tdf#130857 qt weld: Signal container focus on window (de)activation

Set QtInstanceWindow as an event filter for it's
QWidget, and call `signal_container_focus_changed`
when receiving a QEvent::WindowActivate or QEvent::WindowDeactivate
event.
This code path got triggered as expected in a
quick test switching between e.g. the "Help" -> "About"
dialog and other windows in KDE Plasma using the Alt+Tab
shortcut.

The VCL implementation does something similar by
handling VclEventId::WindowActivate and
VclEventId::WindowDeactivate events, see
SalInstanceContainer::HandleEventListener.

For non-top-level containers, a different solution
will probably be needed.
For now, adjust the assert in
QtInstanceContainer::connect_container_focus_changed
to only trigger for non-QtInstanceWindow containers.

And call the base class implementation, so that the
handler is actually set for the QtInstanceWindow
case.

A potential solution for QtInstanceContainer
might be to connect to the QApplication::focusChanged
signal in QtInstanceContainer::connect_container_focus_changed
and in the slot check whether exactly one of the old and
new focus widgets has the container's widget in
hierarchy.

Change-Id: I945c8bf0999d93ae91cf25dcffd3fd3ce164d214
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/176302
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Tested-by: Jenkins

7 files changed, 41 insertions, 5 deletions

diff --git a/vcl/CustomTarget_qt5_moc.mk b/vcl/CustomTarget_qt5_moc.mk
index 672398d4b03f..5af117c05488 100644
--- a/vcl/CustomTarget_qt5_moc.mk
+++ b/vcl/CustomTarget_qt5_moc.mk
@@ -15,6 +15,7 @@ $(call gb_CustomTarget_get_target,vcl/qt5) : \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtFrame.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstance.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstanceComboBox.moc \
+	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstanceContainer.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstanceDialog.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstanceDrawingArea.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstanceEntry.moc \
@@ -23,6 +24,7 @@ $(call gb_CustomTarget_get_target,vcl/qt5) : \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstanceMessageDialog.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstanceProgressBar.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstanceRadioButton.moc \
+	$(gb_CustomTarget_workdir)/vcl/qt5/QtInstanceWindow.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtMainWindow.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtMenu.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt5/QtTransferable.moc \
diff --git a/vcl/CustomTarget_qt6_moc.mk b/vcl/CustomTarget_qt6_moc.mk
index 03d3c079771f..ddb805833b66 100644
--- a/vcl/CustomTarget_qt6_moc.mk
+++ b/vcl/CustomTarget_qt6_moc.mk
@@ -15,6 +15,7 @@ $(call gb_CustomTarget_get_target,vcl/qt6) : \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtFrame.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstance.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstanceComboBox.moc \
+	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstanceContainer.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstanceDialog.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstanceDrawingArea.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstanceEntry.moc \
@@ -23,6 +24,7 @@ $(call gb_CustomTarget_get_target,vcl/qt6) : \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstanceMessageDialog.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstanceProgressBar.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstanceRadioButton.moc \
+	$(gb_CustomTarget_workdir)/vcl/qt6/QtInstanceWindow.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtMainWindow.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtMenu.moc \
 	$(gb_CustomTarget_workdir)/vcl/qt6/QtTransferable.moc \
diff --git a/vcl/inc/qt5/QtInstanceContainer.hxx b/vcl/inc/qt5/QtInstanceContainer.hxx
index 371cc4d46aae..4d5c13dcd12f 100644
--- a/vcl/inc/qt5/QtInstanceContainer.hxx
+++ b/vcl/inc/qt5/QtInstanceContainer.hxx
@@ -13,8 +13,10 @@
 
 #include <QtWidgets/QLayout>
 
-class QtInstanceContainer : public QtInstanceWidget, public virtual weld::Container
+class QtInstanceContainer : public QObject, public QtInstanceWidget, public virtual weld::Container
 {
+    Q_OBJECT
+
 public:
     QtInstanceContainer(QWidget* pWidget);
 
@@ -24,7 +26,7 @@ public:
 
     virtual void child_grab_focus() override;
 
-    virtual void connect_container_focus_changed(const Link<Container&, void>&) override;
+    virtual void connect_container_focus_changed(const Link<Container&, void>& rLink) override;
 
 private:
     QLayout& getLayout();
diff --git a/vcl/inc/qt5/QtInstanceDialog.hxx b/vcl/inc/qt5/QtInstanceDialog.hxx
index d4c8dc3ff9b1..f4ed8d4423c8 100644
--- a/vcl/inc/qt5/QtInstanceDialog.hxx
+++ b/vcl/inc/qt5/QtInstanceDialog.hxx
@@ -13,7 +13,7 @@
 
