android-activity/examples/na-mainloop/src/lib.rs

use native_activity::{PollEvent, MainEvent};
use log::info;

#[no_mangle]
extern "C" fn android_main() {
    android_logger::init_once(
        android_logger::Config::default().with_min_level(log::Level::Info)
    );

    let mut quit = false;
    let mut redraw_pending = true;
    let mut render_state: Option<()> = Default::default();

    let app = native_activity::android_app();
    while !quit {
        app.poll_events(Some(std::time::Duration::from_millis(500)) /* timeout */, |event| {
            match event {
                PollEvent::Wake => { info!("Early wake up"); },
                PollEvent::Timeout => {
                    info!("Timed out");
                    // Real app would probably rely on vblank sync via graphics API...
                    redraw_pending = true;
                },
                PollEvent::Main(main_event) => {
                    info!("Main event: {:?}", main_event);
                    match main_event {
                        MainEvent::SaveState { saver, .. } => {
                            saver.store("foo://bar".as_bytes());
                        },
                        MainEvent::Pause => {},
                        MainEvent::Resume { loader, .. } => {
                            if let Some(state) = loader.load() {
                                if let Ok(uri) = String::from_utf8(state) {
                                    info!("Resumed with saved state = {uri:#?}");
                                }
                            }
                        },
                        MainEvent::InitWindow { .. } => {
                            render_state = Some(());
                            redraw_pending = true;
                        },
                        MainEvent::TerminateWindow { .. } => {
                            render_state = None;
                        }
                        MainEvent::WindowResized { .. } => { redraw_pending = true; },
                        MainEvent::RedrawNeeded { ..} => { redraw_pending = true; },
                        MainEvent::LowMemory => {},

                        MainEvent::Destroy => { quit = true },
                        _ => { /* ... */}
                    }
                },
                _ => {}
            }

            if redraw_pending {
                if let Some(_rs) = render_state {
                    redraw_pending = false;

                    // Handle input
                    app.input_events(|event| {
                        info!("Input Event: {event:?}");

                    });

                    info!("Render...");
                }
            }
        });
    }
}