vcs-controller/src/joystick_loop.rs

use crate::coordinator::{ApplicationEvent, MoveEvent};

use async_channel::Sender;
use gilrs::{ev::filter::FilterFn, Axis, Button, Event, EventType, Filter, Gilrs, GilrsBuilder};
use log::{info, warn};
use std::{
    panic::{self, AssertUnwindSafe},
    sync::{atomic::AtomicBool, Arc},
    time::Duration
};

static MAX_SENT_ZEROS: u32 = 10;

struct UnknownSlayer;
impl FilterFn for UnknownSlayer {
    fn filter(&self, ev: Option<Event>, _gilrs: &mut Gilrs) -> Option<Event> {
        match ev {
            Some(Event {
                event: EventType::ButtonPressed(Button::Unknown, ..),
                id,
                ..
            })
            | Some(Event {
                event: EventType::ButtonReleased(Button::Unknown, ..),
                id,
                ..
            })
            | Some(Event {
                event: EventType::AxisChanged(Axis::Unknown, ..),
                id,
                ..
            }) => Some(Event::new(id, EventType::Dropped)),
            _ => ev,
        }
    }
}

pub async fn joystick_loop(
    tx: Sender<ApplicationEvent>,
    is_alive: Arc<AtomicBool>
) {
    let mut gilrs = GilrsBuilder::new().set_update_state(false).build().unwrap();

    is_alive.store(true, std::sync::atomic::Ordering::SeqCst);

    let mut curr_x: i32 = 0;
    let mut curr_y: i32 = 0;
    let mut past_x: i32 = 0;
    let mut past_y: i32 = 0;
    let mut count_zeros: u32 = 0;

    loop {
        // catch unwind because some buttons on the joystick will panic the gilrs object
        match panic::catch_unwind(AssertUnwindSafe(|| {
            // get the next event, and if it is an axis we are interested in, update the
            // corresponding variable
            while let Some(evt) = gilrs.next_event().filter_ev(&UnknownSlayer {}, &mut gilrs) {
                match evt.event {
                    gilrs::EventType::AxisChanged(gilrs::Axis::LeftStickY, val, _) => {
                        curr_y = (val * 100.0) as i32;
                        if curr_y > -10 && curr_y < 10 {
                            curr_y = 0;
                        }
                    }
                    gilrs::EventType::AxisChanged(gilrs::Axis::LeftStickX, val, _) => {
                        curr_x = (val * 100.0) as i32;
                        if curr_x > -10 && curr_x < 10 {
                            curr_x = 0;
                        }
                    }
                    _ => {}
                }
            }
        })) {
            Ok(_) => {}
            Err(_) => {
                info!("panic-causing event captured in gilrs event handler")
            }
        }

        if (curr_x != past_x || curr_y != past_y) || (count_zeros < MAX_SENT_ZEROS) {
            past_x = curr_x;
            past_y = curr_y;

            if curr_x == 0 && curr_y == 0 {
                count_zeros += 1;
            } else {
                count_zeros = 0;
            }

            match tx.try_send(ApplicationEvent::MoveEvent(MoveEvent { 
                x: curr_x,
                y: curr_y,
            })) {
                Ok(_) => {}
                Err(async_channel::TrySendError::Closed(_)) => {
                    info!("MEC is closed, stopping Joystick loop");
                    break 
                }
                Err(async_channel::TrySendError::Full(_)) => {warn!("[joystick loop] The MEC is full!")}
            }
        }

        tokio::time::sleep(Duration::from_millis(50)).await;
    }
    is_alive.store(false, std::sync::atomic::Ordering::SeqCst);
}