TabBar: Internals: add GetCurrentTabBar(), TabBarFindTabByOrder(), TabBarGetCurrentTab(), TabBarGetTabOrder(), TabBarGetTabName(), TabBarQueueFocus() + clear LastTabItemIdx on EndTabBar(). (#5853, #5997)

ImGuiTabBar::GetTabOrder() -> TabBarGetTabOrder().
ImGuiTabBar::GetTabName() -> TabBarGetTabName()

imgui.cpp

@@ -13938,7 +13938,7 @@ void ImGui::DebugNodeTabBar(ImGuiTabBar* tab_bar, const char* label)
     {
         ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
         p += ImFormatString(p, buf_end - p, "%s'%s'",
-            tab_n > 0 ? ", " : "", (tab->NameOffset != -1) ? tab_bar->GetTabName(tab) : "???");
+            tab_n > 0 ? ", " : "", (tab->NameOffset != -1) ? TabBarGetTabName(tab_bar, tab) : "???");
     }
     p += ImFormatString(p, buf_end - p, (tab_bar->Tabs.Size > 3) ? " ... }" : " } ");
     if (!is_active) { PushStyleColor(ImGuiCol_Text, GetStyleColorVec4(ImGuiCol_TextDisabled)); }
@@ -13955,12 +13955,12 @@ void ImGui::DebugNodeTabBar(ImGuiTabBar* tab_bar, const char* label)
     {
         for (int tab_n = 0; tab_n < tab_bar->Tabs.Size; tab_n++)
         {
-            const ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
+            ImGuiTabItem* tab = &tab_bar->Tabs[tab_n];
             PushID(tab);
             if (SmallButton("<")) { TabBarQueueReorder(tab_bar, tab, -1); } SameLine(0, 2);
             if (SmallButton(">")) { TabBarQueueReorder(tab_bar, tab, +1); } SameLine();
             Text("%02d%c Tab 0x%08X '%s' Offset: %.2f, Width: %.2f/%.2f",
-                tab_n, (tab->ID == tab_bar->SelectedTabId) ? '*' : ' ', tab->ID, (tab->NameOffset != -1) ? tab_bar->GetTabName(tab) : "???", tab->Offset, tab->Width, tab->ContentWidth);
+                tab_n, (tab->ID == tab_bar->SelectedTabId) ? '*' : ' ', tab->ID, (tab->NameOffset != -1) ? TabBarGetTabName(tab_bar, tab) : "???", tab->Offset, tab->Width, tab->ContentWidth);
             PopID();
         }
         TreePop();

imgui_internal.h

@@ -2390,7 +2390,7 @@ struct ImGuiTabItem
     float               RequestedWidth;         // Width optionally requested by caller, -1.0f is unused
     ImS32               NameOffset;             // When Window==NULL, offset to name within parent ImGuiTabBar::TabsNames
     ImS16               BeginOrder;             // BeginTabItem() order, used to re-order tabs after toggling ImGuiTabBarFlags_Reorderable
-    ImS16               IndexDuringLayout;      // Index only used during TabBarLayout()
+    ImS16               IndexDuringLayout;      // Index only used during TabBarLayout(). Tabs gets reordered so 'Tabs[n].IndexDuringLayout == n' but may mismatch during additions.
     bool                WantClose;              // Marked as closed by SetTabItemClosed()
 
     ImGuiTabItem()      { memset(this, 0, sizeof(*this)); LastFrameVisible = LastFrameSelected = -1; RequestedWidth = -1.0f; NameOffset = -1; BeginOrder = IndexDuringLayout = -1; }
@@ -2432,12 +2432,6 @@ struct IMGUI_API ImGuiTabBar
     ImGuiTextBuffer     TabsNames;              // For non-docking tab bar we re-append names in a contiguous buffer.
 
