Nav: Added proper version of ImGuiWindowFlags_NavFlattened that handles scrolling nicely. Marked as private as I'm not happy with the name. (#787)

imgui.cpp

@@ -2254,6 +2254,12 @@ static inline void NavUpdateAnyRequestFlag()
     g.NavAnyRequest = g.NavMoveRequest || g.NavInitRequest || IMGUI_DEBUG_NAV_SCORING;
 }
 
+static bool NavMoveRequestButNoResultYet()
+{
+    ImGuiContext& g = *GImGui;
+    return g.NavMoveRequest && g.NavMoveResultLocal.ID == 0 && g.NavMoveResultOther.ID == 0;
+}
+
 static void NavMoveRequestCancel()
 {
     ImGuiContext& g = *GImGui;
@@ -2288,7 +2294,7 @@ static void ImGui::NavProcessItem(ImGuiWindow* window, const ImRect& nav_bb, con
     // Scoring for navigation
     if (g.NavId != id && !(item_flags & ImGuiItemFlags_NoNav))
     {
-        ImGuiNavMoveResult* result = &g.NavMoveResult;
+        ImGuiNavMoveResult* result = (window == g.NavWindow) ? &g.NavMoveResultLocal : &g.NavMoveResultOther;
 #if IMGUI_DEBUG_NAV_SCORING
         // [DEBUG] Score all items in NavWindow at all times
         if (!g.NavMoveRequest) 
@@ -2333,9 +2339,10 @@ bool ImGui::ItemAdd(const ImRect& bb, ImGuiID id, const ImRect* nav_bb_arg)
         //      it may not scale very well for windows with ten of thousands of item, but at least NavMoveRequest is only set on user interaction, aka maximum once a frame.
         //      We could early out with "if (is_clipped && !g.NavInitRequest) return false;" but when we wouldn't be able to reach unclipped widgets. This would work if user had explicit scrolling control (e.g. mapped on a stick)
         window->DC.NavLayerActiveMaskNext |= window->DC.NavLayerCurrentMask;
-        if (g.NavWindow == window->NavRootWindow)
-            if (g.NavId == id || g.NavAnyRequest)
-                NavProcessItem(window, nav_bb_arg ? *nav_bb_arg : bb, id);
+        if (g.NavId == id || g.NavAnyRequest)
+            if (g.NavWindow->NavRootWindow == window->NavRootWindow)
+                if (window == g.NavWindow || ((window->Flags | g.NavWindow->Flags) & ImGuiWindowFlags_NavFlattened))
+                    NavProcessItem(window, nav_bb_arg ? *nav_bb_arg : bb, id);
     }
 
     window->DC.LastItemId = id;
@@ -2883,9 +2890,14 @@ static void ImGui::NavUpdate()
     g.NavJustMovedToId = 0;
 
     // Process navigation move request
-    if (g.NavMoveRequest && g.NavMoveResult.ID != 0)
+    if (g.NavMoveRequest && (g.NavMoveResultLocal.ID != 0 || g.NavMoveResultOther.ID != 0))
     {
-        ImGuiNavMoveResult* result = &g.NavMoveResult;
+        // Select which result to use
+        ImGuiNavMoveResult* result = (g.NavMoveResultLocal.ID != 0) ? &g.NavMoveResultLocal : &g.NavMoveResultOther;
+        if (g.NavMoveResultOther.ID != 0 && g.NavMoveResultOther.Window->ParentWindow == g.NavWindow) // Maybe entering a flattened child? In this case solve the tie using the regular scoring rules
+            if ((g.NavMoveResultOther.DistBox < g.NavMoveResultLocal.DistBox) || (g.NavMoveResultOther.DistBox == g.NavMoveResultLocal.DistBox && g.NavMoveResultOther.DistCenter < g.NavMoveResultLocal.DistCenter))
+                result = &g.NavMoveResultOther;
+
         IM_ASSERT(g.NavWindow && result->Window);
 
         // Scroll to keep newly navigated item fully into view
@@ -2894,6 +2906,7 @@ static void ImGui::NavUpdate()
 
         // Apply result from previous frame navigation directional move request
         ClearActiveID();
+        g.NavWindow = result->Window;
         SetNavIDAndMoveMouse(result->ID, g.NavLayer, result->RectRel);
         g.NavJustMovedToId = result->ID;
         g.NavMoveFromClampedRefRect = false;
@@ -2903,7 +2916,7 @@ static void ImGui::NavUpdate()
     if (g.NavMoveRequestForward == ImGuiNavForward_ForwardActive)
     {
         IM_ASSERT(g.NavMoveRequest);
-        if (g.NavMoveResult.ID == 0)
+        if (g.NavMoveResultLocal.ID == 0 && g.NavMoveResultOther.ID == 0)
             g.NavDisableHighlight = false;
         g.NavMoveRequestForward = ImGuiNavForward_None;
     }
@@ -3061,11 +3074,9 @@ static void ImGui::NavUpdate()
         }
     }
 
