qtquick: Allow the user to pass a different QQmlEngine to DockWidget

Like was the case in v1.x

src/qtquick/DockWidgetInstantiator.cpp

@@ -11,7 +11,7 @@
 
 #include "DockWidgetInstantiator.h"
 #include "private/DockRegistry_p.h"
-#include "ViewFactory.h"
+#include "ViewFactory_qtquick.h"
 #include "Config.h"
 
 using namespace KDDockWidgets;
@@ -193,8 +193,7 @@ void DockWidgetInstantiator::componentComplete()
         return;
     }
 
-    // TODOm2: Pass qmlEngine(this). Instantiate the DockWidget view directly.
-    m_dockWidget = Config::self().viewFactory()->createDockWidget(m_uniqueName)->asDockWidgetController();
+    m_dockWidget = ViewFactory_qtquick::self()->createDockWidget(m_uniqueName, qmlEngine(this))->asDockWidgetController();
 
     connect(m_dockWidget, &Controllers::DockWidget::titleChanged, this,
             &DockWidgetInstantiator::titleChanged);

src/qtquick/ViewFactory_qtquick.cpp

@@ -53,7 +53,16 @@ View *ViewFactory_qtquick::createDockWidget(const QString &uniqueName,
                                             Controllers::DockWidget::LayoutSaverOptions layoutSaverOptions,
                                             Qt::WindowFlags windowFlags) const
 {
-    return new Views::DockWidget_qtquick(uniqueName, options, layoutSaverOptions, windowFlags);
+    return createDockWidget(uniqueName, /*engine=*/nullptr, options, layoutSaverOptions, windowFlags);
+}
+
+View *ViewFactory_qtquick::createDockWidget(const QString &uniqueName,
+                                            QQmlEngine *qmlEngine,
+                                            Controllers::DockWidget::Options options,
+                                            Controllers::DockWidget::LayoutSaverOptions layoutSaverOptions,
+                                            Qt::WindowFlags windowFlags) const
+{
+    return new Views::DockWidget_qtquick(uniqueName, options, layoutSaverOptions, windowFlags, qmlEngine);
 }
 
 View *ViewFactory_qtquick::createFrame(Controllers::Frame *controller, View *parent) const
@@ -200,3 +209,14 @@ Views::ClassicIndicatorWindow *ViewFactory_qtquick::createClassicIndicatorWindow
 {
     return new IndicatorWindow_qtquick(classicIndicators);
 }
+
+ViewFactory_qtquick *ViewFactory_qtquick::self()
+{
+    auto factory = qobject_cast<ViewFactory_qtquick *>(Config::self().viewFactory());
+
+    if (!factory)
+        qWarning() << Q_FUNC_INFO << "Expected a ViewFactory_qtquick subclass, not"
+                   << Config::self().viewFactory();
+
+    return factory;
+}

src/qtquick/ViewFactory_qtquick.h

@@ -25,12 +25,9 @@
 
 QT_BEGIN_NAMESPACE
 class QAbstractButton;
+class QQmlEngine;
 QT_END_NAMESPACE
 
-namespace Layouting {
-class Widget;
-}
-
 namespace KDDockWidgets {
 
 class DropIndicatorOverlay;
@@ -58,6 +55,10 @@ public:
                            Controllers::DockWidget::Options options = {},
                            Controllers::DockWidget::LayoutSaverOptions layoutSaverOptions = {},
                            Qt::WindowFlags windowFlags = {}) const override;
+    virtual View *createDockWidget(const QString &uniqueName,
+                                   QQmlEngine *, Controllers::DockWidget::Options options = {},
+                                   Controllers::DockWidget::LayoutSaverOptions layoutSaverOptions = {},
+                                   Qt::WindowFlags windowFlags = {}) const;
     View *createFrame(Controllers::Frame *, View *parent) const override;
     View *createTitleBar(Controllers::TitleBar *, Controllers::Frame *) const override;
     View *createTitleBar(Controllers::TitleBar *, Controllers::FloatingWindow *) const override;
@@ -82,6 +83,8 @@ public:
     Views::ClassicIndicatorWindow *createClassicIndicatorWindow(Controllers::ClassicIndicators *) const override;
     View *createSegmentedDropIndicatorOverlayView(Controllers::SegmentedIndicators *controller, View *parent = nullptr) const override;
 
+    static ViewFactory_qtquick *self();
+
 private:
     Q_DISABLE_COPY(ViewFactory_qtquick)
 };

src/qtwidgets/ViewFactory_qtwidgets.h

@@ -27,9 +27,6 @@ QT_BEGIN_NAMESPACE
 class QAbstractButton;
 QT_END_NAMESPACE
 
-namespace Layouting {
-class Widget;
-}
 
 namespace KDDockWidgets {