#![cfg_attr(docsrs, feature(doc_auto_cfg))] #![forbid(unsafe_code)] #![doc( html_logo_url = "https://bevyengine.org/assets/icon.png", html_favicon_url = "https://bevyengine.org/assets/icon.png" )] //! `bevy_winit` provides utilities to handle window creation and the eventloop through [`winit`] //! //! Most commonly, the [`WinitPlugin`] is used as part of //! [`DefaultPlugins`](https://docs.rs/bevy/latest/bevy/struct.DefaultPlugins.html). //! The app's [runner](bevy_app::App::runner) is set by `WinitPlugin` and handles the `winit` [`EventLoop`]. //! See `winit_runner` for details. pub mod accessibility; mod converters; mod system; mod winit_config; pub mod winit_event; mod winit_windows; use std::sync::mpsc::{sync_channel, SyncSender}; use approx::relative_eq; use bevy_a11y::AccessibilityRequested; use bevy_utils::Instant; pub use system::create_windows; use system::{changed_windows, despawn_windows, CachedWindow}; use winit::dpi::{LogicalSize, PhysicalSize}; pub use winit_config::*; pub use winit_event::*; pub use winit_windows::*; use bevy_app::{App, AppExit, Last, Plugin, PluginsState}; use bevy_ecs::event::ManualEventReader; use bevy_ecs::prelude::*; use bevy_ecs::system::SystemState; use bevy_input::{ mouse::{MouseButtonInput, MouseMotion, MouseScrollUnit, MouseWheel}, touchpad::{TouchpadMagnify, TouchpadRotate}, }; use bevy_math::{ivec2, DVec2, Vec2}; #[cfg(not(target_arch = "wasm32"))] use bevy_tasks::tick_global_task_pools_on_main_thread; use bevy_utils::tracing::{error, trace, warn}; #[allow(deprecated)] use bevy_window::{ exit_on_all_closed, ApplicationLifetime, CursorEntered, CursorLeft, CursorMoved, FileDragAndDrop, Ime, ReceivedCharacter, RequestRedraw, Window, WindowBackendScaleFactorChanged, WindowCloseRequested, WindowCreated, WindowDestroyed, WindowFocused, WindowMoved, WindowOccluded, WindowResized, WindowScaleFactorChanged, WindowThemeChanged, }; #[cfg(target_os = "android")] use bevy_window::{PrimaryWindow, RawHandleWrapper}; #[cfg(target_os = "android")] pub use winit::platform::android::activity as android_activity; use winit::event::StartCause; use winit::{ event::{self, DeviceEvent, Event, WindowEvent}, event_loop::{ControlFlow, EventLoop, EventLoopBuilder, EventLoopWindowTarget}, }; use crate::accessibility::{AccessKitAdapters, AccessKitPlugin, WinitActionHandlers}; use crate::converters::convert_winit_theme; /// [`AndroidApp`] provides an interface to query the application state as well as monitor events /// (for example lifecycle and input events). #[cfg(target_os = "android")] pub static ANDROID_APP: std::sync::OnceLock = std::sync::OnceLock::new(); /// A [`Plugin`] that uses `winit` to create and manage windows, and receive window and input /// events. /// /// This plugin will add systems and resources that sync with the `winit` backend and also /// replace the existing [`App`] runner with one that constructs an [event loop](EventLoop) to /// receive window and input events from the OS. #[derive(Default)] pub struct WinitPlugin { /// Allows the window (and the event loop) to be created on any thread /// instead of only the main thread. /// /// See [`EventLoopBuilder::build`] for more information on this. /// /// # Supported platforms /// /// Only works on Linux (X11/Wayland) and Windows. /// This field is ignored on other platforms. pub run_on_any_thread: bool, } impl Plugin for WinitPlugin { fn build(&self, app: &mut App) { let mut event_loop_builder = EventLoopBuilder::::with_user_event(); // linux check is needed because x11 might be enabled on other platforms. #[cfg(all(target_os = "linux", feature = "x11"))] { use winit::platform::x11::EventLoopBuilderExtX11; // This allows a Bevy app to be started and ran outside of the main thread. // A use case for this is to allow external applications to spawn a thread // which runs a Bevy app without requiring the Bevy app to need to reside on // the main thread, which can be problematic. event_loop_builder.with_any_thread(self.run_on_any_thread); } // linux check is needed because wayland might be enabled on other platforms. #[cfg(all(target_os = "linux", feature = "wayland"))] { use