dark-light

Rust crate to detect the system theme mode

Supports macOS, Windows, Linux, BSDs, and WebAssembly.

On Linux the XDG Desktop Portal D-Bus API is checked for the color-scheme preference, which works in Flatpak sandboxes without needing filesystem access.

API Documentation

Usage

Add to your project:

cargo add dark-light

Detect current theme mode

You can detect the current mode by using the detect function. This function returns a Mode value.

fn main() -> Result<(), dark_light::Error> {
    match dark_light::detect()? {
        dark_light::Mode::Dark => println!("Dark mode"),
        dark_light::Mode::Light => println!("Light mode"),
        dark_light::Mode::Unspecified => println!("Unspecified"),
    }
    Ok(())
}

React to theme changes

You can subscribe to theme changes by using the subscribe function. It returns a Watcher that yields a new Mode each time the OS theme changes.

fn main() -> Result<(), dark_light::Error> {
    let watcher = dark_light::subscribe()?;
    for mode in watcher.iter() {
        match mode {
            dark_light::Mode::Dark => println!("Dark mode"),
            dark_light::Mode::Light => println!("Light mode"),
            dark_light::Mode::Unspecified => println!("Unspecified"),
        }
    }
    Ok(())
}

On macOS, theme changes are currently detected by polling once per second rather than through a native notification, since the objc2 bindings this crate uses don't yet expose a safe way to observe NSDistributedNotificationCenter.

Stream theme changes

With the default async-io feature (or tokio) enabled, stream returns a futures_core::Stream of Mode.

use futures_util::StreamExt;

async fn watch_theme() -> Result<(), dark_light::Error> {
    let mut stream = dark_light::stream()?;
    while let Some(mode) = stream.next().await {
        println!("{mode:?}");
    }
    Ok(())
}

License

Licensed under either of the following licenses:

• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)