     ImGuiTabBar();
-    int                 GetTabOrder(const ImGuiTabItem* tab) const  { return Tabs.index_from_ptr(tab); }
-    const char*         GetTabName(const ImGuiTabItem* tab) const
-    {
-        IM_ASSERT(tab->NameOffset != -1 && tab->NameOffset < TabsNames.Buf.Size);
-        return TabsNames.Buf.Data + tab->NameOffset;
-    }
 };
 
 //-----------------------------------------------------------------------------
@@ -3038,12 +3032,18 @@ namespace ImGui
     IMGUI_API ImGuiTableSettings*   TableSettingsFindByID(ImGuiID id);
 
     // Tab Bars
+    inline    ImGuiTabBar*  GetCurrentTabBar() { ImGuiContext& g = *GImGui; return g.CurrentTabBar; }
     IMGUI_API bool          BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& bb, ImGuiTabBarFlags flags);
     IMGUI_API ImGuiTabItem* TabBarFindTabByID(ImGuiTabBar* tab_bar, ImGuiID tab_id);
+    IMGUI_API ImGuiTabItem* TabBarFindTabByOrder(ImGuiTabBar* tab_bar, int order);
+    IMGUI_API ImGuiTabItem* TabBarGetCurrentTab(ImGuiTabBar* tab_bar);
+    inline int              TabBarGetTabOrder(ImGuiTabBar* tab_bar, ImGuiTabItem* tab) { return tab_bar->Tabs.index_from_ptr(tab); }
+    IMGUI_API const char*   TabBarGetTabName(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
     IMGUI_API void          TabBarRemoveTab(ImGuiTabBar* tab_bar, ImGuiID tab_id);
     IMGUI_API void          TabBarCloseTab(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
-    IMGUI_API void          TabBarQueueReorder(ImGuiTabBar* tab_bar, const ImGuiTabItem* tab, int offset);
-    IMGUI_API void          TabBarQueueReorderFromMousePos(ImGuiTabBar* tab_bar, const ImGuiTabItem* tab, ImVec2 mouse_pos);
+    IMGUI_API void          TabBarQueueFocus(ImGuiTabBar* tab_bar, ImGuiTabItem* tab);
+    IMGUI_API void          TabBarQueueReorder(ImGuiTabBar* tab_bar, ImGuiTabItem* tab, int offset);
+    IMGUI_API void          TabBarQueueReorderFromMousePos(ImGuiTabBar* tab_bar, ImGuiTabItem* tab, ImVec2 mouse_pos);
     IMGUI_API bool          TabBarProcessReorder(ImGuiTabBar* tab_bar);
     IMGUI_API bool          TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open, ImGuiTabItemFlags flags, ImGuiWindow* docked_window);
     IMGUI_API ImVec2        TabItemCalcSize(const char* label, bool has_close_button_or_unsaved_marker);

imgui_widgets.cpp

@@ -7282,11 +7282,17 @@ bool ImGui::MenuItem(const char* label, const char* shortcut, bool* p_selected,
 // - TabBarCalcTabID() [Internal]
 // - TabBarCalcMaxTabWidth() [Internal]
 // - TabBarFindTabById() [Internal]
+// - TabBarFindTabByOrder() [Internal]
+// - TabBarGetCurrentTab() [Internal]
+// - TabBarGetTabName() [Internal]
 // - TabBarRemoveTab() [Internal]
 // - TabBarCloseTab() [Internal]
 // - TabBarScrollClamp() [Internal]
 // - TabBarScrollToTab() [Internal]
-// - TabBarQueueChangeTabOrder() [Internal]
+// - TabBarQueueFocus() [Internal]
+// - TabBarQueueReorder() [Internal]
+// - TabBarProcessReorderFromMousePos() [Internal]
+// - TabBarProcessReorder() [Internal]
 // - TabBarScrollingButtons() [Internal]
 // - TabBarTabListPopupButton() [Internal]
 //-------------------------------------------------------------------------
@@ -7411,6 +7417,7 @@ bool    ImGui::BeginTabBarEx(ImGuiTabBar* tab_bar, const ImRect& tab_bar_bb, ImG
     tab_bar->ItemSpacingY = g.Style.ItemSpacing.y;
     tab_bar->FramePadding = g.Style.FramePadding;
     tab_bar->TabsActiveCount = 0;
+    tab_bar->LastTabItemIdx = -1;
     tab_bar->BeginCount = 1;
 
     // Set cursor pos in a way which only be used in the off-chance the user erroneously submits item before BeginTabItem(): items will overlap
@@ -7459,6 +7466,7 @@ void    ImGui::EndTabBar()
     if (tab_bar->BeginCount > 1)
         window->DC.CursorPos = tab_bar->BackupCursorPos;
 
+    tab_bar->LastTabItemIdx = -1;
     if ((tab_bar->Flags & ImGuiTabBarFlags_DockNode) == 0)
         PopID();
 
