Only run observers in the default run loop mode

Introduced in 3a7350c with unclear motivation.

Nowadays, this feature is incomplete and unsound, and the equivalent
functionality can be trivially achieved outside of `winit` using
`objc2-ui-kit`.

.github/CODEOWNERS

@@ -1,10 +1,11 @@
 # Android
-/src/platform/android.rs            @msiglreith @MarijnS95
-/src/platform_impl/android          @msiglreith @MarijnS95
+/src/platform/android.rs            @MarijnS95
+/src/platform_impl/android          @MarijnS95
 
-# iOS
+# Apple (AppKit + UIKit)
 /src/platform/ios.rs                @madsmtm
-/src/platform_impl/ios              @madsmtm
+/src/platform/macos.rs              @madsmtm
+/src/platform_impl/apple            @madsmtm
 
 # Unix
 /src/platform_impl/linux/mod.rs     @kchibisov
@@ -17,17 +18,13 @@
 /src/platform/x11.rs                @kchibisov @notgull
 /src/platform_impl/linux/x11        @kchibisov @notgull
 
-# macOS
-/src/platform/macos.rs              @madsmtm
-/src/platform_impl/macos            @madsmtm
-
 # Web
 /src/platform/web.rs                @daxpedda
 /src/platform_impl/web              @daxpedda
 
 # Windows
-/src/platform/windows.rs            @msiglreith
-/src/platform_impl/windows          @msiglreith
+/src/platform/windows.rs            @notgull
+/src/platform_impl/windows          @notgull
 
 # Orbital (Redox OS)
 /src/platform/orbital.rs            @jackpot51

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ jobs:
     name: Check formatting
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+    - uses: taiki-e/checkout-action@v1
     - uses: dtolnay/rust-toolchain@nightly
       with:
         components: rustfmt
@@ -22,7 +22,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 30
     steps:
-      - uses: actions/checkout@v4
+      - uses: taiki-e/checkout-action@v1
       - uses: taiki-e/install-action@v2
         with:
           tool: typos-cli
@@ -42,7 +42,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        toolchain: [stable, nightly, '1.70.0']
+        toolchain: [stable, nightly, '1.73']
         platform:
           # Note: Make sure that we test all the `docs.rs` targets defined in Cargo.toml!
           - { name: 'Windows 64bit MSVC', target: x86_64-pc-windows-msvc,   os: windows-latest,  }
@@ -61,10 +61,10 @@ jobs:
           - { name: 'web',                target: wasm32-unknown-unknown,   os: ubuntu-latest,   }
         exclude:
           # Android is tested on stable-3
-          - toolchain: '1.70.0'
+          - toolchain: '1.73'
             platform: { name: 'Android', target: aarch64-linux-android, os: ubuntu-latest, options: '--package=winit --features=android-native-activity', cmd: 'apk --' }
         include:
-          - toolchain: '1.70.0'
+          - toolchain: '1.73'
             platform: { name: 'Android', target: aarch64-linux-android, os: ubuntu-latest, options: '--package=winit --features=android-native-activity', cmd: 'apk --' }
           - toolchain: 'nightly'
             platform: {
@@ -88,7 +88,7 @@ jobs:
       CMD: ${{ matrix.platform.cmd }}
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: taiki-e/checkout-action@v1
 
     - name: Restore cache of cargo folder
       # We use `restore` and later `save`, so that we can create the key after
@@ -149,13 +149,13 @@ jobs:
     - name: Test dpi crate
       if: >
         contains(matrix.platform.name, 'Linux 64bit') &&
-        matrix.toolchain != '1.70.0'
+        matrix.toolchain != '1.73'
       run: cargo test -p dpi
 
     - name: Build tests
       if: >
         !contains(matrix.platform.target, 'redox') &&
-        matrix.toolchain != '1.70.0'
+        matrix.toolchain != '1.73'
       run: cargo $CMD test --no-run $OPTIONS
 
     - name: Run tests
@@ -164,7 +164,7 @@ jobs:
         !contains(matrix.platform.target, 'ios') &&
         !contains(matrix.platform.target, 'wasm32') &&
         !contains(matrix.platform.target, 'redox') &&
-        matrix.toolchain != '1.70.0'
+        matrix.toolchain != '1.73'
       run: cargo $CMD test $OPTIONS
 
     - name: Lint with clippy
@@ -174,7 +174,7 @@ jobs:
     - name: Build tests with serde enabled
       if: >
         !contains(matrix.platform.target, 'redox') &&
-        matrix.toolchain != '1.70.0'
+        matrix.toolchain != '1.73'
       run: cargo $CMD test --no-run $OPTIONS --features serde
 
     - name: Run tests with serde enabled
@@ -183,7 +183,7 @@ jobs:
         !contains(matrix.platform.target, 'ios') &&
         !contains(matrix.platform.target, 'wasm32') &&
         !contains(matrix.platform.target, 'redox') &&
-        matrix.toolchain != '1.70.0'
+        matrix.toolchain != '1.73'
       run: cargo $CMD test $OPTIONS --features serde
 
     - name: Check docs.rs documentation
@@ -220,9 +220,24 @@ jobs:
           - { name: 'Windows', target: x86_64-pc-windows-gnu }
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: taiki-e/checkout-action@v1
     - uses: EmbarkStudios/cargo-deny-action@v1
       with:
         command: check
         log-level: error
         arguments: --all-features --target ${{ matrix.platform.target }}
+
+  swc:
+    name: Minimize JavaScript
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: taiki-e/checkout-action@v1
+      - name: Install SWC
+        run: sudo npm i -g @swc/cli
+      - name: Run SWC
+        run: |
+          swc src/platform_impl/web/web_sys/worker.js -o src/platform_impl/web/web_sys/worker.min.js
+      - name: Check for diff
+        run: |
+          [[ -z $(git status -s) ]]

.gitignore

@@ -3,8 +3,5 @@ target/
 rls/
 .vscode/
 *~
-*.wasm
-*.ts
-*.js
 #*#
 .DS_Store

.swcrc

@@ -0,0 +1,12 @@
+{
+	"minify": true,
+	"jsc": {
+		"target": "es2022",
+		"minify": {
+			"compress": {
+				"unused": true
+			},
+			"mangle": true
+		}
+	}
+}

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "winit"
-version = "0.30.1"
+version = "0.30.3"
 authors = [
     "The winit contributors",
     "Pierre Krieger <pierre.krieger1708@gmail.com>",
@@ -86,11 +86,11 @@ rwh_06 = { package = "raw-window-handle", version = "0.6", features = [
 ], optional = true }
 serde = { workspace = true, optional = true }
 smol_str = "0.2.0"
-tracing = { version = "0.1.40", default_features = false }
+tracing = { version = "0.1.40", default-features = false }
 
 [dev-dependencies]
 image = { version = "0.25.0", default-features = false, features = ["png"] }
-tracing = { version = "0.1.40", default_features = false, features = ["log"] }
+tracing = { version = "0.1.40", default-features = false, features = ["log"] }
 tracing-subscriber = { version = "0.3.18", features = ["env-filter"] }
 winit = { path = ".", features = ["rwh_05"] }
 
@@ -102,21 +102,21 @@ softbuffer = { version = "0.4.0", default-features = false, features = [
     "wayland-dlopen",
 ] }
 
+# Android
 [target.'cfg(target_os = "android")'.dependencies]
 android-activity = "0.6.0"
 ndk = { version = "0.9.0", default-features = false }
 
-[target.'cfg(any(target_os = "ios", target_os = "macos"))'.dependencies]
+# AppKit or UIKit
+[target.'cfg(target_vendor = "apple")'.dependencies]
 core-foundation = "0.9.3"
 objc2 = "0.5.2"
 
+# AppKit
 [target.'cfg(target_os = "macos")'.dependencies]
 core-graphics = "0.23.1"
 block2 = "0.5.1"
-
-[target.'cfg(target_os = "macos")'.dependencies.objc2-foundation]
-version = "0.2.2"
-features = [
+objc2-foundation = { version = "0.2.2", features = [
     "block2",
     "dispatch",
     "NSArray",
@@ -125,6 +125,7 @@ features = [
     "NSDictionary",
     "NSDistributedNotificationCenter",
     "NSEnumerator",
+    "NSKeyValueObserving",
     "NSNotification",
     "NSObjCRuntime",
     "NSPathUtilities",
@@ -133,15 +134,13 @@ features = [
     "NSString",
     "NSThread",
     "NSValue",
-]
-
-[target.'cfg(target_os = "macos")'.dependencies.objc2-app-kit]
-version = "0.2.2"
-features = [
+] }
+objc2-app-kit = { version = "0.2.2", features = [
     "NSAppearance",
     "NSApplication",
     "NSBitmapImageRep",
     "NSButton",
+    "NSColor",
     "NSControl",
     "NSCursor",
     "NSDragging",
@@ -163,11 +162,11 @@ features = [
     "NSWindow",
     "NSWindowScripting",
     "NSWindowTabGroup",
-]
+] }
 
-[target.'cfg(target_os = "ios")'.dependencies.objc2-foundation]
-version = "0.2.2"
-features = [
+# UIKit
+[target.'cfg(all(target_vendor = "apple", not(target_os = "macos")))'.dependencies]
+objc2-foundation = { version = "0.2.2", features = [
     "dispatch",
     "NSArray",
     "NSEnumerator",
@@ -177,11 +176,8 @@ features = [
     "NSProcessInfo",
     "NSThread",
     "NSSet",
-]
-
-[target.'cfg(target_os = "ios")'.dependencies.objc2-ui-kit]
-version = "0.2.2"
-features = [
+] }
+objc2-ui-kit = { version = "0.2.2", features = [
     "UIApplication",
     "UIDevice",
     "UIEvent",
@@ -200,14 +196,12 @@ features = [
     "UIView",
     "UIViewController",
     "UIWindow",
-]
+] }
 
+# Windows
 [target.'cfg(target_os = "windows")'.dependencies]
 unicode-segmentation = "1.7.1"
-
-[target.'cfg(target_os = "windows")'.dependencies.windows-sys]
-version = "0.52.0"
-features = [
+windows-sys = { version = "0.52.0", features = [
     "Win32_Devices_HumanInterfaceDevice",
     "Win32_Foundation",
     "Win32_Globalization",
@@ -232,9 +226,10 @@ features = [
     "Win32_UI_Shell",
     "Win32_UI_TextServices",
     "Win32_UI_WindowsAndMessaging",
-]
+] }
 
-[target.'cfg(all(unix, not(any(target_os = "redox", target_family = "wasm", target_os = "android", target_os = "ios", target_os = "macos"))))'.dependencies]
+# Linux
+[target.'cfg(all(unix, not(any(target_os = "redox", target_family = "wasm", target_os = "android", target_vendor = "apple"))))'.dependencies]
 ahash = { version = "0.8.7", features = ["no-rng"], optional = true }
 bytemuck = { version = "1.13.1", default-features = false, optional = true }
 calloop = "0.12.3"
@@ -250,8 +245,8 @@ rustix = { version = "0.38.4", default-features = false, features = [
 sctk = { package = "smithay-client-toolkit", version = "0.18.0", default-features = false, features = [
     "calloop",
 ], optional = true }
-sctk-adwaita = { version = "0.9.0", default_features = false, optional = true }
-wayland-backend = { version = "0.3.0", default_features = false, features = [
+sctk-adwaita = { version = "0.9.0", default-features = false, optional = true }
+wayland-backend = { version = "0.3.0", default-features = false, features = [
     "client_system",
 ], optional = true }
 wayland-client = { version = "0.31.1", optional = true }
@@ -272,17 +267,18 @@ x11rb = { version = "0.13.0", default-features = false, features = [
 ], optional = true }
 xkbcommon-dl = "0.4.2"
 
+# Orbital
 [target.'cfg(target_os = "redox")'.dependencies]
 orbclient = { version = "0.3.47", default-features = false }
 redox_syscall = "0.4.1"
 
-[target.'cfg(target_family = "wasm")'.dependencies.web_sys]
-package = "web-sys"
-version = "0.3.64"
-features = [
+# Web
+[target.'cfg(target_family = "wasm")'.dependencies]
+web_sys = { package = "web-sys", version = "0.3.64", features = [
     'AbortController',
     'AbortSignal',
     'Blob',
+    'BlobPropertyBag',
     'console',
     'CssStyleDeclaration',
     'Document',
@@ -318,10 +314,9 @@ features = [
     'VisibilityState',
     'Window',
     'WheelEvent',
+    'Worker',
     'Url',
-]
-
-[target.'cfg(target_family = "wasm")'.dependencies]
+] }
 js-sys = "0.3.64"
 pin-project = "1"
 wasm-bindgen = "0.2"
@@ -345,7 +340,7 @@ resolver = "2"
 members = ["dpi"]
 
 [workspace.package]
-rust-version = "1.70.0"
+rust-version = "1.73"
 repository = "https://github.com/rust-windowing/winit"
 license = "Apache-2.0"
 edition = "2021"

FEATURES.md

@@ -154,7 +154,6 @@ If your PR makes notable changes to Winit's features, please update this section
 * Home indicator visibility
 * Status bar visibility and style
 * Deferring system gestures
-* Getting the device idiom
 * Getting the preferred video mode
 
 ### Web

README.md

@@ -8,7 +8,7 @@
 
 ```toml
 [dependencies]
-winit = "0.30.1"
+winit = "0.30.3"
 ```
 
 ## [Documentation](https://docs.rs/winit)
@@ -35,7 +35,7 @@ another library.
 
 ## MSRV Policy
 
-This crate's Minimum Supported Rust Version (MSRV) is **1.70**. Changes to
+This crate's Minimum Supported Rust Version (MSRV) is **1.73**. Changes to
 the MSRV will be accompanied by a minor version bump.
 
 As a **tentative** policy, the upper bound of the MSRV is given by the following

build.rs

@@ -10,10 +10,9 @@ fn main() {
         android_platform: { target_os = "android" },
         web_platform: { all(target_family = "wasm", target_os = "unknown") },
         macos_platform: { target_os = "macos" },
-        ios_platform: { target_os = "ios" },
+        ios_platform: { all(target_vendor = "apple", not(target_os = "macos")) },
         windows_platform: { target_os = "windows" },
-        apple: { any(target_os = "ios", target_os = "macos") },
-        free_unix: { all(unix, not(apple), not(android_platform), not(target_os = "emscripten")) },
+        free_unix: { all(unix, not(target_vendor = "apple"), not(android_platform), not(target_os = "emscripten")) },
         redox: { target_os = "redox" },
 
         // Native displays.

clippy.toml

@@ -12,4 +12,6 @@ disallowed-methods = [
     { path = "web_sys::Document::fullscreen_element", reason = "Doesn't account for compatibility with Safari" },
     { path = "objc2_app_kit::NSView::visibleRect", reason = "We expose a render target to the user, and visibility is not really relevant to that (and can break if you don't use the rectangle position as well). Use `frame` instead." },
     { path = "objc2_app_kit::NSWindow::setFrameTopLeftPoint", reason = "Not sufficient when working with Winit's coordinate system, use `flip_window_screen_coordinates` instead" },
+    { path = "core_foundation::runloop::kCFRunLoopCommonModes", reason = "Using the common modes includes the modal panel mode, which we usually want to avoid" },
+    { path = "objc2_foundation::NSRunLoopCommonModes", reason = "Using the common modes includes the modal panel mode, which we usually want to avoid" }
 ]

examples/child_window.rs

@@ -3,50 +3,45 @@
 fn main() -> Result<(), impl std::error::Error> {
     use std::collections::HashMap;
 
+    use winit::application::ApplicationHandler;
     use winit::dpi::{LogicalPosition, LogicalSize, Position};
-    use winit::event::{ElementState, Event, KeyEvent, WindowEvent};
+    use winit::event::{ElementState, KeyEvent, WindowEvent};
     use winit::event_loop::{ActiveEventLoop, EventLoop};
     use winit::raw_window_handle::HasRawWindowHandle;
-    use winit::window::Window;
+    use winit::window::{Window, WindowId};
 
     #[path = "util/fill.rs"]
     mod fill;
 
-    fn spawn_child_window(parent: &Window, event_loop: &ActiveEventLoop) -> Window {
-        let parent = parent.raw_window_handle().unwrap();
-        let mut window_attributes = Window::default_attributes()
-            .with_title("child window")
-            .with_inner_size(LogicalSize::new(200.0f32, 200.0f32))
-            .with_position(Position::Logical(LogicalPosition::new(0.0, 0.0)))
-            .with_visible(true);
-        // `with_parent_window` is unsafe. Parent window must be a valid window.
-        window_attributes = unsafe { window_attributes.with_parent_window(Some(parent)) };
-
-        event_loop.create_window(window_attributes).unwrap()
+    #[derive(Default)]
+    struct Application {
+        parent_window_id: Option<WindowId>,
+        windows: HashMap<WindowId, Window>,
     }
 
-    let mut windows = HashMap::new();
+    impl ApplicationHandler for Application {
+        fn resumed(&mut self, event_loop: &ActiveEventLoop) {
+            let attributes = Window::default_attributes()
+                .with_title("parent window")
+                .with_position(Position::Logical(LogicalPosition::new(0.0, 0.0)))
+                .with_inner_size(LogicalSize::new(640.0f32, 480.0f32));
+            let window = event_loop.create_window(attributes).unwrap();
 
-    let event_loop: EventLoop<()> = EventLoop::new().unwrap();
-    let mut parent_window_id = None;
+            println!("Parent window id: {:?})", window.id());
+            self.parent_window_id = Some(window.id());
 
-    event_loop.run(move |event: Event<()>, event_loop| {
-        match event {
-            Event::Resumed => {
-                let attributes = Window::default_attributes()
-                    .with_title("parent window")
-                    .with_position(Position::Logical(LogicalPosition::new(0.0, 0.0)))
-                    .with_inner_size(LogicalSize::new(640.0f32, 480.0f32));
-                let window = event_loop.create_window(attributes).unwrap();
+            self.windows.insert(window.id(), window);
+        }
 
-                parent_window_id = Some(window.id());
-
-                println!("Parent window id: {parent_window_id:?})");
-                windows.insert(window.id(), window);
-            },
-            Event::WindowEvent { window_id, event } => match event {
+        fn window_event(
+            &mut self,
+            event_loop: &ActiveEventLoop,
+            window_id: winit::window::WindowId,
+            event: WindowEvent,
+        ) {
+            match event {
                 WindowEvent::CloseRequested => {
-                    windows.clear();
+                    self.windows.clear();
                     event_loop.exit();
                 },
                 WindowEvent::CursorEntered { device_id: _ } => {
@@ -61,22 +56,38 @@ fn main() -> Result<(), impl std::error::Error> {
                     event: KeyEvent { state: ElementState::Pressed, .. },
                     ..
                 } => {
-                    let parent_window = windows.get(&parent_window_id.unwrap()).unwrap();
+                    let parent_window = self.windows.get(&self.parent_window_id.unwrap()).unwrap();
                     let child_window = spawn_child_window(parent_window, event_loop);
                     let child_id = child_window.id();
                     println!("Child window created with id: {child_id:?}");
-                    windows.insert(child_id, child_window);
+                    self.windows.insert(child_id, child_window);
                 },
                 WindowEvent::RedrawRequested => {
-                    if let Some(window) = windows.get(&window_id) {
+                    if let Some(window) = self.windows.get(&window_id) {
                         fill::fill_window(window);
                     }
                 },
                 _ => (),
-            },
-            _ => (),
+            }
         }
-    })
+    }
+
+    fn spawn_child_window(parent: &Window, event_loop: &ActiveEventLoop) -> Window {
+        let parent = parent.raw_window_handle().unwrap();
+        let mut window_attributes = Window::default_attributes()
+            .with_title("child window")
+            .with_inner_size(LogicalSize::new(200.0f32, 200.0f32))
+            .with_position(Position::Logical(LogicalPosition::new(0.0, 0.0)))
+            .with_visible(true);
+        // `with_parent_window` is unsafe. Parent window must be a valid window.
+        window_attributes = unsafe { window_attributes.with_parent_window(Some(parent)) };
+
+        event_loop.create_window(window_attributes).unwrap()
+    }
+
+    let event_loop = EventLoop::new().unwrap();
+    let mut app = Application::default();
+    event_loop.run_app(&mut app)
 }
 
 #[cfg(all(feature = "rwh_06", not(any(x11_platform, macos_platform, windows_platform))))]

examples/window.rs

@@ -44,7 +44,7 @@ fn main() -> Result<(), Box<dyn Error>> {
 
     tracing::init();
 
-    let event_loop = EventLoop::<UserEvent>::with_user_event().build()?;
+    let event_loop = EventLoop::new()?;
     let _event_loop_proxy = event_loop.create_proxy();
 
     // Wire the user event from another thread.
@@ -54,7 +54,7 @@ fn main() -> Result<(), Box<dyn Error>> {
         // from a different thread.
         info!("Starting to send user event every second");
         loop {
-            let _ = _event_loop_proxy.send_event(UserEvent::WakeUp);
+            _event_loop_proxy.wake_up();
             std::thread::sleep(std::time::Duration::from_secs(1));
         }
     });
@@ -64,12 +64,6 @@ fn main() -> Result<(), Box<dyn Error>> {
     event_loop.run_app(&mut state).map_err(Into::into)
 }
 
-#[allow(dead_code)]
-#[derive(Debug, Clone, Copy)]
-enum UserEvent {
-    WakeUp,
-}
-
 /// Application state and event handling.
 struct Application {
     /// Custom cursors assets.
@@ -85,7 +79,7 @@ struct Application {
 }
 
 impl Application {
-    fn new<T>(event_loop: &EventLoop<T>) -> Self {
+    fn new(event_loop: &EventLoop) -> Self {
         // SAFETY: we drop the context right before the event loop is stopped, thus making it safe.
         #[cfg(not(any(android_platform, ios_platform)))]
         let context = Some(
@@ -212,6 +206,12 @@ impl Application {
             Action::PrintHelp => self.print_help(),
             #[cfg(macos_platform)]
             Action::CycleOptionAsAlt => window.cycle_option_as_alt(),
+            Action::SetTheme(theme) => {
+                window.window.set_theme(theme);
+                // Get the resulting current theme to draw with
+                let actual_theme = theme.or_else(|| window.window.theme()).unwrap_or(Theme::Dark);
+                window.set_draw_theme(actual_theme);
+            },
             #[cfg(macos_platform)]
             Action::CreateNewTab => {
                 let tab_id = window.window.tabbing_identifier();
@@ -302,9 +302,9 @@ impl Application {
     }
 }
 
-impl ApplicationHandler<UserEvent> for Application {
-    fn user_event(&mut self, _event_loop: &ActiveEventLoop, event: UserEvent) {
-        info!("User event: {event:?}");
+impl ApplicationHandler for Application {
+    fn proxy_wake_up(&mut self, _event_loop: &ActiveEventLoop) {
+        info!("User wake up");
     }
 
     fn window_event(
@@ -334,7 +334,7 @@ impl ApplicationHandler<UserEvent> for Application {
             },
             WindowEvent::ThemeChanged(theme) => {
                 info!("Theme changed to {theme:?}");
-                window.set_theme(theme);
+                window.set_draw_theme(theme);
             },
             WindowEvent::RedrawRequested => {
                 if let Err(err) = window.draw() {
@@ -733,8 +733,8 @@ impl WindowState {
         self.window.request_redraw();
     }
 
-    /// Change the theme.
-    fn set_theme(&mut self, theme: Theme) {
+    /// Change the theme that things are drawn in.
+    fn set_draw_theme(&mut self, theme: Theme) {
         self.theme = theme;
         self.window.request_redraw();
     }
@@ -884,6 +884,7 @@ enum Action {
     ShowWindowMenu,
     #[cfg(macos_platform)]
     CycleOptionAsAlt,
+    SetTheme(Option<Theme>),
     #[cfg(macos_platform)]
     CreateNewTab,
     RequestResize,
@@ -915,6 +916,9 @@ impl Action {
             Action::ShowWindowMenu => "Show window menu",
             #[cfg(macos_platform)]
             Action::CycleOptionAsAlt => "Cycle option as alt mode",
+            Action::SetTheme(None) => "Change to the system theme",
+            Action::SetTheme(Some(Theme::Light)) => "Change to a light theme",
+            Action::SetTheme(Some(Theme::Dark)) => "Change to a dark theme",
             #[cfg(macos_platform)]
             Action::CreateNewTab => "Create new tab",
             Action::RequestResize => "Request a resize",
@@ -1059,6 +1063,10 @@ const KEY_BINDINGS: &[Binding<&'static str>] = &[
         Action::AnimationCustomCursor,
     ),
     Binding::new("Z", ModifiersState::CONTROL, Action::ToggleCursorVisibility),
+    // K.
+    Binding::new("K", ModifiersState::empty(), Action::SetTheme(None)),
+    Binding::new("K", ModifiersState::SUPER, Action::SetTheme(Some(Theme::Light))),
+    Binding::new("K", ModifiersState::CONTROL, Action::SetTheme(Some(Theme::Dark))),
     #[cfg(macos_platform)]
     Binding::new("T", ModifiersState::SUPER, Action::CreateNewTab),
     #[cfg(macos_platform)]

src/application.rs

@@ -5,7 +5,7 @@ use crate::event_loop::ActiveEventLoop;
 use crate::window::WindowId;
 
 /// The handler of the application events.
-pub trait ApplicationHandler<T: 'static = ()> {
+pub trait ApplicationHandler {
     /// Emitted when new events arrive from the OS to be processed.
     ///
     /// This is a useful place to put code that should be done before you start processing
@@ -82,11 +82,95 @@ pub trait ApplicationHandler<T: 'static = ()> {
     /// [`Suspended`]: Self::suspended
     fn resumed(&mut self, event_loop: &ActiveEventLoop);
 
-    /// Emitted when an event is sent from [`EventLoopProxy::send_event`].
+    /// Called after a wake up is requested using [`EventLoopProxy::wake_up()`].
     ///
-    /// [`EventLoopProxy::send_event`]: crate::event_loop::EventLoopProxy::send_event
-    fn user_event(&mut self, event_loop: &ActiveEventLoop, event: T) {
-        let _ = (event_loop, event);
+    /// Multiple calls to the aforementioned method will be merged, and will only wake the event
+    /// loop once; however, due to the nature of multi-threading some wake ups may appear
+    /// spuriously. For these reasons, you should not rely on the number of times that this was
+    /// called.
+    ///
+    /// The order in which this is emitted in relation to other events is not guaranteed. The time
+    /// at which this will be emitted is not guaranteed, only that it will happen "soon". That is,
+    /// there may be several executions of the event loop, including multiple redraws to windows,
+    /// between [`EventLoopProxy::wake_up()`] being called and the event being delivered.
+    ///
+    /// [`EventLoopProxy::wake_up()`]: crate::event_loop::EventLoopProxy::wake_up
+    ///
+    /// # Example
+    ///
+    /// Use a [`std::sync::mpsc`] channel to handle events from a different thread.
+    ///
+    /// ```no_run
+    /// use std::sync::mpsc;
+    /// use std::thread;
+    /// use std::time::Duration;
+    ///
+    /// use winit::application::ApplicationHandler;
+    /// use winit::event_loop::{ActiveEventLoop, EventLoop};
+    ///
+    /// struct MyApp {
+    ///     receiver: mpsc::Receiver<u64>,
+    /// }
+    ///
+    /// impl ApplicationHandler for MyApp {
+    ///     # fn window_event(
+    ///     #     &mut self,
+    ///     #     _event_loop: &ActiveEventLoop,
+    ///     #     _window_id: winit::window::WindowId,
+    ///     #     _event: winit::event::WindowEvent,
+    ///     # ) {
+    ///     # }
+    ///     #
+    ///     # fn resumed(&mut self, _event_loop: &ActiveEventLoop) {}
+    ///     #
+    ///     fn proxy_wake_up(&mut self, _event_loop: &ActiveEventLoop) {
+    ///         // Iterate current events, since wake-ups may have been merged.
+    ///         //
+    ///         // Note: We take care not to use `recv` or `iter` here, as those are blocking,
+    ///         // and that would be bad for performance and might lead to a deadlock.
+    ///         for i in self.receiver.try_iter() {
+    ///             println!("received: {i}");
+    ///         }
+    ///     }
+    ///
+    ///     // Rest of `ApplicationHandler`
+    /// }
+    ///
+    /// fn main() -> Result<(), Box<dyn std::error::Error>> {
+    ///     let event_loop = EventLoop::new()?;
+    ///
+    ///     let (sender, receiver) = mpsc::channel();
+    ///
+    ///     let mut app = MyApp { receiver };
+    ///
+    ///     // Send an event in a loop
+    ///     let proxy = event_loop.create_proxy();
+    ///     let background_thread = thread::spawn(move || {
+    ///         let mut i = 0;
+    ///         loop {
+    ///             println!("sending: {i}");
+    ///             if sender.send(i).is_err() {
+    ///                 // Stop sending once `MyApp` is dropped
+    ///                 break;
+    ///             }
+    ///             // Trigger the wake-up _after_ we placed the event in the channel.
+    ///             // Otherwise, `proxy_wake_up` might be triggered prematurely.
+    ///             proxy.wake_up();
+    ///             i += 1;
+    ///             thread::sleep(Duration::from_secs(1));
+    ///         }
+    ///     });
+    ///
+    ///     event_loop.run_app(&mut app)?;
+    ///
+    ///     drop(app);
+    ///     background_thread.join().unwrap();
+    ///
+    ///     Ok(())
+    /// }
+    /// ```
+    fn proxy_wake_up(&mut self, event_loop: &ActiveEventLoop) {
+        let _ = event_loop;
     }
 
     /// Emitted when the OS sends an event to a winit window.
@@ -224,7 +308,7 @@ pub trait ApplicationHandler<T: 'static = ()> {
     }
 }
 
-impl<A: ?Sized + ApplicationHandler<T>, T: 'static> ApplicationHandler<T> for &mut A {
+impl<A: ?Sized + ApplicationHandler> ApplicationHandler for &mut A {
     #[inline]
     fn new_events(&mut self, event_loop: &ActiveEventLoop, cause: StartCause) {
         (**self).new_events(event_loop, cause);
@@ -236,8 +320,8 @@ impl<A: ?Sized + ApplicationHandler<T>, T: 'static> ApplicationHandler<T> for &m
     }
 
     #[inline]
-    fn user_event(&mut self, event_loop: &ActiveEventLoop, event: T) {
-        (**self).user_event(event_loop, event);
+    fn proxy_wake_up(&mut self, event_loop: &ActiveEventLoop) {
+        (**self).proxy_wake_up(event_loop);
     }
 
     #[inline]
@@ -281,7 +365,7 @@ impl<A: ?Sized + ApplicationHandler<T>, T: 'static> ApplicationHandler<T> for &m
     }
 }
 
-impl<A: ?Sized + ApplicationHandler<T>, T: 'static> ApplicationHandler<T> for Box<A> {
+impl<A: ?Sized + ApplicationHandler> ApplicationHandler for Box<A> {
     #[inline]
     fn new_events(&mut self, event_loop: &ActiveEventLoop, cause: StartCause) {
         (**self).new_events(event_loop, cause);
@@ -293,8 +377,8 @@ impl<A: ?Sized + ApplicationHandler<T>, T: 'static> ApplicationHandler<T> for Bo
     }
 
     #[inline]
-    fn user_event(&mut self, event_loop: &ActiveEventLoop, event: T) {
-        (**self).user_event(event_loop, event);
+    fn proxy_wake_up(&mut self, event_loop: &ActiveEventLoop) {
+        (**self).proxy_wake_up(event_loop);
     }
 
     #[inline]

src/changelog/unreleased.md

@@ -39,3 +39,27 @@ The migration guide could reference other migration examples in the current
 changelog entry.
 
