Add Config::setDockWidgetTabIndexOverrideFunc()

Allows the user to manipulate the tab index when dockwidget
is being redocked.

Fixes issue #165, or is at least the workaround we can manage.

src/Config.cpp

@@ -65,6 +65,7 @@ class Config::Private
     DropIndicatorAllowedFunc m_dropIndicatorAllowedFunc = nullptr;
     DragAboutToStartFunc m_dragAboutToStartFunc = nullptr;
     DragEndedFunc m_dragEndedFunc = nullptr;
+    DockWidgetTabIndexOverrideFunc m_restorePlaceholderTabIndexOverride = nullptr;
     ViewFactory *m_viewFactory = nullptr;
     Flags m_flags = Flag_Default;
     MDIFlags m_mdiFlags = MDIFlag_None;
@@ -276,6 +277,16 @@ DragEndedFunc Config::dragEndedFunc() const
     return d->m_dragEndedFunc;
 }
 
+void Config::setDockWidgetTabIndexOverrideFunc(DockWidgetTabIndexOverrideFunc func)
+{
+    d->m_restorePlaceholderTabIndexOverride = func;
+}
+
+DockWidgetTabIndexOverrideFunc Config::dockWidgetTabIndexOverrideFunc() const
+{
+    return d->m_restorePlaceholderTabIndexOverride;
+}
+
 void Config::setAbsoluteWidgetMinSize(Size size)
 {
     if (!DockRegistry::self()->isEmpty(/*excludeBeingDeleted=*/false)) {

src/Config.h

@@ -30,12 +30,14 @@ class MainWindow;
 class DropArea;
 class Draggable;
 class ViewFactory;
+class Group;
 }
 
 typedef KDDockWidgets::Core::DockWidget *(*DockWidgetFactoryFunc)(const QString &name);
 typedef KDDockWidgets::Core::MainWindow *(*MainWindowFactoryFunc)(const QString &name, KDDockWidgets::MainWindowOptions);
 typedef bool (*DragAboutToStartFunc)(Core::Draggable *draggable);
 typedef void (*DragEndedFunc)();
+typedef int (*DockWidgetTabIndexOverrideFunc)(Core::DockWidget *dw, Core::Group *group, int tabIndex);
 
 /// @brief Function to allow more granularity to disallow where widgets are dropped
 ///
@@ -344,6 +346,13 @@ class DOCKS_EXPORT Config
     void setDragEndedFunc(DragEndedFunc func);
     DragEndedFunc dragEndedFunc() const;
 
+    /// Allows to override the tabindex when restoring a dock widget to a tab
+    /// When a dock widget is un-floated (by double click on titlebar) it goes to its
+    /// previous know position in the main window. If that position was tabbed, the provided
+    /// func can be used to change the actual tabIndex that's used.
+    void setDockWidgetTabIndexOverrideFunc(DockWidgetTabIndexOverrideFunc func);
+    DockWidgetTabIndexOverrideFunc dockWidgetTabIndexOverrideFunc() const;
+
     ///@brief Used internally by the framework. Returns the function which was passed to
     /// setDropIndicatorAllowedFunc()
     /// By default it's nullptr.

src/core/Layout.cpp

@@ -163,10 +163,15 @@ void Layout::restorePlaceholder(Core::DockWidget *dw, Core::Item *item, int tabI
         KDDW_ERROR("Layout::restorePlaceholder: Trying to use a group that's being deleted");
     }
 
-    if (tabIndex != -1 && group->dockWidgetCount() >= tabIndex) {
-        group->insertWidget(dw, tabIndex);
+    if (auto tabIndexFunc = Config::self().dockWidgetTabIndexOverrideFunc()) {
+        // The user wishes to control the tabIndex himself
+        group->insertWidget(dw, tabIndexFunc(dw, group, tabIndex));
     } else {
-        group->addTab(dw);
+        if (tabIndex != -1 && group->dockWidgetCount() >= tabIndex) {
+            group->insertWidget(dw, tabIndex);
+        } else {
+            group->addTab(dw);
+        }
     }
 
     group->Controller::setVisible(true);

tests/tst_docks.cpp

@@ -3081,6 +3081,29 @@ KDDW_QCORO_TASK tst_restoreGroupOptions()
     KDDW_TEST_RETURN(true);
 }
 
+KDDW_QCORO_TASK tst_dockWidgetTabIndexOverride()
+{
+    EnsureTopLevelsDeleted e;
+    Config::self().setDockWidgetTabIndexOverrideFunc([](Core::DockWidget *, Core::Group *, int) {
+        return 0;
+    });
+
+    auto m =
+        createMainWindow(Size(500, 500), MainWindowOption_None);
+    auto dock1 = createDockWidget("1", Platform::instance()->tests_createView({ true }));
+    auto dock2 = createDockWidget("2", Platform::instance()->tests_createView({ true }));
+    m->addDockWidget(dock1, Location_OnTop);
+    dock1->addDockWidgetAsTab(dock2);
+
+    /// Redocking will use our override func and move it to index 0
+    CHECK(dock2->tabIndex() == 1);
+    dock2->setFloating(true);
+    dock2->setFloating(false);
+    CHECK(dock2->tabIndex() == 0);
+
+    KDDW_TEST_RETURN(true);
+}
+
 KDDW_QCORO_TASK tst_restoreWithCentralFrameWithTabs()
 {
     EnsureTopLevelsDeleted e;
@@ -6398,6 +6421,7 @@ static const auto s_tests = std::vector<KDDWTest>
         TEST(tst_mainWindowToggle),
         TEST(tst_startDragging),
 #if !defined(KDDW_FRONTEND_FLUTTER)
+        TEST(tst_dockWidgetTabIndexOverride),
         TEST(tst_restoreWithCentralFrameWithTabs),
         TEST(tst_preferredInitialSize),
         TEST(tst_preferredInitialSizeVsMinSize),

tests/utils.h

@@ -105,6 +105,7 @@ struct EnsureTopLevelsDeleted
         // Other cleanup, since we use this class everywhere
         Config::self().setDockWidgetFactoryFunc(nullptr);
         Config::self().setMainWindowFactoryFunc(nullptr);
+        Config::self().setDockWidgetTabIndexOverrideFunc(nullptr);
         Config::self().setInternalFlags(m_originalInternalFlags);
         Config::self().setFlags(m_originalFlags);
         Config::self().setMDIFlags(m_originalMDIFlags);