GUI: Restore settings if GUI cannot be rendered

PR#921 changes the behavior of the client that if the GUI fails to be
rendered the previously applied settings in the misc category are
restored. Error messages were altered according to the changes.

Bug: #9717 GUI: Indirectly changing 'GUI Language' can produce
                inconsistent behaviour when changing some options.

2 files changed, 62 insertions, 44 deletions

diff --git a/gui/ThemeEngine.cpp b/gui/ThemeEngine.cpp
index c27d36d07e..ecea94524c 100644
--- a/gui/ThemeEngine.cpp
+++ b/gui/ThemeEngine.cpp
@@ -722,7 +722,9 @@ bool ThemeEngine::addFont(TextData textId, const Common::String &file, const Com
 #ifdef USE_TRANSLATION
 			TransMan.setLanguage("C");
 #endif
-			warning("Failed to load localized font '%s'. Using non-localized font and default GUI language instead", localized.c_str());
+			warning("Failed to load localized font '%s'.", localized.c_str());
+
+			return false;
 		}
 	}
 
diff --git a/gui/options.cpp b/gui/options.cpp
index 179fa65991..20191e762d 100644
--- a/gui/options.cpp
+++ b/gui/options.cpp
@@ -1619,7 +1619,7 @@ void GlobalOptionsDialog::build() {
 
 	// Select the currently configured language or default/English if
 	// nothing is specified.
-	if (ConfMan.hasKey("gui_language"))
+	if (ConfMan.hasKey("gui_language") && !ConfMan.get("gui_language").empty())
 		_guiLanguagePopUp->setSelectedTag(TransMan.parseLanguage(ConfMan.get("gui_language")));
 	else
 #ifdef USE_DETECTLANG
@@ -1797,6 +1797,10 @@ void GlobalOptionsDialog::clean() {
 }
 
 void GlobalOptionsDialog::apply() {
+	OptionsDialog::apply();
+
+	bool isRebuildNeeded = false;
+
 	Common::String savePath(_savePath->getLabel());
 	if (!savePath.empty() && (savePath != _("Default")))
 		ConfMan.set("savepath", savePath, _domain);
@@ -1833,15 +1837,6 @@ void GlobalOptionsDialog::apply() {
 
 	ConfMan.setInt("autosave_period", _autosavePeriodPopUp->getSelectedTag(), _domain);
 
-	GUI::ThemeEngine::GraphicsMode selected = (GUI::ThemeEngine::GraphicsMode)_rendererPopUp->getSelectedTag();
-	const char *cfg = GUI::ThemeEngine::findModeConfigName(selected);
-	if (!ConfMan.get("gui_renderer").equalsIgnoreCase(cfg)) {
-		// FIXME: Actually, any changes (including the theme change) should
-		// only become active *after* the options dialog has closed.
-		g_gui.loadNewTheme(g_gui.theme()->getThemeId(), selected);
-		ConfMan.set("gui_renderer", cfg, _domain);
-	}
-
 #ifdef USE_UPDATES
 	ConfMan.setInt("updates_check", _updatesPopUp->getSelectedTag());
 
@@ -1885,52 +1880,73 @@ void GlobalOptionsDialog::apply() {
 #endif // USE_SDL_NET
 #endif // USE_CLOUD
 