 ## Unreleased
+
+### Changed
+
+- On Web, let events wake up event loop immediately when using `ControlFlow::Poll`.
+- Bump MSRV from `1.70` to `1.73`.
+- Changed `ApplicationHandler::user_event` to `user_wake_up`, removing the
+  generic user event.
+
+  Winit will now only indicate that wake up happened, you will have to pair
+  this with an external mechanism like `std::sync::mpsc::channel` if you want
+  to send specific data to be processed on the main thread.
+- Changed `EventLoopProxy::send_event` to `EventLoopProxy::wake_up`, it now
+  only wakes up the loop.
+
+### Removed
+
+- Remove `EventLoop::run`.
+- Remove `EventLoopExtRunOnDemand::run_on_demand`.
+- Remove `EventLoopExtPumpEvents::pump_events`.
+- Remove `Event`.
+- On iOS, remove `platform::ios::EventLoopExtIOS` and related `platform::ios::Idiom` type.
+
+  This feature was incomplete, and the equivalent functionality can be trivially achieved outside
+  of `winit` using `objc2-ui-kit` and calling `UIDevice::currentDevice().userInterfaceIdiom()`.

src/changelog/v0.30.md

@@ -1,9 +1,41 @@
+## 0.30.3
+
+### Added
+
+- On Web, add `EventLoopExtWebSys::(set_)poll_strategy()` to allow setting
+  control flow strategies before starting the event loop.
+- On Web, add `WaitUntilStrategy`, which allows to set different strategies for
+  `ControlFlow::WaitUntil`. By default the Prioritized Task Scheduling API is
+  used, with a fallback to `setTimeout()` with a trick to circumvent throttling
+  to 4ms. But an option to use a Web worker to schedule the timer is available
+  as well, which commonly prevents any throttling when the window is not focused.
+
+### Changed
+
+- On macOS, set the window theme on the `NSWindow` instead of application-wide.
+
+### Fixed
+
+- On X11, build on arm platforms.
+- On macOS, fixed `WindowBuilder::with_theme` not having any effect on the window.
+
+## 0.30.2
+
+### Fixed
+
+- On Web, fix `EventLoopProxy::send_event()` triggering event loop immediately
+  when not called from inside the event loop. Now queues a microtask instead.
+- On Web, stop overwriting default cursor with `CursorIcon::Default`.
+- On Web, prevent crash when using `InnerSizeWriter::request_inner_size()`.
+- On macOS, fix not working opacity for entire window.
+
 ## 0.30.1
 
 ### Added
 
 - Reexport `raw-window-handle` versions 0.4 and 0.5 as `raw_window_handle_04` and `raw_window_handle_05`.
 - Implement `ApplicationHandler` for `&mut` references and heap allocations to something that implements `ApplicationHandler`.
+- Add traits `EventLoopExtWayland` and `EventLoopExtX11`, providing methods `is_wayland` and `is_x11` on `EventLoop`.
 
 ### Fixed
 
@@ -80,7 +112,7 @@
   `Fn`. The semantics are mostly the same, given that the capture list of the
   closure is your new `State`. Consider the following code:
 
-  ```rust,no_run
+  ```rust,no_run,ignore
   use winit::event::Event;
   use winit::event_loop::EventLoop;
   use winit::window::Window;
@@ -116,7 +148,7 @@
   we move particular `match event` arms into methods on `ApplicationHandler`,
   for example:
 
-  ```rust,no_run
+  ```rust,no_run,ignore
   use winit::application::ApplicationHandler;
   use winit::event::{Event, WindowEvent, DeviceEvent, DeviceId};
   use winit::event_loop::{EventLoop, ActiveEventLoop};
@@ -179,7 +211,7 @@
 
   Using the migration example from above, you can change your code as follows:
 
-  ```rust,no_run
+  ```rust,no_run,ignore
   use winit::application::ApplicationHandler;
   use winit::event::{Event, WindowEvent, DeviceEvent, DeviceId};
   use winit::event_loop::{EventLoop, ActiveEventLoop};

src/event.rs

@@ -1,4 +1,4 @@
-//! The [`Event`] enum and assorted supporting types.
+//! The event enums and assorted supporting types.
 //!
 //! These are sent to the closure given to [`EventLoop::run_app(...)`], where they get
 //! processed and used to modify the program state. For more details, see the root-level
@@ -54,11 +54,15 @@ use crate::platform_impl;
 use crate::window::Window;
 use crate::window::{ActivationToken, Theme, WindowId};
 
+// TODO: Remove once the backends can call `ApplicationHandler` methods directly. For now backends
+// like Windows and Web require `Event` to wire user events, otherwise each backend will have to
+// wrap `Event` in some other structure.
 /// Describes a generic event.
 ///
 /// See the module-level docs for more information on the event loop manages each event.
+#[allow(dead_code)]
 #[derive(Debug, Clone, PartialEq)]
-pub enum Event<T: 'static> {
+pub(crate) enum Event {
     /// See [`ApplicationHandler::new_events`] for details.
     ///
     /// [`ApplicationHandler::new_events`]: crate::application::ApplicationHandler::new_events
@@ -67,18 +71,15 @@ pub enum Event<T: 'static> {
     /// See [`ApplicationHandler::window_event`] for details.
     ///
     /// [`ApplicationHandler::window_event`]: crate::application::ApplicationHandler::window_event
+    #[allow(clippy::enum_variant_names)]
     WindowEvent { window_id: WindowId, event: WindowEvent },
 
     /// See [`ApplicationHandler::device_event`] for details.
     ///
     /// [`ApplicationHandler::device_event`]: crate::application::ApplicationHandler::device_event
+    #[allow(clippy::enum_variant_names)]
     DeviceEvent { device_id: DeviceId, event: DeviceEvent },
 
-    /// See [`ApplicationHandler::user_event`] for details.
-    ///
-    /// [`ApplicationHandler::user_event`]: crate::application::ApplicationHandler::user_event
-    UserEvent(T),
-
     /// See [`ApplicationHandler::suspended`] for details.
     ///
     /// [`ApplicationHandler::suspended`]: crate::application::ApplicationHandler::suspended
@@ -103,24 +104,9 @@ pub enum Event<T: 'static> {
     ///
     /// [`ApplicationHandler::memory_warning`]: crate::application::ApplicationHandler::memory_warning
     MemoryWarning,
-}
 
-impl<T> Event<T> {
-    #[allow(clippy::result_large_err)]
-    pub fn map_nonuser_event<U>(self) -> Result<Event<U>, Event<T>> {
-        use self::Event::*;
-        match self {
-            UserEvent(_) => Err(self),
-            WindowEvent { window_id, event } => Ok(WindowEvent { window_id, event }),
-            DeviceEvent { device_id, event } => Ok(DeviceEvent { device_id, event }),
-            NewEvents(cause) => Ok(NewEvents(cause)),
-            AboutToWait => Ok(AboutToWait),
-            LoopExiting => Ok(LoopExiting),
-            Suspended => Ok(Suspended),
-            Resumed => Ok(Resumed),
-            MemoryWarning => Ok(MemoryWarning),
-        }
-    }
+    /// User requested a wake up.
+    UserWakeUp,
 }
 
 /// Describes the reason the event loop is resuming.
@@ -389,6 +375,8 @@ pub enum WindowEvent {
     /// Applications might wish to react to this to change the theme of the content of the window
     /// when the system changes the window theme.
     ///
+    /// This only reports a change if the window theme was not overridden by [`Window::set_theme`].
+    ///
     /// ## Platform-specific
     ///
     /// - **iOS / Android / X11 / Wayland / Orbital:** Unsupported.
@@ -1030,7 +1018,6 @@ mod tests {
 
                 // Mainline events.
                 let wid = unsafe { WindowId::dummy() };
-                x(UserEvent(()));
                 x(NewEvents(event::StartCause::Init));
                 x(AboutToWait);
                 x(LoopExiting);
@@ -1114,25 +1101,12 @@ mod tests {
     #[allow(clippy::redundant_clone)]
     #[test]
     fn test_event_clone() {
-        foreach_event!(|event: event::Event<()>| {
+        foreach_event!(|event: event::Event| {
             let event2 = event.clone();
             assert_eq!(event, event2);
         })
     }
 
-    #[test]
-    fn test_map_nonuser_event() {
-        foreach_event!(|event: event::Event<()>| {
-            let is_user = matches!(event, event::Event::UserEvent(()));
-            let event2 = event.map_nonuser_event::<()>();
-            if is_user {
-                assert_eq!(event2, Err(event::Event::UserEvent(())));
-            } else {
-                assert!(event2.is_ok());
-            }
-        })
-    }
-
     #[test]
     fn test_force_normalize() {
         let force = event::Force::Normalized(0.0);
@@ -1153,7 +1127,7 @@ mod tests {
     #[allow(clippy::clone_on_copy)]
     #[test]
     fn ensure_attrs_do_not_panic() {
-        foreach_event!(|event: event::Event<()>| {
+        foreach_event!(|event: event::Event| {
             let _ = format!("{:?}", event);
         });
         let _ = event::StartCause::Init.clone();

src/event_loop.rs

@@ -3,15 +3,16 @@
 //!
 //! If you want to send custom events to the event loop, use
 //! [`EventLoop::create_proxy`] to acquire an [`EventLoopProxy`] and call its
-//! [`send_event`][EventLoopProxy::send_event] method.
+//! [`wake_up`][EventLoopProxy::wake_up] method. Then during handling the wake up
+//! you can poll your event sources.
 //!
 //! See the root-level documentation for information on how to create and use an event loop to
 //! handle events.
+use std::fmt;
 use std::marker::PhantomData;
 #[cfg(any(x11_platform, wayland_platform))]
 use std::os::unix::io::{AsFd, AsRawFd, BorrowedFd, RawFd};
 use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
-use std::{error, fmt};
 
 #[cfg(not(web_platform))]
 use std::time::{Duration, Instant};
@@ -20,7 +21,6 @@ use web_time::{Duration, Instant};
 
 use crate::application::ApplicationHandler;
 use crate::error::{EventLoopError, OsError};
-use crate::event::Event;
 use crate::monitor::MonitorHandle;
 use crate::platform_impl;
 use crate::window::{CustomCursor, CustomCursorSource, Window, WindowAttributes};
@@ -40,8 +40,8 @@ use crate::window::{CustomCursor, CustomCursorSource, Window, WindowAttributes};
 /// [`EventLoopProxy`] allows you to wake up an `EventLoop` from another thread.
 ///
 /// [`Window`]: crate::window::Window
-pub struct EventLoop<T: 'static> {
-    pub(crate) event_loop: platform_impl::EventLoop<T>,
+pub struct EventLoop {
+    pub(crate) event_loop: platform_impl::EventLoop,
     pub(crate) _marker: PhantomData<*mut ()>, // Not Send nor Sync
 }
 
@@ -59,16 +59,15 @@ pub struct ActiveEventLoop {
 /// This is used to make specifying options that affect the whole application
 /// easier. But note that constructing multiple event loops is not supported.
 ///
-/// This can be created using [`EventLoop::new`] or [`EventLoop::with_user_event`].
+/// This can be created using [`EventLoop::builder`].
 #[derive(Default)]
-pub struct EventLoopBuilder<T: 'static> {
+pub struct EventLoopBuilder {
     pub(crate) platform_specific: platform_impl::PlatformSpecificEventLoopAttributes,
-    _p: PhantomData<T>,
 }
 
 static EVENT_LOOP_CREATED: AtomicBool = AtomicBool::new(false);
 
-impl EventLoopBuilder<()> {
+impl EventLoopBuilder {
     /// Start building a new event loop.
     #[inline]
     #[deprecated = "use `EventLoop::builder` instead"]
@@ -77,7 +76,7 @@ impl EventLoopBuilder<()> {
     }
 }
 
-impl<T> EventLoopBuilder<T> {
+impl EventLoopBuilder {
     /// Builds a new event loop.
     ///
     /// ***For cross-platform compatibility, the [`EventLoop`] must be created on the main thread,
@@ -112,7 +111,7 @@ impl<T> EventLoopBuilder<T> {
         doc = "[`.with_android_app(app)`]: #only-available-on-android"
     )]
     #[inline]
-    pub fn build(&mut self) -> Result<EventLoop<T>, EventLoopError> {
+    pub fn build(&mut self) -> Result<EventLoop, EventLoopError> {
         let _span = tracing::debug_span!("winit::EventLoopBuilder::build").entered();
 
         if EVENT_LOOP_CREATED.swap(true, Ordering::Relaxed) {
@@ -133,7 +132,7 @@ impl<T> EventLoopBuilder<T> {
     }
 }
 
-impl<T> fmt::Debug for EventLoop<T> {
+impl fmt::Debug for EventLoop {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.pad("EventLoop { .. }")
     }
@@ -147,11 +146,12 @@ impl fmt::Debug for ActiveEventLoop {
 
 /// Set through [`ActiveEventLoop::set_control_flow()`].
 ///
-/// Indicates the desired behavior of the event loop after [`Event::AboutToWait`] is emitted.
+/// Indicates the desired behavior of the event loop after [`about_to_wait`] is called.
 ///
 /// Defaults to [`Wait`].
 ///
 /// [`Wait`]: Self::Wait
+/// [`about_to_wait`]: crate::application::ApplicationHandler::about_to_wait
 #[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
 pub enum ControlFlow {
     /// When the current loop iteration finishes, immediately begin a new iteration regardless of
@@ -189,12 +189,12 @@ impl ControlFlow {
     }
 }
 
-impl EventLoop<()> {
+impl EventLoop {
     /// Create the event loop.
     ///
     /// This is an alias of `EventLoop::builder().build()`.
     #[inline]
-    pub fn new() -> Result<EventLoop<()>, EventLoopError> {
+    pub fn new() -> Result<EventLoop, EventLoopError> {
         Self::builder().build()
     }
 
@@ -204,33 +204,12 @@ impl EventLoop<()> {
     ///
     /// To get the actual event loop, call [`build`][EventLoopBuilder::build] on that.
     #[inline]
-    pub fn builder() -> EventLoopBuilder<()> {
-        Self::with_user_event()
+    pub fn builder() -> EventLoopBuilder {
+        EventLoopBuilder { platform_specific: Default::default() }
     }
 }
 
-impl<T> EventLoop<T> {
-    /// Start building a new event loop, with the given type as the user event
-    /// type.
-    pub fn with_user_event() -> EventLoopBuilder<T> {
-        EventLoopBuilder { platform_specific: Default::default(), _p: PhantomData }
-    }
-
-    /// See [`run_app`].
-    ///
-    /// [`run_app`]: Self::run_app
-    #[inline]
-    #[deprecated = "use `EventLoop::run_app` instead"]
-    #[cfg(not(all(web_platform, target_feature = "exception-handling")))]
-    pub fn run<F>(self, event_handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(Event<T>, &ActiveEventLoop),
-    {
-        let _span = tracing::debug_span!("winit::EventLoop::run").entered();
-
-        self.event_loop.run(event_handler)
-    }
-
+impl EventLoop {
     /// Run the application with the event loop on the calling thread.
     ///
     /// See the [`set_control_flow()`] docs on how to change the event loop's behavior.
@@ -261,13 +240,13 @@ impl<T> EventLoop<T> {
     /// [^1]: `EventLoopExtWebSys::spawn_app()` is only available on Web.
     #[inline]
     #[cfg(not(all(web_platform, target_feature = "exception-handling")))]
-    pub fn run_app<A: ApplicationHandler<T>>(self, app: &mut A) -> Result<(), EventLoopError> {
-        self.event_loop.run(|event, event_loop| dispatch_event_for_app(app, event_loop, event))
+    pub fn run_app<A: ApplicationHandler>(self, app: &mut A) -> Result<(), EventLoopError> {
+        self.event_loop.run_app(app)
     }
 
     /// Creates an [`EventLoopProxy`] that can be used to dispatch user events
     /// to the main event loop, possibly from another thread.
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
+    pub fn create_proxy(&self) -> EventLoopProxy {
         EventLoopProxy { event_loop_proxy: self.event_loop.create_proxy() }
     }
 
@@ -323,14 +302,14 @@ impl<T> EventLoop<T> {
 }
 
 #[cfg(feature = "rwh_06")]
-impl<T> rwh_06::HasDisplayHandle for EventLoop<T> {
+impl rwh_06::HasDisplayHandle for EventLoop {
     fn display_handle(&self) -> Result<rwh_06::DisplayHandle<'_>, rwh_06::HandleError> {
         rwh_06::HasDisplayHandle::display_handle(self.event_loop.window_target())
     }
 }
 
 #[cfg(feature = "rwh_05")]
-unsafe impl<T> rwh_05::HasRawDisplayHandle for EventLoop<T> {
+unsafe impl rwh_05::HasRawDisplayHandle for EventLoop {
     /// Returns a [`rwh_05::RawDisplayHandle`] for the event loop.
     fn raw_display_handle(&self) -> rwh_05::RawDisplayHandle {
         rwh_05::HasRawDisplayHandle::raw_display_handle(self.event_loop.window_target())
@@ -338,7 +317,7 @@ unsafe impl<T> rwh_05::HasRawDisplayHandle for EventLoop<T> {
 }
 
 #[cfg(any(x11_platform, wayland_platform))]
-impl<T> AsFd for EventLoop<T> {
+impl AsFd for EventLoop {
     /// Get the underlying [EventLoop]'s `fd` which you can register
     /// into other event loop, like [`calloop`] or [`mio`]. When doing so, the
     /// loop must be polled with the [`pump_app_events`] API.
@@ -352,7 +331,7 @@ impl<T> AsFd for EventLoop<T> {
 }
 
 #[cfg(any(x11_platform, wayland_platform))]
-impl<T> AsRawFd for EventLoop<T> {
+impl AsRawFd for EventLoop {
     /// Get the underlying [EventLoop]'s raw `fd` which you can register
     /// into other event loop, like [`calloop`] or [`mio`]. When doing so, the
     /// loop must be polled with the [`pump_app_events`] API.
@@ -449,7 +428,7 @@ impl ActiveEventLoop {
 
     /// This exits the event loop.
     ///
-    /// See [`LoopExiting`][Event::LoopExiting].
+    /// See [`exiting`][crate::application::ApplicationHandler::exiting].
     pub fn exit(&self) {
         let _span = tracing::debug_span!("winit::ActiveEventLoop::exit",).entered();
 
@@ -534,53 +513,39 @@ unsafe impl rwh_05::HasRawDisplayHandle for OwnedDisplayHandle {
     }
 }
 
-/// Used to send custom events to [`EventLoop`].
-pub struct EventLoopProxy<T: 'static> {
-    event_loop_proxy: platform_impl::EventLoopProxy<T>,
+/// Control the [`EventLoop`], possibly from a different thread, without referencing it directly.
+#[derive(Clone)]
+pub struct EventLoopProxy {
+    event_loop_proxy: platform_impl::EventLoopProxy,
 }
 
-impl<T: 'static> Clone for EventLoopProxy<T> {
-    fn clone(&self) -> Self {
-        Self { event_loop_proxy: self.event_loop_proxy.clone() }
+impl EventLoopProxy {
+    /// Wake up the [`EventLoop`], resulting in [`ApplicationHandler::proxy_wake_up()`] being
+    /// called.
+    ///
+    /// Calls to this method are coalesced into a single call to [`proxy_wake_up`], see the
+    /// documentation on that for details.
+    ///
+    /// If the event loop is no longer running, this is a no-op.
+    ///
+    /// [`proxy_wake_up`]: ApplicationHandler::proxy_wake_up
+    ///
+    /// # Platform-specific
+    ///
+    /// - **Windows**: The wake-up may be ignored under high contention, see [#3687].
+    ///
+    /// [#3687]: https://github.com/rust-windowing/winit/pull/3687
+    pub fn wake_up(&self) {
+        self.event_loop_proxy.wake_up();
     }
 }
 
-impl<T: 'static> EventLoopProxy<T> {
-    /// Send an event to the [`EventLoop`] from which this proxy was created. This emits a
-    /// `UserEvent(event)` event in the event loop, where `event` is the value passed to this
-    /// function.
-    ///
-    /// Returns an `Err` if the associated [`EventLoop`] no longer exists.
-    ///
-    /// [`UserEvent(event)`]: Event::UserEvent
-    pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
-        let _span = tracing::debug_span!("winit::EventLoopProxy::send_event",).entered();
-
-        self.event_loop_proxy.send_event(event)
-    }
-}
-
-impl<T: 'static> fmt::Debug for EventLoopProxy<T> {
+impl fmt::Debug for EventLoopProxy {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.pad("EventLoopProxy { .. }")
     }
 }
 
-/// The error that is returned when an [`EventLoopProxy`] attempts to wake up an [`EventLoop`] that
-/// no longer exists.
-///
-/// Contains the original event given to [`EventLoopProxy::send_event`].
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
-pub struct EventLoopClosed<T>(pub T);
-
-impl<T> fmt::Display for EventLoopClosed<T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.write_str("Tried to wake up a closed `EventLoop`")
-    }
-}
-
-impl<T: fmt::Debug> error::Error for EventLoopClosed<T> {}
-
 /// Control when device events are captured.
 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Default)]
 pub enum DeviceEvents {
@@ -618,23 +583,3 @@ impl AsyncRequestSerial {
         Self { serial }
     }
 }
-
-/// Shim for various run APIs.
-#[inline(always)]
-pub(crate) fn dispatch_event_for_app<T: 'static, A: ApplicationHandler<T>>(
-    app: &mut A,
-    event_loop: &ActiveEventLoop,
-    event: Event<T>,
-) {
-    match event {
-        Event::NewEvents(cause) => app.new_events(event_loop, cause),
-        Event::WindowEvent { window_id, event } => app.window_event(event_loop, window_id, event),
-        Event::DeviceEvent { device_id, event } => app.device_event(event_loop, device_id, event),
-        Event::UserEvent(event) => app.user_event(event_loop, event),
-        Event::Suspended => app.suspended(event_loop),
-        Event::Resumed => app.resumed(event_loop),
-        Event::AboutToWait => app.about_to_wait(event_loop),
-        Event::LoopExiting => app.exiting(event_loop),
-        Event::MemoryWarning => app.memory_warning(event_loop),
-    }
-}

src/lib.rs

@@ -19,12 +19,11 @@
 //! window or a key getting pressed while the window is focused. Devices can generate
 //! [`DeviceEvent`]s, which contain unfiltered event data that isn't specific to a certain window.
 //! Some user activity, like mouse movement, can generate both a [`WindowEvent`] *and* a
-//! [`DeviceEvent`]. You can also create and handle your own custom [`Event::UserEvent`]s, if
-//! desired.
+//! [`DeviceEvent`].
 //!
 //! You can retrieve events by calling [`EventLoop::run_app()`]. This function will
 //! dispatch events for every [`Window`] that was created with that particular [`EventLoop`], and
-//! will run until [`exit()`] is used, at which point [`Event::LoopExiting`].
+//! will run until [`exit()`] is used, at which point [`exiting()`] is called.
 //!
 //! Winit no longer uses a `EventLoop::poll_events() -> impl Iterator<Event>`-based event loop
 //! model, since that can't be implemented properly on some platforms (e.g web, iOS) and works
@@ -163,7 +162,7 @@
 //! [`WindowEvent`]: event::WindowEvent
 //! [`DeviceEvent`]: event::DeviceEvent
 //! [`Event::UserEvent`]: event::Event::UserEvent
-//! [`Event::LoopExiting`]: event::Event::LoopExiting
+//! [`exiting()`]: crate::application::ApplicationHandler::exiting
 //! [`raw_window_handle`]: ./window/struct.Window.html#method.raw_window_handle
 //! [`raw_display_handle`]: ./window/struct.Window.html#method.raw_display_handle
 //! [^1]: `EventLoopExtPumpEvents::pump_app_events()` is only available on Windows, macOS, Android, X11 and Wayland.

src/platform/android.rs

@@ -62,7 +62,7 @@
 //! If your application is currently based on `NativeActivity` via the `ndk-glue` crate and building
 //! with `cargo apk`, then the minimal changes would be:
 //! 1. Remove `ndk-glue` from your `Cargo.toml`
-//! 2. Enable the `"android-native-activity"` feature for Winit: `winit = { version = "0.30.1",
+//! 2. Enable the `"android-native-activity"` feature for Winit: `winit = { version = "0.30.3",
 //!    features = [ "android-native-activity" ] }`
 //! 3. Add an `android_main` entrypoint (as above), instead of using the '`[ndk_glue::main]` proc
 //!    macro from `ndk-macros` (optionally add a dependency on `android_logger` and initialize
@@ -78,7 +78,7 @@ use self::activity::{AndroidApp, ConfigurationRef, Rect};
 /// Additional methods on [`EventLoop`] that are specific to Android.
 pub trait EventLoopExtAndroid {}
 
-impl<T> EventLoopExtAndroid for EventLoop<T> {}
+impl EventLoopExtAndroid for EventLoop {}
 
 /// Additional methods on [`ActiveEventLoop`] that are specific to Android.
 pub trait ActiveEventLoopExtAndroid {}
@@ -119,7 +119,7 @@ pub trait EventLoopBuilderExtAndroid {
     fn handle_volume_keys(&mut self) -> &mut Self;
 }
 
-impl<T> EventLoopBuilderExtAndroid for EventLoopBuilder<T> {
+impl EventLoopBuilderExtAndroid for EventLoopBuilder {
     fn with_android_app(&mut self, app: AndroidApp) -> &mut Self {
         self.platform_specific.android_app = Some(app);
         self

src/platform/ios.rs

@@ -66,22 +66,9 @@
 
 use std::os::raw::c_void;
 
-use crate::event_loop::EventLoop;
 use crate::monitor::{MonitorHandle, VideoModeHandle};
 use crate::window::{Window, WindowAttributes};
 
-/// Additional methods on [`EventLoop`] that are specific to iOS.
-pub trait EventLoopExtIOS {
-    /// Returns the [`Idiom`] (phone/tablet/tv/etc) for the current device.
-    fn idiom(&self) -> Idiom;
-}
-
-impl<T: 'static> EventLoopExtIOS for EventLoop<T> {
-    fn idiom(&self) -> Idiom {
-        self.event_loop.idiom()
-    }
-}
-
 /// Additional methods on [`Window`] that are specific to iOS.
 pub trait WindowExtIOS {
     /// Sets the [`contentScaleFactor`] of the underlying [`UIWindow`] to `scale_factor`.
@@ -379,24 +366,6 @@ pub enum ValidOrientations {
     Portrait,
 }
 
-/// The device [idiom].
-///
-/// [idiom]: https://developer.apple.com/documentation/uikit/uidevice/1620037-userinterfaceidiom?language=objc
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub enum Idiom {
-    Unspecified,
-
-    /// iPhone and iPod touch.
-    Phone,
-
-    /// iPad.
-    Pad,
-
-    /// tvOS and Apple TV.
-    TV,
-    CarPlay,
-}
-
 bitflags::bitflags! {
     /// The [edges] of a screen.
     ///

src/platform/macos.rs

@@ -338,7 +338,7 @@ pub trait EventLoopBuilderExtMacOS {
     fn with_activate_ignoring_other_apps(&mut self, ignore: bool) -> &mut Self;
 }
 
-impl<T> EventLoopBuilderExtMacOS for EventLoopBuilder<T> {
+impl EventLoopBuilderExtMacOS for EventLoopBuilder {
     #[inline]
     fn with_activation_policy(&mut self, activation_policy: ActivationPolicy) -> &mut Self {
         self.platform_specific.activation_policy = activation_policy;

src/platform/pump_events.rs

@@ -1,14 +1,10 @@
 use std::time::Duration;
 
 use crate::application::ApplicationHandler;
-use crate::event::Event;
-use crate::event_loop::{self, ActiveEventLoop, EventLoop};
+use crate::event_loop::EventLoop;
 
 /// Additional methods on [`EventLoop`] for pumping events within an external event loop
 pub trait EventLoopExtPumpEvents {
-    /// A type provided by the user that can be passed through [`Event::UserEvent`].
-    type UserEvent: 'static;
-
     /// Pump the `EventLoop` to check for and dispatch pending events.
     ///
     /// This API is designed to enable applications to integrate Winit into an
@@ -103,34 +99,20 @@ pub trait EventLoopExtPumpEvents {
     ///   If you render outside of Winit you are likely to see window resizing artifacts
     ///   since MacOS expects applications to render synchronously during any `drawRect`
     ///   callback.
-    fn pump_app_events<A: ApplicationHandler<Self::UserEvent>>(
+    fn pump_app_events<A: ApplicationHandler>(
+        &mut self,
+        timeout: Option<Duration>,
+        app: &mut A,
+    ) -> PumpStatus;
+}
+
+impl EventLoopExtPumpEvents for EventLoop {
+    fn pump_app_events<A: ApplicationHandler>(
         &mut self,
         timeout: Option<Duration>,
         app: &mut A,
     ) -> PumpStatus {
-        #[allow(deprecated)]
-        self.pump_events(timeout, |event, event_loop| {
-            event_loop::dispatch_event_for_app(app, event_loop, event)
-        })
-    }
-
-    /// See [`pump_app_events`].
-    ///
-    /// [`pump_app_events`]: Self::pump_app_events
-    #[deprecated = "use EventLoopExtPumpEvents::pump_app_events"]
-    fn pump_events<F>(&mut self, timeout: Option<Duration>, event_handler: F) -> PumpStatus
-    where
-        F: FnMut(Event<Self::UserEvent>, &ActiveEventLoop);
-}
-
-impl<T> EventLoopExtPumpEvents for EventLoop<T> {
-    type UserEvent = T;
-
-    fn pump_events<F>(&mut self, timeout: Option<Duration>, event_handler: F) -> PumpStatus
-    where
-        F: FnMut(Event<Self::UserEvent>, &ActiveEventLoop),
-    {
-        self.event_loop.pump_events(timeout, event_handler)
+        self.event_loop.pump_app_events(timeout, app)
     }
 }
 

src/platform/run_on_demand.rs

@@ -1,24 +1,12 @@
 use crate::application::ApplicationHandler;
 use crate::error::EventLoopError;
-use crate::event::Event;
-use crate::event_loop::{self, ActiveEventLoop, EventLoop};
+use crate::event_loop::{ActiveEventLoop, EventLoop};
 
 #[cfg(doc)]
 use crate::{platform::pump_events::EventLoopExtPumpEvents, window::Window};
 
