QQmlValueTypeWrapper: Use QVariant to QString conversion if possible

This makes it easier to customize displaying Q_GADGETs that don't
have a toString() function defined. Instead of having to define
a wrapper Q_GADGET class, it's more straightforward to register a
meta-type converter. Finally, it ensures consistent value displays
between QML and the rest.

Change-Id: I76f93ee0bafabd74f311130972b49c572b38f43f
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp b/tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp
index 45cbbebdc3..ac9ec37ab3 100644
--- a/tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp
+++ b/tests/auto/qml/qqmlvaluetypes/tst_qqmlvaluetypes.cpp
@@ -91,6 +91,7 @@ private slots:
     void customValueType();
     void customValueTypeInQml();
     void gadgetInheritance();
+    void toStringConversion();
 
 private:
     QQmlEngine engine;
@@ -1559,6 +1560,35 @@ void tst_qqmlvaluetypes::gadgetInheritance()
     QCOMPARE(value.property("baseProperty").toInt(), 42);
 }
 
+struct StringLessGadget {
+    Q_GADGET
+};
+
+Q_DECLARE_METATYPE(StringLessGadget)
+
+static QString StringLessGadget_to_QString(const StringLessGadget &)
+{
+    return QLatin1String("Surprise!");
+}
+
+void tst_qqmlvaluetypes::toStringConversion()
+{
+    QJSEngine engine;
+
+    StringLessGadget g;
+    QJSValue value = engine.toScriptValue(g);
+
+    QJSValue method = value.property("toString");
+    QJSValue stringConversion = method.callWithInstance(value);
+    QCOMPARE(stringConversion.toString(), QString("StringLessGadget()"));
+
+    QMetaType::registerConverter<StringLessGadget, QString>(StringLessGadget_to_QString);
+
+    stringConversion = method.callWithInstance(value);
+    QCOMPARE(stringConversion.toString(), StringLessGadget_to_QString(g));
+}
+
+
 QTEST_MAIN(tst_qqmlvaluetypes)
 
 #include "tst_qqmlvaluetypes.moc"