slint/internal/backends/android-activity/lib.rs

// Copyright © SixtyFPS GmbH <info@slint.dev>
// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-1.1 OR LicenseRef-Slint-commercial

#![doc = include_str!("README.md")]
#![doc(html_logo_url = "https://slint.dev/logo/slint-logo-square-light.svg")]
#![cfg_attr(not(target_os = "android"), allow(rustdoc::broken_intra_doc_links))]
#![cfg(target_os = "android")]

mod androidwindowadapter;
mod javahelper;

use android_activity::PollEvent;
pub use android_activity::{self, AndroidApp};
use androidwindowadapter::AndroidWindowAdapter;
use core::ops::ControlFlow;
use i_slint_core::api::{EventLoopError, PlatformError};
use i_slint_core::platform::WindowAdapter;
use i_slint_renderer_skia::SkiaRendererExt;
use std::cell::RefCell;
use std::rc::{Rc, Weak};
use std::sync::{Arc, Mutex};

thread_local! {
    static CURRENT_WINDOW: RefCell<Weak<AndroidWindowAdapter>> = RefCell::new(Default::default());
}

pub struct AndroidPlatform {
    app: AndroidApp,
    window: Rc<AndroidWindowAdapter>,
    event_listener: Option<Box<dyn Fn(&PollEvent<'_>)>>,
}

impl AndroidPlatform {
    /// Instantiate a new Android backend given the [`android_activity::AndroidApp`]
    ///
    /// Pass the returned value to [`slint::platform::set_platform()`](`i_slint_core::platform::set_platform()`)
    ///
    /// # Example
    /// ```
    /// #[cfg(target_os = "android")]
    /// #[no_mangle]
    /// fn android_main(app: i_slint_backend_android_activity::AndroidApp) {
    ///     slint::platform::set_platform(Box::new(
    ///         i_slint_backend_android_activity::AndroidPlatform::new(app),
    ///     ))
    ///     .unwrap();
    ///     // ... your slint application ...
    /// }
    /// ```
    pub fn new(app: AndroidApp) -> Self {
        let window = AndroidWindowAdapter::new(app.clone());
        CURRENT_WINDOW.set(Rc::downgrade(&window));
        Self { app, window, event_listener: None }
    }

    /// Instantiate a new Android backend given the [`android_activity::AndroidApp`]
    /// and a function to process the events.
    ///
    /// This is the same as [`AndroidPlatform::new()`], but it allow you to get notified
    /// of events.
    ///
    /// Pass the returned value to [`slint::platform::set_platform()`](`i_slint_core::platform::set_platform()`)
    ///
    /// # Example
    /// ```
    /// #[cfg(target_os = "android")]
    /// #[no_mangle]
    /// fn android_main(app: i_slint_backend_android_activity::AndroidApp) {
    ///     slint::platform::set_platform(Box::new(
    ///         i_slint_backend_android_activity::AndroidPlatform::new_with_event_listener(
    ///             app,
    ///             |event| { eprintln!("got event {event:?}") }
    ///         ),
    ///     ))
    ///     .unwrap();
    ///     // ... your slint application ...
    /// }
    /// ```
    pub fn new_with_event_listener(
        app: AndroidApp,
        listener: impl Fn(&PollEvent<'_>) + 'static,
    ) -> Self {
        let mut this = Self::new(app);
        this.event_listener = Some(Box::new(listener));
        this
    }
}

impl i_slint_core::platform::Platform for AndroidPlatform {
    fn create_window_adapter(&self) -> Result<Rc<dyn WindowAdapter>, PlatformError> {
        Ok(self.window.clone())
    }
    fn run_event_loop(&self) -> Result<(), PlatformError> {
        loop {
            let mut timeout = i_slint_core::platform::duration_until_next_timer_update();
            if self.window.window.has_active_animations() {
                // FIXME: we should not hardcode a value here
                let frame_duration = std::time::Duration::from_millis(10);
                timeout = Some(match timeout {
                    Some(x) => x.min(frame_duration),
                    None => frame_duration,
                })
            }
            let mut r = Ok(ControlFlow::Continue(()));
            self.app.poll_events(timeout, |e| {
                i_slint_core::platform::update_timers_and_animations();
                r = self.window.process_event(&e);
                if let Some(event_listener) = &self.event_listener {
                    event_listener(&e)
                }
            });
            if matches!(r.map_err(|e| PlatformError::from(e.to_string()))?, ControlFlow::Break(()))
            {
                return Ok(());
            }
            if self.window.pending_redraw.take() {
                self.window.do_render()?;
            }
        }
    }

    fn new_event_loop_proxy(&self) -> Option<Box<dyn i_slint_core::platform::EventLoopProxy>> {
        Some(Box::new(AndroidEventLoopProxy {
            event_queue: self.window.event_queue.clone(),
            waker: self.app.create_waker(),
        }))
    }
}

enum Event {
    Quit,
    Other(Box<dyn FnOnce() + Send + 'static>),
}

type EventQueue = Arc<Mutex<Vec<Event>>>;

struct AndroidEventLoopProxy {
    event_queue: EventQueue,
    waker: android_activity::AndroidAppWaker,
}

impl i_slint_core::platform::EventLoopProxy for AndroidEventLoopProxy {
    fn quit_event_loop(&self) -> Result<(), EventLoopError> {
        self.event_queue.lock().unwrap().push(Event::Quit);
        self.waker.wake();
        Ok(())
    }

    fn invoke_from_event_loop(
        &self,
        event: Box<dyn FnOnce() + Send>,
    ) -> Result<(), EventLoopError> {
        self.event_queue.lock().unwrap().push(Event::Other(event));
        self.waker.wake();
        Ok(())
    }
}