 /// Additional methods on [`EventLoop`] to return control flow to the caller.
 pub trait EventLoopExtRunOnDemand {
-    /// A type provided by the user that can be passed through [`Event::UserEvent`].
-    type UserEvent: 'static;
-
-    /// See [`run_app_on_demand`].
-    ///
-    /// [`run_app_on_demand`]: Self::run_app_on_demand
-    #[deprecated = "use EventLoopExtRunOnDemand::run_app_on_demand"]
-    fn run_on_demand<F>(&mut self, event_handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(Event<Self::UserEvent>, &ActiveEventLoop);
-
     /// Run the application with the event loop on the calling thread.
     ///
     /// Unlike [`EventLoop::run_app`], this function accepts non-`'static` (i.e. non-`move`)
@@ -65,26 +53,19 @@ pub trait EventLoopExtRunOnDemand {
     ///
     /// [`exit()`]: ActiveEventLoop::exit()
     /// [`set_control_flow()`]: ActiveEventLoop::set_control_flow()
-    fn run_app_on_demand<A: ApplicationHandler<Self::UserEvent>>(
+    fn run_app_on_demand<A: ApplicationHandler>(
+        &mut self,
+        app: &mut A,
+    ) -> Result<(), EventLoopError>;
+}
+
+impl EventLoopExtRunOnDemand for EventLoop {
+    fn run_app_on_demand<A: ApplicationHandler>(
         &mut self,
         app: &mut A,
     ) -> Result<(), EventLoopError> {
-        #[allow(deprecated)]
-        self.run_on_demand(|event, event_loop| {
-            event_loop::dispatch_event_for_app(app, event_loop, event)
-        })
-    }
-}
-
-impl<T> EventLoopExtRunOnDemand for EventLoop<T> {
-    type UserEvent = T;
-
-    fn run_on_demand<F>(&mut self, event_handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(Event<Self::UserEvent>, &ActiveEventLoop),
-    {
         self.event_loop.window_target().clear_exit();
-        self.event_loop.run_on_demand(event_handler)
+        self.event_loop.run_app_on_demand(app)
     }
 }
 

src/platform/wayland.rs

@@ -38,7 +38,7 @@ pub trait EventLoopExtWayland {
     fn is_wayland(&self) -> bool;
 }
 
-impl<T: 'static> EventLoopExtWayland for EventLoop<T> {
+impl EventLoopExtWayland for EventLoop {
     #[inline]
     fn is_wayland(&self) -> bool {
         self.event_loop.is_wayland()
@@ -57,7 +57,7 @@ pub trait EventLoopBuilderExtWayland {
     fn with_any_thread(&mut self, any_thread: bool) -> &mut Self;
 }
 
-impl<T> EventLoopBuilderExtWayland for EventLoopBuilder<T> {
+impl EventLoopBuilderExtWayland for EventLoopBuilder {
     #[inline]
     fn with_wayland(&mut self) -> &mut Self {
         self.platform_specific.forced_backend = Some(crate::platform_impl::Backend::Wayland);

src/platform/web.rs

@@ -55,8 +55,7 @@ use web_sys::HtmlCanvasElement;
 
 use crate::application::ApplicationHandler;
 use crate::cursor::CustomCursorSource;
-use crate::event::Event;
-use crate::event_loop::{self, ActiveEventLoop, EventLoop};
+use crate::event_loop::{ActiveEventLoop, EventLoop};
 #[cfg(web_platform)]
 use crate::platform_impl::CustomCursorFuture as PlatformCustomCursorFuture;
 use crate::platform_impl::PlatformCustomCursorSource;
@@ -156,9 +155,6 @@ impl WindowAttributesExtWebSys for WindowAttributes {
 
 /// Additional methods on `EventLoop` that are specific to the web.
 pub trait EventLoopExtWebSys {
-    /// A type provided by the user that can be passed through `Event::UserEvent`.
-    type UserEvent: 'static;
-
     /// Initializes the winit event loop.
     ///
     /// Unlike
@@ -181,31 +177,56 @@ pub trait EventLoopExtWebSys {
         doc = "[`run_app()`]: EventLoop::run_app()"
     )]
     /// [^1]: `run_app()` is _not_ available on WASM when the target supports `exception-handling`.
-    fn spawn_app<A: ApplicationHandler<Self::UserEvent> + 'static>(self, app: A);
+    fn spawn_app<A: ApplicationHandler + 'static>(self, app: A);
 
-    /// See [`spawn_app`].
+    /// Sets the strategy for [`ControlFlow::Poll`].
     ///
-    /// [`spawn_app`]: Self::spawn_app
-    #[deprecated = "use EventLoopExtWebSys::spawn_app"]
-    fn spawn<F>(self, event_handler: F)
-    where
-        F: 'static + FnMut(Event<Self::UserEvent>, &ActiveEventLoop);
+    /// See [`PollStrategy`].
+    ///
+    /// [`ControlFlow::Poll`]: crate::event_loop::ControlFlow::Poll
+    fn set_poll_strategy(&self, strategy: PollStrategy);
+
+    /// Gets the strategy for [`ControlFlow::Poll`].
+    ///
+    /// See [`PollStrategy`].
+    ///
+    /// [`ControlFlow::Poll`]: crate::event_loop::ControlFlow::Poll
+    fn poll_strategy(&self) -> PollStrategy;
+
+    /// Sets the strategy for [`ControlFlow::WaitUntil`].
+    ///
+    /// See [`WaitUntilStrategy`].
+    ///
+    /// [`ControlFlow::WaitUntil`]: crate::event_loop::ControlFlow::WaitUntil
+    fn set_wait_until_strategy(&self, strategy: WaitUntilStrategy);
+
+    /// Gets the strategy for [`ControlFlow::WaitUntil`].
+    ///
+    /// See [`WaitUntilStrategy`].
+    ///
+    /// [`ControlFlow::WaitUntil`]: crate::event_loop::ControlFlow::WaitUntil
+    fn wait_until_strategy(&self) -> WaitUntilStrategy;
 }
 
-impl<T> EventLoopExtWebSys for EventLoop<T> {
-    type UserEvent = T;
-
-    fn spawn_app<A: ApplicationHandler<Self::UserEvent> + 'static>(self, mut app: A) {
-        self.event_loop.spawn(move |event, event_loop| {
-            event_loop::dispatch_event_for_app(&mut app, event_loop, event)
-        });
+impl EventLoopExtWebSys for EventLoop {
+    fn spawn_app<A: ApplicationHandler + 'static>(self, app: A) {
+        self.event_loop.spawn_app(app);
     }
 
-    fn spawn<F>(self, event_handler: F)
-    where
-        F: 'static + FnMut(Event<Self::UserEvent>, &ActiveEventLoop),
-    {
-        self.event_loop.spawn(event_handler)
+    fn set_poll_strategy(&self, strategy: PollStrategy) {
+        self.event_loop.set_poll_strategy(strategy);
+    }
+
+    fn poll_strategy(&self) -> PollStrategy {
+        self.event_loop.poll_strategy()
+    }
+
+    fn set_wait_until_strategy(&self, strategy: WaitUntilStrategy) {
+        self.event_loop.set_wait_until_strategy(strategy);
+    }
+
+    fn wait_until_strategy(&self) -> WaitUntilStrategy {
+        self.event_loop.wait_until_strategy()
     }
 }
 
@@ -224,6 +245,20 @@ pub trait ActiveEventLoopExtWebSys {
     /// [`ControlFlow::Poll`]: crate::event_loop::ControlFlow::Poll
     fn poll_strategy(&self) -> PollStrategy;
 
+    /// Sets the strategy for [`ControlFlow::WaitUntil`].
+    ///
+    /// See [`WaitUntilStrategy`].
+    ///
+    /// [`ControlFlow::WaitUntil`]: crate::event_loop::ControlFlow::WaitUntil
+    fn set_wait_until_strategy(&self, strategy: WaitUntilStrategy);
+
+    /// Gets the strategy for [`ControlFlow::WaitUntil`].
+    ///
+    /// See [`WaitUntilStrategy`].
+    ///
+    /// [`ControlFlow::WaitUntil`]: crate::event_loop::ControlFlow::WaitUntil
+    fn wait_until_strategy(&self) -> WaitUntilStrategy;
+
     /// Async version of [`ActiveEventLoop::create_custom_cursor()`] which waits until the
     /// cursor has completely finished loading.
     fn create_custom_cursor_async(&self, source: CustomCursorSource) -> CustomCursorFuture;
@@ -244,6 +279,16 @@ impl ActiveEventLoopExtWebSys for ActiveEventLoop {
     fn poll_strategy(&self) -> PollStrategy {
         self.p.poll_strategy()
     }
+
+    #[inline]
+    fn set_wait_until_strategy(&self, strategy: WaitUntilStrategy) {
+        self.p.set_wait_until_strategy(strategy);
+    }
+
+    #[inline]
+    fn wait_until_strategy(&self) -> WaitUntilStrategy {
+        self.p.wait_until_strategy()
+    }
 }
 
 /// Strategy used for [`ControlFlow::Poll`][crate::event_loop::ControlFlow::Poll].
@@ -272,6 +317,29 @@ pub enum PollStrategy {
     Scheduler,
 }
 
+/// Strategy used for [`ControlFlow::WaitUntil`][crate::event_loop::ControlFlow::WaitUntil].
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub enum WaitUntilStrategy {
+    /// Uses the [Prioritized Task Scheduling API] to queue the next event loop. If not available
+    /// this will fallback to [`setTimeout()`].
+    ///
+    /// This strategy is commonly not affected by browser throttling unless the window is not
+    /// focused.
+    ///
+    /// This is the default strategy.
+    ///
+    /// [Prioritized Task Scheduling API]: https://developer.mozilla.org/en-US/docs/Web/API/Prioritized_Task_Scheduling_API
+    /// [`setTimeout()`]: https://developer.mozilla.org/en-US/docs/Web/API/setTimeout
+    #[default]
+    Scheduler,
+    /// Equal to [`Scheduler`][Self::Scheduler] but wakes up the event loop from a [worker].
+    ///
+    /// This strategy is commonly not affected by browser throttling regardless of window focus.
+    ///
+    /// [worker]: https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API
+    Worker,
+}
+
 pub trait CustomCursorExtWebSys {
     /// Returns if this cursor is an animation.
     fn is_animation(&self) -> bool;

src/platform/windows.rs

@@ -227,7 +227,7 @@ pub trait EventLoopBuilderExtWindows {
         F: FnMut(*const c_void) -> bool + 'static;
 }
 
-impl<T> EventLoopBuilderExtWindows for EventLoopBuilder<T> {
+impl EventLoopBuilderExtWindows for EventLoopBuilder {
     #[inline]
     fn with_any_thread(&mut self, any_thread: bool) -> &mut Self {
         self.platform_specific.any_thread = any_thread;

src/platform/x11.rs

@@ -105,7 +105,7 @@ pub trait EventLoopExtX11 {
     fn is_x11(&self) -> bool;
 }
 
-impl<T: 'static> EventLoopExtX11 for EventLoop<T> {
+impl EventLoopExtX11 for EventLoop {
     #[inline]
     fn is_x11(&self) -> bool {
         !self.event_loop.is_wayland()
@@ -124,7 +124,7 @@ pub trait EventLoopBuilderExtX11 {
     fn with_any_thread(&mut self, any_thread: bool) -> &mut Self;
 }
 
-impl<T> EventLoopBuilderExtX11 for EventLoopBuilder<T> {
+impl EventLoopBuilderExtX11 for EventLoopBuilder {
     #[inline]
     fn with_x11(&mut self) -> &mut Self {
         self.platform_specific.forced_backend = Some(crate::platform_impl::Backend::X);

src/platform_impl/android/mod.rs

@@ -1,11 +1,9 @@
-#![cfg(android_platform)]
-
 use std::cell::Cell;
 use std::collections::VecDeque;
 use std::hash::Hash;
 use std::marker::PhantomData;
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::{mpsc, Arc, Mutex};
+use std::sync::{Arc, Mutex};
 use std::time::{Duration, Instant};
 
 use android_activity::input::{InputEvent, KeyAction, Keycode, MotionAction};
@@ -14,12 +12,13 @@ use android_activity::{
 };
 use tracing::{debug, trace, warn};
 
+use crate::application::ApplicationHandler;
 use crate::cursor::Cursor;
 use crate::dpi::{PhysicalPosition, PhysicalSize, Position, Size};
 use crate::error;
 use crate::error::EventLoopError;
 use crate::event::{self, Force, InnerSizeWriter, StartCause};
-use crate::event_loop::{self, ActiveEventLoop as RootAEL, ControlFlow, DeviceEvents};
+use crate::event_loop::{self, ControlFlow, DeviceEvents};
 use crate::platform::pump_events::PumpStatus;
 use crate::platform_impl::Fullscreen;
 use crate::window::{
@@ -43,41 +42,6 @@ fn min_timeout(a: Option<Duration>, b: Option<Duration>) -> Option<Duration> {
     a.map_or(b, |a_timeout| b.map_or(Some(a_timeout), |b_timeout| Some(a_timeout.min(b_timeout))))
 }
 
-struct PeekableReceiver<T> {
-    recv: mpsc::Receiver<T>,
-    first: Option<T>,
-}
-
-impl<T> PeekableReceiver<T> {
-    pub fn from_recv(recv: mpsc::Receiver<T>) -> Self {
-        Self { recv, first: None }
-    }
-
-    pub fn has_incoming(&mut self) -> bool {
-        if self.first.is_some() {
-            return true;
-        }
-        match self.recv.try_recv() {
-            Ok(v) => {
-                self.first = Some(v);
-                true
-            },
-            Err(mpsc::TryRecvError::Empty) => false,
-            Err(mpsc::TryRecvError::Disconnected) => {
-                warn!("Channel was disconnected when checking incoming");
-                false
-            },
-        }
-    }
-
-    pub fn try_recv(&mut self) -> Result<T, mpsc::TryRecvError> {
-        if let Some(first) = self.first.take() {
-            return Ok(first);
-        }
-        self.recv.try_recv()
-    }
-}
-
 #[derive(Clone)]
 struct SharedFlagSetter {
     flag: Arc<AtomicBool>,
@@ -133,13 +97,12 @@ impl RedrawRequester {
 #[derive(Debug, Clone, Eq, PartialEq, Hash)]
 pub struct KeyEventExtra {}
 
-pub struct EventLoop<T: 'static> {
+pub struct EventLoop {
     android_app: AndroidApp,
     window_target: event_loop::ActiveEventLoop,
     redraw_flag: SharedFlag,
-    user_events_sender: mpsc::Sender<T>,
-    user_events_receiver: PeekableReceiver<T>, // must wake looper whenever something gets sent
-    loop_running: bool,                        // Dispatched `NewEvents<Init>`
+    proxy_wake_up: Arc<AtomicBool>,
+    loop_running: bool, // Dispatched `NewEvents<Init>`
     running: bool,
     pending_redraw: bool,
     cause: StartCause,
@@ -159,11 +122,11 @@ impl Default for PlatformSpecificEventLoopAttributes {
     }
 }
 
-impl<T: 'static> EventLoop<T> {
+impl EventLoop {
     pub(crate) fn new(
         attributes: &PlatformSpecificEventLoopAttributes,
     ) -> Result<Self, EventLoopError> {
-        let (user_events_sender, user_events_receiver) = mpsc::channel();
+        let proxy_wake_up = Arc::new(AtomicBool::new(false));
 
         let android_app = attributes.android_app.as_ref().expect(
             "An `AndroidApp` as passed to android_main() is required to create an `EventLoop` on \
@@ -186,8 +149,7 @@ impl<T: 'static> EventLoop<T> {
                 _marker: PhantomData,
             },
             redraw_flag,
-            user_events_sender,
-            user_events_receiver: PeekableReceiver::from_recv(user_events_receiver),
+            proxy_wake_up,
             loop_running: false,
             running: false,
             pending_redraw: false,
@@ -197,27 +159,28 @@ impl<T: 'static> EventLoop<T> {
         })
     }
 
-    fn single_iteration<F>(&mut self, main_event: Option<MainEvent<'_>>, callback: &mut F)
-    where
-        F: FnMut(event::Event<T>, &RootAEL),
-    {
+    fn single_iteration<A: ApplicationHandler>(
+        &mut self,
+        main_event: Option<MainEvent<'_>>,
+        app: &mut A,
+    ) {
         trace!("Mainloop iteration");
 
         let cause = self.cause;
         let mut pending_redraw = self.pending_redraw;
         let mut resized = false;
 
-        callback(event::Event::NewEvents(cause), self.window_target());
+        app.new_events(self.window_target(), cause);
 
         if let Some(event) = main_event {
             trace!("Handling main event {:?}", event);
 
             match event {
                 MainEvent::InitWindow { .. } => {
-                    callback(event::Event::Resumed, self.window_target());
+                    app.resumed(self.window_target());
                 },
                 MainEvent::TerminateWindow { .. } => {
-                    callback(event::Event::Suspended, self.window_target());
+                    app.suspended(self.window_target());
                 },
                 MainEvent::WindowResized { .. } => resized = true,
                 MainEvent::RedrawNeeded { .. } => pending_redraw = true,
@@ -226,23 +189,15 @@ impl<T: 'static> EventLoop<T> {
                 },
                 MainEvent::GainedFocus => {
                     HAS_FOCUS.store(true, Ordering::Relaxed);
-                    callback(
-                        event::Event::WindowEvent {
-                            window_id: window::WindowId(WindowId),
-                            event: event::WindowEvent::Focused(true),
-                        },
-                        self.window_target(),
-                    );
+                    let window_id = window::WindowId(WindowId);
+                    let event = event::WindowEvent::Focused(true);
+                    app.window_event(self.window_target(), window_id, event);
                 },
                 MainEvent::LostFocus => {
                     HAS_FOCUS.store(false, Ordering::Relaxed);
-                    callback(
-                        event::Event::WindowEvent {
-                            window_id: window::WindowId(WindowId),
-                            event: event::WindowEvent::Focused(false),
-                        },
-                        self.window_target(),
-                    );
+                    let window_id = window::WindowId(WindowId);
+                    let event = event::WindowEvent::Focused(false);
+                    app.window_event(self.window_target(), window_id, event);
                 },
                 MainEvent::ConfigChanged { .. } => {
                     let monitor = MonitorHandle::new(self.android_app.clone());
@@ -252,20 +207,19 @@ impl<T: 'static> EventLoop<T> {
                         let new_inner_size = Arc::new(Mutex::new(
                             MonitorHandle::new(self.android_app.clone()).size(),
                         ));
-                        let event = event::Event::WindowEvent {
-                            window_id: window::WindowId(WindowId),
-                            event: event::WindowEvent::ScaleFactorChanged {
-                                inner_size_writer: InnerSizeWriter::new(Arc::downgrade(
-                                    &new_inner_size,
-                                )),
-                                scale_factor,
-                            },
+                        let window_id = window::WindowId(WindowId);
+                        let event = event::WindowEvent::ScaleFactorChanged {
+                            inner_size_writer: InnerSizeWriter::new(Arc::downgrade(
+                                &new_inner_size,
+                            )),
+                            scale_factor,
                         };
-                        callback(event, self.window_target());
+
+                        app.window_event(self.window_target(), window_id, event);
                     }
                 },
                 MainEvent::LowMemory => {
-                    callback(event::Event::MemoryWarning, self.window_target());
+                    app.memory_warning(self.window_target());
                 },
                 MainEvent::Start => {
                     // XXX: how to forward this state to applications?
@@ -313,7 +267,7 @@ impl<T: 'static> EventLoop<T> {
         match android_app.input_events_iter() {
             Ok(mut input_iter) => loop {
                 let read_event =
-                    input_iter.next(|event| self.handle_input_event(&android_app, event, callback));
+                    input_iter.next(|event| self.handle_input_event(&android_app, event, app));
 
                 if !read_event {
                     break;
@@ -324,11 +278,8 @@ impl<T: 'static> EventLoop<T> {
             },
         }
 
-        // Empty the user event buffer
-        {
-            while let Ok(event) = self.user_events_receiver.try_recv() {
-                callback(crate::event::Event::UserEvent(event), self.window_target());
-            }
+        if self.proxy_wake_up.swap(false, Ordering::Relaxed) {
+            app.proxy_wake_up(self.window_target());
         }
 
         if self.running {
@@ -340,39 +291,32 @@ impl<T: 'static> EventLoop<T> {
                 } else {
                     PhysicalSize::new(0, 0)
                 };
-                let event = event::Event::WindowEvent {
-                    window_id: window::WindowId(WindowId),
-                    event: event::WindowEvent::Resized(size),
-                };
-                callback(event, self.window_target());
+                let window_id = window::WindowId(WindowId);
+                let event = event::WindowEvent::Resized(size);
+                app.window_event(self.window_target(), window_id, event);
             }
 
             pending_redraw |= self.redraw_flag.get_and_reset();
             if pending_redraw {
                 pending_redraw = false;
-                let event = event::Event::WindowEvent {
-                    window_id: window::WindowId(WindowId),
-                    event: event::WindowEvent::RedrawRequested,
-                };
-                callback(event, self.window_target());
+                let window_id = window::WindowId(WindowId);
+                let event = event::WindowEvent::RedrawRequested;
+                app.window_event(self.window_target(), window_id, event);
             }
         }
 
         // This is always the last event we dispatch before poll again
-        callback(event::Event::AboutToWait, self.window_target());
+        app.about_to_wait(self.window_target());
 
         self.pending_redraw = pending_redraw;
     }
 
-    fn handle_input_event<F>(
+    fn handle_input_event<A: ApplicationHandler>(
         &mut self,
         android_app: &AndroidApp,
         event: &InputEvent<'_>,
-        callback: &mut F,
-    ) -> InputStatus
-    where
-        F: FnMut(event::Event<T>, &RootAEL),
-    {
+        app: &mut A,
+    ) -> InputStatus {
         let mut input_status = InputStatus::Handled;
         match event {
             InputEvent::MotionEvent(motion_event) => {
@@ -410,17 +354,16 @@ impl<T: 'static> EventLoop<T> {
                             "Input event {device_id:?}, {phase:?}, loc={location:?}, \
                              pointer={pointer:?}"
                         );
-                        let event = event::Event::WindowEvent {
-                            window_id,
-                            event: event::WindowEvent::Touch(event::Touch {
-                                device_id,
-                                phase,
-                                location,
-                                id: pointer.pointer_id() as u64,
-                                force: Some(Force::Normalized(pointer.pressure() as f64)),
-                            }),
-                        };
-                        callback(event, self.window_target());
+
+                        let event = event::WindowEvent::Touch(event::Touch {
+                            device_id,
+                            phase,
+                            location,
+                            id: pointer.pointer_id() as u64,
+                            force: Some(Force::Normalized(pointer.pressure() as f64)),
+                        });
+
+                        app.window_event(self.window_target(), window_id, event);
                     }
                 }
             },
@@ -448,23 +391,22 @@ impl<T: 'static> EventLoop<T> {
                             &mut self.combining_accent,
                         );
 
-                        let event = event::Event::WindowEvent {
-                            window_id: window::WindowId(WindowId),
-                            event: event::WindowEvent::KeyboardInput {
-                                device_id: event::DeviceId(DeviceId(key.device_id())),
-                                event: event::KeyEvent {
-                                    state,
-                                    physical_key: keycodes::to_physical_key(keycode),
-                                    logical_key: keycodes::to_logical(key_char, keycode),
-                                    location: keycodes::to_location(keycode),
-                                    repeat: key.repeat_count() > 0,
-                                    text: None,
-                                    platform_specific: KeyEventExtra {},
-                                },
-                                is_synthetic: false,
+                        let window_id = window::WindowId(WindowId);
+                        let event = event::WindowEvent::KeyboardInput {
+                            device_id: event::DeviceId(DeviceId(key.device_id())),
+                            event: event::KeyEvent {
+                                state,
+                                physical_key: keycodes::to_physical_key(keycode),
+                                logical_key: keycodes::to_logical(key_char, keycode),
+                                location: keycodes::to_location(keycode),
+                                repeat: key.repeat_count() > 0,
+                                text: None,
+                                platform_specific: KeyEventExtra {},
                             },
+                            is_synthetic: false,
                         };
-                        callback(event, self.window_target());
+
+                        app.window_event(self.window_target(), window_id, event);
                     },
                 }
             },
@@ -476,19 +418,16 @@ impl<T: 'static> EventLoop<T> {
         input_status
     }
 
-    pub fn run<F>(mut self, event_handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(event::Event<T>, &event_loop::ActiveEventLoop),
-    {
-        self.run_on_demand(event_handler)
+    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+        self.run_app_on_demand(app)
     }
 
-    pub fn run_on_demand<F>(&mut self, mut event_handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(event::Event<T>, &event_loop::ActiveEventLoop),
-    {
+    pub fn run_app_on_demand<A: ApplicationHandler>(
+        &mut self,
+        app: &mut A,
+    ) -> Result<(), EventLoopError> {
         loop {
-            match self.pump_events(None, &mut event_handler) {
+            match self.pump_app_events(None, app) {
                 PumpStatus::Exit(0) => {
                     break Ok(());
                 },
@@ -502,10 +441,11 @@ impl<T: 'static> EventLoop<T> {
         }
     }
 
-    pub fn pump_events<F>(&mut self, timeout: Option<Duration>, mut callback: F) -> PumpStatus
-    where
-        F: FnMut(event::Event<T>, &RootAEL),
-    {
+    pub fn pump_app_events<A: ApplicationHandler>(
+        &mut self,
+        timeout: Option<Duration>,
+        app: &mut A,
+    ) -> PumpStatus {
         if !self.loop_running {
             self.loop_running = true;
 
@@ -516,18 +456,18 @@ impl<T: 'static> EventLoop<T> {
             self.cause = StartCause::Init;
 
             // run the initial loop iteration
-            self.single_iteration(None, &mut callback);
+            self.single_iteration(None, app);
         }
 
         // Consider the possibility that the `StartCause::Init` iteration could
         // request to Exit
         if !self.exiting() {
-            self.poll_events_with_timeout(timeout, &mut callback);
+            self.poll_events_with_timeout(timeout, app);
         }
         if self.exiting() {
             self.loop_running = false;
 
-            callback(event::Event::LoopExiting, self.window_target());
+            app.exiting(self.window_target());
 
             PumpStatus::Exit(0)
         } else {
@@ -535,32 +475,34 @@ impl<T: 'static> EventLoop<T> {
         }
     }
 
-    fn poll_events_with_timeout<F>(&mut self, mut timeout: Option<Duration>, mut callback: F)
-    where
-        F: FnMut(event::Event<T>, &RootAEL),
-    {
+    fn poll_events_with_timeout<A: ApplicationHandler>(
+        &mut self,
+        mut timeout: Option<Duration>,
+        app: &mut A,
+    ) {
         let start = Instant::now();
 
         self.pending_redraw |= self.redraw_flag.get_and_reset();
 
-        timeout =
-            if self.running && (self.pending_redraw || self.user_events_receiver.has_incoming()) {
-                // If we already have work to do then we don't want to block on the next poll
-                Some(Duration::ZERO)
-            } else {
-                let control_flow_timeout = match self.control_flow() {
-                    ControlFlow::Wait => None,
-                    ControlFlow::Poll => Some(Duration::ZERO),
-                    ControlFlow::WaitUntil(wait_deadline) => {
-                        Some(wait_deadline.saturating_duration_since(start))
-                    },
-                };
-
-                min_timeout(control_flow_timeout, timeout)
+        timeout = if self.running
+            && (self.pending_redraw || self.proxy_wake_up.load(Ordering::Relaxed))
+        {
+            // If we already have work to do then we don't want to block on the next poll
+            Some(Duration::ZERO)
+        } else {
+            let control_flow_timeout = match self.control_flow() {
+                ControlFlow::Wait => None,
+                ControlFlow::Poll => Some(Duration::ZERO),
+                ControlFlow::WaitUntil(wait_deadline) => {
+                    Some(wait_deadline.saturating_duration_since(start))
+                },
             };
 
-        let app = self.android_app.clone(); // Don't borrow self as part of poll expression
-        app.poll_events(timeout, |poll_event| {
+            min_timeout(control_flow_timeout, timeout)
+        };
+
+        let android_app = self.android_app.clone(); // Don't borrow self as part of poll expression
+        android_app.poll_events(timeout, |poll_event| {
             let mut main_event = None;
 
             match poll_event {
@@ -575,7 +517,7 @@ impl<T: 'static> EventLoop<T> {
                     // We also ignore wake ups while suspended.
                     self.pending_redraw |= self.redraw_flag.get_and_reset();
                     if !self.running
-                        || (!self.pending_redraw && !self.user_events_receiver.has_incoming())
+                        || (!self.pending_redraw && !self.proxy_wake_up.load(Ordering::Relaxed))
                     {
                         return;
                     }
@@ -601,7 +543,7 @@ impl<T: 'static> EventLoop<T> {
                 },
             };
 
-            self.single_iteration(main_event, &mut callback);
+            self.single_iteration(main_event, app);
         });
     }
 
@@ -609,9 +551,9 @@ impl<T: 'static> EventLoop<T> {
         &self.window_target
     }
 
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
+    pub fn create_proxy(&self) -> EventLoopProxy {
         EventLoopProxy {
-            user_events_sender: self.user_events_sender.clone(),
+            proxy_wake_up: self.proxy_wake_up.clone(),
             waker: self.android_app.create_waker(),
         }
     }
@@ -625,25 +567,16 @@ impl<T: 'static> EventLoop<T> {
     }
 }
 
-pub struct EventLoopProxy<T: 'static> {
-    user_events_sender: mpsc::Sender<T>,
+#[derive(Clone)]
+pub struct EventLoopProxy {
+    proxy_wake_up: Arc<AtomicBool>,
     waker: AndroidAppWaker,
 }
 
