Select "English" if the current language is not found in Preferences

If the user preferences file (aseprite.ini) contained a non-existent
language, the first option of the languages combo box was selected,
which might lead to a confusing situation where just opening the
preferences dialog will change from English to other
language (non-English, the first language in the combobox).

src/app/commands/cmd_options.cpp

@@ -1317,9 +1317,20 @@ class OptionsWindow : public app::gen::Options {
  if (language()->getItemCount() > 0)
  return;
 
- // Select current language by lang ID
+ // Check if the current language exists, in other case select English.
  Strings* strings = Strings::instance();
  std::string curLang = strings->currentLanguage();
+ bool found = false;
+ for (const LangInfo& lang : strings->availableLanguages()) {
+ if (lang.id == curLang) {
+ found = true;
+ break;
+ }
+ }
+ if (!found)
+ curLang = Strings::kDefLanguage;
+
+ // Select current language by lang ID
  for (const LangInfo& lang : strings->availableLanguages()) {
  int i = language()->addItem(new LangItem(lang));
  if (lang.id == curLang)

src/app/i18n/strings.cpp

@@ -25,7 +25,8 @@
 namespace app {
 
 static Strings* singleton = nullptr;
-static const char* kDefLanguage = "en";
+
+const char* Strings::kDefLanguage = "en";
 
 // static
 void Strings::createInstance(Preferences& pref,

src/app/i18n/strings.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2023 Igara Studio S.A.
+// Copyright (C) 2023-2024 Igara Studio S.A.
 // Copyright (C) 2016-2018 David Capello
 //
 // This program is distributed under the terms of
@@ -25,6 +25,8 @@ namespace app {
  // Singleton class to load and access "strings/en.ini" file.
  class Strings : public app::gen::Strings<app::Strings> {
  public:
+ static const char* kDefLanguage;
+
  static void createInstance(Preferences& pref,
  Extensions& exts);
  static Strings* instance();