindow();
+    ImGuiContext& g = *GImGui;
+    ImGuiWindow* window = g.CurrentWindow;
     Unindent();
+
     window->DC.TreeDepth--;
+    if (g.NavMoveDir == ImGuiDir_Left && g.NavWindow == window && NavMoveRequestButNoResultYet())
+        if (g.NavIdIsAlive && (window->DC.TreeDepthMayCloseOnPop & (1 << window->DC.TreeDepth)))
+        {
+            ImGuiID id = window->IDStack.back();
+            window->DC.StateStorage->SetBool(id, false);
+            SetNavID(id, g.NavLayer);
+            NavMoveRequestCancel();
+        }
+    window->DC.TreeDepthMayCloseOnPop &= (1 << window->DC.TreeDepth) - 1;
+
     PopID();
 }
 

imgui.h

@@ -602,6 +602,7 @@ enum ImGuiTreeNodeFlags_
     ImGuiTreeNodeFlags_FramePadding         = 1 << 10,  // Use FramePadding (even for an unframed text node) to vertically align text baseline to regular widget height. Equivalent to calling AlignTextToFramePadding().
     //ImGuITreeNodeFlags_SpanAllAvailWidth  = 1 << 11,  // FIXME: TODO: Extend hit box horizontally even if not framed
     //ImGuiTreeNodeFlags_NoScrollOnOpen     = 1 << 12,  // FIXME: TODO: Disable automatic scroll on TreePop() if node got just open and contents is not visible
+    ImGuiTreeNodeFlags_NavCloseFromChild    = 1 << 13,  // (WIP) Nav: left direction may close this TreeNode() when focusing on any child (items submitted between TreeNode and TreePop)
     ImGuiTreeNodeFlags_CollapsingHeader     = ImGuiTreeNodeFlags_Framed | ImGuiTreeNodeFlags_NoAutoOpenOnLog
 
     // Obsolete names (will be removed)

imgui_internal.h

@@ -817,6 +817,7 @@ struct IMGUI_API ImGuiDrawContext
     float                   PrevLineTextBaseOffset;
     float                   LogLinePosY;
     int                     TreeDepth;
+    ImU32                   TreeDepthMayCloseOnPop; // Store a copy of !g.NavIdIsAlive for TreeDepth 0..31
     ImGuiID                 LastItemId;
     ImRect                  LastItemRect;
     bool                    LastItemRectHoveredRect;
@@ -855,6 +856,7 @@ struct IMGUI_API ImGuiDrawContext
         CurrentLineTextBaseOffset = PrevLineTextBaseOffset = 0.0f;
         LogLinePosY = -1.0f;
         TreeDepth = 0;
+        TreeDepthMayCloseOnPop = 0x00;
         LastItemId = 0;
         LastItemRect = ImRect();
         LastItemRectHoveredRect = false;