Add ability to retrieve QJSEngine for a given QObject

[ChangeLog][QtQml] Added qjsEngine(QObject*) getter similar to qmlEngine(object)
that allows retrieving the engine for an exposed object.

Change-Id: Id14adec58d45fe58133f65bab773b07d6bc18569
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

2 files changed, 20 insertions, 0 deletions

diff --git a/src/qml/jsapi/qjsengine.cpp b/src/qml/jsapi/qjsengine.cpp
index c6caae2f09..831287d0b3 100644
--- a/src/qml/jsapi/qjsengine.cpp
+++ b/src/qml/jsapi/qjsengine.cpp
@@ -565,6 +565,24 @@ QQmlPropertyCache *QJSEnginePrivate::createCache(const QMetaObject *mo)
     }
 }
 
+/*!
+   \since 5.5
+   \relates QJSEngine
+
+   Returns the QJSEngine associated with \a object, if any.
+
+   This function is useful if you have exposed a QObject to the JavaScript environment
+   and later in your program would like to regain access. It does not require you to
+   keep the wrapper around that was returned from QJSEngine::newQObject().
+ */
+QJSEngine *qjsEngine(const QObject *object)
+{
+    QQmlData *data = QQmlData::get(object, false);
+    if (!data || data->jsWrapper.isNullOrUndefined())
+        return 0;
+    return data->jsWrapper.engine()->jsEngine();
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qjsengine.cpp"
diff --git a/src/qml/jsapi/qjsengine.h b/src/qml/jsapi/qjsengine.h
index bddc6f133c..f24808f503 100644
--- a/src/qml/jsapi/qjsengine.h
+++ b/src/qml/jsapi/qjsengine.h
@@ -127,6 +127,8 @@ inline QVariant qjsvalue_cast<QVariant>(const QJSValue &value)
     return value.toVariant();
 }
 
+Q_QML_EXPORT QJSEngine *qjsEngine(const QObject *);
+
 QT_END_NAMESPACE
 
 #endif // QJSENGINE_H