-impl<T: 'static> Clone for EventLoopProxy<T> {
-    fn clone(&self) -> Self {
-        EventLoopProxy {
-            user_events_sender: self.user_events_sender.clone(),
-            waker: self.waker.clone(),
-        }
-    }
-}
-
-impl<T> EventLoopProxy<T> {
-    pub fn send_event(&self, event: T) -> Result<(), event_loop::EventLoopClosed<T>> {
-        self.user_events_sender.send(event).map_err(|err| event_loop::EventLoopClosed(err.0))?;
+impl EventLoopProxy {
+    pub fn wake_up(&self) {
+        self.proxy_wake_up.store(true, Ordering::Relaxed);
         self.waker.wake();
-        Ok(())
     }
 }
 

src/platform_impl/apple/appkit/app.rs

@@ -5,6 +5,7 @@ use objc2_app_kit::{NSApplication, NSEvent, NSEventModifierFlags, NSEventType, N
 use objc2_foundation::{MainThreadMarker, NSObject};
 
 use super::app_state::ApplicationDelegate;
+use super::DEVICE_ID;
 use crate::event::{DeviceEvent, ElementState};
 
 declare_class!(
@@ -57,29 +58,47 @@ fn maybe_dispatch_device_event(delegate: &ApplicationDelegate, event: &NSEvent)
             let delta_y = unsafe { event.deltaY() } as f64;
 
             if delta_x != 0.0 {
-                delegate.maybe_queue_device_event(DeviceEvent::Motion { axis: 0, value: delta_x });
+                delegate.maybe_queue_with_handler(move |app, event_loop| {
+                    app.device_event(event_loop, DEVICE_ID, DeviceEvent::Motion {
+                        axis: 0,
+                        value: delta_x,
+                    });
+                });
             }
 
             if delta_y != 0.0 {
-                delegate.maybe_queue_device_event(DeviceEvent::Motion { axis: 1, value: delta_y })
+                delegate.maybe_queue_with_handler(move |app, event_loop| {
+                    app.device_event(event_loop, DEVICE_ID, DeviceEvent::Motion {
+                        axis: 1,
+                        value: delta_y,
+                    });
+                })
             }
 
             if delta_x != 0.0 || delta_y != 0.0 {
-                delegate.maybe_queue_device_event(DeviceEvent::MouseMotion {
-                    delta: (delta_x, delta_y),
+                delegate.maybe_queue_with_handler(move |app, event_loop| {
+                    app.device_event(event_loop, DEVICE_ID, DeviceEvent::MouseMotion {
+                        delta: (delta_x, delta_y),
+                    });
                 });
             }
         },
         NSEventType::LeftMouseDown | NSEventType::RightMouseDown | NSEventType::OtherMouseDown => {
-            delegate.maybe_queue_device_event(DeviceEvent::Button {
-                button: unsafe { event.buttonNumber() } as u32,
-                state: ElementState::Pressed,
+            let button = unsafe { event.buttonNumber() } as u32;
+            delegate.maybe_queue_with_handler(move |app, event_loop| {
+                app.device_event(event_loop, DEVICE_ID, DeviceEvent::Button {
+                    button,
+                    state: ElementState::Pressed,
+                });
             });
         },
         NSEventType::LeftMouseUp | NSEventType::RightMouseUp | NSEventType::OtherMouseUp => {
-            delegate.maybe_queue_device_event(DeviceEvent::Button {
-                button: unsafe { event.buttonNumber() } as u32,
-                state: ElementState::Released,
+            let button = unsafe { event.buttonNumber() } as u32;
+            delegate.maybe_queue_with_handler(move |app, event_loop| {
+                app.device_event(event_loop, DEVICE_ID, DeviceEvent::Button {
+                    button,
+                    state: ElementState::Released,
+                });
             });
         },
         _ => (),

src/platform_impl/apple/appkit/app_state.rs

@@ -1,6 +1,8 @@
 use std::cell::{Cell, RefCell};
 use std::mem;
 use std::rc::Weak;
+use std::sync::atomic::{AtomicBool, Ordering as AtomicOrdering};
+use std::sync::Arc;
 use std::time::Instant;
 
 use objc2::rc::Retained;
@@ -8,13 +10,15 @@ use objc2::{declare_class, msg_send_id, mutability, ClassType, DeclaredClass};
 use objc2_app_kit::{NSApplication, NSApplicationActivationPolicy, NSApplicationDelegate};
 use objc2_foundation::{MainThreadMarker, NSNotification, NSObject, NSObjectProtocol};
 
+use crate::application::ApplicationHandler;
+use crate::event::{StartCause, WindowEvent};
+use crate::event_loop::{ActiveEventLoop as RootActiveEventLoop, ControlFlow};
+use crate::window::WindowId as RootWindowId;
+
 use super::event_handler::EventHandler;
 use super::event_loop::{stop_app_immediately, ActiveEventLoop, PanicInfo};
 use super::observer::{EventLoopWaker, RunLoop};
-use super::{menu, WindowId, DEVICE_ID};
-use crate::event::{DeviceEvent, Event, StartCause, WindowEvent};
-use crate::event_loop::{ActiveEventLoop as RootActiveEventLoop, ControlFlow};
-use crate::window::WindowId as RootWindowId;
+use super::{menu, WindowId};
 
 #[derive(Debug)]
 pub(super) struct AppState {
@@ -22,6 +26,7 @@ pub(super) struct AppState {
     default_menu: bool,
     activate_ignoring_other_apps: bool,
     run_loop: RunLoop,
+    proxy_wake_up: Arc<AtomicBool>,
     event_handler: EventHandler,
     stop_on_launch: Cell<bool>,
     stop_before_wait: Cell<bool>,
@@ -75,11 +80,13 @@ impl ApplicationDelegate {
     pub(super) fn new(
         mtm: MainThreadMarker,
         activation_policy: NSApplicationActivationPolicy,
+        proxy_wake_up: Arc<AtomicBool>,
         default_menu: bool,
         activate_ignoring_other_apps: bool,
     ) -> Retained<Self> {
         let this = mtm.alloc().set_ivars(AppState {
             activation_policy,
+            proxy_wake_up,
             default_menu,
             activate_ignoring_other_apps,
             run_loop: RunLoop::main(mtm),
@@ -166,7 +173,7 @@ impl ApplicationDelegate {
     /// of the given closure.
     pub fn set_event_handler<R>(
         &self,
-        handler: impl FnMut(Event<HandlePendingUserEvents>, &RootActiveEventLoop),
+        handler: &mut dyn ApplicationHandler,
         closure: impl FnOnce() -> R,
     ) -> R {
         self.ivars().event_handler.set(handler, closure)
@@ -200,7 +207,9 @@ impl ApplicationDelegate {
     /// NOTE: that if the `NSApplication` has been launched then that state is preserved,
     /// and we won't need to re-launch the app if subsequent EventLoops are run.
     pub fn internal_exit(&self) {
-        self.handle_event(Event::LoopExiting);
+        self.with_handler(|app, event_loop| {
+            app.exiting(event_loop);
+        });
 
         self.set_is_running(false);
         self.set_stop_on_redraw(false);
@@ -241,26 +250,13 @@ impl ApplicationDelegate {
         self.ivars().control_flow.get()
     }
 
-    pub fn maybe_queue_window_event(&self, window_id: WindowId, event: WindowEvent) {
-        self.maybe_queue_event(Event::WindowEvent { window_id: RootWindowId(window_id), event });
-    }
-
-    pub fn handle_window_event(&self, window_id: WindowId, event: WindowEvent) {
-        self.handle_event(Event::WindowEvent { window_id: RootWindowId(window_id), event });
-    }
-
-    pub fn maybe_queue_device_event(&self, event: DeviceEvent) {
-        self.maybe_queue_event(Event::DeviceEvent { device_id: DEVICE_ID, event });
-    }
-
     pub fn handle_redraw(&self, window_id: WindowId) {
         let mtm = MainThreadMarker::from(self);
         // Redraw request might come out of order from the OS.
         // -> Don't go back into the event handler when our callstack originates from there
         if !self.ivars().event_handler.in_use() {
-            self.handle_event(Event::WindowEvent {
-                window_id: RootWindowId(window_id),
-                event: WindowEvent::RedrawRequested,
+            self.with_handler(|app, event_loop| {
+                app.window_event(event_loop, RootWindowId(window_id), WindowEvent::RedrawRequested);
             });
 
             // `pump_events` will request to stop immediately _after_ dispatching RedrawRequested
@@ -282,7 +278,10 @@ impl ApplicationDelegate {
     }
 
     #[track_caller]
-    fn maybe_queue_event(&self, event: Event<HandlePendingUserEvents>) {
+    pub fn maybe_queue_with_handler(
+        &self,
+        callback: impl FnOnce(&mut dyn ApplicationHandler, &RootActiveEventLoop) + 'static,
+    ) {
         // Most programmer actions in AppKit (e.g. change window fullscreen, set focused, etc.)
         // result in an event being queued, and applied at a later point.
         //
@@ -290,25 +289,31 @@ impl ApplicationDelegate {
         // so to make sure that we don't encounter re-entrancy issues, we first check if we're
         // currently handling another event, and if we are, we queue the event instead.
         if !self.ivars().event_handler.in_use() {
-            self.handle_event(event);
+            self.with_handler(callback);
         } else {
-            tracing::debug!(?event, "had to queue event since another is currently being handled");
+            tracing::debug!("had to queue event since another is currently being handled");
             let this = self.retain();
-            self.ivars().run_loop.queue_closure(move || this.handle_event(event));
+            self.ivars().run_loop.queue_closure(move || {
+                this.with_handler(callback);
+            });
         }
     }
 
     #[track_caller]
-    fn handle_event(&self, event: Event<HandlePendingUserEvents>) {
-        self.ivars().event_handler.handle_event(event, &ActiveEventLoop::new_root(self.retain()))
+    fn with_handler(
+        &self,
+        callback: impl FnOnce(&mut dyn ApplicationHandler, &RootActiveEventLoop),
+    ) {
+        let event_loop = ActiveEventLoop::new_root(self.retain());
+        self.ivars().event_handler.handle(callback, &event_loop);
     }
 
     /// dispatch `NewEvents(Init)` + `Resumed`
     pub fn dispatch_init_events(&self) {
-        self.handle_event(Event::NewEvents(StartCause::Init));
+        self.with_handler(|app, event_loop| app.new_events(event_loop, StartCause::Init));
         // NB: For consistency all platforms must emit a 'resumed' event even though macOS
         // applications don't themselves have a formal suspend/resume lifecycle.
-        self.handle_event(Event::Resumed);
+        self.with_handler(|app, event_loop| app.resumed(event_loop));
     }
 
     // Called by RunLoopObserver after finishing waiting for new events
@@ -318,8 +323,7 @@ impl ApplicationDelegate {
             .upgrade()
             .expect("The panic info must exist here. This failure indicates a developer error.");
 
-        // Return when in event handler due to https://github.com/rust-windowing/winit/issues/1779
-        if panic_info.is_panicking() || !self.ivars().event_handler.ready() || !self.is_running() {
+        if panic_info.is_panicking() || !self.is_running() {
             return;
         }
 
@@ -341,7 +345,7 @@ impl ApplicationDelegate {
             },
         };
 
-        self.handle_event(Event::NewEvents(cause));
+        self.with_handler(|app, event_loop| app.new_events(event_loop, cause));
     }
 
     // Called by RunLoopObserver before waiting for new events
@@ -351,24 +355,23 @@ impl ApplicationDelegate {
             .upgrade()
             .expect("The panic info must exist here. This failure indicates a developer error.");
 
-        // Return when in event handler due to https://github.com/rust-windowing/winit/issues/1779
-        // XXX: how does it make sense that `event_handler.ready()` can ever return `false` here if
-        // we're about to return to the `CFRunLoop` to poll for new events?
-        if panic_info.is_panicking() || !self.ivars().event_handler.ready() || !self.is_running() {
+        if panic_info.is_panicking() || !self.is_running() {
             return;
         }
 
-        self.handle_event(Event::UserEvent(HandlePendingUserEvents));
+        if self.ivars().proxy_wake_up.swap(false, AtomicOrdering::Relaxed) {
+            self.with_handler(|app, event_loop| app.proxy_wake_up(event_loop));
+        }
 
         let redraw = mem::take(&mut *self.ivars().pending_redraw.borrow_mut());
         for window_id in redraw {
-            self.handle_event(Event::WindowEvent {
-                window_id: RootWindowId(window_id),
-                event: WindowEvent::RedrawRequested,
+            self.with_handler(|app, event_loop| {
+                app.window_event(event_loop, RootWindowId(window_id), WindowEvent::RedrawRequested);
             });
         }
-
-        self.handle_event(Event::AboutToWait);
+        self.with_handler(|app, event_loop| {
+            app.about_to_wait(event_loop);
+        });
 
         if self.exiting() {
             let app = NSApplication::sharedApplication(mtm);
@@ -390,9 +393,6 @@ impl ApplicationDelegate {
     }
 }
 
-#[derive(Debug)]
-pub(crate) struct HandlePendingUserEvents;
-
 /// Returns the minimum `Option<Instant>`, taking into account that `None`
 /// equates to an infinite timeout, not a zero timeout (so can't just use
 /// `Option::min`)

src/platform_impl/apple/appkit/event.rs

@@ -7,12 +7,12 @@ use objc2_app_kit::{NSEvent, NSEventModifierFlags, NSEventSubtype, NSEventType};
 use objc2_foundation::{run_on_main, NSPoint};
 use smol_str::SmolStr;
 
+use super::ffi;
 use crate::event::{ElementState, KeyEvent, Modifiers};
 use crate::keyboard::{
     Key, KeyCode, KeyLocation, ModifiersKeys, ModifiersState, NamedKey, NativeKey, NativeKeyCode,
     PhysicalKey,
 };
-use crate::platform_impl::platform::ffi;
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct KeyEventExtra {

src/platform_impl/apple/appkit/event_handler.rs

@@ -1,32 +1,31 @@
 use std::cell::RefCell;
 use std::{fmt, mem};
 
-use super::app_state::HandlePendingUserEvents;
-use crate::event::Event;
+use crate::application::ApplicationHandler;
 use crate::event_loop::ActiveEventLoop as RootActiveEventLoop;
 
-struct EventHandlerData {
-    #[allow(clippy::type_complexity)]
-    handler: Box<dyn FnMut(Event<HandlePendingUserEvents>, &RootActiveEventLoop) + 'static>,
-}
-
-impl fmt::Debug for EventHandlerData {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("EventHandlerData").finish_non_exhaustive()
-    }
-}
-
-#[derive(Debug)]
+#[derive(Default)]
 pub(crate) struct EventHandler {
     /// This can be in the following states:
     /// - Not registered by the event loop (None).
     /// - Present (Some(handler)).
     /// - Currently executing the handler / in use (RefCell borrowed).
-    inner: RefCell<Option<EventHandlerData>>,
+    inner: RefCell<Option<&'static mut dyn ApplicationHandler>>,
+}
+
+impl fmt::Debug for EventHandler {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let state = match self.inner.try_borrow().as_deref() {
+            Ok(Some(_)) => "<available>",
+            Ok(None) => "<not set>",
+            Err(_) => "<in use>",
+        };
+        f.debug_struct("EventHandler").field("state", &state).finish_non_exhaustive()
+    }
 }
 
 impl EventHandler {
-    pub(crate) const fn new() -> Self {
+    pub(crate) fn new() -> Self {
         Self { inner: RefCell::new(None) }
     }
 
@@ -37,7 +36,7 @@ impl EventHandler {
     /// from within the closure.
     pub(crate) fn set<'handler, R>(
         &self,
-        handler: impl FnMut(Event<HandlePendingUserEvents>, &RootActiveEventLoop) + 'handler,
+        app: &'handler mut dyn ApplicationHandler,
         closure: impl FnOnce() -> R,
     ) -> R {
         // SAFETY: We extend the lifetime of the handler here so that we can
@@ -48,9 +47,9 @@ impl EventHandler {
         // extended beyond `'handler`.
         let handler = unsafe {
             mem::transmute::<
-                Box<dyn FnMut(Event<HandlePendingUserEvents>, &RootActiveEventLoop) + 'handler>,
-                Box<dyn FnMut(Event<HandlePendingUserEvents>, &RootActiveEventLoop) + 'static>,
-            >(Box::new(handler))
+                &'handler mut dyn ApplicationHandler,
+                &'static mut dyn ApplicationHandler,
+            >(app)
         };
 
         match self.inner.try_borrow_mut().as_deref_mut() {
@@ -58,7 +57,7 @@ impl EventHandler {
                 unreachable!("tried to set handler while another was already set");
             },
             Ok(data @ None) => {
-                *data = Some(EventHandlerData { handler });
+                *data = Some(handler);
             },
             Err(_) => {
                 unreachable!("tried to set handler that is currently in use");
@@ -105,24 +104,20 @@ impl EventHandler {
         self.inner.try_borrow().is_err()
     }
 
-    pub(crate) fn ready(&self) -> bool {
-        matches!(self.inner.try_borrow().as_deref(), Ok(Some(_)))
-    }
-
-    pub(crate) fn handle_event(
+    pub(crate) fn handle(
         &self,
-        event: Event<HandlePendingUserEvents>,
+        callback: impl FnOnce(&mut dyn ApplicationHandler, &RootActiveEventLoop),
         event_loop: &RootActiveEventLoop,
     ) {
         match self.inner.try_borrow_mut().as_deref_mut() {
-            Ok(Some(EventHandlerData { handler })) => {
+            Ok(Some(user_app)) => {
                 // It is important that we keep the reference borrowed here,
                 // so that `in_use` can properly detect that the handler is
                 // still in use.
                 //
                 // If the handler unwinds, the `RefMut` will ensure that the
                 // handler is no longer borrowed.
-                (handler)(event, event_loop);
+                callback(*user_app, event_loop);
             },
             Ok(None) => {
                 // `NSApplication`, our app delegate and this handler are all

src/platform_impl/apple/appkit/event_loop.rs

@@ -6,12 +6,13 @@ use std::os::raw::c_void;
 use std::panic::{catch_unwind, resume_unwind, RefUnwindSafe, UnwindSafe};
 use std::ptr;
 use std::rc::{Rc, Weak};
-use std::sync::mpsc;
+use std::sync::atomic::{AtomicBool, Ordering as AtomicOrdering};
+use std::sync::Arc;
 use std::time::{Duration, Instant};
 
 use core_foundation::base::{CFIndex, CFRelease};
 use core_foundation::runloop::{
-    kCFRunLoopCommonModes, CFRunLoopAddSource, CFRunLoopGetMain, CFRunLoopSourceContext,
+    kCFRunLoopDefaultMode, CFRunLoopAddSource, CFRunLoopGetMain, CFRunLoopSourceContext,
     CFRunLoopSourceCreate, CFRunLoopSourceRef, CFRunLoopSourceSignal, CFRunLoopWakeUp,
 };
 use objc2::rc::{autoreleasepool, Retained};
@@ -21,18 +22,16 @@ use objc2_app_kit::{NSApplication, NSApplicationActivationPolicy, NSWindow};
 use objc2_foundation::{MainThreadMarker, NSObjectProtocol};
 
 use super::app::WinitApplication;
-use super::app_state::{ApplicationDelegate, HandlePendingUserEvents};
+use super::app_state::ApplicationDelegate;
+use super::cursor::CustomCursor;
 use super::event::dummy_event;
 use super::monitor::{self, MonitorHandle};
 use super::observer::setup_control_flow_observers;
+use crate::application::ApplicationHandler;
 use crate::error::EventLoopError;
-use crate::event::Event;
-use crate::event_loop::{
-    ActiveEventLoop as RootWindowTarget, ControlFlow, DeviceEvents, EventLoopClosed,
-};
+use crate::event_loop::{ActiveEventLoop as RootWindowTarget, ControlFlow, DeviceEvents};
 use crate::platform::macos::ActivationPolicy;
 use crate::platform::pump_events::PumpStatus;
-use crate::platform_impl::platform::cursor::CustomCursor;
 use crate::window::{CustomCursor as RootCustomCursor, CustomCursorSource};
 
 #[derive(Default)]
@@ -155,21 +154,7 @@ impl ActiveEventLoop {
     }
 }
 
-fn map_user_event<T: 'static>(
-    mut handler: impl FnMut(Event<T>, &RootWindowTarget),
-    receiver: Rc<mpsc::Receiver<T>>,
-) -> impl FnMut(Event<HandlePendingUserEvents>, &RootWindowTarget) {
-    move |event, window_target| match event.map_nonuser_event() {
-        Ok(event) => (handler)(event, window_target),
-        Err(_) => {
-            for event in receiver.try_iter() {
-                (handler)(Event::UserEvent(event), window_target);
-            }
-        },
-    }
-}
-
-pub struct EventLoop<T: 'static> {
+pub struct EventLoop {
     /// Store a reference to the application for convenience.
     ///
     /// We intentionally don't store `WinitApplication` since we want to have
@@ -181,9 +166,7 @@ pub struct EventLoop<T: 'static> {
     /// keep it around here as well.
     delegate: Retained<ApplicationDelegate>,
 
-    // Event sender and receiver, used for EventLoopProxy.
-    sender: mpsc::Sender<T>,
-    receiver: Rc<mpsc::Receiver<T>>,
+    proxy_wake_up: Arc<AtomicBool>,
 
     window_target: RootWindowTarget,
     panic_info: Rc<PanicInfo>,
@@ -206,7 +189,7 @@ impl Default for PlatformSpecificEventLoopAttributes {
     }
 }
 
-impl<T> EventLoop<T> {
+impl EventLoop {
     pub(crate) fn new(
         attributes: &PlatformSpecificEventLoopAttributes,
     ) -> Result<Self, EventLoopError> {
@@ -228,9 +211,13 @@ impl<T> EventLoop<T> {
             ActivationPolicy::Accessory => NSApplicationActivationPolicy::Accessory,
             ActivationPolicy::Prohibited => NSApplicationActivationPolicy::Prohibited,
         };
+
+        let proxy_wake_up = Arc::new(AtomicBool::new(false));
+
         let delegate = ApplicationDelegate::new(
             mtm,
             activation_policy,
+            proxy_wake_up.clone(),
             attributes.default_menu,
             attributes.activate_ignoring_other_apps,
         );
@@ -242,16 +229,14 @@ impl<T> EventLoop<T> {
         let panic_info: Rc<PanicInfo> = Default::default();
         setup_control_flow_observers(mtm, Rc::downgrade(&panic_info));
 
-        let (sender, receiver) = mpsc::channel();
         Ok(EventLoop {
             app,
             delegate: delegate.clone(),
-            sender,
-            receiver: Rc::new(receiver),
             window_target: RootWindowTarget {
                 p: ActiveEventLoop { delegate, mtm },
                 _marker: PhantomData,
             },
+            proxy_wake_up,
             panic_info,
         })
     }
@@ -260,24 +245,19 @@ impl<T> EventLoop<T> {
         &self.window_target
     }
 
-    pub fn run<F>(mut self, handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(Event<T>, &RootWindowTarget),
-    {
-        self.run_on_demand(handler)
+    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+        self.run_app_on_demand(app)
     }
 
     // NB: we don't base this on `pump_events` because for `MacOs` we can't support
     // `pump_events` elegantly (we just ask to run the loop for a "short" amount of
     // time and so a layered implementation would end up using a lot of CPU due to
     // redundant wake ups.
-    pub fn run_on_demand<F>(&mut self, handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(Event<T>, &RootWindowTarget),
-    {
-        let handler = map_user_event(handler, self.receiver.clone());
-
-        self.delegate.set_event_handler(handler, || {
+    pub fn run_app_on_demand<A: ApplicationHandler>(
+        &mut self,
+        app: &mut A,
+    ) -> Result<(), EventLoopError> {
+        self.delegate.set_event_handler(app, || {
             autoreleasepool(|_| {
                 // clear / normalize pump_events state
                 self.delegate.set_wait_timeout(None);
@@ -310,13 +290,12 @@ impl<T> EventLoop<T> {
         Ok(())
     }
 
-    pub fn pump_events<F>(&mut self, timeout: Option<Duration>, handler: F) -> PumpStatus
-    where
-        F: FnMut(Event<T>, &RootWindowTarget),
-    {
-        let handler = map_user_event(handler, self.receiver.clone());
-
-        self.delegate.set_event_handler(handler, || {
+    pub fn pump_app_events<A: ApplicationHandler>(
+        &mut self,
+        timeout: Option<Duration>,
+        app: &mut A,
+    ) -> PumpStatus {
+        self.delegate.set_event_handler(app, || {
             autoreleasepool(|_| {
                 // As a special case, if the application hasn't been launched yet then we at least
                 // run the loop until it has fully launched.
@@ -380,8 +359,8 @@ impl<T> EventLoop<T> {
         })
     }
 
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
-        EventLoopProxy::new(self.sender.clone())
+    pub fn create_proxy(&self) -> EventLoopProxy {
+        EventLoopProxy::new(self.proxy_wake_up.clone())
     }
 }
 
@@ -439,15 +418,15 @@ pub fn stop_app_on_panic<F: FnOnce() -> R + UnwindSafe, R>(
     }
 }
 
-pub struct EventLoopProxy<T> {
-    sender: mpsc::Sender<T>,
+pub struct EventLoopProxy {
+    proxy_wake_up: Arc<AtomicBool>,
     source: CFRunLoopSourceRef,
 }
 
-unsafe impl<T: Send> Send for EventLoopProxy<T> {}
-unsafe impl<T: Send> Sync for EventLoopProxy<T> {}
+unsafe impl Send for EventLoopProxy {}
+unsafe impl Sync for EventLoopProxy {}
 
-impl<T> Drop for EventLoopProxy<T> {
+impl Drop for EventLoopProxy {
     fn drop(&mut self) {
         unsafe {
             CFRelease(self.source as _);
@@ -455,14 +434,14 @@ impl<T> Drop for EventLoopProxy<T> {
     }
 }
 
-impl<T> Clone for EventLoopProxy<T> {
+impl Clone for EventLoopProxy {
     fn clone(&self) -> Self {
-        EventLoopProxy::new(self.sender.clone())
+        EventLoopProxy::new(self.proxy_wake_up.clone())
     }
 }
 
-impl<T> EventLoopProxy<T> {
-    fn new(sender: mpsc::Sender<T>) -> Self {
+impl EventLoopProxy {
+    fn new(proxy_wake_up: Arc<AtomicBool>) -> Self {
         unsafe {
             // just wake up the eventloop
             extern "C" fn event_loop_proxy_handler(_: *const c_void) {}
@@ -482,23 +461,21 @@ impl<T> EventLoopProxy<T> {
                 cancel: None,
                 perform: event_loop_proxy_handler,
             };
-            let source =
-                CFRunLoopSourceCreate(ptr::null_mut(), CFIndex::max_value() - 1, &mut context);
-            CFRunLoopAddSource(rl, source, kCFRunLoopCommonModes);
+            let source = CFRunLoopSourceCreate(ptr::null_mut(), CFIndex::MAX - 1, &mut context);
+            CFRunLoopAddSource(rl, source, kCFRunLoopDefaultMode);
             CFRunLoopWakeUp(rl);
 
-            EventLoopProxy { sender, source }
+            EventLoopProxy { proxy_wake_up, source }
         }
     }
 
-    pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
-        self.sender.send(event).map_err(|mpsc::SendError(x)| EventLoopClosed(x))?;
+    pub fn wake_up(&self) {
+        self.proxy_wake_up.store(true, AtomicOrdering::Relaxed);
         unsafe {
             // let the main thread know there's a new event
             CFRunLoopSourceSignal(self.source);
             let rl = CFRunLoopGetMain();
             CFRunLoopWakeUp(rl);
         }
-        Ok(())
     }
 }

src/platform_impl/apple/appkit/observer.rs

@@ -13,8 +13,8 @@ use block2::Block;
 use core_foundation::base::{CFIndex, CFOptionFlags, CFRelease, CFTypeRef};
 use core_foundation::date::CFAbsoluteTimeGetCurrent;
 use core_foundation::runloop::{
-    kCFRunLoopAfterWaiting, kCFRunLoopBeforeWaiting, kCFRunLoopCommonModes, kCFRunLoopDefaultMode,
-    kCFRunLoopExit, CFRunLoopActivity, CFRunLoopAddObserver, CFRunLoopAddTimer, CFRunLoopGetMain,
+    kCFRunLoopAfterWaiting, kCFRunLoopBeforeWaiting, kCFRunLoopDefaultMode, kCFRunLoopExit,
+    CFRunLoopActivity, CFRunLoopAddObserver, CFRunLoopAddTimer, CFRunLoopGetMain,
     CFRunLoopObserverCallBack, CFRunLoopObserverContext, CFRunLoopObserverCreate,
     CFRunLoopObserverRef, CFRunLoopRef, CFRunLoopTimerCreate, CFRunLoopTimerInvalidate,
     CFRunLoopTimerRef, CFRunLoopTimerSetNextFireDate, CFRunLoopWakeUp,
@@ -129,7 +129,7 @@ impl RunLoop {
                 context,
             )
         };
-        unsafe { CFRunLoopAddObserver(self.0, observer, kCFRunLoopCommonModes) };
+        unsafe { CFRunLoopAddObserver(self.0, observer, kCFRunLoopDefaultMode) };
     }
 
     /// Submit a closure to run on the main thread as the next step in the run loop, before other
@@ -214,13 +214,13 @@ pub fn setup_control_flow_observers(mtm: MainThreadMarker, panic_info: Weak<Pani
         };
         run_loop.add_observer(
             kCFRunLoopAfterWaiting,
-            CFIndex::min_value(),
+            CFIndex::MIN,
             control_flow_begin_handler,
             &mut context as *mut _,
         );
         run_loop.add_observer(
             kCFRunLoopExit | kCFRunLoopBeforeWaiting,
-            CFIndex::max_value(),
+            CFIndex::MAX,
             control_flow_end_handler,
             &mut context as *mut _,
         );
@@ -260,14 +260,14 @@ impl EventLoopWaker {
             // future, but that gets changed to fire immediately in did_finish_launching
             let timer = CFRunLoopTimerCreate(
                 ptr::null_mut(),
-                std::f64::MAX,
+                f64::MAX,
                 0.000_000_1,
                 0,
                 0,
                 wakeup_main_loop,
                 ptr::null_mut(),
             );
-            CFRunLoopAddTimer(CFRunLoopGetMain(), timer, kCFRunLoopCommonModes);
+            CFRunLoopAddTimer(CFRunLoopGetMain(), timer, kCFRunLoopDefaultMode);
             Self { timer, start_instant: Instant::now(), next_fire_date: None }
         }
     }
@@ -275,14 +275,14 @@ impl EventLoopWaker {
     pub fn stop(&mut self) {
         if self.next_fire_date.is_some() {
             self.next_fire_date = None;
-            unsafe { CFRunLoopTimerSetNextFireDate(self.timer, std::f64::MAX) }
+            unsafe { CFRunLoopTimerSetNextFireDate(self.timer, f64::MAX) }
         }
     }
 
     pub fn start(&mut self) {
         if self.next_fire_date != Some(self.start_instant) {
             self.next_fire_date = Some(self.start_instant);
-            unsafe { CFRunLoopTimerSetNextFireDate(self.timer, std::f64::MIN) }
+            unsafe { CFRunLoopTimerSetNextFireDate(self.timer, f64::MIN) }
         }
     }
 

src/platform_impl/apple/appkit/util.rs

@@ -2,7 +2,8 @@ use tracing::trace;
 
 macro_rules! trace_scope {
     ($s:literal) => {
-        let _crate = $crate::platform_impl::platform::util::TraceGuard::new(module_path!(), $s);
+        let _crate =
+            $crate::platform_impl::platform::appkit::util::TraceGuard::new(module_path!(), $s);
     };
 }
 

src/platform_impl/apple/appkit/view.rs

@@ -31,6 +31,7 @@ use crate::event::{
 };
 use crate::keyboard::{Key, KeyCode, KeyLocation, ModifiersState, NamedKey};
 use crate::platform::macos::OptionAsAlt;
+use crate::window::WindowId as RootWindowId;
 
 #[derive(Debug)]
 struct CursorState {
@@ -686,7 +687,9 @@ declare_class!(
 
             self.update_modifiers(event, false);
 