-    // Reset search 
-    ImGuiNavMoveResult* result = &g.NavMoveResult;
-    result->ID = result->ParentID = 0;
-    result->Window = NULL;
-    result->DistAxial = result->DistBox = result->DistCenter = FLT_MAX;
+    // Reset search results
+    g.NavMoveResultLocal.Clear();
+    g.NavMoveResultOther.Clear();
 
     // When we have manually scrolled (without using navigation) and NavId becomes out of bounds, we project its bounding box to the visible area to restart navigation within visible items
     if (g.NavMoveRequest && g.NavMoveFromClampedRefRect && g.NavLayer == 0)
@@ -4826,7 +4837,7 @@ bool ImGui::BeginPopupModal(const char* name, bool* p_open, ImGuiWindowFlags fla
 static void NavProcessMoveRequestWrapAround(ImGuiWindow* window)
 {
     ImGuiContext& g = *GImGui;
-    if (g.NavMoveRequest && g.NavWindow == window && g.NavMoveResult.ID == 0)
+    if (g.NavWindow == window && NavMoveRequestButNoResultYet())
         if ((g.NavMoveDir == ImGuiDir_Up || g.NavMoveDir == ImGuiDir_Down) && g.NavMoveRequestForward == ImGuiNavForward_None && g.NavLayer == 0)
         {
             g.NavMoveRequestForward = ImGuiNavForward_ForwardQueued;
@@ -4928,7 +4939,7 @@ static bool BeginChildEx(const char* name, ImGuiID id, const ImVec2& size_arg, b
     g.Style.ChildBorderSize = backup_border_size;
 
     // Process navigation-in immediately so NavInit can run on first frame
-    if (/*!(flags & ImGuiWindowFlags_NavFlattened) &&*/ (child_window->DC.NavLayerActiveMask != 0 || child_window->DC.NavHasScroll) && g.NavActivateId == id)
+    if (!(flags & ImGuiWindowFlags_NavFlattened) && (child_window->DC.NavLayerActiveMask != 0 || child_window->DC.NavHasScroll) && g.NavActivateId == id)
     {
         ImGui::FocusWindow(child_window);
         ImGui::NavInitWindow(child_window, false);
@@ -4972,7 +4983,7 @@ void ImGui::EndChild()
         ImGuiWindow* parent_window = GetCurrentWindow();
         ImRect bb(parent_window->DC.CursorPos, parent_window->DC.CursorPos + sz);
         ItemSize(sz);
-        if (/*!(window->Flags & ImGuiWindowFlags_NavFlattened) &&*/ (window->DC.NavLayerActiveMask != 0 || window->DC.NavHasScroll))
+        if (!(window->Flags & ImGuiWindowFlags_NavFlattened) && (window->DC.NavLayerActiveMask != 0 || window->DC.NavHasScroll))
         {
             ItemAdd(bb, window->ChildId);
             RenderNavHighlight(bb, window->ChildId);
@@ -5420,8 +5431,9 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     // Automatically disable manual moving/resizing when NoInputs is set
     if (flags & ImGuiWindowFlags_NoInputs)
         flags |= ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoResize;
-    //if (flags & ImGuiWindowFlags_NavFlattened)
-    //    IM_ASSERT(flags & ImGuiWindowFlags_ChildWindow);
+    
+    if (flags & ImGuiWindowFlags_NavFlattened)
+        IM_ASSERT(flags & ImGuiWindowFlags_ChildWindow);
 
     const int current_frame = g.FrameCount;
     const bool first_begin_of_the_frame = (window->LastFrameActive != current_frame);
@@ -5529,8 +5541,8 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         if (parent_window && !(flags & ImGuiWindowFlags_Modal) && (flags & (ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_Popup)))
             window->RootNonPopupWindow = parent_window->RootNonPopupWindow;
         window->NavRootWindow = window;
-        //while (window->NavRootWindow->Flags & ImGuiWindowFlags_NavFlattened)
-        //    window->NavRootWindow = window->NavRootWindow->ParentWindow;
+        while (window->NavRootWindow->Flags & ImGuiWindowFlags_NavFlattened)
+            window->NavRootWindow = window->NavRootWindow->ParentWindow;
 
         window->Active = true;
         window->BeginOrderWithinParent = 0;
@@ -10861,7 +10873,7 @@ void ImGui::EndMenuBar()
     ImGuiContext& g = *GImGui;
 