 #include <QtWidgets/QAbstractButton>
 
-class QtInstanceDialog : public QObject, public QtInstanceWindow, public virtual weld::Dialog
+class QtInstanceDialog : public QtInstanceWindow, public virtual weld::Dialog
 {
     Q_OBJECT
 
diff --git a/vcl/inc/qt5/QtInstanceWindow.hxx b/vcl/inc/qt5/QtInstanceWindow.hxx
index e84a6071b3f0..ee2cbcb757c6 100644
--- a/vcl/inc/qt5/QtInstanceWindow.hxx
+++ b/vcl/inc/qt5/QtInstanceWindow.hxx
@@ -13,6 +13,8 @@
 
 class QtInstanceWindow : public QtInstanceContainer, public virtual weld::Window
 {
+    Q_OBJECT
+
 public:
     QtInstanceWindow(QWidget* pWidget);
 
@@ -45,6 +47,8 @@ public:
     virtual VclPtr<VirtualDevice> screenshot() override;
 
     virtual const vcl::ILibreOfficeKitNotifier* GetLOKNotifier() override;
+
+    bool eventFilter(QObject* pObject, QEvent* pEvent) override;
 };
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/vcl/qt5/QtInstanceContainer.cxx b/vcl/qt5/QtInstanceContainer.cxx
index 8f8742387235..83909a83675e 100644
--- a/vcl/qt5/QtInstanceContainer.cxx
+++ b/vcl/qt5/QtInstanceContainer.cxx
@@ -8,6 +8,9 @@
  */
 
 #include <QtInstanceContainer.hxx>
+#include <QtInstanceContainer.moc>
+
+#include <QtInstanceWindow.hxx>
 
 QtInstanceContainer::QtInstanceContainer(QWidget* pWidget)
     : QtInstanceWidget(pWidget)
@@ -43,9 +46,13 @@ css::uno::Reference<css::awt::XWindow> QtInstanceContainer::CreateChildFrame()
 
 void QtInstanceContainer::child_grab_focus() { assert(false && "Not implemented yet"); }
 
-void QtInstanceContainer::connect_container_focus_changed(const Link<Container&, void>&)
+void QtInstanceContainer::connect_container_focus_changed(const Link<Container&, void>& rLink)
 {
-    assert(false && "Not implemented yet");
+    // for QtInstanceWindow, no special handling is needed, activate/deactivate events trigger the signal
+    if (!qobject_cast<QtInstanceWindow*>(this))
+        assert(false && "Not implemented yet");
+
+    weld::Container::connect_container_focus_changed(rLink);
 }
 
 QLayout& QtInstanceContainer::getLayout()
diff --git a/vcl/qt5/QtInstanceWindow.cxx b/vcl/qt5/QtInstanceWindow.cxx
index a3c6b3de3687..344db175764b 100644
--- a/vcl/qt5/QtInstanceWindow.cxx
+++ b/vcl/qt5/QtInstanceWindow.cxx
@@ -8,12 +8,15 @@
  */
 
 #include <QtInstanceWindow.hxx>
+#include <QtInstanceWindow.moc>
 
 #include <vcl/qt/QtUtils.hxx>
 
 QtInstanceWindow::QtInstanceWindow(QWidget* pWidget)
     : QtInstanceContainer(pWidget)
 {
+    // install event filter to handle window activation/deactivation events
+    pWidget->installEventFilter(this);
 }
 
 void QtInstanceWindow::set_title(const OUString& rTitle)
@@ -93,4 +96,20 @@ VclPtr<VirtualDevice> QtInstanceWindow::screenshot() { return nullptr; }
 
 const vcl::ILibreOfficeKitNotifier* QtInstanceWindow::GetLOKNotifier() { return nullptr; }
 
+bool QtInstanceWindow::eventFilter(QObject* pObject, QEvent* pEvent)
+{
+    if (pObject != getQWidget())
+        return false;
+
+    switch (pEvent->type())
+    {
+        case QEvent::WindowActivate:
+        case QEvent::WindowDeactivate:
+            signal_container_focus_changed();
+            return false;
+        default:
+            return false;
+    }
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */