QQuickToolTip: fix destruction of the shared tooltip

Make the QML engine the parent of the shared tooltip instance,
and make sure the instances are per engine. This ensures that
the shared tooltip gets properly destructed when the associated
QML engine is destructed. The same technique is used for the
global styles in QQuickStyleAttached.

Change-Id: I08dcb4f9bc6ddafb7449afe43362e560c0952e88
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 12 insertions, 1 deletions

diff --git a/src/quicktemplates2/qquicktooltip.cpp b/src/quicktemplates2/qquicktooltip.cpp
index cc0b6350..65e81fda 100644
--- a/src/quicktemplates2/qquicktooltip.cpp
+++ b/src/quicktemplates2/qquicktooltip.cpp
@@ -325,7 +325,13 @@ public:
 
 QQuickToolTip *QQuickToolTipAttachedPrivate::instance(bool create) const
 {
-    static QPointer<QQuickToolTip> tip;
+    QQmlEngine *engine = qmlEngine(parent);
+    if (!engine)
+        return nullptr;
+
+    static const char *name = "_q_QQuickToolTip";
+
+    QQuickToolTip *tip = engine->property(name).value<QQuickToolTip *>();
     if (!tip && create) {
         // TODO: a cleaner way to create the instance? QQml(Meta)Type?
         QQmlContext *context = qmlContext(parent);
@@ -334,9 +340,14 @@ QQuickToolTip *QQuickToolTipAttachedPrivate::instance(bool create) const
             component.setData("import QtQuick.Controls 2.0; ToolTip { }", QUrl());
 
             QObject *object = component.create(context);
+            if (object)
+                object->setParent(engine);
+
             tip = qobject_cast<QQuickToolTip *>(object);
             if (!tip)
                 delete object;
+            else
+                engine->setProperty(name, QVariant::fromValue(object));
         }
     }
     return tip;