winit::platform::wayland::EventLoopBuilderExtWayland; event_loop_builder.with_any_thread(self.run_on_any_thread); } #[cfg(target_os = "windows")] { use winit::platform::windows::EventLoopBuilderExtWindows; event_loop_builder.with_any_thread(self.run_on_any_thread); } #[cfg(target_os = "android")] { use winit::platform::android::EventLoopBuilderExtAndroid; let msg = "Bevy must be setup with the #[bevy_main] macro on Android"; event_loop_builder.with_android_app(ANDROID_APP.get().expect(msg).clone()); } app.init_non_send_resource::() .init_resource::() .add_event::() .set_runner(winit_runner) .add_systems( Last, ( // `exit_on_all_closed` only checks if windows exist but doesn't access data, // so we don't need to care about its ordering relative to `changed_windows` changed_windows.ambiguous_with(exit_on_all_closed), despawn_windows, ) .chain(), ); app.add_plugins(AccessKitPlugin); let event_loop = event_loop_builder .build() .expect("Failed to build event loop"); // iOS, macOS, and Android don't like it if you create windows before the event loop is // initialized. // // See: // - https://github.com/rust-windowing/winit/blob/master/README.md#macos // - https://github.com/rust-windowing/winit/blob/master/README.md#ios #[cfg(not(any(target_os = "android", target_os = "ios", target_os = "macos")))] { // Otherwise, we want to create a window before `bevy_render` initializes the renderer // so that we have a surface to use as a hint. This improves compatibility with `wgpu` // backends, especially WASM/WebGL2. let mut create_window = SystemState::::from_world(app.world_mut()); create_windows(&event_loop, create_window.get_mut(app.world_mut())); create_window.apply(app.world_mut()); } // `winit`'s windows are bound to the event loop that created them, so the event loop must // be inserted as a resource here to pass it onto the runner. app.insert_non_send_resource(event_loop); } } trait AppSendEvent { fn send(&mut self, event: impl Into); } impl AppSendEvent for Vec { fn send(&mut self, event: impl Into) { self.push(Into::::into(event)); } } /// Persistent state that is used to run the [`App`] according to the current /// [`UpdateMode`]. struct WinitAppRunnerState { /// Current activity state of the app. activity_state: UpdateState, /// Current update mode of the app. update_mode: UpdateMode, /// Is `true` if a new [`WindowEvent`] has been received since the last update. window_event_received: bool, /// Is `true` if a new [`DeviceEvent`] has been received since the last update. device_event_received: bool, /// Is `true` if the app has requested a redraw since the last update. redraw_requested: bool, /// Is `true` if enough time has elapsed since `last_update` to run another update. wait_elapsed: bool, /// Number of "forced" updates to trigger on application start startup_forced_updates: u32, } impl WinitAppRunnerState { fn reset_on_update(&mut self) { self.window_event_received = false; self.device_event_received = false; } } impl Default for WinitAppRunnerState { fn default() -> Self { Self { activity_state: UpdateState::NotYetStarted, update_mode: UpdateMode::Continuous, window_event_received: false, device_event_received: false, redraw_requested: false, wait_elapsed: false, // 3 seems to be enough, 5 is a safe margin startup_forced_updates: 5, } } } #[derive(PartialEq, Eq, Debug)] enum UpdateState { NotYetStarted, Active, Suspended, WillSuspend, WillResume, } impl UpdateState { #[inline] fn is_active(&self) -> bool { match self { Self::NotYetStarted | Self::Suspended => false, Self::Active | Self::WillSuspend | Self::WillResume => true, } } } /// The parameters of the [`create_windows`] system. pub type CreateWindowParams<'w, 's, F = ()> = ( Commands<'w, 's>, Query<'w, 's, (Entity, &'static mut Window), F>, EventWriter<'w, WindowCreated>, NonSendMut<'w, WinitWindows>, NonSendMut<'w, AccessKitAdapters>, ResMut<'w, WinitActionHandlers>, Res<'w, AccessibilityRequested>, ); /// The [`winit::event_loop::EventLoopProxy`] with the specific [`winit::event::Event::UserEvent`] used in the [`winit_runner`]. /// /// The `EventLoopProxy` can be used to request a redraw from outside bevy. /// /// Use `NonSend` to receive this resource. pub type EventLoopProxy = winit::event_loop::EventLoopProxy; type UserEvent = RequestRedraw; /// The default [`App::runner`] for the [`WinitPlugin`] plugin. /// /// Overriding the app's [runner](bevy_app::App::runner) while using `WinitPlugin` will bypass the /// `EventLoop`. pub fn winit_runner(mut app: App) -> AppExit { if app.plugins_state() == PluginsState::Ready { app.finish(); app.cleanup(); } let event_loop = app .world_mut() .remove_non_send_resource::>() .unwrap(); app.world_mut() .insert_non_send_resource(event_loop.create_proxy()); let mut runner_state = WinitAppRunnerState::default(); // Create a channel with a size of 1, since ideally only one exit code will be sent before exiting the app. let (exit_sender, exit_receiver) = sync_channel(1); // prepare structures to access data in the world let mut redraw_event_reader = ManualEventReader::::default(); let mut focused_windows_state: SystemState<(Res, Query<(Entity, &Window)>)> = SystemState::new(app.world_mut()); let mut event_writer_system_state: SystemState<( EventWriter, NonSend, Query<(&mut Window, &mut CachedWindow)>, NonSend, )> = SystemState::new(app.world_mut()); let mut create_window = SystemState::>>::from_world(app.world_mut()); let mut winit_events = Vec::default(); // set up the event loop let event_handler = move |event, event_loop: &EventLoopWindowTarget| { // The event loop is in the process of exiting, so don't deliver any new events if event_loop.exiting() { return; } handle_winit_event( &mut app, &mut runner_state, &mut create_window, &mut event_writer_system_state, &mut focused_windows_state, &mut redraw_event_reader, &mut winit_events, &exit_sender, event, event_loop, ); }; trace!("starting winit event loop"); // TODO(clean): the winit docs mention using `spawn` instead of `run` on WASM. if let Err(err) = event_loop.run(event_handler) { error!("winit event loop returned an error: {err}"); } // If everything is working correctly then the event loop only exits after it's sent a exit code. exit_receiver .try_recv() .map_err(|err| error!("Failed to receive a app exit code! This is a bug. Reason: {err}")) .unwrap_or(AppExit::error()) } #[allow(clippy::too_many_arguments /* TODO: probs can reduce # of args */)] fn handle_winit_event( app: &mut App, runner_state: &mut WinitAppRunnerState, create_window: &mut SystemState>>, event_writer_system_state: &mut SystemState<( EventWriter, NonSend, Query<(&mut Window, &mut CachedWindow)>, NonSend, )>, focused_windows_state: &mut SystemState<(Res, Query<(Entity, &Window)>)>, redraw_event_reader: &mut ManualEventReader, winit_events: &mut Vec, exit_notify: &SyncSender, event: Event, event_loop: &EventLoopWindowTarget, ) { #[cfg(feature = "trace")] let _span = bevy_utils::tracing::info_span!("winit event_handler").entered(); if app.plugins_state() != PluginsState::Cleaned { if app.plugins_state() != PluginsState::Ready { #[cfg(not(target_arch = "wasm32"))] tick_global_task_pools_on_main_thread(); } else { app.finish(); app.cleanup(); } runner_state.redraw_requested = true; } // create any new windows // (even if app did not update, some may have been created by plugin setup) create_windows(event_loop, create_window.get_mut(app.world_mut())); create_window.apply(app.world_mut()); match event { Event::AboutToWait => { if let Some(app_redraw_events) = app.world().get_resource::>() { if redraw_event_reader.read(app_redraw_events).last().is_some() { runner_state.redraw_requested = true; } } let (config, windows) = focused_windows_state.get(app.world()); let focused = windows.iter().any(|(_, window)| window.focused); let mut update_mode = config.update_mode(focused); let mut should_update = should_update(runner_state, update_mode); if runner_state.startup_forced_updates > 0 { runner_state.startup_forced_updates -= 1; // Ensure that an update is triggered on the first iterations for app initialization should_update = true; } if runner_state.activity_state == UpdateState::WillSuspend { runner_state.activity_state = UpdateState::Suspended; // Trigger one last update to enter the suspended state should_update = true; #[cfg(target_os = "android")] { // Remove the `RawHandleWrapper` from the primary window. // This will trigger the surface destruction. let mut query = app .world_mut() .query_filtered::>(); let entity = query.single(&app.world()); app.world_mut() .entity_mut(entity) .remove::(); } } if runner_state.activity_state == UpdateState::WillResume { runner_state.activity_state = UpdateState::Active; // Trigger the update to enter the active state should_update = true; // Trigger the next redraw ro refresh the screen immediately runner_state.redraw_requested = true; #[cfg(target_os = "android")] { // Get windows that are cached but without raw handles. Those window were already created, but got their // handle wrapper removed when the app was suspended. let mut query = app .world_mut() .query_filtered::<(Entity, &Window), (With, Without)>(); if let Ok((entity, window)) = query.get_single(&app.world()) { let window = window.clone(); let ( .., mut winit_windows, mut adapters, mut handlers, accessibility_requested, ) = create_window.get_mut(app.world_mut()); let winit_window = winit_windows.create_window( event_loop, entity, &window, &mut adapters, &mut handlers, &accessibility_requested, ); let wrapper = RawHandleWrapper::new(winit_window).unwrap(); app.world_mut().entity_mut(entity).insert(wrapper); } } } // This is recorded before running app.update(), to run the next cycle after a correct timeout. // If the cycle takes more than the wait timeout, it will be re-executed immediately. let begin_frame_time = Instant::now(); if should_update { // Not redrawing, but the timeout elapsed. run_app_update(runner_state, app, winit_events); // Running the app may have changed the WinitSettings resource, so we have to re-extract it. let (config, windows) = focused_windows_state.get(app.world()); let focused = windows.iter().any(|(_, window)| window.focused); update_mode = config.update_mode(focused); } match update_mode { UpdateMode::Continuous => { // per winit's docs on [Window::is_visible](https://docs.rs/winit/latest/winit/window/struct.Window.html#method.is_visible), // we cannot use the visibility to drive rendering on these platforms // so we cannot discern whether to beneficially use `Poll` or not? cfg_if::cfg_if! { if #[cfg(not(any( target_arch = "wasm32", target_os = "android", target_os = "ios", all(target_os = "linux", any(feature = "x11", feature = "wayland")) )))] { let winit_windows = app.world().non_send_resource::(); let visible = winit_windows.windows.iter().any(|(_, w)| { w.is_visible().unwrap_or(false) }); event_loop.set_control_flow(if visible { ControlFlow::Wait } else { ControlFlow::Poll }); } else { event_loop.set_control_flow(ControlFlow::Wait); } } // Trigger the next redraw to refresh the screen immediately if waiting if let ControlFlow::Wait = event_loop.control_flow() { runner_state.redraw_requested = true; } } UpdateMode::Reactive { wait } | UpdateMode::ReactiveLowPower { wait } => { // Set the next timeout, starting from the instant before running app.update() to avoid frame delays if let Some(next) = begin_frame_time.checked_add(wait) { if runner_state.wait_elapsed { event_loop.set_control_flow(ControlFlow::WaitUntil(next)); } } } } if update_mode != runner_state.update_mode { // Trigger the next redraw since we're changing the update mode runner_state.redraw_requested = true; runner_state.update_mode = update_mode; } if runner_state.redraw_requested && runner_state.activity_state != UpdateState::Suspended { let winit_windows = app.world().non_send_resource::(); for window in winit_windows.windows.values() { window.request_redraw(); } runner_state.redraw_requested = false; } } Event::NewEvents(cause) => { runner_state.wait_elapsed = match cause { StartCause::WaitCancelled { requested_resume: Some(resume), .. } => { // If the resume time is not after now, it means that at least the wait timeout // has elapsed. resume <= Instant::now() } _ => true, }; } Event::WindowEvent { event, window_id, .. } => { let (mut window_resized, winit_windows, mut windows, access_kit_adapters) = event_writer_system_state.get_mut(app.world_mut()); let Some(window) = winit_windows.get_window_entity(window_id) else { warn!