Add new flag that will delete the contained widget and recreate it from a factory when closing and opening the dock widget.

examples/deleteonclose/main.cpp

@@ -41,7 +41,7 @@ int main(int argc, char *argv[])
         now->widget()->setFocus();
     });
 
-    QAction *action = new QAction("New Delete On Close", &w);
+    QAction *action = new QAction("New Delete Dock Widget On Close", &w);
     w.menuBar()->addAction(action);
 
     int i = 0;
@@ -53,7 +53,26 @@ int main(int argc, char *argv[])
         auto area = dockManager->addDockWidgetTab(ads::CenterDockWidgetArea, dw);
         qDebug() << "doc dock widget created!" << dw << area;
     });
-
+	
+	auto dw = new ads::CDockWidget(QStringLiteral("test doc %1").arg(i++), &w);
+	auto editor = new QTextEdit(QStringLiteral("recreated lorem ipsum......"), dw);
+	dw->setWidget(editor);
+	dw->setFeature(ads::CDockWidget::RecreateContentsWidgetOnCloseAndOpen, true);
+	dw->setWidgetFactory([](QWidget* dw){
+		static int timesRecreated = 0;
+		return new QTextEdit(QStringLiteral("recreated lorem ipsum... times %1").arg(++timesRecreated), dw);
+	});
+	auto area = dockManager->addDockWidgetTab(ads::CenterDockWidgetArea, dw);
+	qDebug() << "RecreateContentsWidgetOnCloseAndOpen dock widget created!" << dw << area;
+	
+	action = new QAction("Toggle Recreate Contents Widget On Close and Open", &w);
+    w.menuBar()->addAction(action);
+	
+	QObject::connect(action, &QAction::triggered, [dw]() {
+		dw->toggleView(dw->isClosed());
+		qDebug() << QString("dock widget %1! contents widget %2!").arg(dw->isClosed() ? "closed" : "open", dw->widget() ? "created" : "deleted");
+    });
+	
     action = new QAction("New", &w);
     w.menuBar()->addAction(action);
     QObject::connect(action, &QAction::triggered, [&]() {

src/DockWidget.cpp

@@ -66,6 +66,12 @@ namespace ads
  */
 struct DockWidgetPrivate
 {
+	struct WidgetFactory 
+	{
+		CDockWidget::FactoryFunc createWidget;
+		CDockWidget::eInsertMode insertMode;
+	};	
+	
 	CDockWidget* _this = nullptr;
 	QBoxLayout* Layout = nullptr;
 	QWidget* Widget = nullptr;
@@ -84,7 +90,8 @@ struct DockWidgetPrivate
 	bool IsFloatingTopLevel = false;
 	QList<QAction*> TitleBarActions;
 	CDockWidget::eMinimumSizeHintMode MinimumSizeHintMode = CDockWidget::MinimumSizeHintFromDockWidget;
-
+	WidgetFactory* Factory = nullptr;
+	
 	/**
 	 * Private data constructor
 	 */
@@ -116,6 +123,12 @@ struct DockWidgetPrivate
 	 * Setup the main scroll area
 	 */
 	void setupScrollArea();
+	
+	/**
+	 * Sets the widget factory that will be used to recreate and set the contents widget.
+	 */
+	void setWidgetFactory(CDockWidget::FactoryFunc createWidget, CDockWidget::eInsertMode insertMode);
+	bool createWidgetFromFactory();
 };
 // struct DockWidgetPrivate
 
@@ -130,6 +143,14 @@ DockWidgetPrivate::DockWidgetPrivate(CDockWidget* _public) :
 //============================================================================
 void DockWidgetPrivate::showDockWidget()
 {
+	if (!Widget) {
+		if(!createWidgetFromFactory()) {
+			Q_ASSERT(!Features.testFlag(CDockWidget::RecreateContentsWidgetOnCloseAndOpen) 
+					 && "RecreateContentsWidgetOnCloseAndOpen flag was set, but the widget factory is missing or it doesn't return a valid QWidget.");
+			return;	
+		}
+	}
+	
 	if (!DockArea)
 	{
 		CFloatingDockContainer* FloatingWidget = new CFloatingDockContainer(_this);
@@ -167,6 +188,12 @@ void DockWidgetPrivate::hideDockWidget()
 {
 	TabWidget->hide();
 	updateParentDockArea();
+	
+	if (Features.testFlag(CDockWidget::RecreateContentsWidgetOnCloseAndOpen))
+	{
+		Widget->deleteLater();
+		Widget = nullptr;
+	}
 }
 
 
@@ -219,6 +246,38 @@ void DockWidgetPrivate::setupScrollArea()
 	Layout->addWidget(ScrollArea);
 }
 