@@ -7568,7 +7576,7 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
         // Refresh tab width immediately, otherwise changes of style e.g. style.FramePadding.x would noticeably lag in the tab bar.
         // Additionally, when using TabBarAddTab() to manipulate tab bar order we occasionally insert new tabs that don't have a width yet,
         // and we cannot wait for the next BeginTabItem() call. We cannot compute this width within TabBarAddTab() because font size depends on the active window.
-        const char* tab_name = tab_bar->GetTabName(tab);
+        const char* tab_name = TabBarGetTabName(tab_bar, tab);
         const bool has_close_button_or_unsaved_marker = (tab->Flags & ImGuiTabItemFlags_NoCloseButton) == 0 || (tab->Flags & ImGuiTabItemFlags_UnsavedDocument);
         tab->ContentWidth = (tab->RequestedWidth >= 0.0f) ? tab->RequestedWidth : TabItemCalcSize(tab_name, has_close_button_or_unsaved_marker).x;
 
@@ -7729,7 +7737,28 @@ ImGuiTabItem* ImGui::TabBarFindTabByID(ImGuiTabBar* tab_bar, ImGuiID tab_id)
     return NULL;
 }
 
-// The *TabId fields be already set by the docking system _before_ the actual TabItem was created, so we clear them regardless.
+// Order = visible order, not submission order! (which is tab->BeginOrder)
+ImGuiTabItem* ImGui::TabBarFindTabByOrder(ImGuiTabBar* tab_bar, int order)
+{
+    if (order < 0 || order >= tab_bar->Tabs.Size)
+        return NULL;
+    return &tab_bar->Tabs[order];
+}
+
+ImGuiTabItem* ImGui::TabBarGetCurrentTab(ImGuiTabBar* tab_bar)
+{
+    if (tab_bar->LastTabItemIdx <= 0 || tab_bar->LastTabItemIdx >= tab_bar->Tabs.Size)
+        return NULL;
+    return &tab_bar->Tabs[tab_bar->LastTabItemIdx];
+}
+
+const char* ImGui::TabBarGetTabName(ImGuiTabBar* tab_bar, ImGuiTabItem* tab)
+{
+    IM_ASSERT(tab->NameOffset != -1 && tab->NameOffset < tab_bar->TabsNames.Buf.Size);
+    return tab_bar->TabsNames.Buf.Data + tab->NameOffset;
+}
+
+// The *TabId fields are already set by the docking system _before_ the actual TabItem was created, so we clear them regardless.
 void ImGui::TabBarRemoveTab(ImGuiTabBar* tab_bar, ImGuiID tab_id)
 {
     if (ImGuiTabItem* tab = TabBarFindTabByID(tab_bar, tab_id))
@@ -7760,7 +7789,7 @@ void ImGui::TabBarCloseTab(ImGuiTabBar* tab_bar, ImGuiTabItem* tab)
     {
         // Actually select before expecting closure attempt (on an UnsavedDocument tab user is expect to e.g. show a popup)
         if (tab_bar->VisibleTabId != tab->ID)
-            tab_bar->NextSelectedTabId = tab->ID;
+            TabBarQueueFocus(tab_bar, tab);
     }
 }
 
@@ -7781,7 +7810,7 @@ static void ImGui::TabBarScrollToTab(ImGuiTabBar* tab_bar, ImGuiID tab_id, ImGui
 
     ImGuiContext& g = *GImGui;
     float margin = g.FontSize * 1.0f; // When to scroll to make Tab N+1 visible always make a bit of N visible to suggest more scrolling area (since we don't have a scrollbar)
-    int order = tab_bar->GetTabOrder(tab);
+    int order = TabBarGetTabOrder(tab_bar, tab);
 
     // Scrolling happens only in the central section (leading/trailing sections are not scrolling)
     // FIXME: This is all confusing.
@@ -7805,7 +7834,12 @@ static void ImGui::TabBarScrollToTab(ImGuiTabBar* tab_bar, ImGuiID tab_id, ImGui
     }
 }
 
-void ImGui::TabBarQueueReorder(ImGuiTabBar* tab_bar, const ImGuiTabItem* tab, int offset)
+void ImGui::TabBarQueueFocus(ImGuiTabBar* tab_bar, ImGuiTabItem* tab)
+{
+    tab_bar->NextSelectedTabId = tab->ID;
+}
+
+void ImGui::TabBarQueueReorder(ImGuiTabBar* tab_bar, ImGuiTabItem* tab, int offset)
 {
     IM_ASSERT(offset != 0);
     IM_ASSERT(tab_bar->ReorderRequestTabId == 0);
@@ -7813,7 +7847,7 @@ void ImGui::TabBarQueueReorder(ImGuiTabBar* tab_bar, const ImGuiTabItem* tab, in
     tab_bar->ReorderRequestOffset = (ImS16)offset;
 }
 