("Skipped event {event:?} for unknown winit Window Id {window_id:?}"); return; }; let Ok((mut win, _)) = windows.get_mut(window) else { warn!("Window {window:?} is missing `Window` component, skipping event {event:?}"); return; }; // Allow AccessKit to respond to `WindowEvent`s before they reach // the engine. if let Some(adapter) = access_kit_adapters.get(&window) { if let Some(winit_window) = winit_windows.get_window(window) { adapter.process_event(winit_window, &event); } } runner_state.window_event_received = true; match event { WindowEvent::Resized(size) => { react_to_resize(&mut win, size, &mut window_resized, window); } WindowEvent::CloseRequested => winit_events.send(WindowCloseRequested { window }), WindowEvent::KeyboardInput { ref event, .. } => { if event.state.is_pressed() { if let Some(char) = &event.text { let char = char.clone(); #[allow(deprecated)] winit_events.send(ReceivedCharacter { window, char }); } } winit_events.send(converters::convert_keyboard_input(event, window)); } WindowEvent::CursorMoved { position, .. } => { let physical_position = DVec2::new(position.x, position.y); let last_position = win.physical_cursor_position(); let delta = last_position.map(|last_pos| { (physical_position.as_vec2() - last_pos) / win.resolution.scale_factor() }); win.set_physical_cursor_position(Some(physical_position)); let position = (physical_position / win.resolution.scale_factor() as f64).as_vec2(); winit_events.send(CursorMoved { window, position, delta, }); } WindowEvent::CursorEntered { .. } => { winit_events.send(CursorEntered { window }); } WindowEvent::CursorLeft { .. } => { win.set_physical_cursor_position(None); winit_events.send(CursorLeft { window }); } WindowEvent::MouseInput { state, button, .. } => { winit_events.send(MouseButtonInput { button: converters::convert_mouse_button(button), state: converters::convert_element_state(state), window, }); } WindowEvent::TouchpadMagnify { delta, .. } => { winit_events.send(TouchpadMagnify(delta as f32)); } WindowEvent::TouchpadRotate { delta, .. } => { winit_events.send(TouchpadRotate(delta)); } WindowEvent::MouseWheel { delta, .. } => match delta { event::MouseScrollDelta::LineDelta(x, y) => { winit_events.send(MouseWheel { unit: MouseScrollUnit::Line, x, y, window, }); } event::MouseScrollDelta::PixelDelta(p) => { winit_events.send(MouseWheel { unit: MouseScrollUnit::Pixel, x: p.x as f32, y: p.y as f32, window, }); } }, WindowEvent::Touch(touch) => { let location = touch .location .to_logical(win.resolution.scale_factor() as f64); winit_events.send(converters::convert_touch_input(touch, location, window)); } WindowEvent::ScaleFactorChanged { scale_factor, mut inner_size_writer, } => { let prior_factor = win.resolution.scale_factor(); win.resolution.set_scale_factor(scale_factor as f32); // Note: this may be different from new_scale_factor if // `scale_factor_override` is set to Some(thing) let new_factor = win.resolution.scale_factor(); let mut new_inner_size = PhysicalSize::new(win.physical_width(), win.physical_height()); let scale_factor_override = win.resolution.scale_factor_override(); if let Some(forced_factor) = scale_factor_override { // This window is overriding the OS-suggested DPI, so its physical size // should be set based on the overriding value. Its logical size already // incorporates any resize constraints. let maybe_new_inner_size = LogicalSize::new(win.width(), win.height()) .to_physical::(forced_factor as f64); if let Err(err) = inner_size_writer.request_inner_size(new_inner_size) { warn!("Winit Failed to resize the window: {err}"); } else { new_inner_size = maybe_new_inner_size; } } let new_logical_width = new_inner_size.width as f32 / new_factor; let new_logical_height = new_inner_size.height as f32 / new_factor; let width_equal = relative_eq!(win.width(), new_logical_width); let height_equal = relative_eq!(win.height(), new_logical_height); win.resolution .set_physical_resolution(new_inner_size.width, new_inner_size.height); winit_events.send(WindowBackendScaleFactorChanged { window, scale_factor, }); if scale_factor_override.is_none() && !relative_eq!