wasm: Add QLocale backend

This is a simple backend based on navigator.languages,
which gives us a prioritized list of languages in the
form '["en-US", "zh-CN", "ja-JP"]'.

Use this to implement QSystemLocale::query() for UILanguages
and QSystemLocale::fallbackLocale().

Register an event handler for the native QWindow:languagechange
event in the QSystemLocale constructor. This event handler
stays active for the lifetime of the QSystemLocale object.

Task-number: QTBUG-116613
Change-Id: Ibd176748377e891b63a3f1d57605af0c2a49edb3
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/corelib/text/qlocale.cpp b/src/corelib/text/qlocale.cpp
index 7004ad9f0a..adaa1774ee 100644
--- a/src/corelib/text/qlocale.cpp
+++ b/src/corelib/text/qlocale.cpp
@@ -720,6 +720,17 @@ QSystemLocale::QSystemLocale() : next(_systemLocale)
     _systemLocale = this;
 
     systemLocaleData.m_language_id = 0;
+
+#ifdef Q_OS_WASM
+    onLanguageChanged = std::make_unique<qstdweb::EventCallback>(
+        emscripten::val::global("window"), "languagechange", [](emscripten::val) {
+            systemLocaleData.m_language_id = 0;
+            QEvent languageChangeEvent(QEvent::LanguageChange);
+            QCoreApplication::sendEvent(qApp, &languageChangeEvent);
+            QEvent localeChangeEvent(QEvent::LocaleChange);
+            QCoreApplication::sendEvent(qApp, &localeChangeEvent);
+    });
+#endif
 }
 
 /*!