+void DockWidgetPrivate::setWidgetFactory(CDockWidget::FactoryFunc createWidget, CDockWidget::eInsertMode insertMode)
+{
+	if (Factory)
+	{
+		delete Factory;
+	}
+	
+	Factory = new WidgetFactory { createWidget, insertMode };
+}
+
+bool DockWidgetPrivate::createWidgetFromFactory()
+{
+	if (!Features.testFlag(CDockWidget::RecreateContentsWidgetOnCloseAndOpen)) 
+	{
+		return false;
+	}
+	
+	if (!Factory)
+	{
+		return false;
+	}
+	
+	QWidget* w = Factory->createWidget(_this);
+	if (!w)
+	{
+		return false;
+	}
+	
+	_this->setWidget(w, Factory->insertMode);
+	return true;
+}
+
 
 //============================================================================
 CDockWidget::CDockWidget(const QString &title, QWidget *parent) :
@@ -290,6 +349,11 @@ void CDockWidget::setWidget(QWidget* widget, eInsertMode InsertMode)
 	d->Widget->setProperty("dockWidgetContent", true);
 }
 
+//============================================================================
+void CDockWidget::setWidgetFactory(FactoryFunc createWidget, eInsertMode insertMode) {
+	d->setWidgetFactory(createWidget, insertMode);
+}
+
 
 //============================================================================
 QWidget* CDockWidget::takeWidget()

src/DockWidget.h

@@ -147,18 +147,19 @@ public:
 
     enum DockWidgetFeature
     {
-        DockWidgetClosable = 0x01,///< dock widget has a close button
-        DockWidgetMovable = 0x02,///< dock widget is movable and can be moved to a new position in the current dock container
-        DockWidgetFloatable = 0x04,///< dock widget can be dragged into a floating window
-        DockWidgetDeleteOnClose = 0x08, ///< deletes the dock widget when it is closed
-        CustomCloseHandling = 0x10, ///< clicking the close button will not close the dock widget but emits the closeRequested() signal instead
-        DockWidgetFocusable = 0x20, ///< if this is enabled, a dock widget can get focus highlighting
-        DockWidgetForceCloseWithArea = 0x40, ///< dock widget will be closed when the dock area hosting it is closed
-        NoTab = 0x80, ///< dock widget tab will never be shown if this flag is set
+        DockWidgetClosable = 0x001,///< dock widget has a close button
+        DockWidgetMovable = 0x002,///< dock widget is movable and can be moved to a new position in the current dock container
+        DockWidgetFloatable = 0x004,///< dock widget can be dragged into a floating window
+        DockWidgetDeleteOnClose = 0x008, ///< deletes the dock widget when it is closed
+        CustomCloseHandling = 0x010, ///< clicking the close button will not close the dock widget but emits the closeRequested() signal instead
+        DockWidgetFocusable = 0x020, ///< if this is enabled, a dock widget can get focus highlighting
+        DockWidgetForceCloseWithArea = 0x040, ///< dock widget will be closed when the dock area hosting it is closed
+        NoTab = 0x080, ///< dock widget tab will never be shown if this flag is set
+        RecreateContentsWidgetOnCloseAndOpen = 0x100, ///< deletes only the contained widget on close, keeping the dock widget intact and in place. Attempts to rebuild the contents widget on show if there is a widget factory set.
         DefaultDockWidgetFeatures = DockWidgetClosable | DockWidgetMovable | DockWidgetFloatable | DockWidgetFocusable,
         AllDockWidgetFeatures = DefaultDockWidgetFeatures | DockWidgetDeleteOnClose | CustomCloseHandling,
         DockWidgetAlwaysCloseAndDelete = DockWidgetForceCloseWithArea | DockWidgetDeleteOnClose,
-        NoDockWidgetFeatures = 0x00
+        NoDockWidgetFeatures = 0x000
     };
     Q_DECLARE_FLAGS(DockWidgetFeatures, DockWidgetFeature)
 
@@ -269,7 +270,18 @@ public:
      * provide the InsertMode ForceNoScrollArea
      */
     void setWidget(QWidget* widget, eInsertMode InsertMode = AutoScrollArea);
-
+	
+	/**
+	 * Only used when the flag RecreateContentsWidgetOnCloseAndOpen is set.
+	 * Using the flag and setting a widget factory allows to free the resources of
+	 * the widget of your application while retaining the position the next time you want to
+	 * show your widget, unlike the flag DockWidgetDeleteOnClose which deletes the dock widget itself.
+	 * Since we keep the dock widget, all regular features of ADS should work as normal, including
+	 * saving and restoring the state of the docking system and using perspectives.
+	 */
+	using FactoryFunc = std::function<QWidget*(QWidget*)>;
+	void setWidgetFactory(FactoryFunc createWidget, eInsertMode InsertMode = AutoScrollArea);
+	
     /**
      * Remove the widget from the dock and give ownership back to the caller
      */