Initialize Window by observer instead of by plugin fields

crates/bevy_window/src/lib.rs

@@ -19,6 +19,7 @@ extern crate alloc;
 
 use alloc::sync::Arc;
 
+use bevy_ecs::system::Commands;
 use bevy_platform::sync::Mutex;
 
 mod event;
@@ -56,8 +57,7 @@ use bevy_app::prelude::*;
 impl Default for WindowPlugin {
     fn default() -> Self {
         WindowPlugin {
-            primary_window: Some(Window::default()),
-            primary_cursor_options: Some(CursorOptions::default()),
+            spawn_primary_window: true,
             exit_condition: ExitCondition::OnAllClosed,
             close_when_requested: true,
         }
@@ -66,23 +66,28 @@ impl Default for WindowPlugin {
 
 /// A [`Plugin`] that defines an interface for windowing support in Bevy.
 pub struct WindowPlugin {
-    /// Settings for the primary window.
+    /// Whether or not to spawn a [`PrimaryWindow`] and its associated required components.
+    /// If you want to customize the primary window when it spawns, you can use an observer:
     ///
-    /// `Some(custom_window)` will spawn an entity with `custom_window` and [`PrimaryWindow`] as components.
-    /// `None` will not spawn a primary window.
+    /// ```
+    /// # use bevy_window::{CursorOptions, PresentMode, PrimaryWindow, Window, PresentMode};
+    /// # use bevy_ecs::prelude::*;
+    /// fn configure_window(
+    ///     trigger: On<Add, PrimaryWindow>,
+    ///     mut window: Query<(&mut CursorOptions, &mut PresentMode)>,
+    /// ) {
+    ///     // This unwrap is guaranteed to succeed because the queried components are required on any [`Window`]
+    ///     let (mut cursor_options, mut present_mode) = window.get_mut(trigger.target()).unwrap();
+    ///     cursor_options.visible = false;
+    ///     present_mode = PresentMode::AutoNoVsync;
+    /// }
+    /// ```
     ///
-    /// Defaults to `Some(Window::default())`.
+    /// Defaults to `true`.
     ///
     /// Note that if there are no windows the App will exit (by default) due to
     /// [`exit_on_all_closed`].
-    pub primary_window: Option<Window>,
-
-    /// Settings for the cursor on the primary window.
-    ///
-    /// Defaults to `Some(CursorOptions::default())`.
-    ///
-    /// Has no effect if [`WindowPlugin::primary_window`] is `None`.
-    pub primary_cursor_options: Option<CursorOptions>,
+    pub spawn_primary_window: bool,
 
     /// Whether to exit the app when there are no open windows.
     ///
@@ -129,15 +134,10 @@ impl Plugin for WindowPlugin {
             .add_event::<WindowThemeChanged>()
             .add_event::<AppLifecycle>();
 
-        if let Some(primary_window) = &self.primary_window {
-            let mut entity_commands = app.world_mut().spawn(primary_window.clone());
-            entity_commands.insert((
-                PrimaryWindow,
-                RawHandleWrapperHolder(Arc::new(Mutex::new(None))),
-            ));
-            if let Some(primary_cursor_options) = &self.primary_cursor_options {
-                entity_commands.insert(primary_cursor_options.clone());
-            }
+        if self.spawn_primary_window {
+            app.add_systems(PreStartup, |mut commands: Commands| {
+                commands.spawn(PrimaryWindow);
+            });
         }
 
         match self.exit_condition {

crates/bevy_window/src/raw_handle.rs

@@ -162,5 +162,5 @@ impl HasDisplayHandle for ThreadLockedRawWindowHandleWrapper {
 }
 
 /// Holder of the [`RawHandleWrapper`] with wrappers, to allow use in asynchronous context
-#[derive(Debug, Clone, Component)]
+#[derive(Debug, Clone, Component, Default)]
 pub struct RawHandleWrapperHolder(pub Arc<Mutex<Option<RawHandleWrapper>>>);

crates/bevy_window/src/window.rs

@@ -20,7 +20,7 @@ use {
 #[cfg(all(feature = "serialize", feature = "bevy_reflect"))]
 use bevy_reflect::{ReflectDeserialize, ReflectSerialize};
 
-use crate::VideoMode;
+use crate::{RawHandleWrapperHolder, VideoMode};
 
 /// Default string used for the window title.
 ///
@@ -53,6 +53,7 @@ static DEFAULT_WINDOW_TITLE: LazyLock<String> = LazyLock::new(|| {
     derive(Reflect),
     reflect(Component, Debug, Default, PartialEq, Clone)
 )]
+#[require(Window, RawHandleWrapperHolder)]
 pub struct PrimaryWindow;
 
 /// Reference to a [`Window`], whether it be a direct link to a specific entity or
@@ -469,8 +470,8 @@ impl Default for Window {
     fn default() -> Self {
         Self {
             title: DEFAULT_WINDOW_TITLE.to_owned(),
+            present_mode: PresentMode::default(),
             name: None,
-            present_mode: Default::default(),
             mode: Default::default(),
             position: Default::default(),
             resolution: Default::default(),

examples/3d/anisotropy.rs

@@ -81,13 +81,7 @@ impl Display for Scene {
 fn main() {
     App::new()
         .init_resource::<AppStatus>()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Anisotropy Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .add_systems(Startup, setup)
         .add_systems(Update, create_material_variants)
         .add_systems(Update, animate_light)

examples/3d/clustered_decals.rs

@@ -122,13 +122,7 @@ impl MaterialExtension for CustomDecalExtension {
 /// Entry point.
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Clustered Decals Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugin)
         .add_plugins(MaterialPlugin::<
             ExtendedMaterial<StandardMaterial, CustomDecalExtension>,
         >::default())