+	Common::String oldThemeId = g_gui.theme()->getThemeId();
+	Common::String oldThemeName = g_gui.theme()->getThemeName();
 	if (!_newTheme.empty()) {
+		ConfMan.set("gui_theme", _newTheme);
+	}
+
 #ifdef USE_TRANSLATION
-		Common::String lang = TransMan.getCurrentLanguage();
-#endif
-		Common::String oldTheme = g_gui.theme()->getThemeId();
-		if (g_gui.loadNewTheme(_newTheme)) {
-#ifdef USE_TRANSLATION
-			// If the charset has changed, it means the font were not found for the
-			// new theme. Since for the moment we do not support change of translation
-			// language without restarting, we let the user know about this.
-			if (lang != TransMan.getCurrentLanguage()) {
-				TransMan.setLanguage(lang.c_str());
-				g_gui.loadNewTheme(oldTheme);
-				_curTheme->setLabel(g_gui.theme()->getThemeName());
-				MessageDialog error(_("The theme you selected does not support your current language. If you want to use this theme you need to switch to another language first."));
-				error.runModal();
-			} else {
-#endif
-				ConfMan.set("gui_theme", _newTheme);
-#ifdef USE_TRANSLATION
-			}
+	int selectedLang = _guiLanguagePopUp->getSelectedTag();
+	Common::String oldLang = ConfMan.get("gui_language");
+	Common::String newLang = TransMan.getLangById(selectedLang);
+	Common::String newCharset;
+	if (newLang != oldLang) {
+		TransMan.setLanguage(newLang);
+		ConfMan.set("gui_language", newLang);
+		newCharset = TransMan.getCurrentCharset();
+		isRebuildNeeded = true;
+	}
 #endif
-		}
-		draw();
-		_newTheme.clear();
+
+	GUI::ThemeEngine::GraphicsMode gfxMode = (GUI::ThemeEngine::GraphicsMode)_rendererPopUp->getSelectedTag();
+	Common::String oldGfxConfig = ConfMan.get("gui_renderer");
+	Common::String newGfxConfig = GUI::ThemeEngine::findModeConfigName(gfxMode);
+	if (newGfxConfig != oldGfxConfig) {
+		ConfMan.set("gui_renderer", newGfxConfig, _domain);
 	}
+
+	if (_newTheme.empty())
+		_newTheme = oldThemeId;
+
+	if (!g_gui.loadNewTheme(_newTheme, gfxMode, true)) {
+		Common::String errorMessage;
+
+		_curTheme->setLabel(oldThemeName);
+		_newTheme = oldThemeId;
+		ConfMan.set("gui_theme", _newTheme);
+		gfxMode = GUI::ThemeEngine::findMode(oldGfxConfig);
+		_rendererPopUp->setSelectedTag(gfxMode);
+		newGfxConfig = oldGfxConfig;
+		ConfMan.set("gui_renderer", newGfxConfig, _domain);
 #ifdef USE_TRANSLATION
-	Common::String oldLang = ConfMan.get("gui_language");
-	int selLang = _guiLanguagePopUp->getSelectedTag();
+		bool isCharsetEqual = (newCharset == TransMan.getCurrentCharset());
+		TransMan.setLanguage(oldLang);
+		_guiLanguagePopUp->setSelectedTag(selectedLang);
+		ConfMan.set("gui_language", oldLang);
 
-	ConfMan.set("gui_language", TransMan.getLangById(selLang));
+		if (!isCharsetEqual)
+			errorMessage = _("Theme does not support selected language!");
+		else
+#endif
+			errorMessage = _("Theme cannot be loaded!");
 
-	Common::String newLang = ConfMan.get("gui_language").c_str();
-	if (newLang != oldLang) {
-		// Activate the selected language
-		TransMan.setLanguage(selLang);
+		g_gui.loadNewTheme(_newTheme, gfxMode, true);
+		errorMessage += _("\nMisc settings will be restored.");
+		MessageDialog error(errorMessage);
+		error.runModal();
+	}
 
-		// Rebuild the Launcher and Options dialogs
-		g_gui.loadNewTheme(g_gui.theme()->getThemeId(), ThemeEngine::kGfxDisabled, true);
+	if (isRebuildNeeded) {
 		rebuild();
 		if (_launcher != 0)
 			_launcher->rebuild();
 	}
-#endif // USE_TRANSLATION
 
-	OptionsDialog::apply();
+	_newTheme.clear();
+
+	// Save config file
+	ConfMan.flushToDisk();
 }
 
 void GlobalOptionsDialog::close() {