Refactor language switch, infer user's language on fresh startup

src/slic3r/GUI/GUI_App.cpp

@@ -3,6 +3,8 @@
 #include "GUI_ObjectManipulation.hpp"
 #include "I18N.hpp"
 
+#include <algorithm>
+#include <iterator>
 #include <exception>
 #include <boost/lexical_cast.hpp>
 #include <boost/algorithm/string.hpp>
@@ -21,6 +23,7 @@
 #include <wx/sysopt.h>
 #include <wx/msgdlg.h>
 #include <wx/log.h>
+#include <wx/intl.h>
 
 #include "libslic3r/Utils.hpp"
 #include "libslic3r/Model.hpp"
@@ -516,10 +519,7 @@ void GUI_App::import_model(wxWindow *parent, wxArrayString& input_files)
 
 bool GUI_App::switch_language()
 {
-    wxArrayString names;
-    wxArrayLong identifiers;
-    get_installed_languages(names, identifiers);
-    if (select_language(names, identifiers)) {
+    if (select_language()) {
         save_language();
         _3DScene::remove_all_canvases();
         recreate_GUI();
@@ -530,34 +530,48 @@ bool GUI_App::switch_language()
 }
 
 // select language from the list of installed languages
-bool GUI_App::select_language(  wxArrayString & names,
-                                wxArrayLong & identifiers)
+bool GUI_App::select_language()
 {
-    wxCHECK_MSG(names.Count() == identifiers.Count(), false,
-        _(L("Array of language names and identifiers should have the same size.")));
-    int init_selection = 0;
-    long current_language = m_wxLocale ? m_wxLocale->GetLanguage() : wxLANGUAGE_UNKNOWN;
-    for (auto lang : identifiers) {
-        if (lang == current_language)
-            break;
-        ++init_selection;
+    const auto langs = get_installed_languages();
+    wxArrayString names;
+    names.Alloc(langs.size());
+
+    int init_selection = -1;
+    const auto current_language = m_wxLocale ? m_wxLocale->GetLanguage() : wxLocale::GetSystemLanguage();
+
+    for (size_t i = 0; i < langs.size(); i++) {
+        const auto lang = langs[i]->Language;
+        const bool is_english = lang >= wxLANGUAGE_ENGLISH && lang <= wxLANGUAGE_ENGLISH_ZIMBABWE;
+
+        if (lang == current_language || (current_language == wxLANGUAGE_UNKNOWN && is_english)) {
+            init_selection = i;
+        }
+
+        names.Add(langs[i]->Description);
     }
-    if (init_selection == identifiers.size())
-        init_selection = 0;
-    long index = wxGetSingleChoiceIndex(_(L("Select the language")), _(L("Language")),
-        names, init_selection);
-    if (index != -1)
-    {
-        m_wxLocale = new wxLocale;
-        m_wxLocale->Init(identifiers[index]);
+
+    const long index = wxGetSingleChoiceIndex(
+        _(L("Select the language")),
+        _(L("Language")), names, init_selection >= 0 ? init_selection : 0);
+
+    if (index != -1) {
+        const wxLanguageInfo *lang = langs[index];
+        if (lang->Language == current_language) {
+            // There was no change
+            return false;
+        }
+
+        m_wxLocale = new wxLocale;    // FIXME: leak?
+        m_wxLocale->Init(lang->Language);
 		m_wxLocale->AddCatalogLookupPathPrefix(from_u8(localization_dir()));
         m_wxLocale->AddCatalog("Slic3rPE");
 		//FIXME This is a temporary workaround, the correct solution is to switch to "C" locale during file import / export only.
 		wxSetlocale(LC_NUMERIC, "C");
         Preset::update_suffix_modified();
-		m_imgui->set_language(m_wxLocale->GetCanonicalName().ToUTF8().data());
+        m_imgui->set_language(into_u8(lang->CanonicalName));
         return true;
     }
+
     return false;
 }
 