-            self.ivars().app_delegate.maybe_queue_device_event(DeviceEvent::MouseWheel { delta });
+            self.ivars().app_delegate.maybe_queue_with_handler(move |app, event_loop|
+                app.device_event(event_loop, DEVICE_ID, DeviceEvent::MouseWheel { delta })
+            );
             self.queue_event(WindowEvent::MouseWheel {
                 device_id: DEVICE_ID,
                 delta,
@@ -830,7 +833,10 @@ impl WinitView {
     }
 
     fn queue_event(&self, event: WindowEvent) {
-        self.ivars().app_delegate.maybe_queue_window_event(self.window().id(), event);
+        let window_id = RootWindowId(self.window().id());
+        self.ivars().app_delegate.maybe_queue_with_handler(move |app, event_loop| {
+            app.window_event(event_loop, window_id, event);
+        });
     }
 
     fn scale_factor(&self) -> f64 {

src/platform_impl/apple/appkit/window_delegate.rs

@@ -1,6 +1,8 @@
 #![allow(clippy::unnecessary_cast)]
 use std::cell::{Cell, RefCell};
 use std::collections::VecDeque;
+use std::ffi::c_void;
+use std::ptr;
 use std::sync::{Arc, Mutex};
 
 use core_graphics::display::{CGDisplay, CGPoint};
@@ -9,18 +11,20 @@ use objc2::rc::{autoreleasepool, Retained};
 use objc2::runtime::{AnyObject, ProtocolObject};
 use objc2::{declare_class, msg_send_id, mutability, sel, ClassType, DeclaredClass};
 use objc2_app_kit::{
-    NSAppKitVersionNumber, NSAppKitVersionNumber10_12, NSAppearance, NSApplication,
-    NSApplicationPresentationOptions, NSBackingStoreType, NSDraggingDestination,
-    NSFilenamesPboardType, NSPasteboard, NSRequestUserAttentionType, NSScreen, NSView,
-    NSWindowButton, NSWindowDelegate, NSWindowFullScreenButton, NSWindowLevel,
-    NSWindowOcclusionState, NSWindowOrderingMode, NSWindowSharingType, NSWindowStyleMask,
-    NSWindowTabbingMode, NSWindowTitleVisibility,
+    NSAppKitVersionNumber, NSAppKitVersionNumber10_12, NSAppearance, NSAppearanceCustomization,
+    NSAppearanceNameAqua, NSApplication, NSApplicationPresentationOptions, NSBackingStoreType,
+    NSColor, NSDraggingDestination, NSFilenamesPboardType, NSPasteboard,
+    NSRequestUserAttentionType, NSScreen, NSView, NSWindowButton, NSWindowDelegate,
+    NSWindowFullScreenButton, NSWindowLevel, NSWindowOcclusionState, NSWindowOrderingMode,
+    NSWindowSharingType, NSWindowStyleMask, NSWindowTabbingMode, NSWindowTitleVisibility,
 };
 use objc2_foundation::{
-    ns_string, CGFloat, MainThreadMarker, NSArray, NSCopying, NSDistributedNotificationCenter,
-    NSObject, NSObjectNSDelayedPerforming, NSObjectNSThreadPerformAdditions, NSObjectProtocol,
-    NSPoint, NSRect, NSSize, NSString,
+    ns_string, CGFloat, MainThreadMarker, NSArray, NSCopying, NSDictionary, NSKeyValueChangeKey,
+    NSKeyValueChangeNewKey, NSKeyValueChangeOldKey, NSKeyValueObservingOptions, NSObject,
+    NSObjectNSDelayedPerforming, NSObjectNSKeyValueObserverRegistration, NSObjectProtocol, NSPoint,
+    NSRect, NSSize, NSString,
 };
+use tracing::{trace, warn};
 
 use super::app_state::ApplicationDelegate;
 use super::cursor::cursor_from_icon;
@@ -35,7 +39,7 @@ use crate::event::{InnerSizeWriter, WindowEvent};
 use crate::platform::macos::{OptionAsAlt, WindowExtMacOS};
 use crate::window::{
     Cursor, CursorGrabMode, Icon, ImePurpose, ResizeDirection, Theme, UserAttentionType,
-    WindowAttributes, WindowButtons, WindowLevel,
+    WindowAttributes, WindowButtons, WindowId as RootWindowId, WindowLevel,
 };
 
 #[derive(Clone, Debug)]
@@ -79,8 +83,6 @@ pub(crate) struct State {
 
     window: Retained<WinitWindow>,
 
-    current_theme: Cell<Option<Theme>>,
-
     // During `windowDidResize`, we use this to only send Moved if the position changed.
     //
     // This is expressed in native screen coordinates.
@@ -419,32 +421,66 @@ declare_class!(
         }
     }
 
+    // Key-Value Observing
     unsafe impl WindowDelegate {
-        // Observe theme change
-        #[method(effectiveAppearanceDidChange:)]
-        fn effective_appearance_did_change(&self, sender: Option<&AnyObject>) {
-            trace_scope!("effectiveAppearanceDidChange:");
-            unsafe {
-                self.performSelectorOnMainThread_withObject_waitUntilDone(
-                    sel!(effectiveAppearanceDidChangedOnMainThread:),
-                    sender,
-                    false,
-                )
-            };
-        }
+        #[method(observeValueForKeyPath:ofObject:change:context:)]
+        fn observe_value(
+            &self,
+            key_path: Option<&NSString>,
+            _object: Option<&AnyObject>,
+            change: Option<&NSDictionary<NSKeyValueChangeKey, AnyObject>>,
+            _context: *mut c_void,
+        ) {
+            trace_scope!("observeValueForKeyPath:ofObject:change:context:");
+            // NOTE: We don't _really_ need to check the key path, as there should only be one, but
+            // in the future we might want to observe other key paths.
+            if key_path == Some(ns_string!("effectiveAppearance")) {
+                let change = change.expect("requested a change dictionary in `addObserver`, but none was provided");
+                let old = change.get(unsafe { NSKeyValueChangeOldKey }).expect("requested change dictionary did not contain `NSKeyValueChangeOldKey`");
+                let new = change.get(unsafe { NSKeyValueChangeNewKey }).expect("requested change dictionary did not contain `NSKeyValueChangeNewKey`");
 
-        #[method(effectiveAppearanceDidChangedOnMainThread:)]
-        fn effective_appearance_did_changed_on_main_thread(&self, _: Option<&AnyObject>) {
-            let mtm = MainThreadMarker::from(self);
-            let theme = get_ns_theme(mtm);
-            let old_theme = self.ivars().current_theme.replace(Some(theme));
-            if old_theme != Some(theme) {
-                self.queue_event(WindowEvent::ThemeChanged(theme));
+                // SAFETY: The value of `effectiveAppearance` is `NSAppearance`
+                let old: *const AnyObject = old;
+                let old: *const NSAppearance = old.cast();
+                let old: &NSAppearance = unsafe { &*old };
+                let new: *const AnyObject = new;
+                let new: *const NSAppearance = new.cast();
+                let new: &NSAppearance = unsafe { &*new };
+
+                trace!(old = %unsafe { old.name() }, new = %unsafe { new.name() }, "effectiveAppearance changed");
+
+                // Ignore the change if the window's theme is customized by the user (since in that
+                // case the `effectiveAppearance` is only emitted upon said customization, and then
+                // it's triggered directly by a user action, and we don't want to emit the event).
+                if unsafe { self.window().appearance() }.is_some() {
+                    return;
+                }
+
+                let old = appearance_to_theme(old);
+                let new = appearance_to_theme(new);
+                // Check that the theme changed in Winit's terms (the theme might have changed on
+                // other parameters, such as level of contrast, but the event should not be emitted
+                // in those cases).
+                if old == new {
+                    return;
+                }
+
+                self.queue_event(WindowEvent::ThemeChanged(new));
+            } else {
+                panic!("unknown observed keypath {key_path:?}");
             }
         }
     }
 );
 
+impl Drop for WindowDelegate {
+    fn drop(&mut self) {
+        unsafe {
+            self.window().removeObserver_forKeyPath(self, ns_string!("effectiveAppearance"));
+        }
+    }
+}
+
 fn new_window(
     app_delegate: &ApplicationDelegate,
     attrs: &WindowAttributes,
@@ -613,6 +649,8 @@ fn new_window(
 
         if attrs.transparent {
             window.setOpaque(false);
+            // See `set_transparent` for details on why we do this.
+            window.setBackgroundColor(unsafe { Some(&NSColor::clearColor()) });
         }
 
         // register for drag and drop operations.
@@ -666,15 +704,13 @@ impl WindowDelegate {
 
         let scale_factor = window.backingScaleFactor() as _;
 
-        let current_theme = match attrs.preferred_theme {
-            Some(theme) => Some(theme),
-            None => Some(get_ns_theme(mtm)),
-        };
+        if let Some(appearance) = theme_to_appearance(attrs.preferred_theme) {
+            unsafe { window.setAppearance(Some(&appearance)) };
+        }
 
         let delegate = mtm.alloc().set_ivars(State {
             app_delegate: app_delegate.retain(),
             window: window.retain(),
-            current_theme: Cell::new(current_theme),
             previous_position: Cell::new(None),
             previous_scale_factor: Cell::new(scale_factor),
             resize_increments: Cell::new(resize_increments),
@@ -700,14 +736,16 @@ impl WindowDelegate {
         }
         window.setDelegate(Some(ProtocolObject::from_ref(&*delegate)));
 
-        // Enable theme change event
-        let notification_center = unsafe { NSDistributedNotificationCenter::defaultCenter() };
+        // Listen for theme change event.
+        //
+        // SAFETY: The observer is un-registered in the `Drop` of the delegate.
         unsafe {
-            notification_center.addObserver_selector_name_object(
+            window.addObserver_forKeyPath_options_context(
                 &delegate,
-                sel!(effectiveAppearanceDidChange:),
-                Some(ns_string!("AppleInterfaceThemeChangedNotification")),
-                None,
+                ns_string!("effectiveAppearance"),
+                NSKeyValueObservingOptions::NSKeyValueObservingOptionNew
+                    | NSKeyValueObservingOptions::NSKeyValueObservingOptionOld,
+                ptr::null_mut(),
             )
         };
 
@@ -769,11 +807,13 @@ impl WindowDelegate {
     }
 
     pub(crate) fn queue_event(&self, event: WindowEvent) {
-        self.ivars().app_delegate.maybe_queue_window_event(self.window().id(), event);
+        let window_id = RootWindowId(self.window().id());
+        self.ivars().app_delegate.maybe_queue_with_handler(move |app, event_loop| {
+            app.window_event(event_loop, window_id, event);
+        });
     }
 
     fn handle_scale_factor_changed(&self, scale_factor: CGFloat) {
-        let app_delegate = &self.ivars().app_delegate;
         let window = self.window();
 
         let content_size = window.contentRectForFrameRect(window.frame()).size;
@@ -781,7 +821,7 @@ impl WindowDelegate {
 
         let suggested_size = content_size.to_physical(scale_factor);
         let new_inner_size = Arc::new(Mutex::new(suggested_size));
-        app_delegate.handle_window_event(window.id(), WindowEvent::ScaleFactorChanged {
+        self.queue_event(WindowEvent::ScaleFactorChanged {
             scale_factor,
             inner_size_writer: InnerSizeWriter::new(Arc::downgrade(&new_inner_size)),
         });
@@ -793,7 +833,7 @@ impl WindowDelegate {
             let size = NSSize::new(logical_size.width, logical_size.height);
             window.setContentSize(size);
         }
-        app_delegate.handle_window_event(window.id(), WindowEvent::Resized(physical_size));
+        self.queue_event(WindowEvent::Resized(physical_size));
     }
 
     fn emit_move_event(&self) {
@@ -821,7 +861,23 @@ impl WindowDelegate {
     }
 
     pub fn set_transparent(&self, transparent: bool) {
-        self.window().setOpaque(!transparent)
+        // This is just a hint for Quartz, it doesn't actually speculate with window alpha.
+        // Providing a wrong value here could result in visual artifacts, when the window is
+        // transparent.
+        self.window().setOpaque(!transparent);
+
+        // AppKit draws the window with a background color by default, which is usually really
+        // nice, but gets in the way when we want to allow the contents of the window to be
+        // transparent, as in that case, the transparent contents will just be drawn on top of
+        // the background color. As such, to allow the window to be transparent, we must also set
+        // the background color to one with an empty alpha channel.
+        let color = if transparent {
+            unsafe { NSColor::clearColor() }
+        } else {
+            unsafe { NSColor::windowBackgroundColor() }
+        };
+
+        self.window().setBackgroundColor(Some(&color));
     }
 
     pub fn set_blur(&self, blur: bool) {
@@ -920,8 +976,8 @@ impl WindowDelegate {
 
     pub fn set_max_inner_size(&self, dimensions: Option<Size>) {
         let dimensions = dimensions.unwrap_or(Size::Logical(LogicalSize {
-            width: std::f32::MAX as f64,
-            height: std::f32::MAX as f64,
+            width: f32::MAX as f64,
+            height: f32::MAX as f64,
         }));
         let scale_factor = self.scale_factor();
         let max_size = dimensions.to_logical::<CGFloat>(scale_factor);
@@ -1597,20 +1653,24 @@ impl WindowDelegate {
         }
     }
 
-    #[inline]
-    pub fn theme(&self) -> Option<Theme> {
-        self.ivars().current_theme.get()
-    }
-
     #[inline]
     pub fn has_focus(&self) -> bool {
         self.window().isKeyWindow()
     }
 
+    pub fn theme(&self) -> Option<Theme> {
+        // Note: We could choose between returning the value of `effectiveAppearance` or
+        // `appearance`, depending on what the user is asking about:
+        // - "how should I render on this particular frame".
+        // - "what is the configuration for this window".
+        //
+        // We choose the latter for consistency with the `set_theme` call, though it might also be
+        // useful to expose the former.
+        Some(appearance_to_theme(unsafe { &*self.window().appearance()? }))
+    }
+
     pub fn set_theme(&self, theme: Option<Theme>) {
-        let mtm = MainThreadMarker::from(self);
-        set_ns_theme(theme, mtm);
-        self.ivars().current_theme.set(theme.or_else(|| Some(get_ns_theme(mtm))));
+        unsafe { self.window().setAppearance(theme_to_appearance(theme).as_deref()) };
     }
 
     #[inline]
@@ -1769,34 +1829,39 @@ impl WindowExtMacOS for WindowDelegate {
 const DEFAULT_STANDARD_FRAME: NSRect =
     NSRect::new(NSPoint::new(50.0, 50.0), NSSize::new(800.0, 600.0));
 
-pub(super) fn get_ns_theme(mtm: MainThreadMarker) -> Theme {
-    let app = NSApplication::sharedApplication(mtm);
-    if !app.respondsToSelector(sel!(effectiveAppearance)) {
-        return Theme::Light;
-    }
-    let appearance = app.effectiveAppearance();
-    let name = appearance
-        .bestMatchFromAppearancesWithNames(&NSArray::from_id_slice(&[
-            NSString::from_str("NSAppearanceNameAqua"),
-            NSString::from_str("NSAppearanceNameDarkAqua"),
-        ]))
-        .unwrap();
-    match &*name.to_string() {
-        "NSAppearanceNameDarkAqua" => Theme::Dark,
-        _ => Theme::Light,
+fn dark_appearance_name() -> &'static NSString {
+    // Don't use the static `NSAppearanceNameDarkAqua` to allow linking on macOS < 10.14
+    ns_string!("NSAppearanceNameDarkAqua")
+}
+
+fn appearance_to_theme(appearance: &NSAppearance) -> Theme {
+    let best_match = appearance.bestMatchFromAppearancesWithNames(&NSArray::from_id_slice(&[
+        unsafe { NSAppearanceNameAqua.copy() },
+        dark_appearance_name().copy(),
+    ]));
+    if let Some(best_match) = best_match {
+        if *best_match == *dark_appearance_name() {
+            Theme::Dark
+        } else {
+            Theme::Light
+        }
+    } else {
+        warn!(?appearance, "failed to determine the theme of the appearance");
+        // Default to light in this case
+        Theme::Light
     }
 }
 
-fn set_ns_theme(theme: Option<Theme>, mtm: MainThreadMarker) {
-    let app = NSApplication::sharedApplication(mtm);
-    if app.respondsToSelector(sel!(effectiveAppearance)) {
-        let appearance = theme.map(|t| {
-            let name = match t {
-                Theme::Dark => NSString::from_str("NSAppearanceNameDarkAqua"),
-                Theme::Light => NSString::from_str("NSAppearanceNameAqua"),
-            };
-            NSAppearance::appearanceNamed(&name).unwrap()
-        });
-        app.setAppearance(appearance.as_ref().map(|a| a.as_ref()));
+fn theme_to_appearance(theme: Option<Theme>) -> Option<Retained<NSAppearance>> {
+    let appearance = match theme? {
+        Theme::Light => unsafe { NSAppearance::appearanceNamed(NSAppearanceNameAqua) },
+        Theme::Dark => NSAppearance::appearanceNamed(dark_appearance_name()),
+    };
+    if let Some(appearance) = appearance {
+        Some(appearance)
+    } else {
+        warn!(?theme, "could not find appearance for theme");
+        // Assume system appearance in this case
+        None
     }
 }

src/platform_impl/apple/mod.rs

@@ -0,0 +1,11 @@
+//! Apple/Darwin-specific implementations
+
+#[cfg(target_os = "macos")]
+mod appkit;
+#[cfg(not(target_os = "macos"))]
+mod uikit;
+
+#[cfg(target_os = "macos")]
+pub use self::appkit::*;
+#[cfg(not(target_os = "macos"))]
+pub use self::uikit::*;

src/platform_impl/apple/uikit/app_state.rs

@@ -10,7 +10,7 @@ use std::{fmt, mem, ptr};
 use core_foundation::base::CFRelease;
 use core_foundation::date::CFAbsoluteTimeGetCurrent;
 use core_foundation::runloop::{
-    kCFRunLoopCommonModes, CFRunLoopAddTimer, CFRunLoopGetMain, CFRunLoopRef, CFRunLoopTimerCreate,
+    kCFRunLoopDefaultMode, CFRunLoopAddTimer, CFRunLoopGetMain, CFRunLoopRef, CFRunLoopTimerCreate,
     CFRunLoopTimerInvalidate, CFRunLoopTimerRef, CFRunLoopTimerSetNextFireDate,
 };
 use objc2::rc::Retained;
@@ -40,12 +40,9 @@ macro_rules! bug_assert {
     };
 }
 
-#[derive(Debug)]
-pub(crate) struct HandlePendingUserEvents;
-
 pub(crate) struct EventLoopHandler {
     #[allow(clippy::type_complexity)]
-    pub(crate) handler: Box<dyn FnMut(Event<HandlePendingUserEvents>, &RootActiveEventLoop)>,
+    pub(crate) handler: Box<dyn FnMut(Event, &RootActiveEventLoop)>,
     pub(crate) event_loop: RootActiveEventLoop,
 }
 
@@ -59,14 +56,14 @@ impl fmt::Debug for EventLoopHandler {
 }
 
 impl EventLoopHandler {
-    fn handle_event(&mut self, event: Event<HandlePendingUserEvents>) {
+    fn handle_event(&mut self, event: Event) {
         (self.handler)(event, &self.event_loop)
     }
 }
 
 #[derive(Debug)]
 pub(crate) enum EventWrapper {
-    StaticEvent(Event<HandlePendingUserEvents>),
+    StaticEvent(Event),
     ScaleFactorChanged(ScaleFactorChanged),
 }
 
@@ -88,7 +85,7 @@ enum UserCallbackTransitionResult<'a> {
     },
 }
 
-impl Event<HandlePendingUserEvents> {
+impl Event {
     fn is_redraw(&self) -> bool {
         matches!(self, Event::WindowEvent { event: WindowEvent::RedrawRequested, .. })
     }
@@ -625,7 +622,7 @@ fn handle_user_events(mtm: MainThreadMarker) {
     }
     drop(this);
 
-    handler.handle_event(Event::UserEvent(HandlePendingUserEvents));
+    handler.handle_event(Event::UserWakeUp);
 
     loop {
         let mut this = AppState::get_mut(mtm);
@@ -658,7 +655,7 @@ fn handle_user_events(mtm: MainThreadMarker) {
             }
         }
 
-        handler.handle_event(Event::UserEvent(HandlePendingUserEvents));
+        handler.handle_event(Event::UserWakeUp);
     }
 }
 
@@ -798,25 +795,25 @@ impl EventLoopWaker {
             // future, but that gets changed to fire immediately in did_finish_launching
             let timer = CFRunLoopTimerCreate(
                 ptr::null_mut(),
-                std::f64::MAX,
+                f64::MAX,
                 0.000_000_1,
                 0,
                 0,
                 wakeup_main_loop,
                 ptr::null_mut(),
             );
-            CFRunLoopAddTimer(rl, timer, kCFRunLoopCommonModes);
+            CFRunLoopAddTimer(rl, timer, kCFRunLoopDefaultMode);
 
             EventLoopWaker { timer }
         }
     }
 
     fn stop(&mut self) {
-        unsafe { CFRunLoopTimerSetNextFireDate(self.timer, std::f64::MAX) }
+        unsafe { CFRunLoopTimerSetNextFireDate(self.timer, f64::MAX) }
     }
 
     fn start(&mut self) {
-        unsafe { CFRunLoopTimerSetNextFireDate(self.timer, std::f64::MIN) }
+        unsafe { CFRunLoopTimerSetNextFireDate(self.timer, f64::MIN) }
     }
 
     fn start_at(&mut self, instant: Instant) {

src/platform_impl/apple/uikit/event_loop.rs

@@ -2,27 +2,26 @@ use std::collections::VecDeque;
 use std::ffi::{c_char, c_int, c_void};
 use std::marker::PhantomData;
 use std::ptr::{self, NonNull};
-use std::sync::mpsc::{self, Receiver, Sender};
+use std::sync::atomic::{AtomicBool, Ordering as AtomicOrdering};
+use std::sync::Arc;
 
 use core_foundation::base::{CFIndex, CFRelease};
 use core_foundation::runloop::{
-    kCFRunLoopAfterWaiting, kCFRunLoopBeforeWaiting, kCFRunLoopCommonModes, kCFRunLoopDefaultMode,
-    kCFRunLoopExit, CFRunLoopActivity, CFRunLoopAddObserver, CFRunLoopAddSource, CFRunLoopGetMain,
+    kCFRunLoopAfterWaiting, kCFRunLoopBeforeWaiting, kCFRunLoopDefaultMode, kCFRunLoopExit,
+    CFRunLoopActivity, CFRunLoopAddObserver, CFRunLoopAddSource, CFRunLoopGetMain,
     CFRunLoopObserverCreate, CFRunLoopObserverRef, CFRunLoopSourceContext, CFRunLoopSourceCreate,
     CFRunLoopSourceInvalidate, CFRunLoopSourceRef, CFRunLoopSourceSignal, CFRunLoopWakeUp,
 };
 use objc2::rc::Retained;
 use objc2::{msg_send_id, ClassType};
 use objc2_foundation::{MainThreadMarker, NSString};
-use objc2_ui_kit::{UIApplication, UIApplicationMain, UIDevice, UIScreen, UIUserInterfaceIdiom};
+use objc2_ui_kit::{UIApplication, UIApplicationMain, UIScreen};
 
+use super::app_state::EventLoopHandler;
+use crate::application::ApplicationHandler;
 use crate::error::EventLoopError;
 use crate::event::Event;
-use crate::event_loop::{
-    ActiveEventLoop as RootActiveEventLoop, ControlFlow, DeviceEvents, EventLoopClosed,
-};
-use crate::platform::ios::Idiom;
-use crate::platform_impl::platform::app_state::{EventLoopHandler, HandlePendingUserEvents};
+use crate::event_loop::{ActiveEventLoop as RootActiveEventLoop, ControlFlow, DeviceEvents};
 use crate::window::{CustomCursor, CustomCursorSource};
 
 use super::app_delegate::AppDelegate;
@@ -108,34 +107,44 @@ impl OwnedDisplayHandle {
     }
 }
 
-fn map_user_event<T: 'static>(
-    mut handler: impl FnMut(Event<T>, &RootActiveEventLoop),
-    receiver: mpsc::Receiver<T>,
-) -> impl FnMut(Event<HandlePendingUserEvents>, &RootActiveEventLoop) {
-    move |event, window_target| match event.map_nonuser_event() {
-        Ok(event) => (handler)(event, window_target),
-        Err(_) => {
-            for event in receiver.try_iter() {
-                (handler)(Event::UserEvent(event), window_target);
+fn map_user_event<A: ApplicationHandler>(
+    app: &mut A,
+    proxy_wake_up: Arc<AtomicBool>,
+) -> impl FnMut(Event, &RootActiveEventLoop) + '_ {
+    move |event, window_target| match event {
+        Event::NewEvents(cause) => app.new_events(window_target, cause),
+        Event::WindowEvent { window_id, event } => {
+            app.window_event(window_target, window_id, event)
+        },
+        Event::DeviceEvent { device_id, event } => {
+            app.device_event(window_target, device_id, event)
+        },
+        Event::UserWakeUp => {
+            if proxy_wake_up.swap(false, AtomicOrdering::Relaxed) {
+                app.proxy_wake_up(window_target);
             }
         },
+        Event::Suspended => app.suspended(window_target),
+        Event::Resumed => app.resumed(window_target),
+        Event::AboutToWait => app.about_to_wait(window_target),
+        Event::LoopExiting => app.exiting(window_target),
+        Event::MemoryWarning => app.memory_warning(window_target),
     }
 }
 
-pub struct EventLoop<T: 'static> {
+pub struct EventLoop {
     mtm: MainThreadMarker,
-    sender: Sender<T>,
-    receiver: Receiver<T>,
+    proxy_wake_up: Arc<AtomicBool>,
     window_target: RootActiveEventLoop,
 }
 
 #[derive(Default, Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub(crate) struct PlatformSpecificEventLoopAttributes {}
 
-impl<T: 'static> EventLoop<T> {
+impl EventLoop {
     pub(crate) fn new(
         _: &PlatformSpecificEventLoopAttributes,
-    ) -> Result<EventLoop<T>, EventLoopError> {
+    ) -> Result<EventLoop, EventLoopError> {
         let mtm = MainThreadMarker::new()
             .expect("On iOS, `EventLoop` must be created on the main thread");
 
@@ -148,23 +157,19 @@ impl<T: 'static> EventLoop<T> {
             SINGLETON_INIT = true;
         }
 
-        let (sender, receiver) = mpsc::channel();
-
         // this line sets up the main run loop before `UIApplicationMain`
         setup_control_flow_observers();
 
+        let proxy_wake_up = Arc::new(AtomicBool::new(false));
+
         Ok(EventLoop {
             mtm,
-            sender,
-            receiver,
+            proxy_wake_up,
             window_target: RootActiveEventLoop { p: ActiveEventLoop { mtm }, _marker: PhantomData },
         })
     }
 
-    pub fn run<F>(self, handler: F) -> !
-    where
-        F: FnMut(Event<T>, &RootActiveEventLoop),
-    {
+    pub fn run_app<A: ApplicationHandler>(self, app: &mut A) -> ! {
         let application: Option<Retained<UIApplication>> =
             unsafe { msg_send_id![UIApplication::class(), sharedApplication] };
         assert!(
@@ -174,12 +179,12 @@ impl<T: 'static> EventLoop<T> {
              `EventLoop::run_app` calls `UIApplicationMain` on iOS",
         );
 
-        let handler = map_user_event(handler, self.receiver);
+        let handler = map_user_event(app, self.proxy_wake_up.clone());
 
         let handler = unsafe {
             std::mem::transmute::<
-                Box<dyn FnMut(Event<HandlePendingUserEvents>, &RootActiveEventLoop)>,
-                Box<dyn FnMut(Event<HandlePendingUserEvents>, &RootActiveEventLoop)>,
+                Box<dyn FnMut(Event, &RootActiveEventLoop)>,
+                Box<dyn FnMut(Event, &RootActiveEventLoop)>,
             >(Box::new(handler))
         };
 
@@ -207,8 +212,8 @@ impl<T: 'static> EventLoop<T> {
         unreachable!()
     }
 
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
-        EventLoopProxy::new(self.sender.clone())
+    pub fn create_proxy(&self) -> EventLoopProxy {
+        EventLoopProxy::new(self.proxy_wake_up.clone())
     }
 
     pub fn window_target(&self) -> &RootActiveEventLoop {
@@ -216,35 +221,21 @@ impl<T: 'static> EventLoop<T> {
     }
 }
 
-// EventLoopExtIOS
-impl<T: 'static> EventLoop<T> {
-    pub fn idiom(&self) -> Idiom {
-        match UIDevice::currentDevice(self.mtm).userInterfaceIdiom() {
-            UIUserInterfaceIdiom::Unspecified => Idiom::Unspecified,
-            UIUserInterfaceIdiom::Phone => Idiom::Phone,
-            UIUserInterfaceIdiom::Pad => Idiom::Pad,
-            UIUserInterfaceIdiom::TV => Idiom::TV,
-            UIUserInterfaceIdiom::CarPlay => Idiom::CarPlay,
-            _ => Idiom::Unspecified,
-        }
-    }
-}
-
-pub struct EventLoopProxy<T> {
-    sender: Sender<T>,
+pub struct EventLoopProxy {
+    proxy_wake_up: Arc<AtomicBool>,
     source: CFRunLoopSourceRef,
 }
 
-unsafe impl<T: Send> Send for EventLoopProxy<T> {}
-unsafe impl<T: Send> Sync for EventLoopProxy<T> {}
+unsafe impl Send for EventLoopProxy {}
+unsafe impl Sync for EventLoopProxy {}
 
-impl<T> Clone for EventLoopProxy<T> {
-    fn clone(&self) -> EventLoopProxy<T> {
-        EventLoopProxy::new(self.sender.clone())
+impl Clone for EventLoopProxy {
+    fn clone(&self) -> EventLoopProxy {
+        EventLoopProxy::new(self.proxy_wake_up.clone())
     }
 }
 
-impl<T> Drop for EventLoopProxy<T> {
+impl Drop for EventLoopProxy {
     fn drop(&mut self) {
         unsafe {
             CFRunLoopSourceInvalidate(self.source);
@@ -253,8 +244,8 @@ impl<T> Drop for EventLoopProxy<T> {
     }
 }
 
-impl<T> EventLoopProxy<T> {
-    fn new(sender: Sender<T>) -> EventLoopProxy<T> {
+impl EventLoopProxy {
+    fn new(proxy_wake_up: Arc<AtomicBool>) -> EventLoopProxy {
         unsafe {
             // just wake up the eventloop
             extern "C" fn event_loop_proxy_handler(_: *const c_void) {}
@@ -274,24 +265,22 @@ impl<T> EventLoopProxy<T> {
                 cancel: None,
                 perform: event_loop_proxy_handler,
             };
-            let source =
-                CFRunLoopSourceCreate(ptr::null_mut(), CFIndex::max_value() - 1, &mut context);
-            CFRunLoopAddSource(rl, source, kCFRunLoopCommonModes);
+            let source = CFRunLoopSourceCreate(ptr::null_mut(), CFIndex::MAX - 1, &mut context);
+            CFRunLoopAddSource(rl, source, kCFRunLoopDefaultMode);
             CFRunLoopWakeUp(rl);
 
-            EventLoopProxy { sender, source }
+            EventLoopProxy { proxy_wake_up, source }
         }
     }
 
-    pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
-        self.sender.send(event).map_err(|::std::sync::mpsc::SendError(x)| EventLoopClosed(x))?;
+    pub fn wake_up(&self) {
+        self.proxy_wake_up.store(true, AtomicOrdering::Relaxed);
         unsafe {
             // let the main thread know there's a new event
             CFRunLoopSourceSignal(self.source);
             let rl = CFRunLoopGetMain();
             CFRunLoopWakeUp(rl);
         }
-        Ok(())
     }
 }
 
