Centralize maybeLastWindowClosed checking in QWindow

Instead of plumbing QWidgetWindow close events via handleCloseEvent,
we just implement closeEvent directly. This allows QWindow do save
the state of the window/widget before the close event, so that we
know whether we should trigger lastWindowClosed handling, even if
the window was deleted as a result of the close event.

This also relieves QGuiApplication and QApplication from dealing
with the close logic in their notify functions, so that these
functions can focus on the propagation of events -- not how the
event is handled.

Change-Id: I8b586b53a53b1df1d8630c1acb635c60f191bb4b
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 23 insertions, 3 deletions

diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 561682f65d..631b1fe723 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -2292,6 +2292,12 @@ bool QWindowPrivate::participatesInLastWindowClosed() const
     return true;
 }
 
+bool QWindowPrivate::treatAsVisible() const
+{
+    Q_Q(const QWindow);
+    return q->isVisible();
+}
+
 /*!
     The expose event (\a ev) is sent by the window system when a window moves
     between the un-exposed and exposed states.
@@ -2466,11 +2472,25 @@ bool QWindow::event(QEvent *ev)
         break;
 #endif
 
-    case QEvent::Close:
+    case QEvent::Close: {
+
+        Q_D(QWindow);
+        const bool wasVisible = d->treatAsVisible();
+        const bool participatesInLastWindowClosed = d->participatesInLastWindowClosed();
+
+        // The window might be deleted in the close event handler
+        QPointer<QWindow> deletionGuard(this);
         closeEvent(static_cast<QCloseEvent*>(ev));
-        if (ev->isAccepted())
-            destroy();
+
+        if (ev->isAccepted()) {
+            if (deletionGuard)
+                destroy();
+            if (wasVisible && participatesInLastWindowClosed)
+                QGuiApplicationPrivate::instance()->maybeLastWindowClosed();
+        }
+
         break;
+    }
 
     case QEvent::Expose:
         exposeEvent(static_cast<QExposeEvent *>(ev));