TabBar: Fixed a crash when using BeginTabBar() recursively (didn't affect docking). (#2371)

Added ImPool::Contains() helper.

docs/CHANGELOG.txt

@@ -40,6 +40,7 @@ Other Changes:
   meant to be square (to align with e.g. color button) we always use FramePadding.y. (#2367)
 - InputText: Fixed an edge case crash that would happen if another widget sharing the same ID
   is being swapped with an InputText that has yet to be activated.
+- TabBar: Fixed a crash when using BeginTabBar() recursively (didn't affect docking). (#2371)
 - Examples: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read GL_CLIP_ORIGIN
   even if the OpenGL headers/loader happens to define the value. (#2366, #2186)
 

imgui_internal.h

@@ -275,7 +275,8 @@ struct IMGUI_API ImPool
     T*          GetByIndex(ImPoolIdx n)             { return &Data[n]; }
     ImPoolIdx   GetIndex(const T* p) const          { IM_ASSERT(p >= Data.Data && p < Data.Data + Data.Size); return (ImPoolIdx)(p - Data.Data); }
     T*          GetOrAddByKey(ImGuiID key)          { int* p_idx = Map.GetIntRef(key, -1); if (*p_idx != -1) return &Data[*p_idx]; *p_idx = FreeIdx; return Add(); }
-    void        Clear()                             { for (int n = 0; n < Map.Data.Size; n++) { int idx = Map.Data[n].val_i; if (idx != -1) Data[idx].~T(); }  Map.Clear(); Data.clear(); FreeIdx = 0; }
+    bool        Contains(const T* p) const          { return (p >= Data.Data && p < Data.Data + Data.Size); }
+    void        Clear()                             { for (int n = 0; n < Map.Data.Size; n++) { int idx = Map.Data[n].val_i; if (idx != -1) Data[idx].~T(); } Map.Clear(); Data.clear(); FreeIdx = 0; }
     T*          Add()                               { int idx = FreeIdx; if (idx == Data.Size) { Data.resize(Data.Size + 1); FreeIdx++; } else { FreeIdx = *(int*)&Data[idx]; } IM_PLACEMENT_NEW(&Data[idx]) T(); return &Data[idx]; }
     void        Remove(ImGuiID key, const T* p)     { Remove(key, GetIndex(p)); }
     void        Remove(ImGuiID key, ImPoolIdx idx)  { Data[idx].~T(); *(int*)&Data[idx] = FreeIdx; FreeIdx = idx; Map.SetInt(key, -1); }
@@ -749,8 +750,17 @@ struct ImGuiNextWindowData
 
 struct ImGuiTabBarSortItem
 {
-    int         Index;
-    float       Width;
+    int             Index;
+    float           Width;
+};
+
+struct ImGuiTabBarRef
+{
+    ImGuiTabBar*    Ptr;                    // Either field can be set, not both. Dock node tab bars are loose while BeginTabBar() ones are in a pool.
+    int             IndexInMainPool;
+
+    ImGuiTabBarRef(ImGuiTabBar* ptr)        { Ptr = ptr; IndexInMainPool = -1; }
+    ImGuiTabBarRef(int index_in_main_pool)  { Ptr = NULL; IndexInMainPool = index_in_main_pool; }
 };
 
 //-----------------------------------------------------------------------------
@@ -883,8 +893,9 @@ struct ImGuiContext
     unsigned char           DragDropPayloadBufLocal[8];         // Local buffer for small payloads
 
     // Tab bars
-    ImPool<ImGuiTabBar>     TabBars;
-    ImVector<ImGuiTabBar*>  CurrentTabBar;
+    ImPool<ImGuiTabBar>             TabBars;
+    ImGuiTabBar*                    CurrentTabBar;
+    ImVector<ImGuiTabBarRef>        CurrentTabBarStack;
     ImVector<ImGuiTabBarSortItem>   TabSortByWidthBuffer;
 
     // Widget state
@@ -1246,7 +1257,7 @@ struct ImGuiItemHoveredDataBackup
 
 enum ImGuiTabBarFlagsPrivate_
 {
-    ImGuiTabBarFlags_DockNode                   = 1 << 20,  // Part of a dock node
+    ImGuiTabBarFlags_DockNode                   = 1 << 20,  // Part of a dock node [we don't use this in the master branch but it facilitate branch syncing to keep this around]
     ImGuiTabBarFlags_IsFocused                  = 1 << 21,
     ImGuiTabBarFlags_SaveSettings               = 1 << 22   // FIXME: Settings are handled by the docking system, this only request the tab bar to mark settings dirty when reordering tabs
 };

imgui_widgets.cpp

@@ -5905,6 +5905,20 @@ static int IMGUI_CDECL TabBarSortItemComparer(const void* lhs, const void* rhs)
     return (b->Index - a->Index);
 }
 