@@ -358,7 +347,7 @@ fn setup_control_flow_observers() {
             ptr::null_mut(),
             kCFRunLoopAfterWaiting,
             1, // repeat = true
-            CFIndex::min_value(),
+            CFIndex::MIN,
             control_flow_begin_handler,
             ptr::null_mut(),
         );
@@ -378,7 +367,7 @@ fn setup_control_flow_observers() {
             ptr::null_mut(),
             kCFRunLoopExit | kCFRunLoopBeforeWaiting,
             1, // repeat = true
-            CFIndex::max_value(),
+            CFIndex::MAX,
             control_flow_end_handler,
             ptr::null_mut(),
         );

src/platform_impl/apple/uikit/mod.rs

@@ -1,4 +1,3 @@
-#![cfg(ios_platform)]
 #![allow(clippy::let_unit_value)]
 
 mod app_delegate;

src/platform_impl/apple/uikit/monitor.rs

@@ -9,9 +9,9 @@ use objc2::Message;
 use objc2_foundation::{run_on_main, MainThreadBound, MainThreadMarker, NSInteger};
 use objc2_ui_kit::{UIScreen, UIScreenMode};
 
+use super::app_state;
 use crate::dpi::{PhysicalPosition, PhysicalSize};
 use crate::monitor::VideoModeHandle as RootVideoModeHandle;
-use crate::platform_impl::platform::app_state;
 
 // Workaround for `MainThreadBound` implementing almost no traits
 #[derive(Debug)]

src/platform_impl/apple/uikit/view.rs

@@ -14,9 +14,9 @@ use objc2_ui_kit::{
 
 use super::app_state::{self, EventWrapper};
 use super::window::WinitUIWindow;
+use super::DEVICE_ID;
 use crate::dpi::PhysicalPosition;
 use crate::event::{Event, Force, Touch, TouchPhase, WindowEvent};
-use crate::platform_impl::platform::DEVICE_ID;
 use crate::window::{WindowAttributes, WindowId as RootWindowId};
 
 pub struct WinitViewState {

src/platform_impl/apple/uikit/window.rs

@@ -17,15 +17,13 @@ use tracing::{debug, warn};
 use super::app_state::EventWrapper;
 use super::view::WinitView;
 use super::view_controller::WinitViewController;
+use super::{app_state, monitor, ActiveEventLoop, Fullscreen, MonitorHandle};
 use crate::cursor::Cursor;
 use crate::dpi::{LogicalPosition, LogicalSize, PhysicalPosition, PhysicalSize, Position, Size};
 use crate::error::{ExternalError, NotSupportedError, OsError as RootOsError};
 use crate::event::{Event, WindowEvent};
 use crate::icon::Icon;
 use crate::platform::ios::{ScreenEdge, StatusBarStyle, ValidOrientations};
-use crate::platform_impl::platform::{
-    app_state, monitor, ActiveEventLoop, Fullscreen, MonitorHandle,
-};
 use crate::window::{
     CursorGrabMode, ImePurpose, ResizeDirection, Theme, UserAttentionType, WindowAttributes,
     WindowButtons, WindowId as RootWindowId, WindowLevel,

src/platform_impl/linux/mod.rs

@@ -11,6 +11,8 @@ use std::{env, fmt};
 #[cfg(x11_platform)]
 use std::{ffi::CStr, mem::MaybeUninit, os::raw::*, sync::Mutex};
 
+use crate::application::ApplicationHandler;
+use crate::platform::pump_events::PumpStatus;
 #[cfg(x11_platform)]
 use crate::utils::Lazy;
 use smol_str::SmolStr;
@@ -19,12 +21,9 @@ use smol_str::SmolStr;
 use self::x11::{X11Error, XConnection, XError, XNotSupported};
 use crate::dpi::{PhysicalPosition, PhysicalSize, Position, Size};
 use crate::error::{EventLoopError, ExternalError, NotSupportedError, OsError as RootOsError};
-use crate::event_loop::{
-    ActiveEventLoop as RootELW, AsyncRequestSerial, ControlFlow, DeviceEvents, EventLoopClosed,
-};
+use crate::event_loop::{AsyncRequestSerial, ControlFlow, DeviceEvents};
 use crate::icon::Icon;
 use crate::keyboard::Key;
-use crate::platform::pump_events::PumpStatus;
 #[cfg(x11_platform)]
 use crate::platform::x11::{WindowType as XWindowType, XlibErrorHook};
 use crate::window::{
@@ -692,27 +691,22 @@ unsafe extern "C" fn x_error_callback(
     0
 }
 
-pub enum EventLoop<T: 'static> {
+pub enum EventLoop {
     #[cfg(wayland_platform)]
-    Wayland(Box<wayland::EventLoop<T>>),
+    Wayland(Box<wayland::EventLoop>),
     #[cfg(x11_platform)]
-    X(x11::EventLoop<T>),
+    X(x11::EventLoop),
 }
 
-pub enum EventLoopProxy<T: 'static> {
+#[derive(Clone)]
+pub enum EventLoopProxy {
     #[cfg(x11_platform)]
-    X(x11::EventLoopProxy<T>),
+    X(x11::EventLoopProxy),
     #[cfg(wayland_platform)]
-    Wayland(wayland::EventLoopProxy<T>),
+    Wayland(wayland::EventLoopProxy),
 }
 
-impl<T: 'static> Clone for EventLoopProxy<T> {
-    fn clone(&self) -> Self {
-        x11_or_wayland!(match self; EventLoopProxy(proxy) => proxy.clone(); as EventLoopProxy)
-    }
-}
-
-impl<T: 'static> EventLoop<T> {
+impl EventLoop {
     pub(crate) fn new(
         attributes: &PlatformSpecificEventLoopAttributes,
     ) -> Result<Self, EventLoopError> {
@@ -771,12 +765,12 @@ impl<T: 'static> EventLoop<T> {
     }
 
     #[cfg(wayland_platform)]
-    fn new_wayland_any_thread() -> Result<EventLoop<T>, EventLoopError> {
+    fn new_wayland_any_thread() -> Result<EventLoop, EventLoopError> {
         wayland::EventLoop::new().map(|evlp| EventLoop::Wayland(Box::new(evlp)))
     }
 
     #[cfg(x11_platform)]
-    fn new_x11_any_thread() -> Result<EventLoop<T>, EventLoopError> {
+    fn new_x11_any_thread() -> Result<EventLoop, EventLoopError> {
         let xconn = match X11_BACKEND.lock().unwrap().as_ref() {
             Ok(xconn) => xconn.clone(),
             Err(_) => return Err(EventLoopError::NotSupported(NotSupportedError::new())),
@@ -795,29 +789,27 @@ impl<T: 'static> EventLoop<T> {
         }
     }
 
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
+    pub fn create_proxy(&self) -> EventLoopProxy {
         x11_or_wayland!(match self; EventLoop(evlp) => evlp.create_proxy(); as EventLoopProxy)
     }
 
-    pub fn run<F>(mut self, callback: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(crate::event::Event<T>, &RootELW),
-    {
-        self.run_on_demand(callback)
+    pub fn run_app<A: ApplicationHandler>(self, app: &mut A) -> Result<(), EventLoopError> {
+        x11_or_wayland!(match self; EventLoop(evlp) => evlp.run_app(app))
     }
 
-    pub fn run_on_demand<F>(&mut self, callback: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(crate::event::Event<T>, &RootELW),
-    {
-        x11_or_wayland!(match self; EventLoop(evlp) => evlp.run_on_demand(callback))
+    pub fn run_app_on_demand<A: ApplicationHandler>(
+        &mut self,
+        app: &mut A,
+    ) -> Result<(), EventLoopError> {
+        x11_or_wayland!(match self; EventLoop(evlp) => evlp.run_app_on_demand(app))
     }
 
-    pub fn pump_events<F>(&mut self, timeout: Option<Duration>, callback: F) -> PumpStatus
-    where
-        F: FnMut(crate::event::Event<T>, &RootELW),
-    {
-        x11_or_wayland!(match self; EventLoop(evlp) => evlp.pump_events(timeout, callback))
+    pub fn pump_app_events<A: ApplicationHandler>(
+        &mut self,
+        timeout: Option<Duration>,
+        app: &mut A,
+    ) -> PumpStatus {
+        x11_or_wayland!(match self; EventLoop(evlp) => evlp.pump_app_events(timeout, app))
     }
 
     pub fn window_target(&self) -> &crate::event_loop::ActiveEventLoop {
@@ -825,21 +817,21 @@ impl<T: 'static> EventLoop<T> {
     }
 }
 
-impl<T> AsFd for EventLoop<T> {
+impl AsFd for EventLoop {
     fn as_fd(&self) -> BorrowedFd<'_> {
         x11_or_wayland!(match self; EventLoop(evlp) => evlp.as_fd())
     }
 }
 
-impl<T> AsRawFd for EventLoop<T> {
+impl AsRawFd for EventLoop {
     fn as_raw_fd(&self) -> RawFd {
         x11_or_wayland!(match self; EventLoop(evlp) => evlp.as_raw_fd())
     }
 }
 
-impl<T: 'static> EventLoopProxy<T> {
-    pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
-        x11_or_wayland!(match self; EventLoopProxy(proxy) => proxy.send_event(event))
+impl EventLoopProxy {
+    pub fn wake_up(&self) {
+        x11_or_wayland!(match self; EventLoopProxy(proxy) => proxy.wake_up())
     }
 }
 

src/platform_impl/linux/wayland/event_loop/mod.rs

@@ -5,7 +5,6 @@ use std::io::Result as IOResult;
 use std::marker::PhantomData;
 use std::mem;
 use std::os::unix::io::{AsFd, AsRawFd, BorrowedFd, RawFd};
-use std::rc::Rc;
 use std::sync::atomic::Ordering;
 use std::sync::{Arc, Mutex};
 use std::time::{Duration, Instant};
@@ -14,6 +13,7 @@ use sctk::reexports::calloop::Error as CalloopError;
 use sctk::reexports::calloop_wayland_source::WaylandSource;
 use sctk::reexports::client::{globals, Connection, QueueHandle};
 
+use crate::application::ApplicationHandler;
 use crate::cursor::OnlyCursorImage;
 use crate::dpi::LogicalSize;
 use crate::error::{EventLoopError, OsError as RootOsError};
@@ -39,7 +39,7 @@ use super::{logical_to_physical_rounded, DeviceId, WaylandError, WindowId};
 type WaylandDispatcher = calloop::Dispatcher<'static, WaylandSource<WinitState>, WinitState>;
 
 /// The Wayland event loop.
-pub struct EventLoop<T: 'static> {
+pub struct EventLoop {
     /// Has `run` or `run_on_demand` been called or a call to `pump_events` that starts the loop
     loop_running: bool,
 
@@ -47,13 +47,8 @@ pub struct EventLoop<T: 'static> {
     compositor_updates: Vec<WindowCompositorUpdate>,
     window_ids: Vec<WindowId>,
 
-    /// Sender of user events.
-    user_events_sender: calloop::channel::Sender<T>,
-
-    // XXX can't remove RefCell out of here, unless we can plumb generics into the `Window`, which
-    // we don't really want, since it'll break public API by a lot.
-    /// Pending events from the user.
-    pending_user_events: Rc<RefCell<Vec<T>>>,
+    /// Event loop proxy
+    event_loop_proxy: EventLoopProxy,
 
     /// The Wayland dispatcher to has raw access to the queue when needed, such as
     /// when creating a new window.
@@ -70,8 +65,8 @@ pub struct EventLoop<T: 'static> {
     event_loop: calloop::EventLoop<'static, WinitState>,
 }
 
-impl<T: 'static> EventLoop<T> {
-    pub fn new() -> Result<EventLoop<T>, EventLoopError> {
+impl EventLoop {
+    pub fn new() -> Result<EventLoop, EventLoopError> {
         macro_rules! map_err {
             ($e:expr, $err:expr) => {
                 $e.map_err(|error| os_error!($err(error).into()))
@@ -114,16 +109,12 @@ impl<T: 'static> EventLoop<T> {
         )?;
 
         // Setup the user proxy.
-        let pending_user_events = Rc::new(RefCell::new(Vec::new()));
-        let pending_user_events_clone = pending_user_events.clone();
-        let (user_events_sender, user_events_channel) = calloop::channel::channel();
+        let (ping, ping_source) = calloop::ping::make_ping().unwrap();
         let result = event_loop
             .handle()
-            .insert_source(user_events_channel, move |event, _, winit_state: &mut WinitState| {
-                if let calloop::channel::Event::Msg(msg) = event {
-                    winit_state.dispatched_events = true;
-                    pending_user_events_clone.borrow_mut().push(msg);
-                }
+            .insert_source(ping_source, move |_, _, winit_state: &mut WinitState| {
+                winit_state.dispatched_events = true;
+                winit_state.proxy_wake_up = true;
             })
             .map_err(|error| error.error);
         map_err!(result, WaylandError::Calloop)?;
@@ -161,8 +152,7 @@ impl<T: 'static> EventLoop<T> {
             window_ids: Vec::new(),
             connection,
             wayland_dispatcher,
-            user_events_sender,
-            pending_user_events,
+            event_loop_proxy: EventLoopProxy::new(ping),
             event_loop,
             window_target: RootActiveEventLoop {
                 p: PlatformActiveEventLoop::Wayland(window_target),
@@ -173,12 +163,16 @@ impl<T: 'static> EventLoop<T> {
         Ok(event_loop)
     }
 
-    pub fn run_on_demand<F>(&mut self, mut event_handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(Event<T>, &RootActiveEventLoop),
-    {
+    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+        self.run_app_on_demand(app)
+    }
+
+    pub fn run_app_on_demand<A: ApplicationHandler>(
+        &mut self,
+        app: &mut A,
+    ) -> Result<(), EventLoopError> {
         let exit = loop {
-            match self.pump_events(None, &mut event_handler) {
+            match self.pump_app_events(None, app) {
                 PumpStatus::Exit(0) => {
                     break Ok(());
                 },
@@ -200,26 +194,27 @@ impl<T: 'static> EventLoop<T> {
         exit
     }
 
-    pub fn pump_events<F>(&mut self, timeout: Option<Duration>, mut callback: F) -> PumpStatus
-    where
-        F: FnMut(Event<T>, &RootActiveEventLoop),
-    {
+    pub fn pump_app_events<A: ApplicationHandler>(
+        &mut self,
+        timeout: Option<Duration>,
+        app: &mut A,
+    ) -> PumpStatus {
         if !self.loop_running {
             self.loop_running = true;
 
             // Run the initial loop iteration.
-            self.single_iteration(&mut callback, StartCause::Init);
+            self.single_iteration(app, StartCause::Init);
         }
 
         // Consider the possibility that the `StartCause::Init` iteration could
         // request to Exit.
         if !self.exiting() {
-            self.poll_events_with_timeout(timeout, &mut callback);
+            self.poll_events_with_timeout(timeout, app);
         }
         if let Some(code) = self.exit_code() {
             self.loop_running = false;
 
-            callback(Event::LoopExiting, self.window_target());
+            app.exiting(&self.window_target);
 
             PumpStatus::Exit(code)
         } else {
@@ -227,10 +222,11 @@ impl<T: 'static> EventLoop<T> {
         }
     }
 
-    pub fn poll_events_with_timeout<F>(&mut self, mut timeout: Option<Duration>, mut callback: F)
-    where
-        F: FnMut(Event<T>, &RootActiveEventLoop),
-    {
+    pub fn poll_events_with_timeout<A: ApplicationHandler>(
+        &mut self,
+        mut timeout: Option<Duration>,
+        app: &mut A,
+    ) {
         let cause = loop {
             let start = Instant::now();
 
@@ -292,13 +288,10 @@ impl<T: 'static> EventLoop<T> {
             break cause;
         };
 
-        self.single_iteration(&mut callback, cause);
+        self.single_iteration(app, cause);
     }
 
-    fn single_iteration<F>(&mut self, callback: &mut F, cause: StartCause)
-    where
-        F: FnMut(Event<T>, &RootActiveEventLoop),
-    {
+    fn single_iteration<A: ApplicationHandler>(&mut self, app: &mut A, cause: StartCause) {
         // NOTE currently just indented to simplify the diff
 
         // We retain these grow-only scratch buffers as part of the EventLoop
@@ -309,18 +302,17 @@ impl<T: 'static> EventLoop<T> {
         let mut buffer_sink = std::mem::take(&mut self.buffer_sink);
         let mut window_ids = std::mem::take(&mut self.window_ids);
 
-        callback(Event::NewEvents(cause), &self.window_target);
+        app.new_events(&self.window_target, cause);
 
         // NB: For consistency all platforms must emit a 'resumed' event even though Wayland
         // applications don't themselves have a formal suspend/resume lifecycle.
         if cause == StartCause::Init {
-            callback(Event::Resumed, &self.window_target);
+            app.resumed(&self.window_target);
         }
 
-        // Handle pending user events. We don't need back buffer, since we can't dispatch
-        // user events indirectly via callback to the user.
-        for user_event in self.pending_user_events.borrow_mut().drain(..) {
-            callback(Event::UserEvent(user_event), &self.window_target);
+        // Indicate user wake up.
+        if self.with_state(|state| mem::take(&mut state.proxy_wake_up)) {
+            app.proxy_wake_up(&self.window_target);
         }
 
         // Drain the pending compositor updates.
@@ -341,18 +333,13 @@ impl<T: 'static> EventLoop<T> {
                 let old_physical_size = physical_size;
 
                 let new_inner_size = Arc::new(Mutex::new(physical_size));
-                callback(
-                    Event::WindowEvent {
-                        window_id: crate::window::WindowId(window_id),
-                        event: WindowEvent::ScaleFactorChanged {
-                            scale_factor,
-                            inner_size_writer: InnerSizeWriter::new(Arc::downgrade(
-                                &new_inner_size,
-                            )),
-                        },
-                    },
-                    &self.window_target,
-                );
+                let root_window_id = crate::window::WindowId(window_id);
+                let event = WindowEvent::ScaleFactorChanged {
+                    scale_factor,
+                    inner_size_writer: InnerSizeWriter::new(Arc::downgrade(&new_inner_size)),
+                };
+
+                app.window_event(&self.window_target, root_window_id, event);
 
                 let physical_size = *new_inner_size.lock().unwrap();
                 drop(new_inner_size);
@@ -395,23 +382,14 @@ impl<T: 'static> EventLoop<T> {
                     size
                 });
 
-                callback(
-                    Event::WindowEvent {
-                        window_id: crate::window::WindowId(window_id),
-                        event: WindowEvent::Resized(physical_size),
-                    },
-                    &self.window_target,
-                );
+                let window_id = crate::window::WindowId(window_id);
+                let event = WindowEvent::Resized(physical_size);
+                app.window_event(&self.window_target, window_id, event);
             }
 
             if compositor_update.close_window {
-                callback(
-                    Event::WindowEvent {
-                        window_id: crate::window::WindowId(window_id),
-                        event: WindowEvent::CloseRequested,
-                    },
-                    &self.window_target,
-                );
+                let window_id = crate::window::WindowId(window_id);
+                app.window_event(&self.window_target, window_id, WindowEvent::CloseRequested);
             }
         }
 
@@ -420,8 +398,15 @@ impl<T: 'static> EventLoop<T> {
             buffer_sink.append(&mut state.window_events_sink.lock().unwrap());
         });
         for event in buffer_sink.drain() {
-            let event = event.map_nonuser_event().unwrap();
-            callback(event, &self.window_target);
+            match event {
+                Event::WindowEvent { window_id, event } => {
+                    app.window_event(&self.window_target, window_id, event)
+                },
+                Event::DeviceEvent { device_id, event } => {
+                    app.device_event(&self.window_target, device_id, event)
+                },
+                _ => unreachable!("event which is neither device nor window event."),
+            }
         }
 
         // Handle non-synthetic events.
@@ -429,8 +414,15 @@ impl<T: 'static> EventLoop<T> {
             buffer_sink.append(&mut state.events_sink);
         });
         for event in buffer_sink.drain() {
-            let event = event.map_nonuser_event().unwrap();
-            callback(event, &self.window_target);
+            match event {
+                Event::WindowEvent { window_id, event } => {
+                    app.window_event(&self.window_target, window_id, event)
+                },
+                Event::DeviceEvent { device_id, event } => {
+                    app.device_event(&self.window_target, device_id, event)
+                },
+                _ => unreachable!("event which is neither device nor window event."),
+            }
         }
 
         // Collect the window ids
@@ -466,10 +458,8 @@ impl<T: 'static> EventLoop<T> {
             });
 
             if let Some(event) = event {
-                callback(
-                    Event::WindowEvent { window_id: crate::window::WindowId(*window_id), event },
-                    &self.window_target,
-                );
+                let window_id = crate::window::WindowId(*window_id);
+                app.window_event(&self.window_target, window_id, event);
             }
         }
 
@@ -479,7 +469,7 @@ impl<T: 'static> EventLoop<T> {
         });
 
         // This is always the last event we dispatch before poll again
-        callback(Event::AboutToWait, &self.window_target);
+        app.about_to_wait(&self.window_target);
 
         // Update the window frames and schedule redraws.
         let mut wake_up = false;
@@ -523,8 +513,8 @@ impl<T: 'static> EventLoop<T> {
     }
 
     #[inline]
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
-        EventLoopProxy::new(self.user_events_sender.clone())
+    pub fn create_proxy(&self) -> EventLoopProxy {
+        self.event_loop_proxy.clone()
     }
 
     #[inline]
@@ -586,13 +576,13 @@ impl<T: 'static> EventLoop<T> {
     }
 }
 
-impl<T> AsFd for EventLoop<T> {
+impl AsFd for EventLoop {
     fn as_fd(&self) -> BorrowedFd<'_> {
         self.event_loop.as_fd()
     }
 }
 
-impl<T> AsRawFd for EventLoop<T> {
+impl AsRawFd for EventLoop {
     fn as_raw_fd(&self) -> RawFd {
         self.event_loop.as_raw_fd()
     }

src/platform_impl/linux/wayland/event_loop/proxy.rs

@@ -1,28 +1,19 @@
 //! An event loop proxy.
 
-use std::sync::mpsc::SendError;
-
-use sctk::reexports::calloop::channel::Sender;
-
-use crate::event_loop::EventLoopClosed;
+use sctk::reexports::calloop::ping::Ping;
 
 /// A handle that can be sent across the threads and used to wake up the `EventLoop`.
-pub struct EventLoopProxy<T: 'static> {
-    user_events_sender: Sender<T>,
+#[derive(Clone)]
+pub struct EventLoopProxy {
+    ping: Ping,
 }
 
-impl<T: 'static> Clone for EventLoopProxy<T> {
-    fn clone(&self) -> Self {
-        EventLoopProxy { user_events_sender: self.user_events_sender.clone() }
-    }
-}
-
-impl<T: 'static> EventLoopProxy<T> {
-    pub fn new(user_events_sender: Sender<T>) -> Self {
-        Self { user_events_sender }
+impl EventLoopProxy {
+    pub fn new(ping: Ping) -> Self {
+        Self { ping }
     }
 
-    pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
-        self.user_events_sender.send(event).map_err(|SendError(error)| EventLoopClosed(error))
+    pub fn wake_up(&self) {
+        self.ping.ping();
     }
 }

src/platform_impl/linux/wayland/event_loop/sink.rs

@@ -12,7 +12,7 @@ use super::{DeviceId, WindowId};
 /// to the winit's user.
 #[derive(Default)]
 pub struct EventSink {
-    pub window_events: Vec<Event<()>>,
+    pub(crate) window_events: Vec<Event>,
 }
 
 impl EventSink {
@@ -47,7 +47,7 @@ impl EventSink {
     }
 
     #[inline]
-    pub fn drain(&mut self) -> Drain<'_, Event<()>> {
+    pub(crate) fn drain(&mut self) -> Drain<'_, Event> {
         self.window_events.drain(..)
     }
 }

src/platform_impl/linux/wayland/mod.rs

@@ -1,5 +1,3 @@
-#![cfg(wayland_platform)]
-
 //! Winit's Wayland backend.
 
 use std::fmt::Display;

src/platform_impl/linux/wayland/state.rs

@@ -115,6 +115,9 @@ pub struct WinitState {
     /// Whether we have dispatched events to the user thus we want to
     /// send `AboutToWait` and normally wakeup the user.
     pub dispatched_events: bool,
+
+    /// Whether the user initiated a wake up.
+    pub proxy_wake_up: bool,
 }
 
 impl WinitState {
@@ -192,6 +195,7 @@ impl WinitState {
             loop_handle,
             // Make it true by default.
             dispatched_events: true,
+            proxy_wake_up: false,
         })
     }
 

src/platform_impl/linux/x11/event_processor.rs

@@ -72,9 +72,9 @@ pub struct EventProcessor {
 }
 
 impl EventProcessor {
-    pub fn process_event<T: 'static, F>(&mut self, xev: &mut XEvent, mut callback: F)
+    pub(crate) fn process_event<F>(&mut self, xev: &mut XEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         self.process_xevent(xev, &mut callback);
 
@@ -139,9 +139,9 @@ impl EventProcessor {
         }
     }
 
-    fn process_xevent<T: 'static, F>(&mut self, xev: &mut XEvent, mut callback: F)
+    fn process_xevent<F>(&mut self, xev: &mut XEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let event_type = xev.get_type();
 
@@ -387,9 +387,9 @@ impl EventProcessor {
         }
     }
 
-    fn client_message<T: 'static, F>(&mut self, xev: &XClientMessageEvent, mut callback: F)
+    fn client_message<F>(&mut self, xev: &XClientMessageEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
         let atoms = wt.xconn.atoms();
@@ -434,7 +434,7 @@ impl EventProcessor {
             let flags = xev.data.get_long(1);
             let version = flags >> 24;
             self.dnd.version = Some(version);
-            let has_more_types = flags - (flags & (c_long::max_value() - 1)) == 1;
+            let has_more_types = flags - (flags & (c_long::MAX - 1)) == 1;
             if !has_more_types {
                 let type_list = vec![
                     xev.data.get_long(2) as xproto::Atom,
@@ -552,9 +552,9 @@ impl EventProcessor {
         }
     }
 
-    fn selection_notify<T: 'static, F>(&mut self, xev: &XSelectionEvent, mut callback: F)
+    fn selection_notify<F>(&mut self, xev: &XSelectionEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
         let atoms = wt.xconn.atoms();
@@ -586,9 +586,9 @@ impl EventProcessor {
         }
     }
 
-    fn configure_notify<T: 'static, F>(&self, xev: &XConfigureEvent, mut callback: F)
+    fn configure_notify<F>(&self, xev: &XConfigureEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -781,9 +781,9 @@ impl EventProcessor {
         });
     }
 
-    fn map_notify<T: 'static, F>(&self, xev: &XMapEvent, mut callback: F)
+    fn map_notify<F>(&self, xev: &XMapEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let window = xev.window as xproto::Window;
         let window_id = mkwid(window);
@@ -799,9 +799,9 @@ impl EventProcessor {
         callback(&self.target, event);
     }
 
-    fn destroy_notify<T: 'static, F>(&self, xev: &XDestroyWindowEvent, mut callback: F)
+    fn destroy_notify<F>(&self, xev: &XDestroyWindowEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -823,9 +823,9 @@ impl EventProcessor {
         callback(&self.target, Event::WindowEvent { window_id, event: WindowEvent::Destroyed });
     }
 
-    fn property_notify<T: 'static, F>(&mut self, xev: &XPropertyEvent, mut callback: F)
+    fn property_notify<F>(&mut self, xev: &XPropertyEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
         let atoms = wt.x_connection().atoms();
@@ -838,9 +838,9 @@ impl EventProcessor {
         }
     }
 
-    fn visibility_notify<T: 'static, F>(&self, xev: &XVisibilityEvent, mut callback: F)
+    fn visibility_notify<F>(&self, xev: &XVisibilityEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let xwindow = xev.window as xproto::Window;
 
@@ -855,9 +855,9 @@ impl EventProcessor {
         });
     }
 
-    fn expose<T: 'static, F>(&self, xev: &XExposeEvent, mut callback: F)
+    fn expose<F>(&self, xev: &XExposeEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         // Multiple Expose events may be received for subareas of a window.
         // We issue `RedrawRequested` only for the last event of such a series.
@@ -871,13 +871,9 @@ impl EventProcessor {
         }
     }
 
-    fn xinput_key_input<T: 'static, F>(
-        &mut self,
-        xev: &mut XKeyEvent,
-        state: ElementState,
-        mut callback: F,
-    ) where
-        F: FnMut(&RootAEL, Event<T>),
+    fn xinput_key_input<F>(&mut self, xev: &mut XKeyEvent, state: ElementState, mut callback: F)
+    where
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -989,13 +985,13 @@ impl EventProcessor {
         }
     }
 
-    fn send_synthic_modifier_from_core<T: 'static, F>(
+    fn send_synthic_modifier_from_core<F>(
         &mut self,
         window_id: crate::window::WindowId,
         state: u16,
         mut callback: F,
     ) where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let keymap = match self.xkb_context.keymap_mut() {
             Some(keymap) => keymap,
@@ -1022,13 +1018,9 @@ impl EventProcessor {
         callback(&self.target, event);
     }
 
-    fn xinput2_button_input<T: 'static, F>(
-        &self,
-        event: &XIDeviceEvent,
-        state: ElementState,
-        mut callback: F,
-    ) where
-        F: FnMut(&RootAEL, Event<T>),
+    fn xinput2_button_input<F>(&self, event: &XIDeviceEvent, state: ElementState, mut callback: F)
+    where
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
         let window_id = mkwid(event.event as xproto::Window);
@@ -1079,9 +1071,9 @@ impl EventProcessor {
         callback(&self.target, event);
     }
 
-    fn xinput2_mouse_motion<T: 'static, F>(&self, event: &XIDeviceEvent, mut callback: F)
+    fn xinput2_mouse_motion<F>(&self, event: &XIDeviceEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -1157,9 +1149,9 @@ impl EventProcessor {
         }
     }
 
-    fn xinput2_mouse_enter<T: 'static, F>(&self, event: &XIEnterEvent, mut callback: F)
+    fn xinput2_mouse_enter<F>(&self, event: &XIEnterEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -1202,9 +1194,9 @@ impl EventProcessor {
         }
     }
 
-    fn xinput2_mouse_left<T: 'static, F>(&self, event: &XILeaveEvent, mut callback: F)
+    fn xinput2_mouse_left<F>(&self, event: &XILeaveEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
         let window = event.event as xproto::Window;
@@ -1225,9 +1217,9 @@ impl EventProcessor {
         }
     }
 
-    fn xinput2_focused<T: 'static, F>(&mut self, xev: &XIFocusInEvent, mut callback: F)
+    fn xinput2_focused<F>(&mut self, xev: &XIFocusInEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
         let window = xev.event as xproto::Window;
@@ -1284,9 +1276,9 @@ impl EventProcessor {
         callback(&self.target, event);
     }
 
-    fn xinput2_unfocused<T: 'static, F>(&mut self, xev: &XIFocusOutEvent, mut callback: F)
+    fn xinput2_unfocused<F>(&mut self, xev: &XIFocusOutEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
         let window = xev.event as xproto::Window;
@@ -1336,13 +1328,9 @@ impl EventProcessor {
         }
     }
 
-    fn xinput2_touch<T: 'static, F>(
-        &mut self,
-        xev: &XIDeviceEvent,
-        phase: TouchPhase,
-        mut callback: F,
-    ) where
-        F: FnMut(&RootAEL, Event<T>),
+    fn xinput2_touch<F>(&mut self, xev: &XIDeviceEvent, phase: TouchPhase, mut callback: F)
+    where
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -1382,13 +1370,9 @@ impl EventProcessor {
         }
     }
 