     // Nav: When a move request within one of our child menu failed, capture the request to navigate among our siblings.
-    if (g.NavMoveRequest && g.NavMoveResult.ID == 0 && (g.NavMoveDir == ImGuiDir_Left || g.NavMoveDir == ImGuiDir_Right) && (g.NavWindow->Flags & ImGuiWindowFlags_ChildMenu))
+    if (NavMoveRequestButNoResultYet() && (g.NavMoveDir == ImGuiDir_Left || g.NavMoveDir == ImGuiDir_Right) && (g.NavWindow->Flags & ImGuiWindowFlags_ChildMenu))
     {
         ImGuiWindow* nav_earliest_child = g.NavWindow;
         while (nav_earliest_child->ParentWindow && (nav_earliest_child->ParentWindow->Flags & ImGuiWindowFlags_ChildMenu))
@@ -11029,7 +11041,7 @@ void ImGui::EndMenu()
     // Nav: When a left move request within our child menu failed, close the menu
     ImGuiContext& g = *GImGui;
     ImGuiWindow* window = g.CurrentWindow;
-    if (g.NavWindow && g.NavWindow->ParentWindow == window && g.NavMoveRequest && g.NavMoveResult.ID == 0 && g.NavMoveDir == ImGuiDir_Left && window->DC.LayoutType == ImGuiLayoutType_Vertical)
+    if (g.NavWindow && g.NavWindow->ParentWindow == window && NavMoveRequestButNoResultYet() && g.NavMoveDir == ImGuiDir_Left && window->DC.LayoutType == ImGuiLayoutType_Vertical)
     {
         ClosePopupToLevel(g.OpenPopupStack.Size - 1);
         NavMoveRequestCancel();

imgui.h

@@ -552,9 +552,9 @@ enum ImGuiWindowFlags_
     ImGuiWindowFlags_ResizeFromAnySide      = 1 << 17,  // (WIP) Enable resize from any corners and borders. Your back-end needs to honor the different values of io.MouseCursor set by imgui.
     ImGuiWindowFlags_NoNavFocus             = 1 << 18,  // No focusing of this window with gamepad/keyboard navigation
     ImGuiWindowFlags_NoNavInputs            = 1 << 19,  // No gamepad/keyboard navigation within the window
-    //ImGuiWindowFlags_NavFlattened         = 1 << 20,  // Allow gamepad/keyboard navigation to cross over parent border to this child (only use on child that have no scrolling!)
 
     // [Internal]
+    ImGuiWindowFlags_NavFlattened           = 1 << 20,  // (WIP) Allow gamepad/keyboard navigation to cross over parent border to this child (only use on child that have no scrolling!)
     ImGuiWindowFlags_ChildWindow            = 1 << 24,  // Don't use! For internal use by BeginChild()
     ImGuiWindowFlags_Tooltip                = 1 << 25,  // Don't use! For internal use by BeginTooltip()
     ImGuiWindowFlags_Popup                  = 1 << 26,  // Don't use! For internal use by BeginPopup()

imgui_demo.cpp

@@ -2148,7 +2148,7 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
         ImGui::RadioButton("Alpha", &alpha_flags, ImGuiColorEditFlags_AlphaPreview); ImGui::SameLine(); 
         ImGui::RadioButton("Both", &alpha_flags, ImGuiColorEditFlags_AlphaPreviewHalf);
 
-        ImGui::BeginChild("#colors", ImVec2(0, 300), true, ImGuiWindowFlags_AlwaysVerticalScrollbar | ImGuiWindowFlags_AlwaysHorizontalScrollbar);
+        ImGui::BeginChild("#colors", ImVec2(0, 300), true, ImGuiWindowFlags_AlwaysVerticalScrollbar | ImGuiWindowFlags_AlwaysHorizontalScrollbar | ImGuiWindowFlags_NavFlattened);
         ImGui::PushItemWidth(-160);
         for (int i = 0; i < ImGuiCol_COUNT; i++)
         {

imgui_internal.h

@@ -514,7 +514,8 @@ struct ImGuiNavMoveResult
     float         DistAxial;
     ImRect        RectRel;      // Best candidate bounding box in window relative space
 
-    ImGuiNavMoveResult() { ID = ParentID = 0; Window = NULL; DistBox = DistCenter = DistAxial = 0.0f; }
+    ImGuiNavMoveResult() { Clear(); }
+    void Clear()         { ID = ParentID = 0; Window = NULL; DistBox = DistCenter = DistAxial = FLT_MAX; RectRel = ImRect(); }
 };
 
 // Storage for SetNexWindow** functions
@@ -633,7 +634,8 @@ struct ImGuiContext
     ImGuiNavForward         NavMoveRequestForward;              // None / ForwardQueued / ForwardActive (this is used to navigate sibling parent menus from a child menu)
     ImGuiDir                NavMoveDir;                         // Direction of the move request (left/right/up/down)
     ImGuiDir                NavMoveDirLast;                     // Direction of the previous move request
-    ImGuiNavMoveResult      NavMoveResult;                      // Best move request candidate
+    ImGuiNavMoveResult      NavMoveResultLocal;                 // Best move request candidate within NavWindow
+    ImGuiNavMoveResult      NavMoveResultOther;                 // Best move request candidate within NavWindow's flattened hierarchy (when using the NavFlattened flag)
 
     // Render
     ImDrawData              DrawData;                           // Main ImDrawData instance to pass render information to the user