Fix visual parent ownership with scenes that create windows

Commit 39540124dd0900e0c99dcda8c0ebdf4f3cea8d5e introduced the concept that
a visual parent marks its children, by recursively marking the children of
the root item in a QQuickView. This allowed for the removal of an ugly hack
in QtQuick Controls.

Unfortunately that fix is incomplete in the sense that it makes the incorrect
assumption that a QQuickView is always used. The use-case in the bug report is
to have child items inside a QtQuick.Window (a regular ApplicationWindow in
fact). That window - implemented by QQuickWindowQmlImpl - also needs to mark
its children, so this patch introduces the use of the same GC marking helper
class (which now operates on a QQuickWindow instead of a QQuickViewPrivate).

Task-number: QTBUG-37711
Change-Id: Id788e84dbb041ac8ba6ff23dc4ef56f6fe9e465a
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/tests/auto/quick/qquickitem/tst_qquickitem.cpp b/tests/auto/quick/qquickitem/tst_qquickitem.cpp
index a1d9d0c73b..6f11986e20 100644
--- a/tests/auto/quick/qquickitem/tst_qquickitem.cpp
+++ b/tests/auto/quick/qquickitem/tst_qquickitem.cpp
@@ -169,6 +169,7 @@ private slots:
     void acceptedMouseButtons();
 
     void visualParentOwnership();
+    void visualParentOwnershipWindow();
 
 private:
 
@@ -1821,6 +1822,63 @@ void tst_qquickitem::visualParentOwnership()
     }
 }
 
+void tst_qquickitem::visualParentOwnershipWindow()
+{
+    QQmlEngine engine;
+    QQmlComponent component(&engine, testFileUrl("visualParentOwnershipWindow.qml"));
+
+    QQuickWindow *window = qobject_cast<QQuickWindow*>(component.create());
+    QVERIFY(window);
+    QQuickItem *root = window->contentItem();
+
+    QVariant newObject;
+    {
+        QVERIFY(QMetaObject::invokeMethod(window, "createItemWithoutParent", Q_RETURN_ARG(QVariant, newObject)));
+        QPointer<QQuickItem> newItem = qvariant_cast<QQuickItem*>(newObject);
+        QVERIFY(!newItem.isNull());
+
+        QVERIFY(!newItem->parent());
+        QVERIFY(!newItem->parentItem());
+
+        newItem->setParentItem(root);
+
+        gc(engine);
+
+        QVERIFY(!newItem.isNull());
+        newItem->setParentItem(0);
+
+        gc(engine);
+        QVERIFY(newItem.isNull());
+    }
+    {
+        QVERIFY(QMetaObject::invokeMethod(window, "createItemWithoutParent", Q_RETURN_ARG(QVariant, newObject)));
+        QPointer<QQuickItem> firstItem = qvariant_cast<QQuickItem*>(newObject);
+        QVERIFY(!firstItem.isNull());
+
+        firstItem->setParentItem(root);
+
+        QVERIFY(QMetaObject::invokeMethod(window, "createItemWithoutParent", Q_RETURN_ARG(QVariant, newObject)));
+        QPointer<QQuickItem> secondItem = qvariant_cast<QQuickItem*>(newObject);
+        QVERIFY(!firstItem.isNull());
+
+        secondItem->setParentItem(firstItem);
+
+        gc(engine);
+
+        delete firstItem;
+
+        window->setProperty("keepAliveProperty", newObject);
+
+        gc(engine);
+        QVERIFY(!secondItem.isNull());
+
+        window->setProperty("keepAliveProperty", QVariant());
+
+        gc(engine);
+        QVERIFY(secondItem.isNull());
+    }
+}
+
 QTEST_MAIN(tst_qquickitem)
 
 #include "tst_qquickitem.moc"