-void ImGui::TabBarQueueReorderFromMousePos(ImGuiTabBar* tab_bar, const ImGuiTabItem* src_tab, ImVec2 mouse_pos)
+void ImGui::TabBarQueueReorderFromMousePos(ImGuiTabBar* tab_bar, ImGuiTabItem* src_tab, ImVec2 mouse_pos)
 {
     ImGuiContext& g = *GImGui;
     IM_ASSERT(tab_bar->ReorderRequestTabId == 0);
@@ -7856,7 +7890,7 @@ bool ImGui::TabBarProcessReorder(ImGuiTabBar* tab_bar)
         return false;
 
     //IM_ASSERT(tab_bar->Flags & ImGuiTabBarFlags_Reorderable); // <- this may happen when using debug tools
-    int tab2_order = tab_bar->GetTabOrder(tab1) + tab_bar->ReorderRequestOffset;
+    int tab2_order = TabBarGetTabOrder(tab_bar, tab1) + tab_bar->ReorderRequestOffset;
     if (tab2_order < 0 || tab2_order >= tab_bar->Tabs.Size)
         return false;
 
@@ -7916,7 +7950,7 @@ static ImGuiTabItem* ImGui::TabBarScrollingButtons(ImGuiTabBar* tab_bar)
     if (select_dir != 0)
         if (ImGuiTabItem* tab_item = TabBarFindTabByID(tab_bar, tab_bar->SelectedTabId))
         {
-            int selected_order = tab_bar->GetTabOrder(tab_item);
+            int selected_order = TabBarGetTabOrder(tab_bar, tab_item);
             int target_order = selected_order + select_dir;
 
             // Skip tab item buttons until another tab item is found or end is reached
@@ -7968,7 +8002,7 @@ static ImGuiTabItem* ImGui::TabBarTabListPopupButton(ImGuiTabBar* tab_bar)
             if (tab->Flags & ImGuiTabItemFlags_Button)
                 continue;
 
-            const char* tab_name = tab_bar->GetTabName(tab);
+            const char* tab_name = TabBarGetTabName(tab_bar, tab);
             if (Selectable(tab_name, tab_bar->SelectedTabId == tab->ID))
                 tab_to_select = tab;
         }
@@ -8132,9 +8166,9 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     {
         if (tab_appearing && (tab_bar->Flags & ImGuiTabBarFlags_AutoSelectNewTabs) && tab_bar->NextSelectedTabId == 0)
             if (!tab_bar_appearing || tab_bar->SelectedTabId == 0)
-                tab_bar->NextSelectedTabId = id;  // New tabs gets activated
+                TabBarQueueFocus(tab_bar, tab); // New tabs gets activated
         if ((flags & ImGuiTabItemFlags_SetSelected) && (tab_bar->SelectedTabId != id)) // _SetSelected can only be passed on explicit tab bar
-            tab_bar->NextSelectedTabId = id;
+            TabBarQueueFocus(tab_bar, tab);
     }
 
     // Lock visibility
@@ -8198,7 +8232,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     bool hovered, held;
     bool pressed = ButtonBehavior(bb, id, &hovered, &held, button_flags);
     if (pressed && !is_tab_button)
-        tab_bar->NextSelectedTabId = id;
+        TabBarQueueFocus(tab_bar, tab);
 
     // Allow the close button to overlap unless we are dragging (in which case we don't want any overlapping tabs to be hovered)
     if (g.ActiveId != id)
@@ -8239,9 +8273,8 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
 
     // Select with right mouse button. This is so the common idiom for context menu automatically highlight the current widget.
     const bool hovered_unblocked = IsItemHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup);
-    if (hovered_unblocked && (IsMouseClicked(1) || IsMouseReleased(1)))
-        if (!is_tab_button)
-            tab_bar->NextSelectedTabId = id;
+    if (hovered_unblocked && (IsMouseClicked(1) || IsMouseReleased(1)) && !is_tab_button)
+        TabBarQueueFocus(tab_bar, tab);
 
     if (tab_bar->Flags & ImGuiTabBarFlags_NoCloseWithMiddleMouseButton)
         flags |= ImGuiTabItemFlags_NoCloseWithMiddleMouseButton;