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, 45 insertions, 1 deletions

diff --git a/src/qml/qml/qqmlbinding.cpp b/src/qml/qml/qqmlbinding.cpp
index 62288a5845..0ccb4e8e4e 100644
--- a/src/qml/qml/qqmlbinding.cpp
+++ b/src/qml/qml/qqmlbinding.cpp
@@ -195,7 +195,7 @@ class QQmlNonbindingBinding: public QQmlBinding
 {
 protected:
     void doUpdate(const DeleteWatcher &watcher,
-                  QQmlPropertyData::WriteFlags flags, QV4::Scope &scope) Q_DECL_OVERRIDE Q_DECL_FINAL
+                  QQmlPropertyData::WriteFlags flags, QV4::Scope &scope) Q_DECL_OVERRIDE
     {
         auto ep = QQmlEnginePrivate::get(scope.engine);
         ep->referenceScarceResources();
@@ -296,6 +296,50 @@ protected:
     }
 };
 
+class QQmlTranslationBinding : public GenericBinding<QMetaType::QString> {
+public:
+    QQmlTranslationBinding(QV4::CompiledData::CompilationUnit *compilationUnit, const QV4::CompiledData::Binding *binding)
+    {
+        setCompilationUnit(compilationUnit);
+        m_binding = binding;
+        setSourceLocation(QQmlSourceLocation(compilationUnit->fileName(), binding->valueLocation.line, binding->valueLocation.column));
+    }
+
+    void doUpdate(const DeleteWatcher &watcher,
+                  QQmlPropertyData::WriteFlags flags, QV4::Scope &) Q_DECL_OVERRIDE Q_DECL_FINAL
+    {
+        if (watcher.wasDeleted())
+            return;
+
+        if (!isAddedToObject() || hasError())
+            return;
+
+        const QString result = m_binding->valueAsString(m_compilationUnit->data);
+
+        Q_ASSERT(targetObject());
+
+        QQmlPropertyData *pd;
+        QQmlPropertyData vpd;
+        getPropertyData(&pd, &vpd);
+        Q_ASSERT(pd);
+        doStore(result, pd, flags);
+    }
+
+private:
+    const QV4::CompiledData::Binding *m_binding;
+};
+
+QQmlBinding *QQmlBinding::createTranslationBinding(QV4::CompiledData::CompilationUnit *unit, const QV4::CompiledData::Binding *binding, QObject *obj, QQmlContextData *ctxt)
+{
+    QQmlTranslationBinding *b = new QQmlTranslationBinding(unit, binding);
+
+    b->setNotifyOnValueChanged(true);
+    b->QQmlJavaScriptExpression::setContext(ctxt);
+    b->setScopeObject(obj);
+
+    return b;
+}
+
 Q_NEVER_INLINE bool QQmlBinding::slowWrite(const QQmlPropertyData &core,
                                            const QQmlPropertyData &valueTypeData,
                                            const QV4::Value &result,