cosmic-comp/src/backend/mod.rs

// SPDX-License-Identifier: GPL-3.0-only

use crate::state::{Data, State};
use anyhow::{Context, Result};
use smithay::reexports::{calloop::EventLoop, wayland_server::DisplayHandle};

pub mod render;

pub mod kms;
pub mod winit;
pub mod x11;
// TODO
// pub mod wayland; // tbd in smithay

pub fn init_backend_auto(
    dh: &DisplayHandle,
    event_loop: &mut EventLoop<'static, Data>,
    state: &mut State,
) -> Result<()> {
    let res = match std::env::var("COSMIC_BACKEND") {
        Ok(x) if x == "x11" => x11::init_backend(dh, event_loop, state),
        Ok(x) if x == "winit" => winit::init_backend(dh, event_loop, state),
        Ok(x) if x == "kms" => kms::init_backend(dh, event_loop, state),
        Ok(_) => unimplemented!("There is no backend with this identifier"),
        Err(_) => {
            if std::env::var_os("DISPLAY").is_some()
                || std::env::var_os("WAYLAND_DISPLAY").is_some()
            {
                match x11::init_backend(dh, event_loop, state) {
                    Ok(_) => Ok(()),
                    Err(err) => {
                        slog_scope::warn!("X11 Backend failed with error: {}", err);
                        slog_scope::info!("Falling back to winit backend.");
                        winit::init_backend(dh, event_loop, state)
                    }
                }
            } else {
                kms::init_backend(dh, event_loop, state)
            }
        }
    };

    if res.is_ok() {
        let output = state
            .common
            .shell
            .outputs()
            .next()
            .with_context(|| "Backend initialized without output")?;
        let initial_seat = crate::input::add_seat(
            dh,
            &mut state.common.seat_state,
            output,
            &state.common.config,
            "seat-0".into(),
        );
        state.common.add_seat(initial_seat);
    }
    res
}