Add support for QEvent::LanguageChange

Respond to the language change event by refreshing all binding
expressions. For constant string translation bindings we must now create
special QQmlBinding instances instead of a one-time property write
meta-call upon instantiation. Those however are more lightweight than an
entire JavaScript expression.

In addition this provides a slot to explicitly trigger a re-evaluation
of bindings, to make it a little easier to discover for the developer.

[ChangeLog][QtQml][QQmlEngine] Added retranslate() slot and
QEvent::LanguageChange support to refresh bindings when changing the
language at run-time.

Task-number: QTBUG-15602
Change-Id: Ide174648e1d8a5738acb88e15495018d0869d7bc
Reviewed-by: Michael Brasser <michael.brasser@live.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/tests/auto/qml/qqmltranslation/tst_qqmltranslation.cpp b/tests/auto/qml/qqmltranslation/tst_qqmltranslation.cpp
index 1fc803a395..1c9523fc38 100644
--- a/tests/auto/qml/qqmltranslation/tst_qqmltranslation.cpp
+++ b/tests/auto/qml/qqmltranslation/tst_qqmltranslation.cpp
@@ -44,6 +44,7 @@ private slots:
     void translation_data();
     void translation();
     void idTranslation();
+    void translationChange();
 };
 
 void tst_qqmltranslation::translation_data()
@@ -162,6 +163,51 @@ void tst_qqmltranslation::idTranslation()
     delete object;
 }
 
+class DummyTranslator : public QTranslator
+{
+    Q_OBJECT
+
+    QString translate(const char *context, const char *sourceText, const char *disambiguation, int n) const override
+    {
+        Q_UNUSED(context);
+        Q_UNUSED(disambiguation);
+        Q_UNUSED(n);
+        if (!qstrcmp(sourceText, "translate me"))
+            return QString::fromUtf8("xxx");
+        return QString();
+    }
+
+    bool isEmpty() const override
+    {
+        return false;
+    }
+};
+
+void tst_qqmltranslation::translationChange()
+{
+    QQmlEngine engine;
+
+    QQmlComponent component(&engine, testFileUrl("translationChange.qml"));
+    QScopedPointer<QObject> object(component.create());
+    QVERIFY(!object.isNull());
+
+    QCOMPARE(object->property("baseProperty").toString(), QString::fromUtf8("do not translate"));
+    QCOMPARE(object->property("text1").toString(), QString::fromUtf8("translate me"));
+    QCOMPARE(object->property("text2").toString(), QString::fromUtf8("translate me"));
+
+    DummyTranslator translator;
+    QCoreApplication::installTranslator(&translator);
+
+    QEvent ev(QEvent::LanguageChange);
+    QCoreApplication::sendEvent(&engine, &ev);
+
+    QCOMPARE(object->property("baseProperty").toString(), QString::fromUtf8("do not translate"));
+    QCOMPARE(object->property("text1").toString(), QString::fromUtf8("xxx"));
+    QCOMPARE(object->property("text2").toString(), QString::fromUtf8("xxx"));
+
+    QCoreApplication::removeTranslator(&translator);
+}
+
 QTEST_MAIN(tst_qqmltranslation)
 
 #include "tst_qqmltranslation.moc"