Tab Bar: Allow calling SetTabItemClosed() after a tab has been submitted (will process next frame).

+ larger combo height on TabBarTabListPopupButton()

docs/CHANGELOG.txt

@@ -55,6 +55,7 @@ Other Changes:
   limits when close-enough by (WindowPadding - ItemPadding), which was a tweak with too many
   side-effects. The behavior is still present in SetScrollHere functions as they are more explicitly
   aiming at making widgets visible. May later be moved to a flag.
+- Tab Bar: Allow calling SetTabItemClosed() after a tab has been submitted (will process next frame).
 - InvisibleButton: Made public a small selection of ImGuiButtonFlags (previously in imgui_internal.h)
   and allowed to pass them to InvisibleButton(): ImGuiButtonFlags_MouseButtonLeft/Right/Middle.
   This is a small but rather important change because lots of multi-button behaviors could previously

docs/TODO.txt

@@ -161,6 +161,7 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - dock: merge docking branch (#2109)
  - dock: dock out from a collapsing header? would work nicely but need emitting window to keep submitting the code.
 
+ - tabs: while dragging/reordering a tab, close button decoration shouldn't appear on other tabs
  - tabs: make EndTabBar fail if users doesn't respect BeginTabBar return value, for consistency/future-proofing.
  - tabs: persistent order/focus in BeginTabBar() api (#261, #351)
  - tabs: TabItem could honor SetNextItemWidth()?

imgui_internal.h

@@ -1696,19 +1696,20 @@ enum ImGuiTabItemFlagsPrivate_
     ImGuiTabItemFlags_NoCloseButton             = 1 << 20   // Track whether p_open was set or not (we'll need this info on the next frame to recompute ContentWidth during layout)
 };
 
-// Storage for one active tab item (sizeof() 26~32 bytes)
+// Storage for one active tab item (sizeof() 28~32 bytes)
 struct ImGuiTabItem
 {
     ImGuiID             ID;
     ImGuiTabItemFlags   Flags;
     int                 LastFrameVisible;
     int                 LastFrameSelected;      // This allows us to infer an ordered list of the last activated tabs with little maintenance
-    int                 NameOffset;             // When Window==NULL, offset to name within parent ImGuiTabBar::TabsNames
     float               Offset;                 // Position relative to beginning of tab
     float               Width;                  // Width currently displayed
     float               ContentWidth;           // Width of actual contents, stored during BeginTabItem() call
+    ImS16               NameOffset;             // When Window==NULL, offset to name within parent ImGuiTabBar::TabsNames
+    bool                WantClose;              // Marked as closed by SetTabItemClosed()
 
-    ImGuiTabItem()      { ID = 0; Flags = ImGuiTabItemFlags_None; LastFrameVisible = LastFrameSelected = -1; NameOffset = -1; Offset = Width = ContentWidth = 0.0f; }
+    ImGuiTabItem()      { ID = 0; Flags = ImGuiTabItemFlags_None; LastFrameVisible = LastFrameSelected = -1; NameOffset = -1; Offset = Width = ContentWidth = 0.0f; WantClose = false; }
 };
 
 // Storage for a tab bar (sizeof() 92~96 bytes)
@@ -1743,7 +1744,7 @@ struct 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);
+        IM_ASSERT(tab->NameOffset != -1 && (int)tab->NameOffset < TabsNames.Buf.Size);
         return TabsNames.Buf.Data + tab->NameOffset;
     }
 };

imgui_widgets.cpp

@@ -6709,15 +6709,17 @@ static void ImGui::TabBarLayout(ImGuiTabBar* tab_bar)
     ImGuiContext& g = *GImGui;
     tab_bar->WantLayout = false;
 
-    // Garbage collect
+    // Garbage collect by compacting list
     int tab_dst_n = 0;
     for (int tab_src_n = 0; tab_src_n < tab_bar->Tabs.Size; tab_src_n++)
     {
         ImGuiTabItem* tab = &tab_bar->Tabs[tab_src_n];
-        if (tab->LastFrameVisible < tab_bar->PrevFrameVisible)
+        if (tab->LastFrameVisible < tab_bar->PrevFrameVisible || tab->WantClose)
         {
-            if (tab->ID == tab_bar->SelectedTabId)
+            // Remove tab
-                tab_bar->SelectedTabId = 0;
+            if (tab_bar->VisibleTabId == tab->ID) { tab_bar->VisibleTabId = 0; }
+            if (tab_bar->SelectedTabId == tab->ID) { tab_bar->SelectedTabId = 0; }
+            if (tab_bar->NextSelectedTabId == tab->ID) { tab_bar->NextSelectedTabId = 0; }
             continue;
         }
         if (tab_dst_n != tab_src_n)
@@ -7039,7 +7041,7 @@ static ImGuiTabItem* ImGui::TabBarTabListPopupButton(ImGuiTabBar* tab_bar)
     arrow_col.w *= 0.5f;
     PushStyleColor(ImGuiCol_Text, arrow_col);
     PushStyleColor(ImGuiCol_Button, ImVec4(0, 0, 0, 0));
-    bool open = BeginCombo("##v", NULL, ImGuiComboFlags_NoPreview);
+    bool open = BeginCombo("##v", NULL, ImGuiComboFlags_NoPreview | ImGuiComboFlags_HeightLargest);
     PopStyleColor(2);
 
     ImGuiTabItem* tab_to_select = NULL;
@@ -7167,7 +7169,7 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
     tab->Flags = flags;
 
     // Append name with zero-terminator
-    tab->NameOffset = tab_bar->TabsNames.size();
+    tab->NameOffset = (ImS16)tab_bar->TabsNames.size();
     tab_bar->TabsNames.append(label, label + strlen(label) + 1);
 
     // If we are not reorderable, always reset offset based on submission order.
@@ -7316,9 +7318,8 @@ bool    ImGui::TabItemEx(ImGuiTabBar* tab_bar, const char* label, bool* p_open,
 }
 
 // [Public] This is call is 100% optional but it allows to remove some one-frame glitches when a tab has been unexpectedly removed.
-// To use it to need to call the function SetTabItemClosed() after BeginTabBar() and before any call to BeginTabItem().
+// To use it to need to call the function SetTabItemClosed() between BeginTabBar() and EndTabBar().
 // Tabs closed by the close button will automatically be flagged to avoid this issue.
-// FIXME: We should aim to support calling SetTabItemClosed() after the tab submission (for next frame)
 void    ImGui::SetTabItemClosed(const char* label)
 {
     ImGuiContext& g = *GImGui;
@@ -7326,9 +7327,9 @@ void    ImGui::SetTabItemClosed(const char* label)
     if (is_within_manual_tab_bar)
     {
         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);
+        if (ImGuiTabItem* tab = TabBarFindTabByID(tab_bar, tab_id))
+            tab->WantClose = true; // Will be processed by next call to TabBarLayout()
     }
 }