examples/3d/depth_of_field.rs

@@ -52,13 +52,7 @@ struct AppSettings {
 fn main() {
     App::new()
         .init_resource::<AppSettings>()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Depth of Field Example".to_string(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .add_systems(Startup, setup)
         .add_systems(Update, tweak_scene)
         .add_systems(

examples/3d/fog_volumes.rs

@@ -15,13 +15,7 @@ use bevy::{
 /// Entry point.
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Fog Volumes Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .insert_resource(AmbientLight::NONE)
         .add_systems(Startup, setup)
         .add_systems(Update, rotate_camera)

examples/3d/irradiance_volumes.rs

@@ -147,13 +147,7 @@ struct VoxelVisualizationIrradianceVolumeInfo {
 fn main() {
     // Create the example app.
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Irradiance Volumes Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .add_plugins(MaterialPlugin::<VoxelVisualizationMaterial>::default())
         .init_resource::<AppStatus>()
         .init_resource::<ExampleAssets>()

examples/3d/light_textures.rs

@@ -105,13 +105,7 @@ struct HelpText;
 /// Entry point.
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Light Textures Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .init_resource::<AppStatus>()
         .add_event::<WidgetClickEvent<Selection>>()
         .add_event::<WidgetClickEvent<Visibility>>()

examples/3d/mixed_lighting.rs

@@ -116,13 +116,7 @@ const INITIAL_SPHERE_POSITION: Vec3 = vec3(0.0, 0.5233223, 0.0);
 
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Mixed Lighting Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .add_plugins(MeshPickingPlugin)
         .insert_resource(AmbientLight {
             color: ClearColor::default().0,

examples/3d/occlusion_culling.rs

@@ -182,13 +182,6 @@ fn main() {
     App::new()
         .add_plugins(
             DefaultPlugins
-                .set(WindowPlugin {
-                    primary_window: Some(Window {
-                        title: "Bevy Occlusion Culling Example".into(),
-                        ..default()
-                    }),
-                    ..default()
-                })
                 .set(RenderPlugin {
                     debug_flags: render_debug_flags,
                     ..default()

examples/3d/pcss.rs

@@ -113,13 +113,7 @@ enum AppSetting {
 fn main() {
     App::new()
         .init_resource::<AppStatus>()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Percentage Closer Soft Shadows Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .add_event::<WidgetClickEvent<AppSetting>>()
         .add_systems(Startup, setup)
         .add_systems(Update, widgets::handle_ui_interactions::<AppSetting>)

examples/3d/post_processing.rs

@@ -27,13 +27,7 @@ struct AppSettings {
 fn main() {
     App::new()
         .init_resource::<AppSettings>()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Chromatic Aberration Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .add_systems(Startup, setup)
         .add_systems(Update, handle_keyboard_input)
         .add_systems(

examples/3d/scrolling_fog.rs

@@ -24,13 +24,7 @@ use bevy::{
 /// Initializes the example.
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Scrolling Fog".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .insert_resource(DirectionalLightShadowMap { size: 4096 })
         .add_systems(Startup, setup)
         .add_systems(Update, scroll_fog)

examples/3d/specular_tint.rs

@@ -50,13 +50,7 @@ enum TintType {
 /// The entry point.
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Specular Tint Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .init_resource::<AppAssets>()
         .init_resource::<AppStatus>()
         .insert_resource(AmbientLight {

examples/3d/ssr.rs

@@ -101,13 +101,7 @@ fn main() {
     App::new()
         .insert_resource(DefaultOpaqueRendererMethod::deferred())
         .init_resource::<AppSettings>()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Screen Space Reflections Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .add_plugins(MaterialPlugin::<ExtendedMaterial<StandardMaterial, Water>>::default())
         .add_systems(Startup, setup)
         .add_systems(Update, rotate_model)

examples/3d/visibility_range.rs

@@ -71,13 +71,7 @@ struct AppStatus {
 // Sets up the app.
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Visibility Range Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .init_resource::<AppStatus>()
         .add_systems(Startup, setup)
         .add_systems(

examples/animation/animation_graph.rs

@@ -74,13 +74,7 @@ fn main() {
     let args = Args::from_args(&[], &[]).unwrap();
 
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Animation Graph Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .add_systems(Startup, (setup_assets, setup_scene, setup_ui))
         .add_systems(Update, init_animations)
         .add_systems(

examples/animation/animation_masks.rs

@@ -94,13 +94,7 @@ struct MaskGroupState {
 // The application entry point.
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "Bevy Animation Masks Example".into(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .add_systems(Startup, (setup_scene, setup_ui))
         .add_systems(Update, setup_animation_graph_once_loaded)
         .add_systems(Update, handle_button_toggles)

examples/animation/morph_targets.rs

@@ -12,13 +12,7 @@ use std::f32::consts::PI;
 
 fn main() {
     App::new()
-        .add_plugins(DefaultPlugins.set(WindowPlugin {
-            primary_window: Some(Window {
-                title: "morph targets".to_string(),
-                ..default()
-            }),
-            ..default()
-        }))
+        .add_plugins(DefaultPlugins)
         .insert_resource(AmbientLight {
             brightness: 150.0,
             ..default()

examples/app/headless_renderer.rs

@@ -89,7 +89,7 @@ fn main() {
                 // Not strictly necessary, as the inclusion of ScheduleRunnerPlugin below
                 // replaces the bevy_winit app runner and so a window is never created.
                 .set(WindowPlugin {
-                    primary_window: None,
+                    spawn_primary_window: false,
                     // Don’t automatically exit due to having no windows.
                     // Instead, the code in `update()` will explicitly produce an `AppExit` event.
                     exit_condition: bevy::window::ExitCondition::DontExit,