Shortcut()/SetShortcutRouting(): use mixed current window focus scope + ParentWindowForFocusRoute. (#6798, #2637, #456)

Amend d474836
Begin: tweak clearing of CurrentWindow as FocusWindow() relies on it now.
Addded SetWindowParentWindowForFocusRoute() helper.

imgui.cpp

@@ -6439,13 +6439,9 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     }
 
     // Add to focus scope stack
-    if ((flags & ImGuiWindowFlags_NavFlattened) == 0)
-        PushFocusScope(window->ID);
+    PushFocusScope((flags & ImGuiWindowFlags_NavFlattened) ? g.CurrentFocusScopeId : window->ID);
     window->NavRootFocusScopeId = g.CurrentFocusScopeId;
 
-    // We intentionally set g.CurrentWindow to NULL to prevent usage until when the viewport is set, then will call SetCurrentWindow()
-    g.CurrentWindow = NULL;
-
     // Add to popup stack
     if (flags & ImGuiWindowFlags_Popup)
     {
@@ -6510,6 +6506,9 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     if (window->Appearing)
         SetWindowConditionAllowFlags(window, ImGuiCond_Appearing, false);
 
+    // We intentionally set g.CurrentWindow to NULL to prevent usage until when the viewport is set, then will call SetCurrentWindow()
+    g.CurrentWindow = NULL;
+
     // When reusing window again multiple times a frame, just append content (don't need to setup again)
     if (first_begin_of_the_frame)
     {
@@ -7083,8 +7082,7 @@ void ImGui::End()
     if (window->DC.CurrentColumns)
         EndColumns();
     PopClipRect();   // Inner window clip rectangle
-    if ((window->Flags & ImGuiWindowFlags_NavFlattened) == 0)
-        PopFocusScope();
+    PopFocusScope();
 
     // Stop logging
     if (!(window->Flags & ImGuiWindowFlags_ChildWindow))    // FIXME: add more options for scope of logging
@@ -7209,7 +7207,7 @@ void ImGui::FocusWindow(ImGuiWindow* window, ImGuiFocusRequestFlags flags)
             g.NavMousePosDirty = true;
         g.NavId = window ? window->NavLastIds[0] : 0; // Restore NavId
         g.NavLayer = ImGuiNavLayer_Main;
-        g.NavFocusScopeId = window ? window->NavRootFocusScopeId : 0;
+        SetNavFocusScope(window ? window->NavRootFocusScopeId : 0);
         g.NavIdIsAlive = false;
         g.NavLastValidSelectionUserData = ImGuiSelectionUserData_Invalid;
 
@@ -7822,6 +7820,33 @@ void ImGui::PopFocusScope()
     g.CurrentFocusScopeId = g.FocusScopeStack.Size ? g.FocusScopeStack.back().ID : 0;
 }
 
+void ImGui::SetNavFocusScope(ImGuiID focus_scope_id)
+{
+    ImGuiContext& g = *GImGui;
+    g.NavFocusScopeId = focus_scope_id;
+    g.NavFocusScopePath.resize(0); // Invalidate
+    if (focus_scope_id == 0)
+        return;
+    IM_ASSERT(g.NavWindow != NULL);
+
+    // Store current path (in reverse order)
+    if (focus_scope_id == g.CurrentFocusScopeId)
+    {
+        // Top of focus stack contains local focus scopes inside current window
+        for (int n = g.FocusScopeStack.Size - 1; n >= 0 && g.FocusScopeStack.Data[n].WindowID == g.CurrentWindow->ID; n--)
+            g.NavFocusScopePath.push_back(g.FocusScopeStack.Data[n]);
+    }
+    else if (focus_scope_id == g.NavWindow->NavRootFocusScopeId)
+        g.NavFocusScopePath.push_back({ focus_scope_id, g.NavWindow->ID });
+    else
+        return;
+
+    // Then follow on manually set ParentWindowForFocusRoute field (#6798)
+    for (ImGuiWindow* window = g.NavWindow->ParentWindowForFocusRoute; window != NULL; window = window->ParentWindowForFocusRoute)
+        g.NavFocusScopePath.push_back({ window->NavRootFocusScopeId, window->ID });
+    IM_ASSERT(g.NavFocusScopePath.Size < 100); // Maximum depth is technically 251 as per CalcRoutingScore(): 254 - 3
+}
+
 // Focus = move navigation cursor, set scrolling, set focus window.
 void ImGui::FocusItem()
 {
@@ -8318,12 +8343,11 @@ ImGuiKeyRoutingData* ImGui::GetShortcutRoutingData(ImGuiKeyChord key_chord)
 //  - 254: ImGuiInputFlags_RouteGlobalLow
 //  - 255: never route
 // 'flags' should include an explicit routing policy
-static int CalcRoutingScore(ImGuiWindow* location, ImGuiID owner_id, ImGuiInputFlags flags)
+static int CalcRoutingScore(ImGuiID focus_scope_id, ImGuiID owner_id, ImGuiInputFlags flags)
 {
     if (flags & ImGuiInputFlags_RouteFocused)
     {
         ImGuiContext& g = *GImGui;
-        ImGuiWindow* focused = g.NavWindow;
 