(new_factor, prior_factor) { winit_events.send(WindowScaleFactorChanged { window, scale_factor, }); } if !width_equal || !height_equal { winit_events.send(WindowResized { window, width: new_logical_width, height: new_logical_height, }); } } WindowEvent::Focused(focused) => { win.focused = focused; winit_events.send(WindowFocused { window, focused }); } WindowEvent::Occluded(occluded) => { winit_events.send(WindowOccluded { window, occluded }); } WindowEvent::DroppedFile(path_buf) => { winit_events.send(FileDragAndDrop::DroppedFile { window, path_buf }); } WindowEvent::HoveredFile(path_buf) => { winit_events.send(FileDragAndDrop::HoveredFile { window, path_buf }); } WindowEvent::HoveredFileCancelled => { winit_events.send(FileDragAndDrop::HoveredFileCanceled { window }); } WindowEvent::Moved(position) => { let position = ivec2(position.x, position.y); win.position.set(position); winit_events.send(WindowMoved { window, position }); } WindowEvent::Ime(event) => match event { event::Ime::Preedit(value, cursor) => { winit_events.send(Ime::Preedit { window, value, cursor, }); } event::Ime::Commit(value) => { winit_events.send(Ime::Commit { window, value }); } event::Ime::Enabled => { winit_events.send(Ime::Enabled { window }); } event::Ime::Disabled => { winit_events.send(Ime::Disabled { window }); } }, WindowEvent::ThemeChanged(theme) => { winit_events.send(WindowThemeChanged { window, theme: convert_winit_theme(theme), }); } WindowEvent::Destroyed => { winit_events.send(WindowDestroyed { window }); } WindowEvent::RedrawRequested => { run_app_update(runner_state, app, winit_events); } _ => {} } let mut windows = app.world_mut().query::<(&mut Window, &mut CachedWindow)>(); if let Ok((window_component, mut cache)) = windows.get_mut(app.world_mut(), window) { if window_component.is_changed() { cache.window = window_component.clone(); } } } Event::DeviceEvent { event, .. } => { runner_state.device_event_received = true; if let DeviceEvent::MouseMotion { delta: (x, y) } = event { let delta = Vec2::new(x as f32, y as f32); winit_events.send(MouseMotion { delta }); } } Event::Suspended => { winit_events.send(ApplicationLifetime::Suspended); // Mark the state as `WillSuspend`. This will let the schedule run one last time // before actually suspending to let the application react runner_state.activity_state = UpdateState::WillSuspend; } Event::Resumed => { match runner_state.activity_state { UpdateState::NotYetStarted => winit_events.send(ApplicationLifetime::Started), _ => winit_events.send(ApplicationLifetime::Resumed), } runner_state.activity_state = UpdateState::WillResume; } Event::UserEvent(RequestRedraw) => { runner_state.redraw_requested = true; } _ => (), } if let Some(app_exit) = app.should_exit() { if let Err(err) = exit_notify.try_send(app_exit) { error!("Failed to send a app exit notification! This is a bug. Reason: {err}"); }; event_loop.exit(); return; } // We drain events after every received winit event in addition to on app update to ensure // the work of pushing events into event queues is spread out over time in case the app becomes // dormant for a long stretch. forward_winit_events(winit_events, app); } fn should_update(runner_state: &WinitAppRunnerState, update_mode: UpdateMode) -> bool { let handle_event = match update_mode { UpdateMode::Continuous | UpdateMode::Reactive { .. } => { runner_state.wait_elapsed || runner_state.window_event_received || runner_state.device_event_received } UpdateMode::ReactiveLowPower { .. } => { runner_state.wait_elapsed || runner_state.window_event_received } }; handle_event && runner_state.activity_state.is_active() } fn run_app_update( runner_state: &mut WinitAppRunnerState, app: &mut App, winit_events: &mut Vec, ) { runner_state.reset_on_update(); forward_winit_events(winit_events, app); if app.plugins_state() == PluginsState::Cleaned { app.update(); } } fn react_to_resize( win: &mut Mut<'_, Window>, size: winit::dpi::PhysicalSize, window_resized: &mut EventWriter, window: Entity, ) { win.resolution .set_physical_resolution(size.width, size.height); window_resized.send(WindowResized { window, width: win.width(), height: win.height(), }); }