Add Q_GADGET Wrapper for QQmlProperty

This enable exposing a QQmlProperty as a value type to QML code.
Only object and name are exposed as a properties to keep it simple.

We might want later to expose the property of a Binding or a Behavior
as a property for complex usecases. This permits exposing it as one
self contained value instead of a pair of unrelated object and name.

Task-number: QTBUG-70964
Task-number: QTBUG-73892
Change-Id: I3a46212446f43f3a7e301943cb49d3a48c377de3
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

6 files changed, 55 insertions, 3 deletions

diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index d7001dbbe3..73d3ba1863 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -101,8 +101,6 @@
 #  endif
 #endif // Q_OS_WIN
 
-Q_DECLARE_METATYPE(QQmlProperty)
-
 QT_BEGIN_NAMESPACE
 
 // Declared in qqml.h
diff --git a/src/qml/qml/qqmlvaluetype.cpp b/src/qml/qml/qqmlvaluetype.cpp
index a4737b3da9..90a10c8d9a 100644
--- a/src/qml/qml/qqmlvaluetype.cpp
+++ b/src/qml/qml/qqmlvaluetype.cpp
@@ -48,6 +48,8 @@
 #endif
 #include <private/qmetatype_p.h>
 
+Q_DECLARE_METATYPE(QQmlProperty)
+
 QT_BEGIN_NAMESPACE
 
 namespace {
@@ -143,7 +145,8 @@ const QMetaObject *QQmlValueTypeFactoryImpl::metaObjectForMetaType(int t)
         if (t == qMetaTypeId<QItemSelectionRange>())
             return &QQmlItemSelectionRangeValueType::staticMetaObject;
 #endif
-
+        if (t == qMetaTypeId<QQmlProperty>())
+            return &QQmlPropertyValueType::staticMetaObject;
         if (const QMetaObject *mo = QQml_valueTypeProvider()->metaObjectForMetaType(t))
             return mo;
         break;
@@ -580,6 +583,16 @@ void QQmlEasingValueType::setBezierCurve(const QVariantList &customCurveVariant)
     v = newEasingCurve;
 }
 
+QObject *QQmlPropertyValueType::object() const
+{
+    return v.object();
+}
+
+QString QQmlPropertyValueType::name() const
+{
+    return v.name();
+}
+
 QVariantList QQmlEasingValueType::bezierCurve() const
 {
     QVariantList rv;
diff --git a/src/qml/qml/qqmlvaluetype_p.h b/src/qml/qml/qqmlvaluetype_p.h
index 9c008859da..0d581c7be8 100644
--- a/src/qml/qml/qqmlvaluetype_p.h
+++ b/src/qml/qml/qqmlvaluetype_p.h
@@ -264,6 +264,17 @@ public:
     QVariantList bezierCurve() const;
 };
 
+struct QQmlPropertyValueType
+{
+    QQmlProperty v;
+    Q_PROPERTY(QObject *object READ object CONSTANT FINAL)
+    Q_PROPERTY(QString name READ name CONSTANT FINAL)
+    Q_GADGET
+public:
+    QObject *object() const;
+    QString name() const;
+};
+
 template<typename T>
 int qmlRegisterValueTypeEnums(const char *uri, int versionMajor, int versionMinor, const char *qmlName)
 {
diff --git a/tests/auto/qml/qqmlvaluetypes/data/qmlproperty_read.qml b/tests/auto/qml/qqmlvaluetypes/data/qmlproperty_read.qml
new file mode 100644
index 0000000000..b9c9ee779b
--- /dev/null
+++ b/tests/auto/qml/qqmlvaluetypes/data/qmlproperty_read.qml
@@ -0,0 +1,9 @@
+import Test 1.0
+import QtQml 2.0
+
+MyTypeObject {
+    property QtObject colorPropertyObject: colorProperty.object
+    property string colorPropertyName: colorProperty.name
+    property QtObject invalidPropertyObject: invalidProperty.object
+    property string invalidPropertyName: invalidProperty.name
+}
diff --git a/tests/auto/qml/qqmlvaluetypes/testtypes.h b/tests/auto/qml/qqmlvaluetypes/testtypes.h
index 798c96e188..e11d831236 100644
--- a/tests/auto/qml/qqmlvaluetypes/testtypes.h
+++ b/tests/auto/qml/qqmlvaluetypes/testtypes.h
@@ -71,6 +71,8 @@ class MyTypeObject : public QObject
     Q_PROPERTY(QColor color READ color WRITE setColor NOTIFY changed)
     Q_PROPERTY(QColor invalidColor READ invalidColor CONSTANT)
     Q_PROPERTY(QVariant variant READ variant NOTIFY changed)
+    Q_PROPERTY(QQmlProperty colorProperty READ colorProperty CONSTANT)
+    Q_PROPERTY(QQmlProperty invalidProperty READ invalidProperty CONSTANT)
 
 public:
     MyTypeObject() :
@@ -173,6 +175,10 @@ public:
 
     QVariant variant() const { return sizef(); }
 
+    QQmlProperty colorProperty() { return QQmlProperty(this, "color"); }
+
+    QQmlProperty invalidProperty() const { return QQmlProperty(); }
+
     void emitRunScript() { emit runScript(); }
 
 signals:
diff --git a/tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp b/tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp
index 3e9047cc5a..7c75743311 100644
--- a/tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp
+++ b/tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp
@@ -67,6 +67,7 @@ private slots:
     void color();
     void variant();
     void locale();
+    void qmlproperty();
 
     void bindingAssignment();
     void bindingRead();
@@ -360,6 +361,20 @@ void tst_qqmlvaluetypes::locale()
     }
 }
 
+void tst_qqmlvaluetypes::qmlproperty()
+{
+    QQmlComponent component(&engine, testFileUrl("qmlproperty_read.qml"));
+    MyTypeObject *object = qobject_cast<MyTypeObject *>(component.create());
+    QVERIFY(object != nullptr);
+
+    QCOMPARE(object->property("colorPropertyObject").value<QObject *>(), object);
+    QCOMPARE(object->property("colorPropertyName").toString(), "color");
+    QCOMPARE(object->property("invalidPropertyObject").value<QObject *>(), nullptr);
+    QCOMPARE(object->property("invalidPropertyName").toString(), "");
+
+    delete object;
+}
+
 void tst_qqmlvaluetypes::sizereadonly()
 {
     {