         // ActiveID gets top priority
         // (we don't check g.ActiveIdUsingAllKeys here. Routing is applied but if input ownership is tested later it may discard it)
@@ -8336,13 +8360,12 @@ static int CalcRoutingScore(ImGuiWindow* location, ImGuiID owner_id, ImGuiInputF
         // - When Window/ChildB is focused -> Window scores 4,        Window/ChildB scores 3 (best)
         // Assuming only WindowA is submitting a routing request,
         // - When Window/ChildB is focused -> Window scores 4 (best), Window/ChildB doesn't have a score.
-        // FIXME: This could be later abstracted as a focus path
-        for (int next_score = 3; focused != NULL; next_score++, focused = focused->ParentWindowForFocusRoute)
-            if (focused == location)
-            {
-                IM_ASSERT(next_score < 255);
-                return next_score;
-            }
+        if (focus_scope_id == 0)
+            return 255;
+        for (int index_in_focus_path = 0; index_in_focus_path < g.NavFocusScopePath.Size; index_in_focus_path++)
+            if (g.NavFocusScopePath.Data[index_in_focus_path].ID == focus_scope_id)
+                return 3 + index_in_focus_path;
+
         return 255;
     }
 
@@ -8383,7 +8406,7 @@ bool ImGui::SetShortcutRouting(ImGuiKeyChord key_chord, ImGuiID owner_id, ImGuiI
         return true;
     }
 
-    const int score = CalcRoutingScore(g.CurrentWindow, owner_id, flags);
+    const int score = CalcRoutingScore(g.CurrentFocusScopeId, owner_id, flags);
     IMGUI_DEBUG_LOG_INPUTROUTING("SetShortcutRouting(%s, owner_id=0x%08X, flags=%04X) -> score %d\n", GetKeyChordName(key_chord), owner_id, flags, score);
     if (score == 255)
         return false;
@@ -11095,7 +11118,7 @@ void ImGui::SetNavID(ImGuiID id, ImGuiNavLayer nav_layer, ImGuiID focus_scope_id
     IM_ASSERT(nav_layer == ImGuiNavLayer_Main || nav_layer == ImGuiNavLayer_Menu);
     g.NavId = id;
     g.NavLayer = nav_layer;
-    g.NavFocusScopeId = focus_scope_id;
+    SetNavFocusScope(focus_scope_id);
     g.NavWindow->NavLastIds[nav_layer] = id;
     g.NavWindow->NavRectRel[nav_layer] = rect_rel;
 
@@ -11117,7 +11140,7 @@ void ImGui::SetFocusID(ImGuiID id, ImGuiWindow* window)
     const ImGuiNavLayer nav_layer = window->DC.NavLayerCurrent;
     g.NavId = id;
     g.NavLayer = nav_layer;
-    g.NavFocusScopeId = g.CurrentFocusScopeId;
+    SetNavFocusScope(g.CurrentFocusScopeId);
     window->NavLastIds[nav_layer] = id;
     if (g.LastItemData.ID == id)
         window->NavRectRel[nav_layer] = WindowRectAbsToRel(window, g.LastItemData.NavRect);
@@ -11375,6 +11398,7 @@ static void ImGui::NavProcessItem()
         if (g.NavWindow != window)
             SetNavWindow(window); // Always refresh g.NavWindow, because some operations such as FocusItem() may not have a window.
         g.NavLayer = window->DC.NavLayerCurrent;
+        SetNavFocusScope(g.CurrentFocusScopeId); // Will set g.NavFocusScopeId AND store g.NavFocusScopePath
         g.NavFocusScopeId = g.CurrentFocusScopeId;
         g.NavIdIsAlive = true;
         if (g.LastItemData.InFlags & ImGuiItemFlags_HasSelectionUserData)
@@ -11604,7 +11628,7 @@ void ImGui::NavInitWindow(ImGuiWindow* window, bool force_reinit)
     if (window->Flags & ImGuiWindowFlags_NoNavInputs)
     {
         g.NavId = 0;
-        g.NavFocusScopeId = window->NavRootFocusScopeId;
+        SetNavFocusScope(window->NavRootFocusScopeId);
         return;
     }
 
@@ -11623,7 +11647,7 @@ void ImGui::NavInitWindow(ImGuiWindow* window, bool force_reinit)
     else
     {
         g.NavId = window->NavLastIds[0];
-        g.NavFocusScopeId = window->NavRootFocusScopeId;
+        SetNavFocusScope(window->NavRootFocusScopeId);
     }
 }
 
