LayoutSaver: Support the user's factory func doing remapping

While restoring a layout, we expect all widgets to exist already,
but we allow the user to create them delayed, by providing
us a factory function.

What we're supporting in this commit is the ability of the user's
factory function returning a dock widget with an ID different
than the one that was requested. We then save that mapping so the
rest of the layout restore works with the new ID.

src/DockWidgetBase.cpp

@@ -776,11 +776,18 @@ void DockWidgetBase::onCloseEvent(QCloseEvent *e)
 
 DockWidgetBase *DockWidgetBase::deserialize(const LayoutSaver::DockWidget::Ptr &saved)
 {
-    DockWidgetBase *dw = DockRegistry::self()->dockByName(saved->uniqueName);
+    auto dr = DockRegistry::self();
+    DockWidgetBase *dw = dr->dockByName(saved->uniqueName);
     if (!dw) {
+        // DockWidget doesn't exist, ask to create it
         if (auto factoryFunc = Config::self().dockWidgetFactoryFunc()) {
-            // DockWidget doesn't exist, ask to create it
             dw = factoryFunc(saved->uniqueName);
+            if (dw && dw->uniqueName() != saved->uniqueName) {
+                // Very special case
+                // The user's factory function returned a dock widget with a different ID.
+                // We support it. Save the mapping though.
+                dr->dockWidgetIdRemapping().insert(saved->uniqueName, dw->uniqueName());
+            }
         }
     }
 

src/LayoutSaver.cpp

@@ -313,7 +313,8 @@ bool LayoutSaver::restoreLayout(const QByteArray &data)
         if (!d->matchesAffinity(dw->affinities))
             continue;
 
-        if (DockWidgetBase *dockWidget = d->m_dockRegistry->dockByName(dw->uniqueName)) {
+        if (DockWidgetBase *dockWidget =
+                d->m_dockRegistry->dockByName(dw->uniqueName, /*consultRemapping=*/true)) {
             dockWidget->d->lastPositions().deserialize(dw->lastPosition);
         } else {
             qWarning() << Q_FUNC_INFO << "Couldn't find dock widget" << dw->uniqueName;

src/private/DockRegistry.cpp

@@ -256,6 +256,11 @@ Frame *DockRegistry::frameInMDIResize() const
     return nullptr;
 }
 
+QHash<QString, QString> &DockRegistry::dockWidgetIdRemapping()
+{
+    return m_dockWidgetIdRemapping;
+}
+
 MainWindowBase::List DockRegistry::mainWindowsWithAffinity(const QStringList &affinities) const
 {
     MainWindowBase::List result;
@@ -383,13 +388,20 @@ bool DockRegistry::containsMainWindow(const QString &uniqueName) const
     return mainWindowByName(uniqueName) != nullptr;
 }
 
-DockWidgetBase *DockRegistry::dockByName(const QString &name) const
+DockWidgetBase *DockRegistry::dockByName(const QString &name, bool consultRemapping) const
 {
     for (auto dock : qAsConst(m_dockWidgets)) {
         if (dock->uniqueName() == name)
             return dock;
     }
 
+    if (consultRemapping) {
+        // Name doesn't exist, let's check if it was remapped during a layout restore.
+        const QString newName = m_dockWidgetIdRemapping.value(name);
+        if (!newName.isEmpty())
+            return dockByName(newName);
+    }
+
     return nullptr;
 }
 

src/private/DockRegistry_p.h

@@ -64,7 +64,8 @@ public:
     Q_INVOKABLE bool containsDockWidget(const QString &uniqueName) const;
     Q_INVOKABLE bool containsMainWindow(const QString &uniqueName) const;
 
-    Q_INVOKABLE KDDockWidgets::DockWidgetBase *dockByName(const QString &) const;
+    Q_INVOKABLE KDDockWidgets::DockWidgetBase *dockByName(const QString &,
+                                                          bool consultRemapping = false) const;
     Q_INVOKABLE KDDockWidgets::MainWindowBase *mainWindowByName(const QString &) const;
     Q_INVOKABLE KDDockWidgets::MainWindowMDI *mdiMainWindowByName(const QString &) const;
 
@@ -219,6 +220,14 @@ public:
     ///@brief Returns the Frame which is being resized in a MDI layout. nullptr if none
     Frame *frameInMDIResize() const;
 
+    ///@brief Returns the dock widget id remapping, used by LayoutSaver
+    ///
+    /// When LayoutSaver is trying to restore dock widget "foo", but it doesn't exist, it will
+    /// attempt to call a user provided factory function. That function can however return a dock
+    /// widget with another ID, such as "bar". When that happens this QHash gets a "foo" : "bar"
+    /// entry
+    QHash<QString, QString> &dockWidgetIdRemapping();
+
 Q_SIGNALS:
     /// @brief emitted when a main window or a floating window change screen
     void windowChangedScreen(QWindow *);
@@ -243,6 +252,7 @@ private:
     QVector<FloatingWindow*> m_floatingWindows;
     QVector<LayoutWidget *> m_layouts;
     QPointer<DockWidgetBase> m_focusedDockWidget;
+    QHash<QString, QString> m_dockWidgetIdRemapping;
 };
 
 }

tests/tst_docks.cpp

@@ -134,6 +134,7 @@ private Q_SLOTS:
     void tst_marginsAfterRestore();
     void tst_restoreWithNewDockWidgets();
     void tst_restoreWithDockFactory();
+    void tst_restoreWithDockFactory2();
     void tst_lastFloatingPositionIsRestored();
     void tst_restoreSimple();
     void tst_restoreSimplest();
@@ -4055,6 +4056,31 @@ void TestDocks::tst_restoreWithDockFactory()
     layout->checkSanity();
 }
 
+void TestDocks::tst_restoreWithDockFactory2()
+{
+    // Teste that the factory function can do id remapping.
+    // For example, if id "foo" is missing, the factory can return a
+    // dock widget with id "bar" if it feels like it
+
+    auto m = createMainWindow(QSize(501, 500), MainWindowOption_None);
+
+    auto dock1 = createDockWidget("dw1", new QPushButton("1"));
+    m->addDockWidget(dock1, Location_OnLeft);
+    dock1->setFloating(true);
+
+    LayoutSaver saver;
+    const QByteArray saved = saver.serializeLayout();
+    delete dock1;
+
+    DockWidgetFactoryFunc func = [] (const QString &) {
+        // A factory func which does id remapping
+        return createDockWidget("dw2", new QPushButton("w"), {}, {}, /*show=*/ false);
+    };
+
+    KDDockWidgets::Config::self().setDockWidgetFactoryFunc(func);
+    saver.restoreLayout(saved);
+}
+
 void TestDocks::tst_addDockWidgetToMainWindow()
 {
     EnsureTopLevelsDeleted e;