-    fn xinput2_raw_button_input<T: 'static, F>(
-        &self,
-        xev: &XIRawEvent,
-        state: ElementState,
-        mut callback: F,
-    ) where
-        F: FnMut(&RootAEL, Event<T>),
+    fn xinput2_raw_button_input<F>(&self, xev: &XIRawEvent, state: ElementState, mut callback: F)
+    where
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -1404,9 +1388,9 @@ impl EventProcessor {
         }
     }
 
-    fn xinput2_raw_mouse_motion<T: 'static, F>(&self, xev: &XIRawEvent, mut callback: F)
+    fn xinput2_raw_mouse_motion<F>(&self, xev: &XIRawEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -1464,13 +1448,9 @@ impl EventProcessor {
         }
     }
 
-    fn xinput2_raw_key_input<T: 'static, F>(
-        &mut self,
-        xev: &XIRawEvent,
-        state: ElementState,
-        mut callback: F,
-    ) where
-        F: FnMut(&RootAEL, Event<T>),
+    fn xinput2_raw_key_input<F>(&mut self, xev: &XIRawEvent, state: ElementState, mut callback: F)
+    where
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -1490,9 +1470,9 @@ impl EventProcessor {
         });
     }
 
-    fn xinput2_hierarchy_changed<T: 'static, F>(&mut self, xev: &XIHierarchyEvent, mut callback: F)
+    fn xinput2_hierarchy_changed<F>(&mut self, xev: &XIHierarchyEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -1517,9 +1497,9 @@ impl EventProcessor {
         }
     }
 
-    fn xkb_event<T: 'static, F>(&mut self, xev: &XkbAnyEvent, mut callback: F)
+    fn xkb_event<F>(&mut self, xev: &XkbAnyEvent, mut callback: F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
         match xev.xkb_type {
@@ -1596,14 +1576,14 @@ impl EventProcessor {
         }
     }
 
-    pub fn update_mods_from_xinput2_event<T: 'static, F>(
+    pub(crate) fn update_mods_from_xinput2_event<F>(
         &mut self,
         mods: &XIModifierState,
         group: &XIModifierState,
         force: bool,
         mut callback: F,
     ) where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         if let Some(state) = self.xkb_context.state_mut() {
             state.update_modifiers(
@@ -1627,12 +1607,9 @@ impl EventProcessor {
         }
     }
 
-    fn update_mods_from_query<T: 'static, F>(
-        &mut self,
-        window_id: crate::window::WindowId,
-        mut callback: F,
-    ) where
-        F: FnMut(&RootAEL, Event<T>),
+    fn update_mods_from_query<F>(&mut self, window_id: crate::window::WindowId, mut callback: F)
+    where
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
 
@@ -1661,13 +1638,13 @@ impl EventProcessor {
         self.send_modifiers(window_id, mods.into(), true, &mut callback)
     }
 
-    pub fn update_mods_from_core_event<T: 'static, F>(
+    pub(crate) fn update_mods_from_core_event<F>(
         &mut self,
         window_id: crate::window::WindowId,
         state: u16,
         mut callback: F,
     ) where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let xkb_mask = self.xkb_mod_mask_from_core(state);
         let xkb_state = match self.xkb_context.state_mut() {
@@ -1740,7 +1717,7 @@ impl EventProcessor {
     ///
     /// The event won't be sent when the `modifiers` match the previously `sent` modifiers value,
     /// unless `force` is passed. The `force` should be passed when the active window changes.
-    fn send_modifiers<T: 'static, F: FnMut(&RootAEL, Event<T>)>(
+    fn send_modifiers<F: FnMut(&RootAEL, Event)>(
         &self,
         window_id: crate::window::WindowId,
         modifiers: ModifiersState,
@@ -1758,14 +1735,14 @@ impl EventProcessor {
         }
     }
 
-    fn handle_pressed_keys<T: 'static, F>(
+    fn handle_pressed_keys<F>(
         target: &RootAEL,
         window_id: crate::window::WindowId,
         state: ElementState,
         xkb_context: &mut Context,
         callback: &mut F,
     ) where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let device_id = mkdid(util::VIRTUAL_CORE_KEYBOARD);
 
@@ -1800,9 +1777,9 @@ impl EventProcessor {
         }
     }
 
-    fn process_dpi_change<T: 'static, F>(&self, callback: &mut F)
+    fn process_dpi_change<F>(&self, callback: &mut F)
     where
-        F: FnMut(&RootAEL, Event<T>),
+        F: FnMut(&RootAEL, Event),
     {
         let wt = Self::window_target(&self.target);
         wt.xconn.reload_database().expect("failed to reload Xft database");

src/platform_impl/linux/x11/ime/context.rs

@@ -158,7 +158,9 @@ struct PreeditCallbacks {
 impl PreeditCallbacks {
     pub fn new(client_data: ffi::XPointer) -> PreeditCallbacks {
         let start_callback = create_xim_callback(client_data, unsafe {
-            mem::transmute(preedit_start_callback as usize)
+            mem::transmute::<usize, unsafe extern "C" fn(ffi::XIM, ffi::XPointer, ffi::XPointer)>(
+                preedit_start_callback as usize,
+            )
         });
         let done_callback = create_xim_callback(client_data, preedit_done_callback);
         let caret_callback = create_xim_callback(client_data, preedit_caret_callback);

src/platform_impl/linux/x11/mod.rs

@@ -1,5 +1,3 @@
-#![cfg(x11_platform)]
-
 use std::cell::{Cell, RefCell};
 use std::collections::{HashMap, HashSet, VecDeque};
 use std::ffi::CStr;
@@ -11,7 +9,7 @@ use std::os::unix::io::{AsFd, AsRawFd, BorrowedFd, RawFd};
 use std::sync::mpsc::{self, Receiver, Sender, TryRecvError};
 use std::sync::{Arc, Weak};
 use std::time::{Duration, Instant};
-use std::{fmt, ptr, slice, str};
+use std::{fmt, mem, ptr, slice, str};
 
 use calloop::generic::Generic;
 use calloop::ping::Ping;
@@ -27,9 +25,10 @@ use x11rb::protocol::xproto::{self, ConnectionExt as _};
 use x11rb::x11_utils::X11Error as LogicalError;
 use x11rb::xcb_ffi::ReplyOrIdError;
 
+use crate::application::ApplicationHandler;
 use crate::error::{EventLoopError, OsError as RootOsError};
 use crate::event::{Event, StartCause, WindowEvent};
-use crate::event_loop::{ActiveEventLoop as RootAEL, ControlFlow, DeviceEvents, EventLoopClosed};
+use crate::event_loop::{ActiveEventLoop as RootAEL, ControlFlow, DeviceEvents};
 use crate::platform::pump_events::PumpStatus;
 use crate::platform_impl::common::xkb::Context;
 use crate::platform_impl::platform::{min_timeout, WindowId};
@@ -82,12 +81,11 @@ impl<T> Clone for WakeSender<T> {
 }
 
 impl<T> WakeSender<T> {
-    pub fn send(&self, t: T) -> Result<(), EventLoopClosed<T>> {
-        let res = self.sender.send(t).map_err(|e| EventLoopClosed(e.0));
+    pub fn send(&self, t: T) {
+        let res = self.sender.send(t);
         if res.is_ok() {
             self.waker.ping();
         }
-        res
     }
 }
 
@@ -142,15 +140,13 @@ pub struct ActiveEventLoop {
     device_events: Cell<DeviceEvents>,
 }
 
-pub struct EventLoop<T: 'static> {
+pub struct EventLoop {
     loop_running: bool,
     event_loop: Loop<'static, EventLoopState>,
-    waker: calloop::ping::Ping,
     event_processor: EventProcessor,
     redraw_receiver: PeekableReceiver<WindowId>,
-    user_receiver: PeekableReceiver<T>,
     activation_receiver: PeekableReceiver<ActivationToken>,
-    user_sender: Sender<T>,
+    event_loop_proxy: EventLoopProxy,
 
     /// The current state of the event loop.
     state: EventLoopState,
@@ -161,20 +157,13 @@ type ActivationToken = (WindowId, crate::event_loop::AsyncRequestSerial);
 struct EventLoopState {
     /// The latest readiness state for the x11 file descriptor
     x11_readiness: Readiness,
+
+    /// User requested a wake up.
+    proxy_wake_up: bool,
 }
 
-pub struct EventLoopProxy<T: 'static> {
-    user_sender: WakeSender<T>,
-}
-
-impl<T: 'static> Clone for EventLoopProxy<T> {
-    fn clone(&self) -> Self {
-        EventLoopProxy { user_sender: self.user_sender.clone() }
-    }
-}
-
-impl<T: 'static> EventLoop<T> {
-    pub(crate) fn new(xconn: Arc<XConnection>) -> EventLoop<T> {
+impl EventLoop {
+    pub(crate) fn new(xconn: Arc<XConnection>) -> EventLoop {
         let root = xconn.default_root().root;
         let atoms = xconn.atoms();
 
@@ -278,7 +267,16 @@ impl<T: 'static> EventLoop<T> {
         let (activation_token_sender, activation_token_channel) = mpsc::channel();
 
         // Create a channel for sending user events.
-        let (user_sender, user_channel) = mpsc::channel();
+        let (user_waker, user_waker_source) =
+            calloop::ping::make_ping().expect("Failed to create user event loop waker.");
+        event_loop
+            .handle()
+            .insert_source(user_waker_source, move |_, _, state| {
+                // No extra handling is required, we just need to wake-up.
+                state.proxy_wake_up = true;
+            })
+            .expect("Failed to register the event loop waker source");
+        let event_loop_proxy = EventLoopProxy::new(user_waker);
 
         let xkb_context =
             Context::from_x11_xkb(xconn.xcb_connection().get_raw_xcb_connection()).unwrap();
@@ -359,32 +357,32 @@ impl<T: 'static> EventLoop<T> {
         EventLoop {
             loop_running: false,
             event_loop,
-            waker,
             event_processor,
             redraw_receiver: PeekableReceiver::from_recv(redraw_channel),
             activation_receiver: PeekableReceiver::from_recv(activation_token_channel),
-            user_receiver: PeekableReceiver::from_recv(user_channel),
-            user_sender,
-            state: EventLoopState { x11_readiness: Readiness::EMPTY },
+            event_loop_proxy,
+            state: EventLoopState { x11_readiness: Readiness::EMPTY, proxy_wake_up: false },
         }
     }
 
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
-        EventLoopProxy {
-            user_sender: WakeSender { sender: self.user_sender.clone(), waker: self.waker.clone() },
-        }
+    pub fn create_proxy(&self) -> EventLoopProxy {
+        self.event_loop_proxy.clone()
     }
 
     pub(crate) fn window_target(&self) -> &RootAEL {
         &self.event_processor.target
     }
 
-    pub fn run_on_demand<F>(&mut self, mut event_handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(Event<T>, &RootAEL),
-    {
+    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+        self.run_app_on_demand(app)
+    }
+
+    pub fn run_app_on_demand<A: ApplicationHandler>(
+        &mut self,
+        app: &mut A,
+    ) -> Result<(), EventLoopError> {
         let exit = loop {
-            match self.pump_events(None, &mut event_handler) {
+            match self.pump_app_events(None, app) {
                 PumpStatus::Exit(0) => {
                     break Ok(());
                 },
@@ -409,26 +407,27 @@ impl<T: 'static> EventLoop<T> {
         exit
     }
 
-    pub fn pump_events<F>(&mut self, timeout: Option<Duration>, mut callback: F) -> PumpStatus
-    where
-        F: FnMut(Event<T>, &RootAEL),
-    {
+    pub fn pump_app_events<A: ApplicationHandler>(
+        &mut self,
+        timeout: Option<Duration>,
+        app: &mut A,
+    ) -> PumpStatus {
         if !self.loop_running {
             self.loop_running = true;
 
             // run the initial loop iteration
-            self.single_iteration(&mut callback, StartCause::Init);
+            self.single_iteration(app, StartCause::Init);
         }
 
         // Consider the possibility that the `StartCause::Init` iteration could
         // request to Exit.
         if !self.exiting() {
-            self.poll_events_with_timeout(timeout, &mut callback);
+            self.poll_events_with_timeout(timeout, app);
         }
         if let Some(code) = self.exit_code() {
             self.loop_running = false;
 
-            callback(Event::LoopExiting, self.window_target());
+            app.exiting(self.window_target());
 
             PumpStatus::Exit(code)
         } else {
@@ -438,14 +437,15 @@ impl<T: 'static> EventLoop<T> {
 
     fn has_pending(&mut self) -> bool {
         self.event_processor.poll()
-            || self.user_receiver.has_incoming()
+            || self.state.proxy_wake_up
             || self.redraw_receiver.has_incoming()
     }
 
-    pub fn poll_events_with_timeout<F>(&mut self, mut timeout: Option<Duration>, mut callback: F)
-    where
-        F: FnMut(Event<T>, &RootAEL),
-    {
+    pub fn poll_events_with_timeout<A: ApplicationHandler>(
+        &mut self,
+        mut timeout: Option<Duration>,
+        app: &mut A,
+    ) {
         let start = Instant::now();
 
         let has_pending = self.has_pending();
@@ -503,23 +503,20 @@ impl<T: 'static> EventLoop<T> {
             return;
         }
 
-        self.single_iteration(&mut callback, cause);
+        self.single_iteration(app, cause);
     }
 
-    fn single_iteration<F>(&mut self, callback: &mut F, cause: StartCause)
-    where
-        F: FnMut(Event<T>, &RootAEL),
-    {
-        callback(Event::NewEvents(cause), &self.event_processor.target);
+    fn single_iteration<A: ApplicationHandler>(&mut self, app: &mut A, cause: StartCause) {
+        app.new_events(&self.event_processor.target, cause);
 
         // NB: For consistency all platforms must emit a 'resumed' event even though X11
         // applications don't themselves have a formal suspend/resume lifecycle.
         if cause == StartCause::Init {
-            callback(Event::Resumed, &self.event_processor.target);
+            app.resumed(&self.event_processor.target)
         }
 
         // Process all pending events
-        self.drain_events(callback);
+        self.drain_events(app);
 
         // Empty activation tokens.
         while let Ok((window_id, serial)) = self.activation_receiver.try_recv() {
@@ -529,14 +526,12 @@ impl<T: 'static> EventLoop<T> {
 
             match token {
                 Some(Ok(token)) => {
-                    let event = Event::WindowEvent {
-                        window_id: crate::window::WindowId(window_id),
-                        event: WindowEvent::ActivationTokenDone {
-                            serial,
-                            token: crate::window::ActivationToken::_new(token),
-                        },
+                    let window_id = crate::window::WindowId(window_id);
+                    let event = WindowEvent::ActivationTokenDone {
+                        serial,
+                        token: crate::window::ActivationToken::_new(token),
                     };
-                    callback(event, &self.event_processor.target)
+                    app.window_event(&self.event_processor.target, window_id, event);
                 },
                 Some(Err(e)) => {
                     tracing::error!("Failed to get activation token: {}", e);
@@ -546,10 +541,8 @@ impl<T: 'static> EventLoop<T> {
         }
 
         // Empty the user event buffer
-        {
-            while let Ok(event) = self.user_receiver.try_recv() {
-                callback(Event::UserEvent(event), &self.event_processor.target);
-            }
+        if mem::take(&mut self.state.proxy_wake_up) {
+            app.proxy_wake_up(&self.event_processor.target);
         }
 
         // Empty the redraw requests
@@ -562,37 +555,41 @@ impl<T: 'static> EventLoop<T> {
 
             for window_id in windows {
                 let window_id = crate::window::WindowId(window_id);
-                callback(
-                    Event::WindowEvent { window_id, event: WindowEvent::RedrawRequested },
+                app.window_event(
                     &self.event_processor.target,
+                    window_id,
+                    WindowEvent::RedrawRequested,
                 );
             }
         }
 
         // This is always the last event we dispatch before poll again
-        {
-            callback(Event::AboutToWait, &self.event_processor.target);
-        }
+        app.about_to_wait(&self.event_processor.target);
     }
 
-    fn drain_events<F>(&mut self, callback: &mut F)
-    where
-        F: FnMut(Event<T>, &RootAEL),
-    {
+    fn drain_events<A: ApplicationHandler>(&mut self, app: &mut A) {
         let mut xev = MaybeUninit::uninit();
 
         while unsafe { self.event_processor.poll_one_event(xev.as_mut_ptr()) } {
             let mut xev = unsafe { xev.assume_init() };
-            self.event_processor.process_event(&mut xev, |window_target, event| {
+            self.event_processor.process_event(&mut xev, |window_target, event: Event| {
                 if let Event::WindowEvent {
                     window_id: crate::window::WindowId(wid),
                     event: WindowEvent::RedrawRequested,
                 } = event
                 {
                     let window_target = EventProcessor::window_target(window_target);
-                    window_target.redraw_sender.send(wid).unwrap();
+                    window_target.redraw_sender.send(wid);
                 } else {
-                    callback(event, window_target);
+                    match event {
+                        Event::WindowEvent { window_id, event } => {
+                            app.window_event(window_target, window_id, event)
+                        },
+                        Event::DeviceEvent { device_id, event } => {
+                            app.device_event(window_target, device_id, event)
+                        },
+                        _ => unreachable!("event which is neither device nor window event."),
+                    }
                 }
             });
         }
@@ -619,13 +616,13 @@ impl<T: 'static> EventLoop<T> {
     }
 }
 
-impl<T> AsFd for EventLoop<T> {
+impl AsFd for EventLoop {
     fn as_fd(&self) -> BorrowedFd<'_> {
         self.event_loop.as_fd()
     }
 }
 
-impl<T> AsRawFd for EventLoop<T> {
+impl AsRawFd for EventLoop {
     fn as_raw_fd(&self) -> RawFd {
         self.event_loop.as_raw_fd()
     }
@@ -725,9 +722,9 @@ impl ActiveEventLoop {
     }
 }
 
-impl<T: 'static> EventLoopProxy<T> {
-    pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
-        self.user_sender.send(event).map_err(|e| EventLoopClosed(e.0))
+impl EventLoopProxy {
+    pub fn wake_up(&self) {
+        self.ping.ping();
     }
 }
 
@@ -811,6 +808,17 @@ impl Drop for Window {
     }
 }
 
+#[derive(Clone)]
+pub struct EventLoopProxy {
+    ping: Ping,
+}
+
+impl EventLoopProxy {
+    fn new(ping: Ping) -> Self {
+        Self { ping }
+    }
+}
+
 /// Generic sum error type for X11 errors.
 #[derive(Debug)]
 pub enum X11Error {

src/platform_impl/linux/x11/window.rs

@@ -876,11 +876,11 @@ impl UnownedWindow {
 
     /// Refresh the API for the given monitor.
     #[inline]
-    pub(super) fn refresh_dpi_for_monitor<T: 'static>(
+    pub(super) fn refresh_dpi_for_monitor(
         &self,
         new_monitor: &X11MonitorHandle,
         maybe_prev_scale_factor: Option<f64>,
-        mut callback: impl FnMut(Event<T>),
+        mut callback: impl FnMut(Event),
     ) {
         // Check if the self is on this monitor
         let monitor = self.shared_state_lock().last_monitor.clone();
@@ -1805,9 +1805,7 @@ impl UnownedWindow {
     #[inline]
     pub fn request_activation_token(&self) -> Result<AsyncRequestSerial, NotSupportedError> {
         let serial = AsyncRequestSerial::get();
-        self.activation_sender
-            .send((self.id(), serial))
-            .expect("activation token channel should never be closed");
+        self.activation_sender.send((self.id(), serial));
         Ok(serial)
     }
 
@@ -1818,7 +1816,7 @@ impl UnownedWindow {
 
     #[inline]
     pub fn request_redraw(&self) {
-        self.redraw_sender.send(WindowId(self.xwindow as _)).unwrap();
+        self.redraw_sender.send(WindowId(self.xwindow as _));
     }
 
     #[inline]

src/platform_impl/mod.rs

@@ -1,27 +1,31 @@
 use crate::monitor::{MonitorHandle as RootMonitorHandle, VideoModeHandle as RootVideoModeHandle};
 use crate::window::Fullscreen as RootFullscreen;
 
-#[cfg(windows_platform)]
-#[path = "windows/mod.rs"]
-mod platform;
-#[cfg(any(x11_platform, wayland_platform))]
-#[path = "linux/mod.rs"]
-mod platform;
-#[cfg(macos_platform)]
-#[path = "macos/mod.rs"]
-mod platform;
 #[cfg(android_platform)]
-#[path = "android/mod.rs"]
-mod platform;
-#[cfg(ios_platform)]
-#[path = "ios/mod.rs"]
-mod platform;
-#[cfg(web_platform)]
-#[path = "web/mod.rs"]
-mod platform;
+mod android;
+#[cfg(target_vendor = "apple")]
+mod apple;
+#[cfg(any(x11_platform, wayland_platform))]
+mod linux;
 #[cfg(orbital_platform)]
-#[path = "orbital/mod.rs"]
-mod platform;
+mod orbital;
+#[cfg(web_platform)]
+mod web;
+#[cfg(windows_platform)]
+mod windows;
+
+#[cfg(android_platform)]
+use self::android as platform;
+#[cfg(target_vendor = "apple")]
+use self::apple as platform;
+#[cfg(any(x11_platform, wayland_platform))]
+use self::linux as platform;
+#[cfg(orbital_platform)]
+use self::orbital as platform;
+#[cfg(web_platform)]
+use self::web as platform;
+#[cfg(windows_platform)]
+use self::windows as platform;
 
 pub use self::platform::*;
 

src/platform_impl/orbital/event_loop.rs

@@ -12,6 +12,7 @@ use orbclient::{
 };
 use smol_str::SmolStr;
 
+use crate::application::ApplicationHandler;
 use crate::error::EventLoopError;
 use crate::event::{self, Ime, Modifiers, StartCause};
 use crate::event_loop::{self, ControlFlow, DeviceEvents};
@@ -271,16 +272,18 @@ impl EventState {
     }
 }
 
-pub struct EventLoop<T> {
+pub struct EventLoop {
     windows: Vec<(Arc<RedoxSocket>, EventState)>,
     window_target: event_loop::ActiveEventLoop,
-    user_events_sender: mpsc::Sender<T>,
-    user_events_receiver: mpsc::Receiver<T>,
+    user_events_sender: mpsc::SyncSender<()>,
+    user_events_receiver: mpsc::Receiver<()>,
 }
 
-impl<T: 'static> EventLoop<T> {
+impl EventLoop {
     pub(crate) fn new(_: &PlatformSpecificEventLoopAttributes) -> Result<Self, EventLoopError> {
-        let (user_events_sender, user_events_receiver) = mpsc::channel();
+        // NOTE: Create a channel which can hold only one event to automatically _squash_ user
+        // events.
+        let (user_events_sender, user_events_receiver) = mpsc::sync_channel(1);
 
         let event_socket = Arc::new(
             RedoxSocket::event()
@@ -322,14 +325,13 @@ impl<T: 'static> EventLoop<T> {
         })
     }
 
-    fn process_event<F>(
+    fn process_event<A: ApplicationHandler>(
         window_id: WindowId,
         event_option: EventOption,
         event_state: &mut EventState,
-        mut event_handler: F,
-    ) where
-        F: FnMut(event::Event<T>),
-    {
+        window_target: &event_loop::ActiveEventLoop,
+        app: &mut A,
+    ) {
         match event_option {
             EventOption::Key(KeyEvent { character, scancode, pressed }) => {
                 // Convert scancode
@@ -371,125 +373,128 @@ impl<T: 'static> EventLoop<T> {
                     key_without_modifiers = logical_key.clone();
                 }
 
-                event_handler(event::Event::WindowEvent {
-                    window_id: RootWindowId(window_id),
-                    event: event::WindowEvent::KeyboardInput {
-                        device_id: event::DeviceId(DeviceId),
-                        event: event::KeyEvent {
-                            logical_key,
-                            physical_key,
-                            location: KeyLocation::Standard,
-                            state: element_state(pressed),
-                            repeat: false,
-                            text,
-                            platform_specific: KeyEventExtra {
-                                key_without_modifiers,
-                                text_with_all_modifiers,
-                            },
+                let window_id = RootWindowId(window_id);
+                let event = event::WindowEvent::KeyboardInput {
+                    device_id: event::DeviceId(DeviceId),
+                    event: event::KeyEvent {
+                        logical_key,
+                        physical_key,
+                        location: KeyLocation::Standard,
+                        state: element_state(pressed),
+                        repeat: false,
+                        text,
+                        platform_specific: KeyEventExtra {
+                            key_without_modifiers,
+                            text_with_all_modifiers,
                         },
-                        is_synthetic: false,
                     },
-                });
+                    is_synthetic: false,
+                };
+
+                app.window_event(window_target, window_id, event);
 
                 // If the state of the modifiers has changed, send the event.
                 if modifiers_before != event_state.keyboard {
-                    event_handler(event::Event::WindowEvent {
-                        window_id: RootWindowId(window_id),
-                        event: event::WindowEvent::ModifiersChanged(event_state.modifiers()),
-                    })
+                    app.window_event(
+                        window_target,
+                        window_id,
+                        event::WindowEvent::ModifiersChanged(event_state.modifiers()),
+                    );
                 }
             },
             EventOption::TextInput(TextInputEvent { character }) => {
-                event_handler(event::Event::WindowEvent {
-                    window_id: RootWindowId(window_id),
-                    event: event::WindowEvent::Ime(Ime::Preedit("".into(), None)),
-                });
-                event_handler(event::Event::WindowEvent {
-                    window_id: RootWindowId(window_id),
-                    event: event::WindowEvent::Ime(Ime::Commit(character.into())),
-                });
+                app.window_event(
+                    window_target,
+                    RootWindowId(window_id),
+                    event::WindowEvent::Ime(Ime::Preedit("".into(), None)),
+                );
+                app.window_event(
+                    window_target,
+                    RootWindowId(window_id),
+                    event::WindowEvent::Ime(Ime::Commit(character.into())),
+                );
             },
             EventOption::Mouse(MouseEvent { x, y }) => {
-                event_handler(event::Event::WindowEvent {
-                    window_id: RootWindowId(window_id),
-                    event: event::WindowEvent::CursorMoved {
+                app.window_event(
+                    window_target,
+                    RootWindowId(window_id),
+                    event::WindowEvent::CursorMoved {
                         device_id: event::DeviceId(DeviceId),
                         position: (x, y).into(),
                     },
-                });
+                );
             },
             EventOption::MouseRelative(MouseRelativeEvent { dx, dy }) => {
-                event_handler(event::Event::DeviceEvent {
-                    device_id: event::DeviceId(DeviceId),
-                    event: event::DeviceEvent::MouseMotion { delta: (dx as f64, dy as f64) },
-                });
+                app.device_event(
+                    window_target,
+                    event::DeviceId(DeviceId),
+                    event::DeviceEvent::MouseMotion { delta: (dx as f64, dy as f64) },
+                );
             },
             EventOption::Button(ButtonEvent { left, middle, right }) => {
                 while let Some((button, state)) = event_state.mouse(left, middle, right) {
-                    event_handler(event::Event::WindowEvent {
-                        window_id: RootWindowId(window_id),
-                        event: event::WindowEvent::MouseInput {
+                    app.window_event(
+                        window_target,
+                        RootWindowId(window_id),
+                        event::WindowEvent::MouseInput {
                             device_id: event::DeviceId(DeviceId),
                             state,
                             button,
                         },
-                    });
+                    );
                 }
             },
             EventOption::Scroll(ScrollEvent { x, y }) => {
-                event_handler(event::Event::WindowEvent {
-                    window_id: RootWindowId(window_id),
-                    event: event::WindowEvent::MouseWheel {
+                app.window_event(
+                    window_target,
+                    RootWindowId(window_id),
+                    event::WindowEvent::MouseWheel {
                         device_id: event::DeviceId(DeviceId),
                         delta: event::MouseScrollDelta::LineDelta(x as f32, y as f32),
                         phase: event::TouchPhase::Moved,
                     },
-                });
+                );
             },
             EventOption::Quit(QuitEvent {}) => {
-                event_handler(event::Event::WindowEvent {
-                    window_id: RootWindowId(window_id),
-                    event: event::WindowEvent::CloseRequested,
-                });
+                app.window_event(
+                    window_target,
+                    RootWindowId(window_id),
+                    event::WindowEvent::CloseRequested,
+                );
             },
             EventOption::Focus(FocusEvent { focused }) => {
-                event_handler(event::Event::WindowEvent {
-                    window_id: RootWindowId(window_id),
-                    event: event::WindowEvent::Focused(focused),
-                });
+                app.window_event(
+                    window_target,
+                    RootWindowId(window_id),
+                    event::WindowEvent::Focused(focused),
+                );
             },
             EventOption::Move(MoveEvent { x, y }) => {
-                event_handler(event::Event::WindowEvent {
-                    window_id: RootWindowId(window_id),
-                    event: event::WindowEvent::Moved((x, y).into()),
-                });
+                app.window_event(
+                    window_target,
+                    RootWindowId(window_id),
+                    event::WindowEvent::Moved((x, y).into()),
+                );
             },
             EventOption::Resize(ResizeEvent { width, height }) => {
-                event_handler(event::Event::WindowEvent {
-                    window_id: RootWindowId(window_id),
-                    event: event::WindowEvent::Resized((width, height).into()),
-                });
+                app.window_event(
+                    window_target,
+                    RootWindowId(window_id),
+                    event::WindowEvent::Resized((width, height).into()),
+                );
 
                 // Acknowledge resize after event loop.
                 event_state.resize_opt = Some((width, height));
             },
             // TODO: Screen, Clipboard, Drop
             EventOption::Hover(HoverEvent { entered }) => {
-                if entered {
-                    event_handler(event::Event::WindowEvent {
-                        window_id: RootWindowId(window_id),
-                        event: event::WindowEvent::CursorEntered {
-                            device_id: event::DeviceId(DeviceId),
-                        },
-                    });
+                let event = if entered {
+                    event::WindowEvent::CursorEntered { device_id: event::DeviceId(DeviceId) }
                 } else {
-                    event_handler(event::Event::WindowEvent {
-                        window_id: RootWindowId(window_id),
-                        event: event::WindowEvent::CursorLeft {
-                            device_id: event::DeviceId(DeviceId),
-                        },
-                    });
-                }
+                    event::WindowEvent::CursorLeft { device_id: event::DeviceId(DeviceId) }
+                };
+
+                app.window_event(window_target, RootWindowId(window_id), event);
             },
             other => {
                 tracing::warn!("unhandled event: {:?}", other);
@@ -497,22 +502,13 @@ impl<T: 'static> EventLoop<T> {
         }
     }
 
-    pub fn run<F>(mut self, mut event_handler_inner: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(event::Event<T>, &event_loop::ActiveEventLoop),
-    {
-        let mut event_handler =
-            move |event: event::Event<T>, window_target: &event_loop::ActiveEventLoop| {
-                event_handler_inner(event, window_target);
-            };
-
+    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
         let mut start_cause = StartCause::Init;
-
         loop {
-            event_handler(event::Event::NewEvents(start_cause), &self.window_target);
+            app.new_events(&self.window_target, start_cause);
 
             if start_cause == StartCause::Init {
-                event_handler(event::Event::Resumed, &self.window_target);
+                app.resumed(&self.window_target);
             }
 
