GUI: assure UI language is a known one

Fixes #1434.

ChangeLog

@@ -1,5 +1,9 @@
 2015-09-20  Moritz Bunkus  <moritz@bunkus.org>
 
+        * MKVToolNix GUI: bug fix: the interface language selection has
+        been improved not to select wrong entries resulting in error
+        messages from mkvmerge about unknown translations. Fixes #1434.
+
         * MKVToolNix GUI: bug fix: if the Windows version of the GUI was
         started from a symbolically linked folder then it would crash when
         the user added a file. Fixes #1315.

src/mkvtoolnix-gui/app.cpp

@@ -12,7 +12,6 @@
 #include "common/fs_sys_helpers.h"
 #include "common/iso639.h"
 #include "common/qt.h"
-#include "common/translation.h"
 #include "common/unique_numbers.h"
 #include "common/version.h"
 #include "mkvtoolnix-gui/app.h"
@@ -254,47 +253,31 @@ App::isInstalled() {
 
 void
 App::initializeLocale(QString const &requestedLocale) {
-  auto locale = to_utf8(requestedLocale);
+  auto locale = Util::Settings::get().localeToUse(requestedLocale);
 
 #if defined(HAVE_LIBINTL_H)
-  auto &cfg = Util::Settings::get();
+  if (!locale.isEmpty()) {
+    if (m_currentTranslator)
+      removeTranslator(m_currentTranslator.get());
+    m_currentTranslator.reset();
 
-  if (m_currentTranslator)
-    removeTranslator(m_currentTranslator.get());
-  m_currentTranslator.reset();
-
-  translation_c::initialize_available_translations();
-
-  if (locale.empty())
-    locale = to_utf8(cfg.m_uiLocale);
-
-  if (-1 == translation_c::look_up_translation(locale))
-    locale = "";
-
-  if (locale.empty()) {
-    locale = boost::regex_replace(translation_c::get_default_ui_locale(), boost::regex{"\\..*", boost::regex::perl}, "");
-    if (-1 == translation_c::look_up_translation(locale))
-      locale = "";
-  }
-
-  if (!locale.empty()) {
     auto translator = std::make_unique<QTranslator>();
-    auto paths      = QStringList{} << Q("%1/locale/%2/LC_MESSAGES").arg(applicationDirPath()).arg(Q(locale))
+    auto paths      = QStringList{} << Q("%1/locale/%2/LC_MESSAGES").arg(applicationDirPath()).arg(locale)
                                     << QLibraryInfo::location(QLibraryInfo::TranslationsPath);
 
     for (auto const &path : paths)
-      if (translator->load(Q("qtbase_%1").arg(Q(locale)), path))
+      if (translator->load(Q("qtbase_%1").arg(locale), path))
         break;
 
     installTranslator(translator.get());
 
-    m_currentTranslator = std::move(translator);
-    cfg.m_uiLocale      = Q(locale);
+    m_currentTranslator              = std::move(translator);
+    Util::Settings::get().m_uiLocale = locale;
   }
 
 #endif  // HAVE_LIBINTL_H
 
-  init_locales(locale);
+  init_locales(to_utf8(locale));
 
   retranslateUi();
 }

src/mkvtoolnix-gui/merge/mux_config.cpp

@@ -395,8 +395,10 @@ MuxConfig::buildMkvmergeOptions()
   auto options = QStringList{};
 
   auto &settings = Util::Settings::get();
+  auto locale    = settings.localeToUse();
 
-  options << Q("--ui-language") << settings.m_uiLocale;
+  if (!locale.isEmpty())
+    options << Q("--ui-language") << locale;
 
   if (Util::Settings::NormalPriority != settings.m_priority)
     options << Q("--priority") << settings.priorityAsString();

src/mkvtoolnix-gui/util/settings.cpp

@@ -396,4 +396,27 @@ Settings::storeSplitterSizes() {
     qDebug() << "storeSplitterSize() signal from non-splitter" << sender() << sender()->objectName();
 }
 
+QString
+Settings::localeToUse(QString const &requestedLocale) {
+  auto locale = to_utf8(requestedLocale);
+
+#if defined(HAVE_LIBINTL_H)
+  translation_c::initialize_available_translations();
+
+  if (locale.empty())
+    locale = to_utf8(m_uiLocale);
+
+  if (-1 == translation_c::look_up_translation(locale))
+    locale = "";
+
+  if (locale.empty()) {
+    locale = boost::regex_replace(translation_c::get_default_ui_locale(), boost::regex{"\\..*", boost::regex::perl}, "");
+    if (-1 == translation_c::look_up_translation(locale))
+      locale = "";
+  }
+#endif
+
+  return to_qs(locale);
+}
+
 }}}

src/mkvtoolnix-gui/util/settings.h

@@ -9,6 +9,8 @@
 #include <QTabWidget>
 #include <QVariant>
 
+#include "common/translation.h"
+
 class QSettings;
 class QSplitter;
 
@@ -106,6 +108,8 @@ public:
   void handleSplitterSizes(QSplitter *splitter);
   void restoreSplitterSizes(QSplitter *splitter);
 
+  QString localeToUse(QString const &requestedLocale = {});
+
 public slots:
   void storeSplitterSizes();