IPlatformSettings.PreferredApplicationLanguage API

[maxkatz6]

What does the pull request do?

public interface IPlatformSettings
{
+        /// <summary>
+        /// Gets the preferred application language as specified in the operating system settings.
+        /// </summary>
+        string PreferredApplicationLanguage { get; }

+        /// <summary>
+        /// Raises when the preferred application language is changed in the operating system settings.
+        /// </summary>
+        event EventHandler? PreferredApplicationLanguageChanged;
}

Status

• Default - fallbacks to CultureInfo.CurrentUICulture.Name, not sure if it's ideal
• Windows - GetUserDefaultLocaleName
• Browser - navigator.language
• macOS
• LANG/LC_MESSAGES could be used, but it's already respected by CultureInfo.InstalledUICulture
• iOS
• Android

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/avalonia-docs with user documentation

Fixed issues

Partially implements #19402

[maxkatz6]

@MrJul I resurrected this PR. So far tested on Windows, Android and Browser. Linux should be no-op. Will check iOS tomorrow.

[avaloniaui-bot]

You can test this PR using the following package version. 12.2.999-cibuild0068452-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[MrJul]

Tested:

OS	Getting language	Change event
Windows	✅ OK	✅ OK
macOS	✅ OK	✅ OK
Browser	✅ OK	✅ OK
Android	✅ OK	⚠️ The application is automatically restarted
iOS	✅ OK	⚠️ The application is automatically restarted
Linux (KDE)	✅ OK	⚠️ A logoff/logon is required

So everything works as expected on all OSes, as the change callbacks are platform limitations.

[avaloniaui-bot]

You can test this PR using the following package version. 12.2.999-cibuild0068479-alpha. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[MrJul]

LGTM!