cranpose_services/
system_bars.rs

1//! The color of the icons the platform draws in its status and navigation bars
2//! over an app that paints its own background under them.
3
4use std::sync::{Mutex, PoisonError, atomic::Ordering};
5
6use cranpose_core::DisposableEffect;
7use portable_atomic::AtomicU64;
8
9use crate::host_controller;
10
11/// The color of the icons the platform draws in its status and navigation bars
12/// over the app.
13#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash)]
14pub enum SystemBarIcons {
15    /// What the platform shows for the system's light or dark theme.
16    #[default]
17    FollowSystem,
18    /// Dark icons, readable over a light background.
19    Dark,
20    /// Light icons, readable over a dark background.
21    Light,
22}
23
24// Every active `SystemBarAppearance` with the icons it asks for, oldest first.
25static REQUESTS: Mutex<Vec<(u64, SystemBarIcons)>> = Mutex::new(Vec::new());
26static NEXT_REQUEST: AtomicU64 = AtomicU64::new(0);
27
28/// The icons the most recent active [`SystemBarAppearance`] asks for, or
29/// [`SystemBarIcons::FollowSystem`] when none is in composition.
30pub fn system_bar_icons() -> SystemBarIcons {
31    REQUESTS
32        .lock()
33        .unwrap_or_else(PoisonError::into_inner)
34        .last()
35        .map_or(SystemBarIcons::FollowSystem, |&(_, icons)| icons)
36}
37
38pub(crate) fn show_current_system_bar_icons() {
39    if let Some(host) = host_controller() {
40        host.set_system_bar_icons(system_bar_icons());
41    }
42}
43
44fn request(icons: SystemBarIcons) -> u64 {
45    let id = NEXT_REQUEST.fetch_add(1, Ordering::Relaxed);
46    REQUESTS
47        .lock()
48        .unwrap_or_else(PoisonError::into_inner)
49        .push((id, icons));
50    show_current_system_bar_icons();
51    id
52}
53
54fn withdraw(id: u64) {
55    REQUESTS
56        .lock()
57        .unwrap_or_else(PoisonError::into_inner)
58        .retain(|&(request, _)| request != id);
59    show_current_system_bar_icons();
60}
61
62/// Shows `icons` in the status and navigation bars while this call stays in
63/// composition, for an app that paints its own background under the bars:
64/// Android's light and dark system bar appearance, and the iOS status bar
65/// style. The most recent active call wins; when it leaves composition the one
66/// before it applies again, and with none left the bars follow the system
67/// theme. Platforms without system bars over the app ignore it.
68#[expect(non_snake_case, reason = "names follow Compose's casing")]
69#[track_caller]
70pub fn SystemBarAppearance(icons: SystemBarIcons) {
71    DisposableEffect(icons, move |scope| {
72        let id = request(icons);
73        scope.on_dispose(move || withdraw(id))
74    });
75}
76
77#[cfg(test)]
78#[path = "tests/system_bars_tests.rs"]
79mod tests;
cranpose_services/system_bars.rs

cranpose_services/
system_bars.rs
