Add virtual QWindow::closeEvent handler

The default implementation does nothing; the processing of accepted
close events remains in the QWidget::event handler, so that subclasses
don't have to call the super class in order to free window system
resources and emit lastWindowClosed signals.

QWidgetWindow::event is reimplemented to handle QEvent::Close as well,
calling QWidgetPrivate::close_helper, which then delivers a separate
QCloseEvent to the widget.

The order of execution for widgets is after this change:

1) QWidgetWindow::event
2) QWidgetWindow::handleCloseEvent (calls QWidget::event/closeEvent)
3) QWindow::event
4) QWindow::closeEvent <- does nothing, not overridden
5) default cleanup handling in QWindow::event

and for Qt Quick after the corresponding change in qtdeclarative:

1) QQuickWindow::event
2) QWindow::event
3) QQuickWindow::closeEvent <- emits closed
4) default cleanup handling in QWindow::event

[ChangeLog][QtGui][QWindow] closeEvent has been added as a virtual
function.

Task-number: QTBUG-31019
Change-Id: I201f5ee9c6a73b949986648e3bd288d2c7898f28
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/gui/kernel/qwindow.h b/src/gui/kernel/qwindow.h
index de6d7ffd31..b7c2af4916 100644
--- a/src/gui/kernel/qwindow.h
+++ b/src/gui/kernel/qwindow.h
@@ -69,6 +69,7 @@ class QMoveEvent;
 class QResizeEvent;
 class QShowEvent;
 class QHideEvent;
+class QCloseEvent;
 class QKeyEvent;
 class QMouseEvent;
 #if QT_CONFIG(wheelevent)
@@ -350,7 +351,7 @@ protected:
 
     virtual void showEvent(QShowEvent *);
     virtual void hideEvent(QHideEvent *);
-    // TODO Qt 6 - add closeEvent virtual handler
+    virtual void closeEvent(QCloseEvent *);
 
     virtual bool event(QEvent *) override;
     virtual void keyPressEvent(QKeyEvent *);