Launcher translations enabled

Translations are build into the executable at compile time, providing
FGData is available during the build.

CMakeLists.txt

@@ -326,12 +326,15 @@ endif (USE_DBUS)
 ## Qt5 setup setup
 if (ENABLE_QT)
     message(STATUS "Qt launcher enabled, checking for Qt >= 5.4 / qmake")
-    find_package(Qt5 5.4 COMPONENTS Widgets Network Qml Quick Svg)
+    find_package(Qt5 5.4 COMPONENTS Widgets Network Qml Quick Svg LinguistTools)
     if (Qt5Widgets_FOUND)
         message(STATUS "Will enable Qt launcher GUI")
         message(STATUS "  Qt5Widgets version: ${Qt5Widgets_VERSION_STRING}")
         message(STATUS "  Qt5Widgets include dir: ${Qt5Widgets_INCLUDE_DIRS}")
         set(HAVE_QT 1)
+
+
+        include (Translations)
     else()
         # don't try to build FGQCanvas if Qt wasn't found correctly
         set(ENABLE_FGQCANVAS OFF)

CMakeModules/Translations.cmake

@@ -0,0 +1,43 @@
+
+GET_FILENAME_COMPONENT(SRC_PARENT_DIR ${PROJECT_SOURCE_DIR} PATH)
+SET(FGDATA_SRC_DIR "${SRC_PARENT_DIR}/fgdata")
+
+if(EXISTS ${TRANSLATIONS_SRC_DIR})
+    message(STATUS "Using explicitly defined translations from: ${TRANSLATIONS_SRC_DIR}")
+    set(do_translate TRUE)
+elseif(EXISTS ${FGDATA_SRC_DIR})
+    SET(TRANSLATIONS_SRC_DIR "${FGDATA_SRC_DIR}/Translations")
+    message(STATUS "Found translations dir implicitly: ${TRANSLATIONS_SRC_DIR}")
+    set(do_translate TRUE)
+else()
+    message(STATUS "Couldn't find translations data, will not include translated string in the executable")
+endif()
+
+if (${do_translate})
+    # FIXME - determine this based on subdirs of TRANSLATIONS_SRC_DIR
+    set(LANGUAGES en_US de es nl fr it pl pt zh_CN)
+    set(translation_res "${PROJECT_BINARY_DIR}/translations.qrc")
+
+    add_custom_target(fgfs_qm_files ALL)
+
+    file(WRITE ${translation_res} "<RCC>\n<qresource prefix=\"/\">")
+
+    # qm generation and installation
+    foreach(LANG ${LANGUAGES})
+        set(out_file "${PROJECT_BINARY_DIR}/FlightGear_${LANG}.qm")
+        add_custom_command(
+            OUTPUT ${out_file}
+            COMMAND Qt5::lrelease ${TRANSLATIONS_SRC_DIR}/${LANG}/FlightGear-Qt.xlf
+                -qm ${out_file}
+            DEPENDS ${TRANSLATIONS_SRC_DIR}/${LANG}/FlightGear-Qt.xlf
+        )
+        add_custom_target(fgfs_${LANG}_qm ALL DEPENDS ${out_file})
+
+        add_dependencies(fgfs_qm_files fgfs_${LANG}_qm)
+
+        # local path needed here, not absolute
+        file(APPEND ${translation_res} "<file>FlightGear_${LANG}.qm</file>\n")
+    endforeach()
+
+    file(APPEND ${translation_res} "</qresource>\n</RCC>")
+endif() # of do translate

src/GUI/CMakeLists.txt

@@ -70,7 +70,7 @@ if (HAVE_QT)
     qt5_wrap_ui(uic_sources SetupRootDialog.ui
                             InstallSceneryDialog.ui
                             )
-    qt5_add_resources(qrc_sources resources.qrc)
+    qt5_add_resources(qrc_sources resources.qrc ${PROJECT_BINARY_DIR}/translations.qrc)
 
     add_library(fglauncher QtLauncher.cxx
                             QtLauncher.hxx

src/GUI/QtLauncher.cxx

@@ -42,6 +42,7 @@
 #include <QDoubleSpinBox>
 #include <QThread>
 #include <QProcess>
+#include <QTranslator>
 
 // Simgear
 #include <simgear/timing/timestamp.hxx>
@@ -206,10 +207,9 @@ private:
 static void initQtResources()
 {
     Q_INIT_RESOURCE(resources);
+    Q_INIT_RESOURCE(translations);
 }
 
-
-
 static void simgearMessageOutput(QtMsgType type, const QMessageLogContext &context, const QString &msg)
 {
     sgDebugPriority mappedPriority = SG_WARN;
@@ -240,7 +240,7 @@ namespace flightgear
 // cleanly on quit. However, at present, the official policy is that static
 // destruction is too late to call this, hence why we have shutdownQtApp()
 
-std::unique_ptr<QApplication> static_qApp;
+static std::unique_ptr<QApplication> static_qApp;
 
 // Only requires FGGlobals to be initialized if 'doInitQSettings' is true.
 // Safe to call several times.
@@ -285,6 +285,22 @@ void initApp(int& argc, char** argv, bool doInitQSettings)
         static_qApp->setDesktopFileName(
           QStringLiteral("org.flightgear.FlightGear.desktop"));
 #endif
+        QTranslator* fallbackTranslator = new QTranslator(static_qApp.get());
+        if (!fallbackTranslator->load(QLatin1String(":/FlightGear_en_US.qm"))) {
+            qWarning() << "Failed to load default (en) translations";
+            delete fallbackTranslator;
+        } else {
+            static_qApp->installTranslator(fallbackTranslator);
+        }
+
+        QTranslator* translator = new QTranslator(static_qApp.get());
+        // look up e.g. :/FlightGear_de.qm
+        if (translator->load(QLocale(), QLatin1String("FlightGear"), QLatin1String("_"), QLatin1String(":/"))) {
+            qInfo() << "Loaded translations";
+            static_qApp->installTranslator(translator);
+        } else {
+            delete translator;
+        }
 
         // reset numeric / collation locales as described at:
         // http://doc.qt.io/qt-5/qcoreapplication.html#details