QWidget: close the QWindow in QWidget::close

We want to close the window, end full screen mode on macOS, and free
platform resources. This is all done by QWindow::close. QWindow::close
closes the platform window, triggering a closeEvent to QWidgetWindow,
which then calls QWidgetPrivate::close_helper.

This way, closing a window via QWidget::close, QWindow::close, or
interactively by the user are all equivalent.

The QCloseEvent generated by the widget needs to be spontaneous for
window-system generated events (i.e. the user clicked the close button),
and non-spontaneous if the window closes because of a call to
QWindow::close. To keep track of whether the event originated in an
explicit call to QWindow::close, add a boolean to the QWindowPrivate.

Add a test case that verifies that the window resources is destroyed,
and that events are delivered as they should.

Done-with: Morten Johan Sørvig <morten.sorvig@qt.io>
Fixes: QTBUG-46701
Pick-to: 6.2
Change-Id: Iacb6a2c8d5e880b16b0c8f0c9257ed94bed36f5b
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>

1 files changed, 25 insertions, 0 deletions

diff --git a/src/widgets/kernel/qwidget.cpp b/src/widgets/kernel/qwidget.cpp
index 61a8605d22..c96b422b14 100644
--- a/src/widgets/kernel/qwidget.cpp
+++ b/src/widgets/kernel/qwidget.cpp
@@ -8360,6 +8360,24 @@ void QWidgetPrivate::hideChildren(bool spontaneous)
     }
 }
 
+/*!
+    \internal
+
+    For windows, this is called from the QWidgetWindow::handleCloseEvent implementation,
+    which QWidget::close indirectly calls by closing the QWindow. \a mode will be
+    CloseWithEvent if QWidgetWindow::handleCloseEvent is called indirectly by
+    QWindow::close, and CloseWithSpontaneousEvent if the close event originates from the
+    system (i.e. the user clicked the close button in the title bar).
+
+    QDialog calls this method directly in its hide() implementation, which might be
+    called from the QDialog::closeEvent override. \a mode will be set to CloseNoEvent
+    to prevent recursion.
+
+    For non-windows, this is called directly by QWidget::close, and \a mode will be
+    CloseWithEvent.
+
+    The function is also called by the QWidget destructor, with \a mode set to CloseNoEvent.
+*/
 bool QWidgetPrivate::close_helper(CloseMode mode)
 {
     if (data.is_closing)
@@ -8384,6 +8402,7 @@ bool QWidgetPrivate::close_helper(CloseMode mode)
         }
     }
 
+    // even for windows, make sure we deliver a hide event and that all children get hidden
     if (!that.isNull() && !q->isHidden())
         q->hide();
 
@@ -8446,6 +8465,12 @@ bool QWidgetPrivate::close_helper(CloseMode mode)
 
 bool QWidget::close()
 {
+    // Close native widgets via QWindow::close() in order to run QWindow
+    // close code. The QWidget-specific close code in close_helper() will
+    // in this case be called from the Close event handler in QWidgetWindow.
+    if (QWindow *widgetWindow = windowHandle())
+        return widgetWindow->close();
+
     return d_func()->close_helper(QWidgetPrivate::CloseWithEvent);
 }