@@ -14507,6 +14531,14 @@ void ImGui::ShowMetricsWindow(bool* p_open)
         Text("NavActivateFlags: %04X", g.NavActivateFlags);
         Text("NavDisableHighlight: %d, NavDisableMouseHover: %d", g.NavDisableHighlight, g.NavDisableMouseHover);
         Text("NavFocusScopeId = 0x%08X", g.NavFocusScopeId);
+        Text("NavFocusScopePath[] = ");
+        for (int path_n = g.NavFocusScopePath.Size - 1; path_n >= 0; path_n--)
+        {
+            const ImGuiFocusScopeData& focus_scope = g.NavFocusScopePath[path_n];
+            SameLine(0.0f, 0.0f);
+            Text("0x%08X/", focus_scope.ID);
+            SetItemTooltip("In window \"%s\"", FindWindowByID(focus_scope.WindowID)->Name);
+        }
         Text("NavWindowingTarget: '%s'", g.NavWindowingTarget ? g.NavWindowingTarget->Name : "NULL");
         Unindent();
 

imgui_internal.h

@@ -2003,6 +2003,7 @@ struct ImGuiContext
     ImGuiWindow*            NavWindow;                          // Focused window for navigation. Could be called 'FocusedWindow'
     ImGuiID                 NavId;                              // Focused item for navigation
     ImGuiID                 NavFocusScopeId;                    // Focused focus scope (e.g. selection code often wants to "clear other items" when landing on an item of the same scope)
+    ImVector<ImGuiFocusScopeData> NavFocusScopePath;            // Reversed copy focus scope stack for NavId (should contains NavFocusScopeId)
     ImGuiID                 NavActivateId;                      // ~~ (g.ActiveId == 0) && (IsKeyPressed(ImGuiKey_Space) || IsKeyDown(ImGuiKey_Enter) || IsKeyPressed(ImGuiKey_NavGamepadActivate)) ? NavId : 0, also set when calling ActivateItem()
     ImGuiID                 NavActivateDownId;                  // ~~ IsKeyDown(ImGuiKey_Space) || IsKeyDown(ImGuiKey_Enter) || IsKeyDown(ImGuiKey_NavGamepadActivate) ? NavId : 0
     ImGuiID                 NavActivatePressedId;               // ~~ IsKeyPressed(ImGuiKey_Space) || IsKeyPressed(ImGuiKey_Enter) || IsKeyPressed(ImGuiKey_NavGamepadActivate) ? NavId : 0 (no repeat)
@@ -2952,6 +2953,7 @@ namespace ImGui
     IMGUI_API void          SetWindowCollapsed(ImGuiWindow* window, bool collapsed, ImGuiCond cond = 0);
     IMGUI_API void          SetWindowHitTestHole(ImGuiWindow* window, const ImVec2& pos, const ImVec2& size);
     IMGUI_API void          SetWindowHiddenAndSkipItemsForCurrentFrame(ImGuiWindow* window);
+    inline void             SetWindowParentWindowForFocusRoute(ImGuiWindow* window, ImGuiWindow* parent_window) { window->ParentWindowForFocusRoute = parent_window; }
     inline ImRect           WindowRectAbsToRel(ImGuiWindow* window, const ImRect& r) { ImVec2 off = window->DC.CursorStartPos; return ImRect(r.Min.x - off.x, r.Min.y - off.y, r.Max.x - off.x, r.Max.y - off.y); }
     inline ImRect           WindowRectRelToAbs(ImGuiWindow* window, const ImRect& r) { ImVec2 off = window->DC.CursorStartPos; return ImRect(r.Min.x + off.x, r.Min.y + off.y, r.Max.x + off.x, r.Max.y + off.y); }
     inline ImVec2           WindowPosRelToAbs(ImGuiWindow* window, const ImVec2& p)  { ImVec2 off = window->DC.CursorStartPos; return ImVec2(p.x + off.x, p.y + off.y); }
@@ -3110,6 +3112,7 @@ namespace ImGui
     IMGUI_API void          NavUpdateCurrentWindowIsScrollPushableX();
     IMGUI_API void          SetNavWindow(ImGuiWindow* window);
     IMGUI_API void          SetNavID(ImGuiID id, ImGuiNavLayer nav_layer, ImGuiID focus_scope_id, const ImRect& rect_rel);
+    IMGUI_API void          SetNavFocusScope(ImGuiID focus_scope_id);
 
     // Focus/Activation
     // This should be part of a larger set of API: FocusItem(offset = -1), FocusItemByID(id), ActivateItem(offset = -1), ActivateItemByID(id) etc. which are