+static ImGuiTabBar* GetTabBarFromTabBarRef(const ImGuiTabBarRef& ref)
+{
+    ImGuiContext& g = *GImGui;
+    return ref.Ptr ? ref.Ptr : g.TabBars.GetByIndex(ref.IndexInMainPool);
+}
+
+static ImGuiTabBarRef GetTabBarRefFromTabBar(ImGuiTabBar* tab_bar)
+{
+    ImGuiContext& g = *GImGui;
+    if (g.TabBars.Contains(tab_bar))
+        return ImGuiTabBarRef(g.TabBars.GetIndex(tab_bar));
+    return ImGuiTabBarRef(tab_bar);
+}
+
 bool    ImGui::BeginTabBar(const char* str_id, ImGuiTabBarFlags flags)
 {
     ImGuiContext& g = *GImGui;
@@ -5929,7 +5943,10 @@ bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImG
     if ((flags & ImGuiTabBarFlags_DockNode) == 0)
         window->IDStack.push_back(tab_bar->ID);
 
-    g.CurrentTabBar.push_back(tab_bar);
+    // Add to stack
+    g.CurrentTabBarStack.push_back(GetTabBarRefFromTabBar(tab_bar));
+    g.CurrentTabBar = tab_bar;
+
     if (tab_bar->CurrFrameVisible == g.FrameCount)
     {
         //IMGUI_DEBUG_LOG("BeginTabBarEx already called this frame\n", g.FrameCount);
@@ -5975,8 +5992,8 @@ void    ImGui::EndTabBar()
     if (window->SkipItems)
         return;
 
-    IM_ASSERT(!g.CurrentTabBar.empty());      // Mismatched BeginTabBar/EndTabBar
-    ImGuiTabBar* tab_bar = g.CurrentTabBar.back();
+    ImGuiTabBar* tab_bar = g.CurrentTabBar;
+    IM_ASSERT(tab_bar != NULL && "Mismatched BeginTabBar()/EndTabBar()!");
     if (tab_bar->WantLayout)
         TabBarLayout(tab_bar);
 
@@ -5989,7 +6006,9 @@ void    ImGui::EndTabBar()
 
     if ((tab_bar->Flags & ImGuiTabBarFlags_DockNode) == 0)
         PopID();
-    g.CurrentTabBar.pop_back();
+
+    g.CurrentTabBarStack.pop_back();
+    g.CurrentTabBar = g.CurrentTabBarStack.empty() ? NULL : GetTabBarFromTabBarRef(g.CurrentTabBarStack.back());
 }
 
 // This is called only once a frame before by the first call to ItemTab()
@@ -6356,8 +6375,8 @@ bool    ImGui::BeginTabItem(const char* label, bool* p_open, ImGuiTabItemFlags f
     if (g.CurrentWindow->SkipItems)
         return false;
 
-    IM_ASSERT(g.CurrentTabBar.Size > 0 && "Needs to be called between BeginTabBar() and EndTabBar()!");
-    ImGuiTabBar* tab_bar = g.CurrentTabBar.back();
+    ImGuiTabBar* tab_bar = g.CurrentTabBar;
+    IM_ASSERT(tab_bar && "Needs to be called between BeginTabBar() and EndTabBar()!");
     bool ret = TabItemEx(tab_bar, label, p_open, flags);
     if (ret && !(flags & ImGuiTabItemFlags_NoPushId))
     {
@@ -6373,9 +6392,9 @@ void    ImGui::EndTabItem()
     if (g.CurrentWindow->SkipItems)
         return;
 
-    IM_ASSERT(g.CurrentTabBar.Size > 0 && "Needs to be called between BeginTabBar() and EndTabBar()!");
-    ImGuiTabBar* tab_bar = g.CurrentTabBar.back();
-    IM_ASSERT(tab_bar->LastTabItemIdx >= 0 && "Needs to be called between BeginTabItem() and EndTabItem()");
+    ImGuiTabBar* tab_bar = g.CurrentTabBar;
+    IM_ASSERT(tab_bar != NULL && "Needs to be called between BeginTabBar() and EndTabBar()!");
+    IM_ASSERT(tab_bar->LastTabItemIdx >= 0);
     ImGuiTabItem* tab = &tab_bar->Tabs[tab_bar->LastTabItemIdx];
     if (!(tab->Flags & ImGuiTabItemFlags_NoPushId))
         g.CurrentWindow->IDStack.pop_back();
@@ -6575,10 +6594,10 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
 void    ImGui::SetTabItemClosed(const char* label)
 {
     ImGuiContext& g = *GImGui;
-    bool is_within_manual_tab_bar = (g.CurrentTabBar.Size > 0) && !(g.CurrentTabBar.back()->Flags & ImGuiTabBarFlags_DockNode);
+    bool is_within_manual_tab_bar = g.CurrentTabBar && !(g.CurrentTabBar->Flags & ImGuiTabBarFlags_DockNode);
     if (is_within_manual_tab_bar)
     {
-        ImGuiTabBar* tab_bar = g.CurrentTabBar.back();
+        ImGuiTabBar* tab_bar = g.CurrentTabBar;
         IM_ASSERT(tab_bar->WantLayout);         // Needs to be called AFTER BeginTabBar() and BEFORE the first call to BeginTabItem()
         ImGuiID tab_id = TabBarCalcTabID(tab_bar, label);
         TabBarRemoveTab(tab_bar, tab_id);