Added ability for applications to propose their own preferred languages

src/lib.rs

@@ -91,6 +91,7 @@ pub mod icon_theme;
 pub mod keyboard_nav;
 
 mod localize;
+pub use localize::prepend_languages;
 
 #[cfg(all(target_env = "gnu", not(target_os = "windows")))]
 pub(crate) mod malloc;

src/localize.rs

@@ -3,9 +3,10 @@
 use i18n_embed::{
     DefaultLocalizer, LanguageLoader, Localizer,
     fluent::{FluentLanguageLoader, fluent_language_loader},
+    unic_langid::LanguageIdentifier
 };
 use rust_embed::RustEmbed;
-use std::sync::{LazyLock, OnceLock};
+use std::sync::{LazyLock, Mutex, MutexGuard, OnceLock, PoisonError};
 
 #[derive(RustEmbed)]
 #[folder = "i18n/"]
@@ -23,6 +24,15 @@ pub static LANGUAGE_LOADER: LazyLock<FluentLanguageLoader> = LazyLock::new(|| {
 
 static LOCALIZATION_INITIALIZED: OnceLock<()> = OnceLock::new();
 
+static LANGS_TO_PREPEND: LazyLock<Mutex<Vec<LanguageIdentifier>>> = LazyLock::new(|| Mutex::new(Vec::new()));
+
+pub type LanguagePrependingError = PoisonError<MutexGuard<'static, Vec<LanguageIdentifier>>>;
+
+pub fn prepend_languages<'a>(langs: impl Into<Vec<&'a str>>) -> Result<(), LanguagePrependingError> {
+    *LANGS_TO_PREPEND.lock()? = langs.into().iter().filter_map(|lang| lang.parse::<LanguageIdentifier>().ok()).collect();
+    Ok(())
+}
+
 #[macro_export]
 macro_rules! fl {
     ($message_id:literal) => {{
@@ -43,7 +53,8 @@ pub fn localizer() -> Box<dyn Localizer> {
 pub fn localize() {
     LOCALIZATION_INITIALIZED.get_or_init(|| {
         let localizer = localizer();
-        let requested_languages = i18n_embed::DesktopLanguageRequester::requested_languages();
+        let mut requested_languages = LANGS_TO_PREPEND.lock().map(|mutex_guard| mutex_guard.clone()).unwrap_or_default();
+        requested_languages.extend_from_slice(&i18n_embed::DesktopLanguageRequester::requested_languages());
         if let Err(error) = localizer.select(&requested_languages) {
             eprintln!("Error while loading language for libcosmic {}", error);
         }