@@ -570,21 +584,20 @@ bool GUI_App::load_language()
 
     if (language.IsEmpty())
         return false;
-    wxArrayString	names;
-    wxArrayLong		identifiers;
-    get_installed_languages(names, identifiers);
-    for (size_t i = 0; i < identifiers.Count(); i++)
+
+    const auto langs = get_installed_languages();
+    for (const wxLanguageInfo *info : langs)
     {
-        if (wxLocale::GetLanguageCanonicalName(identifiers[i]) == language)
+        if (info->CanonicalName == language)
         {
             m_wxLocale = new wxLocale;
-            m_wxLocale->Init(identifiers[i]);
+            m_wxLocale->Init(info->Language);
 			m_wxLocale->AddCatalogLookupPathPrefix(from_u8(localization_dir()));
             m_wxLocale->AddCatalog("Slic3rPE");
 			//FIXME This is a temporary workaround, the correct solution is to switch to "C" locale during file import / export only.
             wxSetlocale(LC_NUMERIC, "C");
 			Preset::update_suffix_modified();
-			m_imgui->set_language(m_wxLocale->GetCanonicalName().ToUTF8().data());
+			m_imgui->set_language(into_u8(info->CanonicalName));
             return true;
         }
     }
@@ -602,36 +615,31 @@ void GUI_App::save_language()
     app_config->save();
 }
 
-// get list of installed languages 
-void GUI_App::get_installed_languages(wxArrayString & names, wxArrayLong & identifiers)
+// Get a list of installed languages
+std::vector<const wxLanguageInfo*> GUI_App::get_installed_languages()
 {
-    names.Clear();
-    identifiers.Clear();
+    std::vector<const wxLanguageInfo*> res;
 
 	wxDir dir(from_u8(localization_dir()));
     wxString filename;
     const wxLanguageInfo * langinfo;
     wxString name = wxLocale::GetLanguageName(wxLANGUAGE_DEFAULT);
-    if (!name.IsEmpty())
-    {
-        names.Add(_(L("Default")));
-        identifiers.Add(wxLANGUAGE_DEFAULT);
+    if (!name.IsEmpty()) {
+        res.push_back(wxLocale::GetLanguageInfo(wxLANGUAGE_DEFAULT));
     }
-    for (bool cont = dir.GetFirst(&filename, wxEmptyString, wxDIR_DIRS);
-        cont; cont = dir.GetNext(&filename))
-    {
+
+    for (bool cont = dir.GetFirst(&filename, wxEmptyString, wxDIR_DIRS); cont; cont = dir.GetNext(&filename)) {
         langinfo = wxLocale::FindLanguageInfo(filename);
-        if (langinfo != NULL)
-        {
+        if (langinfo != NULL) {
             auto full_file_name = dir.GetName() + wxFileName::GetPathSeparator() +
                 filename + wxFileName::GetPathSeparator() + "Slic3rPE" + wxT(".mo");
-            if (wxFileExists(full_file_name))
-            {
-                names.Add(langinfo->Description);
-                identifiers.Add(langinfo->Language);
+            if (wxFileExists(full_file_name)) {
+                res.push_back(langinfo);
             }
         }
     }
+
+    return res;
 }
 
 Tab* GUI_App::get_tab(Preset::Type type)

src/slic3r/GUI/GUI_App.hpp

@@ -19,6 +19,7 @@ class wxMenuItem;
 class wxMenuBar;
 class wxTopLevelWindow;
 class wxNotebook;
+class wxLanguageInfo;
 
 namespace Slic3r {
 class AppConfig;
@@ -119,19 +120,16 @@ public:
     void            keyboard_shortcuts();
     void            load_project(wxWindow *parent, wxString& input_file);
     void            import_model(wxWindow *parent, wxArrayString& input_files);
-    static bool     catch_error(std::function<void()> cb,
-//                                 wxMessageDialog* message_dialog,
-                                const std::string& err);
-//     void            notify(/*message*/);
+    static bool     catch_error(std::function<void()> cb, const std::string& err);
 
     void            persist_window_geometry(wxTopLevelWindow *window, bool default_maximized = false);
     void            update_ui_from_settings();
 
     bool            switch_language();
-    bool            select_language(wxArrayString & names, wxArrayLong & identifiers);
+    bool            select_language();
     bool            load_language();
     void            save_language();
-    void            get_installed_languages(wxArrayString & names, wxArrayLong & identifiers);
+    std::vector<const wxLanguageInfo*> get_installed_languages();
 
     Tab*            get_tab(Preset::Type type);
     ConfigOptionMode get_mode();