A rust module for tauri applications that provides a trait which can let window background color automatically adapts to the configurated theme.

apply_theme.rs

use dark_light;
use tauri::{
    AppHandle,
    Manager,
    Theme,
    WebviewWindowBuilder,
};
use crate::app_state::AppState;

enum ConfigTheme { System, Light, Dark }
impl From<&str> for ConfigTheme {
    fn from(s: &str) -> Self {
        match s {
            "dark" => ConfigTheme::Dark,
            "light" => ConfigTheme::Light,
            _ => ConfigTheme::System,
        }
    }
}

pub trait ApplyTheme {
    fn apply_theme(self, app_handle: &AppHandle) -> Self;
}

impl<'a, R: tauri::Runtime, M: Manager<R>> ApplyTheme for WebviewWindowBuilder<'a, R, M> {
    fn apply_theme(self, app_handle: &AppHandle) -> Self {
        let app_state = app_handle.state::<AppState>();
        let theme = match app_state.config.lock() {
            Ok(config) => config.theme.clone(),
            Err(_) => "system".to_string(),
        };
        let config_theme = ConfigTheme::from(theme.as_str());
        // set window frame theme
        let builder = match config_theme {
            ConfigTheme::Dark => self.theme(Some(Theme::Dark)),
            ConfigTheme::Light => self.theme(Some(Theme::Light)),
            ConfigTheme::System => self.theme(None),
        };

        // apply proper webview window background color
        let Ok(system_mode) = dark_light::detect() else {
            return builder;
        };
        let dark_background_color = "#121212".parse().unwrap();
        let light_background_color = "#ffffff".parse().unwrap();
        let builder = match config_theme {
            ConfigTheme::Dark => builder.background_color(dark_background_color),
            ConfigTheme::Light => builder.background_color(light_background_color),
            ConfigTheme::System => match system_mode {
                dark_light::Mode::Dark => builder.background_color(dark_background_color),
                dark_light::Mode::Light => builder.background_color(light_background_color),
                dark_light::Mode::Unspecified => builder,
            },
        };
        return builder;
    }
}