Add support to bevy_window for closing windows

Make the rest of bevy work with multiple windows

Remove exit_on_esc

Add suggested docs

crates/bevy_input/src/lib.rs

@@ -3,7 +3,6 @@ pub mod gamepad;
 mod input;
 pub mod keyboard;
 pub mod mouse;
-pub mod system;
 pub mod touch;
 
 pub use axis::*;

crates/bevy_pbr/src/light.rs

@@ -371,9 +371,13 @@ pub fn add_clusters(
 
 pub fn update_clusters(windows: Res<Windows>, mut views: Query<(&Camera, &mut Clusters)>) {
     for (camera, mut clusters) in views.iter_mut() {
+        // If the window doesn't exist, we won't render anything to it, so don't need to calculate the clusters for it
+        let window = match windows.get(camera.window) {
+            Some(window) => window,
+            _ => continue,
+        };
         let is_orthographic = camera.projection_matrix.w_axis.w == 1.0;
         let inverse_projection = camera.projection_matrix.inverse();
-        let window = windows.get(camera.window).unwrap();
         let screen_size_u32 = UVec2::new(window.physical_width(), window.physical_height());
         // Don't update clusters if screen size is 0.
         if screen_size_u32.x == 0 || screen_size_u32.y == 0 {

crates/bevy_render/src/view/window.rs

@@ -7,7 +7,7 @@ use crate::{
 use bevy_app::{App, Plugin};
 use bevy_ecs::prelude::*;
 use bevy_utils::{tracing::debug, HashMap, HashSet};
-use bevy_window::{PresentMode, RawWindowHandleWrapper, WindowId, Windows};
+use bevy_window::{PresentMode, RawWindowHandleWrapper, WindowClosed, WindowId, Windows};
 use std::ops::{Deref, DerefMut};
 use wgpu::TextureFormat;
 
@@ -67,7 +67,11 @@ impl DerefMut for ExtractedWindows {
     }
 }
 
-fn extract_windows(mut render_world: ResMut<RenderWorld>, windows: Res<Windows>) {
+fn extract_windows(
+    mut render_world: ResMut<RenderWorld>,
+    mut closed: EventReader<WindowClosed>,
+    windows: Res<Windows>,
+) {
     let mut extracted_windows = render_world.get_resource_mut::<ExtractedWindows>().unwrap();
     for window in windows.iter() {
         let (new_width, new_height) = (
@@ -105,6 +109,9 @@ fn extract_windows(mut render_world: ResMut<RenderWorld>, windows: Res<Windows>)
             extracted_window.physical_height = new_height;
         }
     }
+    for closed_window in closed.iter() {
+        extracted_windows.remove(&closed_window.id);
+    }
 }
 
 #[derive(Default)]

crates/bevy_window/Cargo.toml

@@ -10,6 +10,9 @@ keywords = ["bevy"]
 
 [dependencies]
 # bevy
+bevy_ecs = { path = "../bevy_ecs", version = "0.6.0" }
+# Used for close_on_esc
+bevy_input = { path = "../bevy_input", version = "0.6.0" }
 bevy_app = { path = "../bevy_app", version = "0.6.0" }
 bevy_math = { path = "../bevy_math", version = "0.6.0" }
 bevy_utils = { path = "../bevy_utils", version = "0.6.0" }

crates/bevy_window/src/event.rs

@@ -20,12 +20,6 @@ pub struct CreateWindow {
     pub descriptor: WindowDescriptor,
 }
 
-/// An event that indicates a window should be closed.
-#[derive(Debug, Clone)]
-pub struct CloseWindow {
-    pub id: WindowId,
-}
-
 /// An event that is sent whenever a new window is created.
 #[derive(Debug, Clone)]
 pub struct WindowCreated {
@@ -34,11 +28,26 @@ pub struct WindowCreated {
 
 /// An event that is sent whenever a close was requested for a window. For example: when the "close"
 /// button is pressed on a window.
+///
+/// By default, these events are handled by closing the corresponding [`crate::Window`].
+/// To disable this behaviour, set `close_when_requested` on the [`crate::WindowPlugin`] to `false`
 #[derive(Debug, Clone)]
 pub struct WindowCloseRequested {
     pub id: WindowId,
 }
 
+/// An event that is sent whenever a window is closed.
+/// This will only be sent in response to the [`Window::close`] method.
+///
+/// By default, when no windows are open, the app will close.
+/// To disable this behaviour, set `exit_on_all_closed` on the [`crate::WindowPlugin`] to `false`
+///
+/// [`Window::close`]: crate::Window::close
+#[derive(Debug, Clone)]
+pub struct WindowClosed {
+    pub id: WindowId,
+}
+
 #[derive(Debug, Clone)]
 pub struct CursorMoved {
     pub id: WindowId,

crates/bevy_window/src/lib.rs

@@ -24,14 +24,25 @@ use bevy_app::{prelude::*, Events};
 
