nigig-org/crates/nigig-system-prefs/README.md

nigig-system-prefs

Cross-platform reader for OS-level preferences (dark mode, locale, accent color). Follows the robius-sms cross-platform pattern: a cfg_if! block dispatches to a per-platform sys/*.rs submodule.

Why this exists

Makepad's Cx does not expose platform_is_dark_mode() on all branches of its public API, and even where it does the value is cached at window creation time — it does not update when the user toggles dark mode while the app is running. This crate queries the OS directly on every call.

API

// Boolean convenience:
let dark: bool = nigig_system_prefs::is_dark_mode().unwrap_or(false);

// Three-way (Linux exposes "no preference"):
let scheme: ColorScheme = nigig_system_prefs::color_scheme()?;

// BCP-47 locale tag ("en-US", "sw-KE"):
let locale: String = nigig_system_prefs::system_locale()?;

// Language subtag only ("en", "sw"):
let lang: String = nigig_system_prefs::system_language()?;

// Accent color as [r, g, b, a] floats (macOS / Windows only):
let rgba: [f32; 4] = nigig_system_prefs::accent_color()?;

Platform support

Platform	Dark mode	Locale	Accent
Android	✅ Configuration.uiMode	✅ Configuration.locales[0]	❌
macOS	✅ NSUserDefaults	✅ NSLocale.currentLocale	✅ NSColor.controlAccentColor
iOS	⚠️ TODO (UITraitCollection)	✅ NSLocale.currentLocale	❌
Windows	✅ registry AppsUseLightTheme	✅ GetUserDefaultLocaleName	✅ registry AccentColor
Linux	✅ gsettings (GNOME 42+)	✅ $LANG / $LC_ALL	❌
Other	❌ PermanentlyUnavailable	❌	❌

Layout

nigig-system-prefs/
├── Cargo.toml             # cfg-if + per-platform target deps
├── README.md
└── src/
    ├── lib.rs             # public API + tests
    ├── error.rs           # Error / Result
    └── sys/
        ├── mod.rs         # cfg_if! dispatch
        ├── android.rs     # JNI via robius-android-env
        ├── apple.rs       # objc2 + objc2-foundation (NSUserDefaults, NSLocale)
        ├── windows.rs     # windows crate (registry + Globalization)
        ├── linux.rs       # std::process::Command + std::env
        └── unsupported.rs # fallback

objc2 feature notes (Apple targets)

NSUserDefaults and NSLocale are Foundation classes — their cargo features live on objc2-foundation, NOT on objc2-app-kit.

[target.'cfg(target_vendor = "apple")'.dependencies]
objc2-foundation = { version = "0.3", default-features = false, features = [
    "std", "NSString", "NSArray", "NSObjCRuntime",
    "NSUserDefaults",   # ← Foundation feature
    "NSLocale",         # ← Foundation feature
] }

[target.'cfg(all(target_vendor = "apple", target_os = "macos"))'.dependencies]
objc2-app-kit = { version = "0.3", default-features = false, features = [
    "std", "NSColor", "NSApplication",
    # NOTE: objc2-app-kit 0.3.x does NOT have an NSUserDefaults feature.
    # If you add it here you'll get:
    #   error: failed to select a version for `objc2-app-kit`.
    #   package depends on `objc2-app-kit` with feature `NSUserDefaults`
    #   but `objc2-app-kit` does not have that feature.
] }

The objc2-app-kit 0.3.x feature list is large (NSColor, NSApplication, NSWindow, NSView, ...) but NSUserDefaults is not on it.