Add QJSEngine::newQMetaObject

QJSEngine::newQMetaObject let us expose QMetaObject to the QJSEngine,
allowing to construct QObjects instance from javascript.

Additionally, enums values are exposed as property of the QMetaObject
wrapper.

(The engine takes ownership of the created objects)

Change-Id: I5428d4b7061cceacfa89f51e703dce3379b2c329
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

4 files changed, 89 insertions, 0 deletions

diff --git a/src/qml/jsapi/qjsengine.cpp b/src/qml/jsapi/qjsengine.cpp
index 09e8bbda55..4404a5d79f 100644
--- a/src/qml/jsapi/qjsengine.cpp
+++ b/src/qml/jsapi/qjsengine.cpp
@@ -166,6 +166,17 @@ Q_DECLARE_METATYPE(QList<int>)
   properties of the proxy object. No binding code is needed because it
   is done dynamically using the Qt meta object system.
 
+  Use newQMetaObject() to wrap a QMetaObject; this gives you a
+  "script representation" of a QObject-based class. newQMetaObject()
+  returns a proxy script object; enum values of the class are available
+  as properties of the proxy object.
+
+  Constructors exposed to the meta-object system ( using Q_INVOKABLE ) can be
+  called from the script to create a new QObject instance with
+  JavaScriptOwnership.
+
+
+
   \snippet code/src_script_qjsengine.cpp 5
 
   \section1 Extensions
@@ -511,6 +522,38 @@ QJSValue QJSEngine::newQObject(QObject *object)
 }
 
 /*!
+  \since 5.8
+
+  Creates a JavaScript object that wraps the given QMetaObject
+  The metaObject must outlive the script engine. It is recommended to only
+  use this method with static metaobjects.
+
+
+  When called as a constructor, a new instance of the class will be created.
+  Only constructors exposed by Q_INVOKABLE will be visible from the script engine.
+
+  \sa newQObject()
+*/
+
+QJSValue QJSEngine::newQMetaObject(const QMetaObject* metaObject) {
+    Q_D(QJSEngine);
+    QV4::ExecutionEngine *v4 = QV8Engine::getV4(d);
+    QV4::Scope scope(v4);
+    QV4::ScopedValue v(scope, QV4::QMetaObjectWrapper::create(v4, metaObject));
+    return QJSValue(v4, v->asReturnedValue());
+}
+
+/*! \fn QJSValue QJSEngine::newQMetaObject<T>()
+
+  \since 5.8
+  Creates a JavaScript object that wraps the static QMetaObject associated
+  with class \c{T}.
+
+  \sa newQObject()
+*/
+
+
+/*!
   Returns this engine's Global Object.
 
   By default, the Global Object contains the built-in objects that are
diff --git a/src/qml/jsapi/qjsengine.h b/src/qml/jsapi/qjsengine.h
index 6ecd0c7ec0..41c4b81270 100644
--- a/src/qml/jsapi/qjsengine.h
+++ b/src/qml/jsapi/qjsengine.h
@@ -74,6 +74,14 @@ public:
 
     QJSValue newQObject(QObject *object);
 
+    QJSValue newQMetaObject(const QMetaObject* metaObject);
+
+    template <typename T>
+    QJSValue newQMetaObject()
+    {
+        return newQMetaObject(&T::staticMetaObject);
+    }
+
     template <typename T>
     inline QJSValue toScriptValue(const T &value)
     {
diff --git a/src/qml/jsapi/qjsvalue.cpp b/src/qml/jsapi/qjsvalue.cpp
index 4860908bd3..44746b8c2b 100644
--- a/src/qml/jsapi/qjsvalue.cpp
+++ b/src/qml/jsapi/qjsvalue.cpp
@@ -1234,6 +1234,28 @@ QObject *QJSValue::toQObject() const
 }
 
 /*!
+  \since 5.8
+
+ * If this QJSValue is a QMetaObject, returns the QMetaObject pointer
+ * that the QJSValue represents; otherwise, returns 0.
+ *
+ * \sa isQMetaObject()
+ */
+const QMetaObject *QJSValue::toQMetaObject() const
+{
+    QV4::ExecutionEngine *engine = QJSValuePrivate::engine(this);
+    if (!engine)
+        return 0;
+    QV4::Scope scope(engine);
+    QV4::Scoped<QV4::QMetaObjectWrapper> wrapper(scope, QJSValuePrivate::getValue(this));
+    if (!wrapper)
+        return 0;
+
+    return wrapper->metaObject();
+}
+
+
+/*!
   Returns a QDateTime representation of this value, in local time.
   If this QJSValue is not a date, or the value of the date is NaN
   (Not-a-Number), an invalid QDateTime is returned.
@@ -1286,4 +1308,18 @@ bool QJSValue::isQObject() const
     return val && val->as<QV4::QObjectWrapper>() != 0;
 }
 
+/*!
+  \since 5.8
+
+  Returns true if this QJSValue is a QMetaObject; otherwise returns
+  false.
+
+  \sa toQMetaObject(), QJSEngine::newQMetaObject()
+*/
+bool QJSValue::isQMetaObject() const
+{
+    QV4::Value *val = QJSValuePrivate::getValue(this);
+    return val && val->as<QV4::QMetaObjectWrapper>() != 0;
+}
+
 QT_END_NAMESPACE
diff --git a/src/qml/jsapi/qjsvalue.h b/src/qml/jsapi/qjsvalue.h
index e207e1b099..ab20a2607d 100644
--- a/src/qml/jsapi/qjsvalue.h
+++ b/src/qml/jsapi/qjsvalue.h
@@ -98,6 +98,7 @@ public:
     bool isUndefined() const;
     bool isVariant() const;
     bool isQObject() const;
+    bool isQMetaObject() const;
     bool isObject() const;
     bool isDate() const;
     bool isRegExp() const;
@@ -111,6 +112,7 @@ public:
     bool toBool() const;
     QVariant toVariant() const;
     QObject *toQObject() const;
+    const QMetaObject *toQMetaObject() const;
     QDateTime toDateTime() const;
 
     bool equals(const QJSValue &other) const;