 pub struct WindowPlugin {
     pub add_primary_window: bool,
-    pub exit_on_close: bool,
+    /// Whether to close the app when there are no open windows.
+    /// If disabling this, consider ensuring that you send a [`bevy_app::AppExit`] event yourself
+    /// when the app should exit; otherwise you will create headless processes, which would be
+    /// surprising for your users.
+    ///
+    /// This setting controls whether this plugin adds [`exit_on_all_closed`]
+    pub exit_on_all_closed: bool,
+    /// Whether to close windows when they are requested to be closed (i.e. when the close button is pressed)
+    ///
+    /// This setting controls whether this plugin adds [`close_when_requested`]
+    pub close_when_requested: bool,
 }
 
 impl Default for WindowPlugin {
     fn default() -> Self {
         WindowPlugin {
             add_primary_window: true,
-            exit_on_close: true,
+            exit_on_all_closed: true,
+            close_when_requested: true,
         }
     }
 }
@@ -41,8 +52,8 @@ impl Plugin for WindowPlugin {
         app.add_event::<WindowResized>()
             .add_event::<CreateWindow>()
             .add_event::<WindowCreated>()
+            .add_event::<WindowClosed>()
             .add_event::<WindowCloseRequested>()
-            .add_event::<CloseWindow>()
             .add_event::<CursorMoved>()
             .add_event::<CursorEntered>()
             .add_event::<CursorLeft>()
@@ -70,8 +81,11 @@ impl Plugin for WindowPlugin {
             });
         }
 
-        if self.exit_on_close {
-            app.add_system(exit_on_window_close_system);
+        if self.exit_on_all_closed {
+            app.add_system(exit_on_all_closed);
+        }
+        if self.close_when_requested {
+            app.add_system(close_when_requested);
         }
     }
 }

crates/bevy_window/src/system.rs

@@ -1,11 +1,55 @@
-use crate::WindowCloseRequested;
+use crate::{Window, WindowCloseRequested, WindowFocused, WindowId, Windows};
 use bevy_app::{AppExit, EventReader, EventWriter};
+use bevy_ecs::prelude::*;
+use bevy_input::{keyboard::KeyCode, Input};
 
-pub fn exit_on_window_close_system(
-    mut app_exit_events: EventWriter<AppExit>,
-    mut window_close_requested_events: EventReader<WindowCloseRequested>,
-) {
-    if window_close_requested_events.iter().next().is_some() {
+/// Whether to exit the application when there are no open windows.
+///
+/// By default, this system is added by the [`crate::WindowPlugin`].
+/// To disable this behaviour, set `close_when_requested` (on the [`crate::WindowPlugin`]) to `false`.
+/// Please ensure that you read the caveats documented on that field.
+
+pub fn exit_on_all_closed(mut app_exit_events: EventWriter<AppExit>, windows: Res<Windows>) {
+    if windows.iter().count() == 0 {
         app_exit_events.send(AppExit);
     }
 }
+
+/// Whether to close windows when they are requested to be closed (i.e. when the close button is pressed).
+/// Not adding this system (without replacement) will lead to the close button having no effect.
+///
+/// By default, this system is added by the [`crate::WindowPlugin`].
+/// To disable this behaviour, set `close_when_requested` (on the [`crate::WindowPlugin`]) to `false`
+pub fn close_when_requested(
+    mut windows: ResMut<Windows>,
+    mut closed: EventReader<WindowCloseRequested>,
+) {
+    for event in closed.iter() {
+        windows.get_mut(event.id).map(Window::close);
+    }
+}
+
+// TODO: Consider using the kbd tag here for escape: <kbd>esc</kbd>
+// Currently, it isn't rendered by vscode's hover markdown provider (and the contents are lost)
+/// Close the focused window whenever the escape key is pressed
+///
+/// This is useful for examples
+pub fn close_on_esc(
+    mut focused: Local<Option<WindowId>>,
+    mut focused_events: EventReader<WindowFocused>,
+    mut windows: ResMut<Windows>,
+    input: Res<Input<KeyCode>>,
+) {
+    // TODO: Track this in e.g. a resource to ensure consistent behaviour across similar systems
+    for event in focused_events.iter() {
+        *focused = event.focused.then(|| event.id);
+    }
+
+    if let Some(focused) = &*focused {
+        if input.just_pressed(KeyCode::Escape) {
+            if let Some(window) = windows.get_mut(*focused) {
+                window.close();
+            }
+        }
+    }
+}

crates/bevy_window/src/window.rs

@@ -219,6 +219,7 @@ pub enum WindowCommand {
     SetResizeConstraints {
         resize_constraints: WindowResizeConstraints,
     },
+    Close,
 }
 
 /// Defines the way a window is displayed
@@ -571,6 +572,10 @@ impl Window {
         });
     }
 
+    pub fn close(&mut self) {
+        self.command_queue.push(WindowCommand::Close);
+    }
+
     #[inline]
     pub fn drain_commands(&mut self) -> impl Iterator<Item = WindowCommand> + '_ {
         self.command_queue.drain(..)

crates/bevy_window/src/windows.rs

@@ -34,4 +34,8 @@ impl Windows {
     pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut Window> {
         self.windows.values_mut()
     }
+
+    pub fn remove(&mut self, id: WindowId) -> Option<Window> {
+        self.windows.remove(&id)
+    }
 }

crates/bevy_winit/src/lib.rs

@@ -13,11 +13,11 @@ pub use winit_windows::*;
 use bevy_app::{App, AppExit, CoreStage, Events, ManualEventReader, Plugin};
 use bevy_ecs::{system::IntoExclusiveSystem, world::World};
 use bevy_math::{ivec2, DVec2, Vec2};
-use bevy_utils::tracing::{error, trace, warn};
+use bevy_utils::tracing::{error, info, trace, warn};
 use bevy_window::{
     CreateWindow, CursorEntered, CursorLeft, CursorMoved, FileDragAndDrop, ReceivedCharacter,
-    WindowBackendScaleFactorChanged, WindowCloseRequested, WindowCreated, WindowFocused,
-    WindowMoved, WindowResized, WindowScaleFactorChanged, Windows,
+    WindowBackendScaleFactorChanged, WindowCloseRequested, WindowClosed, WindowCreated,
+    WindowFocused, WindowMoved, WindowResized, WindowScaleFactorChanged, Windows,
 };
 use winit::{
     dpi::PhysicalPosition,
@@ -43,8 +43,9 @@ impl Plugin for WinitPlugin {
 
 fn change_window(world: &mut World) {
     let world = world.cell();
-    let winit_windows = world.get_resource::<WinitWindows>().unwrap();
+    let mut winit_windows = world.get_resource_mut::<WinitWindows>().unwrap();
     let mut windows = world.get_resource_mut::<Windows>().unwrap();
+    let mut removed_windows = Vec::new();
 
     for bevy_window in windows.iter_mut() {
         let id = bevy_window.id();
@@ -160,9 +161,26 @@ fn change_window(world: &mut World) {
                         window.set_max_inner_size(Some(max_inner_size));
                     }
                 }
+                bevy_window::WindowCommand::Close => {
+                    let window = winit_windows.remove_window(id);
+                    // Close the window
+                    drop(window);
+                    // Since we borrow `windows` here to iterate through them, we can't mutate it here.
+                    // Add it to the queue to solve this
+                    removed_windows.push(id);
+                    // No need to run any further commands - this drops the rest of the commands, although the `bevy_window::Window` will be dropped later anyway
+                    break;
+                }
             }
         }
     }
+    if !removed_windows.is_empty() {
+        let mut events = world.get_resource_mut::<Events<WindowClosed>>().unwrap();
+        for id in removed_windows {
+            windows.remove(id);
+            events.send(WindowClosed { id });
+        }
+    }
 }
 
 fn run<F>(event_loop: EventLoop<()>, event_handler: F) -> !
@@ -280,7 +298,8 @@ pub fn winit_runner_with(mut app: App) {
                 let window = if let Some(window) = windows.get_mut(window_id) {
                     window
                 } else {
-                    warn!("Skipped event for unknown Window Id {:?}", winit_window_id);
+                    // If we're here, this window was previously opened
+                    info!("Skipped event for closed window: {:?}", window_id);
                     return;
                 };
 

crates/bevy_winit/src/winit_windows.rs

@@ -184,6 +184,12 @@ impl WinitWindows {
     pub fn get_window_id(&self, id: winit::window::WindowId) -> Option<WindowId> {
         self.winit_to_window_id.get(&id).cloned()
     }
+
+    pub fn remove_window(&mut self, id: WindowId) -> Option<winit::window::Window> {
+        let winit_id = self.window_id_to_winit.remove(&id)?;
+        // Don't remove from winit_to_window_id, to track that we used to know about this winit window
+        self.windows.remove(&winit_id)
+    }
 }
 
 pub fn get_fitting_videomode(

examples/2d/rotation.rs

@@ -18,7 +18,7 @@ fn main() {
                 .with_system(snap_to_player_system)
                 .with_system(rotate_to_player_system),
         )
-        .add_system(bevy::input::system::exit_on_esc_system)
+        .add_system(bevy::window::close_on_esc)
         .run();
 }
 

examples/game/alien_cake_addict.rs

@@ -1,5 +1,6 @@
 use bevy::{
     core::FixedTimestep, ecs::schedule::SystemSet, prelude::*, render::camera::CameraPlugin,
+    window::close_on_esc,
 };
 use rand::Rng;
 
@@ -33,7 +34,7 @@ fn main() {
                 .with_run_criteria(FixedTimestep::step(5.0))
                 .with_system(spawn_bonus),
         )
-        .add_system(bevy::input::system::exit_on_esc_system)
+        .add_system(close_on_esc)
         .run();
 }
 

examples/game/breakout.rs

@@ -2,6 +2,7 @@ use bevy::{
     core::FixedTimestep,
     prelude::*,
     sprite::collide_aabb::{collide, Collision},
+    window::close_on_esc,
 };
 
 /// An implementation of the classic game "Breakout"
@@ -20,7 +21,7 @@ fn main() {
                 .with_system(ball_movement_system),
         )
         .add_system(scoreboard_system)
-        .add_system(bevy::input::system::exit_on_esc_system)
+        .add_system(close_on_esc)
         .run();
 }