             // Handle window creates.
@@ -528,23 +524,15 @@ impl<T: 'static> EventLoop<T> {
 
                 self.windows.push((window, EventState::default()));
 
-                // Send resize event on create to indicate first size.
-                event_handler(
-                    event::Event::WindowEvent {
-                        window_id: RootWindowId(window_id),
-                        event: event::WindowEvent::Resized((properties.w, properties.h).into()),
-                    },
-                    &self.window_target,
-                );
+                let window_id = RootWindowId(window_id);
 
-                // Send resize event on create to indicate first position.
-                event_handler(
-                    event::Event::WindowEvent {
-                        window_id: RootWindowId(window_id),
-                        event: event::WindowEvent::Moved((properties.x, properties.y).into()),
-                    },
-                    &self.window_target,
-                );
+                // Send resize event on create to indicate first size.
+                let event = event::WindowEvent::Resized((properties.w, properties.h).into());
+                app.window_event(&self.window_target, window_id, event);
+
+                // Send moved event on create to indicate first position.
+                let event = event::WindowEvent::Moved((properties.x, properties.y).into());
+                app.window_event(&self.window_target, window_id, event);
             }
 
             // Handle window destroys.
@@ -552,14 +540,8 @@ impl<T: 'static> EventLoop<T> {
                 let mut destroys = self.window_target.p.destroys.lock().unwrap();
                 destroys.pop_front()
             } {
-                event_handler(
-                    event::Event::WindowEvent {
-                        window_id: RootWindowId(destroy_id),
-                        event: event::WindowEvent::Destroyed,
-                    },
-                    &self.window_target,
-                );
-
+                let window_id = RootWindowId(destroy_id);
+                app.window_event(&self.window_target, window_id, event::WindowEvent::Destroyed);
                 self.windows.retain(|(window, _event_state)| window.fd as u64 != destroy_id.fd);
             }
 
@@ -586,7 +568,8 @@ impl<T: 'static> EventLoop<T> {
                         window_id,
                         orbital_event.to_option(),
                         event_state,
-                        |event| event_handler(event, &self.window_target),
+                        &self.window_target,
+                        app,
                     );
                 }
 
@@ -613,8 +596,8 @@ impl<T: 'static> EventLoop<T> {
                 i += 1;
             }
 
-            while let Ok(event) = self.user_events_receiver.try_recv() {
-                event_handler(event::Event::UserEvent(event), &self.window_target);
+            while self.user_events_receiver.try_recv().is_ok() {
+                app.proxy_wake_up(&self.window_target);
             }
 
             // To avoid deadlocks the redraws lock is not held during event processing.
@@ -622,16 +605,14 @@ impl<T: 'static> EventLoop<T> {
                 let mut redraws = self.window_target.p.redraws.lock().unwrap();
                 redraws.pop_front()
             } {
-                event_handler(
-                    event::Event::WindowEvent {
-                        window_id: RootWindowId(window_id),
-                        event: event::WindowEvent::RedrawRequested,
-                    },
+                app.window_event(
                     &self.window_target,
+                    RootWindowId(window_id),
+                    event::WindowEvent::RedrawRequested,
                 );
             }
 
-            event_handler(event::Event::AboutToWait, &self.window_target);
+            app.about_to_wait(&self.window_target);
 
             if self.window_target.p.exiting() {
                 break;
@@ -695,7 +676,7 @@ impl<T: 'static> EventLoop<T> {
             }
         }
 
-        event_handler(event::Event::LoopExiting, &self.window_target);
+        app.exiting(&self.window_target);
 
         Ok(())
     }
@@ -704,7 +685,7 @@ impl<T: 'static> EventLoop<T> {
         &self.window_target
     }
 
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
+    pub fn create_proxy(&self) -> EventLoopProxy {
         EventLoopProxy {
             user_events_sender: self.user_events_sender.clone(),
             wake_socket: self.window_target.p.wake_socket.clone(),
@@ -712,24 +693,22 @@ impl<T: 'static> EventLoop<T> {
     }
 }
 
-pub struct EventLoopProxy<T: 'static> {
-    user_events_sender: mpsc::Sender<T>,
+pub struct EventLoopProxy {
+    user_events_sender: mpsc::SyncSender<()>,
     wake_socket: Arc<TimeSocket>,
 }
 
-impl<T> EventLoopProxy<T> {
-    pub fn send_event(&self, event: T) -> Result<(), event_loop::EventLoopClosed<T>> {
-        self.user_events_sender
-            .send(event)
-            .map_err(|mpsc::SendError(x)| event_loop::EventLoopClosed(x))?;
-
-        self.wake_socket.wake().unwrap();
-
-        Ok(())
+impl EventLoopProxy {
+    pub fn wake_up(&self) {
+        // When we fail to send the event it means that we haven't woken up to read the previous
+        // event.
+        if self.user_events_sender.try_send(()).is_ok() {
+            self.wake_socket.wake().unwrap();
+        }
     }
 }
 
-impl<T> Clone for EventLoopProxy<T> {
+impl Clone for EventLoopProxy {
     fn clone(&self) -> Self {
         Self {
             user_events_sender: self.user_events_sender.clone(),
@@ -738,7 +717,7 @@ impl<T> Clone for EventLoopProxy<T> {
     }
 }
 
-impl<T> Unpin for EventLoopProxy<T> {}
+impl Unpin for EventLoopProxy {}
 
 pub struct ActiveEventLoop {
     control_flow: Cell<ControlFlow>,

src/platform_impl/orbital/mod.rs

@@ -103,7 +103,7 @@ pub struct WindowId {
 
 impl WindowId {
     pub const fn dummy() -> Self {
-        WindowId { fd: u64::max_value() }
+        WindowId { fd: u64::MAX }
     }
 }
 

src/platform_impl/web/async/channel.rs

@@ -1,8 +1,7 @@
 use std::future;
-use std::rc::Rc;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::mpsc::{self, RecvError, SendError, TryRecvError};
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 use std::task::Poll;
 
 use super::AtomicWaker;
@@ -11,54 +10,35 @@ pub fn channel<T>() -> (Sender<T>, Receiver<T>) {
     let (sender, receiver) = mpsc::channel();
     let shared = Arc::new(Shared { closed: AtomicBool::new(false), waker: AtomicWaker::new() });
 
-    let sender =
-        Sender(Arc::new(SenderInner { sender: Mutex::new(sender), shared: Arc::clone(&shared) }));
-    let receiver = Receiver { receiver: Rc::new(receiver), shared };
+    let sender = Sender { sender, shared: Arc::clone(&shared) };
+    let receiver = Receiver { receiver, shared };
 
     (sender, receiver)
 }
 
-pub struct Sender<T>(Arc<SenderInner<T>>);
-
-struct SenderInner<T> {
-    // We need to wrap it into a `Mutex` to make it `Sync`. So the sender can't
-    // be accessed on the main thread, as it could block. Additionally we need
-    // to wrap `Sender` in an `Arc` to make it clonable on the main thread without
-    // having to block.
-    sender: Mutex<mpsc::Sender<T>>,
+pub struct Sender<T> {
+    sender: mpsc::Sender<T>,
     shared: Arc<Shared>,
 }
 
 impl<T> Sender<T> {
     pub fn send(&self, event: T) -> Result<(), SendError<T>> {
-        self.0.sender.lock().unwrap().send(event)?;
-        self.0.shared.waker.wake();
+        self.sender.send(event)?;
+        self.shared.waker.wake();
 
         Ok(())
     }
 }
 
-impl<T> SenderInner<T> {
-    fn close(&self) {
+impl<T> Drop for Sender<T> {
+    fn drop(&mut self) {
         self.shared.closed.store(true, Ordering::Relaxed);
         self.shared.waker.wake();
     }
 }
 
-impl<T> Clone for Sender<T> {
-    fn clone(&self) -> Self {
-        Self(Arc::clone(&self.0))
-    }
-}
-
-impl<T> Drop for SenderInner<T> {
-    fn drop(&mut self) {
-        self.close();
-    }
-}
-
 pub struct Receiver<T> {
-    receiver: Rc<mpsc::Receiver<T>>,
+    receiver: mpsc::Receiver<T>,
     shared: Arc<Shared>,
 }
 
@@ -95,18 +75,6 @@ impl<T> Receiver<T> {
     }
 }
 
-impl<T> Clone for Receiver<T> {
-    fn clone(&self) -> Self {
-        Self { receiver: Rc::clone(&self.receiver), shared: Arc::clone(&self.shared) }
-    }
-}
-
-impl<T> Drop for Receiver<T> {
-    fn drop(&mut self) {
-        self.shared.closed.store(true, Ordering::Relaxed);
-    }
-}
-
 struct Shared {
     closed: AtomicBool,
     waker: AtomicWaker,

src/platform_impl/web/async/dispatcher.rs

@@ -1,9 +1,10 @@
 use super::super::main_thread::MainThreadMarker;
 use super::{channel, Receiver, Sender, Wrapper};
 use std::cell::Ref;
+use std::rc::Rc;
 use std::sync::{Arc, Condvar, Mutex};
 
-pub struct Dispatcher<T: 'static>(Wrapper<T, Sender<Closure<T>>, Closure<T>>);
+pub struct Dispatcher<T: 'static>(Wrapper<T, Arc<Sender<Closure<T>>>, Closure<T>>);
 
 struct Closure<T>(Box<dyn FnOnce(&T) + Send>);
 
@@ -11,6 +12,8 @@ impl<T> Dispatcher<T> {
     #[track_caller]
     pub fn new(main_thread: MainThreadMarker, value: T) -> Option<(Self, DispatchRunner<T>)> {
         let (sender, receiver) = channel::<Closure<T>>();
+        let sender = Arc::new(sender);
+        let receiver = Rc::new(receiver);
 
         Wrapper::new(
             main_thread,
@@ -21,7 +24,7 @@ impl<T> Dispatcher<T> {
                 closure(value.borrow().as_ref().unwrap())
             },
             {
-                let receiver = receiver.clone();
+                let receiver = Rc::clone(&receiver);
                 move |value| async move {
                     while let Ok(Closure(closure)) = receiver.next().await {
                         // SAFETY: The given `Closure` here isn't really `'static`, so we shouldn't
@@ -68,7 +71,12 @@ impl<T> Dispatcher<T> {
             // SAFETY: The `transmute` is necessary because `Closure` requires `'static`. This is
             // safe because this function won't return until `f` has finished executing. See
             // `Self::new()`.
-            let closure = Closure(unsafe { std::mem::transmute(closure) });
+            let closure = Closure(unsafe {
+                std::mem::transmute::<
+                    Box<dyn FnOnce(&T) + Send>,
+                    Box<dyn FnOnce(&T) + Send + 'static>,
+                >(closure)
+            });
 
             self.0.send(closure);
 
@@ -84,8 +92,8 @@ impl<T> Dispatcher<T> {
 }
 
 pub struct DispatchRunner<T: 'static> {
-    wrapper: Wrapper<T, Sender<Closure<T>>, Closure<T>>,
-    receiver: Receiver<Closure<T>>,
+    wrapper: Wrapper<T, Arc<Sender<Closure<T>>>, Closure<T>>,
+    receiver: Rc<Receiver<Closure<T>>>,
 }
 
 impl<T> DispatchRunner<T> {

src/platform_impl/web/async/waker.rs

@@ -1,18 +1,18 @@
 use std::future;
-use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 use std::task::Poll;
 
 use super::super::main_thread::MainThreadMarker;
 use super::{AtomicWaker, Wrapper};
 
-pub struct WakerSpawner<T: 'static>(Wrapper<Handler<T>, Sender, usize>);
+pub struct WakerSpawner<T: 'static>(Wrapper<Handler<T>, Sender, ()>);
 
-pub struct Waker<T: 'static>(Wrapper<Handler<T>, Sender, usize>);
+pub struct Waker<T: 'static>(Wrapper<Handler<T>, Sender, ()>);
 
 struct Handler<T> {
     value: T,
-    handler: fn(&T, usize),
+    handler: fn(&T, bool),
 }
 
 #[derive(Clone)]
@@ -20,9 +20,9 @@ struct Sender(Arc<Inner>);
 
 impl<T> WakerSpawner<T> {
     #[track_caller]
-    pub fn new(main_thread: MainThreadMarker, value: T, handler: fn(&T, usize)) -> Option<Self> {
+    pub fn new(main_thread: MainThreadMarker, value: T, handler: fn(&T, bool)) -> Option<Self> {
         let inner = Arc::new(Inner {
-            counter: AtomicUsize::new(0),
+            awoken: AtomicBool::new(false),
             waker: AtomicWaker::new(),
             closed: AtomicBool::new(false),
         });
@@ -34,30 +34,26 @@ impl<T> WakerSpawner<T> {
         let wrapper = Wrapper::new(
             main_thread,
             handler,
-            |handler, count| {
+            |handler, _| {
                 let handler = handler.borrow();
                 let handler = handler.as_ref().unwrap();
-                (handler.handler)(&handler.value, count);
+                (handler.handler)(&handler.value, true);
             },
             {
                 let inner = Arc::clone(&inner);
 
                 move |handler| async move {
-                    while let Some(count) = future::poll_fn(|cx| {
-                        let count = inner.counter.swap(0, Ordering::Relaxed);
-
-                        if count > 0 {
-                            Poll::Ready(Some(count))
+                    while future::poll_fn(|cx| {
+                        if inner.awoken.swap(false, Ordering::Relaxed) {
+                            Poll::Ready(true)
                         } else {
                             inner.waker.register(cx.waker());
 
-                            let count = inner.counter.swap(0, Ordering::Relaxed);
-
-                            if count > 0 {
-                                Poll::Ready(Some(count))
+                            if inner.awoken.swap(false, Ordering::Relaxed) {
+                                Poll::Ready(true)
                             } else {
                                 if inner.closed.load(Ordering::Relaxed) {
-                                    return Poll::Ready(None);
+                                    return Poll::Ready(false);
                                 }
 
                                 Poll::Pending
@@ -68,13 +64,13 @@ impl<T> WakerSpawner<T> {
                     {
                         let handler = handler.borrow();
                         let handler = handler.as_ref().unwrap();
-                        (handler.handler)(&handler.value, count);
+                        (handler.handler)(&handler.value, false);
                     }
                 }
             },
             sender,
             |inner, _| {
-                inner.0.counter.fetch_add(1, Ordering::Relaxed);
+                inner.0.awoken.store(true, Ordering::Relaxed);
                 inner.0.waker.wake();
             },
         )?;
@@ -86,13 +82,13 @@ impl<T> WakerSpawner<T> {
         Waker(self.0.clone())
     }
 
-    pub fn fetch(&self) -> usize {
+    pub fn take(&self) -> bool {
         debug_assert!(
             MainThreadMarker::new().is_some(),
             "this should only be called from the main thread"
         );
 
-        self.0.with_sender_data(|inner| inner.0.counter.swap(0, Ordering::Relaxed))
+        self.0.with_sender_data(|inner| inner.0.awoken.swap(false, Ordering::Relaxed))
     }
 }
 
@@ -107,7 +103,7 @@ impl<T> Drop for WakerSpawner<T> {
 
 impl<T> Waker<T> {
     pub fn wake(&self) {
-        self.0.send(1)
+        self.0.send(())
     }
 }
 
@@ -118,7 +114,7 @@ impl<T> Clone for Waker<T> {
 }
 
 struct Inner {
-    counter: AtomicUsize,
+    awoken: AtomicBool,
     waker: AtomicWaker,
     closed: AtomicBool,
 }

src/platform_impl/web/cursor.rs

@@ -324,7 +324,11 @@ impl Inner {
             match &self.cursor {
                 SelectedCursor::Icon(icon)
                 | SelectedCursor::Loading { previous: Previous::Icon(icon), .. } => {
-                    self.style.set("cursor", icon.name())
+                    if let CursorIcon::Default = icon {
+                        self.style.remove("cursor")
+                    } else {
+                        self.style.set("cursor", icon.name())
+                    }
                 },
                 SelectedCursor::Loading { previous: Previous::Image(cursor), .. }
                 | SelectedCursor::Image(cursor) => {

src/platform_impl/web/event_loop/mod.rs

@@ -1,9 +1,10 @@
 use std::marker::PhantomData;
-use std::sync::mpsc::{self, Receiver, Sender};
 
+use crate::application::ApplicationHandler;
 use crate::error::EventLoopError;
 use crate::event::Event;
 use crate::event_loop::ActiveEventLoop as RootActiveEventLoop;
+use crate::platform::web::{ActiveEventLoopExtWebSys, PollStrategy, WaitUntilStrategy};
 
 use super::{backend, device, window};
 
@@ -15,45 +16,31 @@ mod window_target;
 pub(crate) use proxy::EventLoopProxy;
 pub(crate) use window_target::{ActiveEventLoop, OwnedDisplayHandle};
 
-pub struct EventLoop<T: 'static> {
+pub struct EventLoop {
     elw: RootActiveEventLoop,
-    user_event_sender: Sender<T>,
-    user_event_receiver: Receiver<T>,
 }
 
 #[derive(Default, Debug, Copy, Clone, PartialEq, Eq, Hash)]
 pub(crate) struct PlatformSpecificEventLoopAttributes {}
 
-impl<T> EventLoop<T> {
+impl EventLoop {
     pub(crate) fn new(_: &PlatformSpecificEventLoopAttributes) -> Result<Self, EventLoopError> {
-        let (user_event_sender, user_event_receiver) = mpsc::channel();
         let elw = RootActiveEventLoop { p: ActiveEventLoop::new(), _marker: PhantomData };
-        Ok(EventLoop { elw, user_event_sender, user_event_receiver })
+        Ok(EventLoop { elw })
     }
 
-    pub fn run<F>(self, mut event_handler: F) -> !
-    where
-        F: FnMut(Event<T>, &RootActiveEventLoop),
-    {
+    pub fn run_app<A: ApplicationHandler>(self, app: &mut A) -> ! {
         let target = RootActiveEventLoop { p: self.elw.p.clone(), _marker: PhantomData };
 
         // SAFETY: Don't use `move` to make sure we leak the `event_handler` and `target`.
-        let handler: Box<dyn FnMut(Event<()>)> = Box::new(|event| {
-            let event = match event.map_nonuser_event() {
-                Ok(event) => event,
-                Err(Event::UserEvent(())) => Event::UserEvent(
-                    self.user_event_receiver
-                        .try_recv()
-                        .expect("handler woken up without user event"),
-                ),
-                Err(_) => unreachable!(),
-            };
-            event_handler(event, &target)
-        });
+        let handler: Box<dyn FnMut(Event)> = Box::new(|event| handle_event(app, &target, event));
+
         // SAFETY: The `transmute` is necessary because `run()` requires `'static`. This is safe
         // because this function will never return and all resources not cleaned up by the point we
         // `throw` will leak, making this actually `'static`.
-        let handler = unsafe { std::mem::transmute(handler) };
+        let handler = unsafe {
+            std::mem::transmute::<Box<dyn FnMut(Event)>, Box<dyn FnMut(Event) + 'static>>(handler)
+        };
         self.elw.p.run(handler, false);
 
         // Throw an exception to break out of Rust execution and use unreachable to tell the
@@ -65,34 +52,47 @@ impl<T> EventLoop<T> {
         unreachable!();
     }
 
-    pub fn spawn<F>(self, mut event_handler: F)
-    where
-        F: 'static + FnMut(Event<T>, &RootActiveEventLoop),
-    {
+    pub fn spawn_app<A: ApplicationHandler + 'static>(self, mut app: A) {
         let target = RootActiveEventLoop { p: self.elw.p.clone(), _marker: PhantomData };
 
-        self.elw.p.run(
-            Box::new(move |event| {
-                let event = match event.map_nonuser_event() {
-                    Ok(event) => event,
-                    Err(Event::UserEvent(())) => Event::UserEvent(
-                        self.user_event_receiver
-                            .try_recv()
-                            .expect("handler woken up without user event"),
-                    ),
-                    Err(_) => unreachable!(),
-                };
-                event_handler(event, &target)
-            }),
-            true,
-        );
+        self.elw.p.run(Box::new(move |event| handle_event(&mut app, &target, event)), true);
     }
 
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
-        EventLoopProxy::new(self.elw.p.waker(), self.user_event_sender.clone())
+    pub fn create_proxy(&self) -> EventLoopProxy {
+        EventLoopProxy::new(self.elw.p.waker())
     }
 
     pub fn window_target(&self) -> &RootActiveEventLoop {
         &self.elw
     }
+
+    pub fn set_poll_strategy(&self, strategy: PollStrategy) {
+        self.elw.set_poll_strategy(strategy);
+    }
+
+    pub fn poll_strategy(&self) -> PollStrategy {
+        self.elw.poll_strategy()
+    }
+
+    pub fn set_wait_until_strategy(&self, strategy: WaitUntilStrategy) {
+        self.elw.set_wait_until_strategy(strategy);
+    }
+
+    pub fn wait_until_strategy(&self) -> WaitUntilStrategy {
+        self.elw.wait_until_strategy()
+    }
+}
+
+fn handle_event<A: ApplicationHandler>(app: &mut A, target: &RootActiveEventLoop, event: Event) {
+    match event {
+        Event::NewEvents(cause) => app.new_events(target, cause),
+        Event::WindowEvent { window_id, event } => app.window_event(target, window_id, event),
+        Event::DeviceEvent { device_id, event } => app.device_event(target, device_id, event),
+        Event::UserWakeUp => app.proxy_wake_up(target),
+        Event::Suspended => app.suspended(target),
+        Event::Resumed => app.resumed(target),
+        Event::AboutToWait => app.about_to_wait(target),
+        Event::LoopExiting => app.exiting(target),
+        Event::MemoryWarning => app.memory_warning(target),
+    }
 }

src/platform_impl/web/event_loop/proxy.rs

@@ -1,29 +1,19 @@
 use std::rc::Weak;
-use std::sync::mpsc::{SendError, Sender};
 
 use super::runner::Execution;
-use crate::event_loop::EventLoopClosed;
 use crate::platform_impl::platform::r#async::Waker;
 
-pub struct EventLoopProxy<T: 'static> {
+#[derive(Clone)]
+pub struct EventLoopProxy {
     runner: Waker<Weak<Execution>>,
-    sender: Sender<T>,
 }
 
-impl<T: 'static> EventLoopProxy<T> {
-    pub fn new(runner: Waker<Weak<Execution>>, sender: Sender<T>) -> Self {
-        Self { runner, sender }
+impl EventLoopProxy {
+    pub fn new(runner: Waker<Weak<Execution>>) -> Self {
+        Self { runner }
     }
 
-    pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
-        self.sender.send(event).map_err(|SendError(event)| EventLoopClosed(event))?;
+    pub fn wake_up(&self) {
         self.runner.wake();
-        Ok(())
-    }
-}
-
-impl<T: 'static> Clone for EventLoopProxy<T> {
-    fn clone(&self) -> Self {
-        Self { runner: self.runner.clone(), sender: self.sender.clone() }
     }
 }

src/platform_impl/web/event_loop/runner.rs

@@ -8,24 +8,26 @@ use crate::event::{
     WindowEvent,
 };
 use crate::event_loop::{ControlFlow, DeviceEvents};
-use crate::platform::web::PollStrategy;
+use crate::platform::web::{PollStrategy, WaitUntilStrategy};
 use crate::platform_impl::platform::backend::EventListenerHandle;
 use crate::platform_impl::platform::r#async::{DispatchRunner, Waker, WakerSpawner};
 use crate::platform_impl::platform::window::Inner;
 use crate::window::WindowId;
 
+use js_sys::Function;
 use std::cell::{Cell, RefCell};
 use std::collections::{HashSet, VecDeque};
 use std::iter;
 use std::ops::Deref;
 use std::rc::{Rc, Weak};
-use wasm_bindgen::prelude::Closure;
+use wasm_bindgen::prelude::{wasm_bindgen, Closure};
+use wasm_bindgen::JsCast;
 use web_sys::{Document, KeyboardEvent, PageTransitionEvent, PointerEvent, WheelEvent};
 use web_time::{Duration, Instant};
 
 pub struct Shared(Rc<Execution>);
 
-pub(super) type EventHandler = dyn FnMut(Event<()>);
+pub(super) type EventHandler = dyn FnMut(Event);
 
 impl Clone for Shared {
     fn clone(&self) -> Self {
@@ -40,6 +42,7 @@ pub struct Execution {
     proxy_spawner: WakerSpawner<Weak<Self>>,
     control_flow: Cell<ControlFlow>,
     poll_strategy: Cell<PollStrategy>,
+    wait_until_strategy: Cell<WaitUntilStrategy>,
     exit: Cell<bool>,
     runner: RefCell<RunnerEnum>,
     suspended: Cell<bool>,
@@ -133,9 +136,9 @@ impl Shared {
         let document = window.document().expect("Failed to obtain document");
 
         Shared(Rc::<Execution>::new_cyclic(|weak| {
-            let proxy_spawner = WakerSpawner::new(main_thread, weak.clone(), |runner, count| {
+            let proxy_spawner = WakerSpawner::new(main_thread, weak.clone(), |runner, local| {
                 if let Some(runner) = runner.upgrade() {
-                    Shared(runner).send_events(iter::repeat(Event::UserEvent(())).take(count))
+                    Shared(runner).send_proxy_wake_up(local);
                 }
             })
             .expect("`EventLoop` has to be created in the main thread");
@@ -145,6 +148,7 @@ impl Shared {
                 proxy_spawner,
                 control_flow: Cell::new(ControlFlow::default()),
                 poll_strategy: Cell::new(PollStrategy::default()),
+                wait_until_strategy: Cell::new(WaitUntilStrategy::default()),
                 exit: Cell::new(false),
                 runner: RefCell::new(RunnerEnum::Pending),
                 suspended: Cell::new(false),
@@ -197,7 +201,7 @@ impl Shared {
     // Set the event callback to use for the event loop runner
     // This the event callback is a fairly thin layer over the user-provided callback that closes
     // over a RootActiveEventLoop reference
-    pub fn set_listener(&self, event_handler: Box<EventHandler>) {
+    pub(crate) fn set_listener(&self, event_handler: Box<EventHandler>) {
         {
             let mut runner = self.0.runner.borrow_mut();
             assert!(matches!(*runner, RunnerEnum::Pending));
@@ -460,6 +464,46 @@ impl Shared {
         self.send_events(iter::once(event));
     }
 
+    // Add a user event to the event loop runner.
+    //
+    // This will schedule the event loop to wake up instead of waking it up immediately if its not
+    // running.
+    pub(crate) fn send_proxy_wake_up(&self, local: bool) {
+        // If the event loop is closed, it should discard any new events
+        if self.is_closed() {
+            return;
+        }
+
+        if local {
+            // If the loop is not running and triggered locally, queue on next microtick.
+            if let Ok(RunnerEnum::Running(_)) =
+                self.0.runner.try_borrow().as_ref().map(Deref::deref)
+            {
+                #[wasm_bindgen]
+                extern "C" {
+                    #[wasm_bindgen(js_name = queueMicrotask)]
+                    fn queue_microtask(task: Function);
+                }
+
+                queue_microtask(
+                    Closure::once_into_js({
+                        let this = Rc::downgrade(&self.0);
+                        move || {
+                            if let Some(shared) = this.upgrade() {
+                                Shared(shared).send_event(Event::UserWakeUp)
+                            }
+                        }
+                    })
+                    .unchecked_into(),
+                );
+
+                return;
+            }
+        }
+
+        self.send_event(Event::UserWakeUp);
+    }
+
     // Add a series of events to the event loop runner
     //
     // It will determine if the event should be immediately sent to the user or buffered for later
@@ -471,13 +515,8 @@ impl Shared {
         // If we can run the event processing right now, or need to queue this and wait for later
         let mut process_immediately = true;
         match self.0.runner.try_borrow().as_ref().map(Deref::deref) {
-            Ok(RunnerEnum::Running(ref runner)) => {
-                // If we're currently polling, queue this and wait for the poll() method to be
-                // called
-                if let State::Poll { .. } = runner.state {
-                    process_immediately = false;
-                }
-            },
+            // If the runner is attached but not running, we always wake it up.
+            Ok(RunnerEnum::Running(_)) => (),
             Ok(RunnerEnum::Pending) => {
                 // The runner still hasn't been attached: queue this event and wait for it to be
                 process_immediately = false;
@@ -605,8 +644,10 @@ impl Shared {
 
                 // Pre-fetch `UserEvent`s to avoid having to wait until the next event loop cycle.
                 events.extend(
-                    iter::repeat(Event::UserEvent(()))
-                        .take(self.0.proxy_spawner.fetch())
+                    self.0
+                        .proxy_spawner
+                        .take()
+                        .then_some(Event::UserWakeUp)
                         .map(EventWrapper::from),
                 );
 
@@ -647,6 +688,7 @@ impl Shared {
                         start,
                         end,
                         _timeout: backend::Schedule::new_with_duration(
+                            self.wait_until_strategy(),
                             self.window(),
                             move || cloned.resume_time_reached(start, end),
                             delay,
@@ -693,7 +735,7 @@ impl Shared {
         //     * The `register_redraw_request` closure.
         //     * The `destroy_fn` closure.
         if self.0.event_loop_recreation.get() {
-            crate::event_loop::EventLoopBuilder::<()>::allow_event_loop_recreation();
+            crate::event_loop::EventLoopBuilder::allow_event_loop_recreation();
         }
     }
 
@@ -759,18 +801,26 @@ impl Shared {
         self.0.poll_strategy.get()
     }
 
+    pub(crate) fn set_wait_until_strategy(&self, strategy: WaitUntilStrategy) {
+        self.0.wait_until_strategy.set(strategy)
+    }
+
+    pub(crate) fn wait_until_strategy(&self) -> WaitUntilStrategy {
+        self.0.wait_until_strategy.get()
+    }
+
     pub(crate) fn waker(&self) -> Waker<Weak<Execution>> {
         self.0.proxy_spawner.waker()
     }
 }
 
 pub(crate) enum EventWrapper {
-    Event(Event<()>),
+    Event(Event),
     ScaleChange { canvas: Weak<RefCell<backend::Canvas>>, size: PhysicalSize<u32>, scale: f64 },
 }
 
-impl From<Event<()>> for EventWrapper {
-    fn from(value: Event<()>) -> Self {
+impl From<Event> for EventWrapper {
+    fn from(value: Event) -> Self {
         Self::Event(value)
     }
 }

src/platform_impl/web/event_loop/window_target.rs

@@ -18,7 +18,7 @@ use crate::event::{
 };
 use crate::event_loop::{ControlFlow, DeviceEvents};
 use crate::keyboard::ModifiersState;
-use crate::platform::web::{CustomCursorFuture, PollStrategy};
+use crate::platform::web::{CustomCursorFuture, PollStrategy, WaitUntilStrategy};
 use crate::platform_impl::platform::cursor::CustomCursor;
 use crate::platform_impl::platform::r#async::Waker;
 use crate::window::{
@@ -55,7 +55,11 @@ impl ActiveEventLoop {
         Self { runner: runner::Shared::new(), modifiers: ModifiersShared::default() }
     }
 
-    pub fn run(&self, event_handler: Box<runner::EventHandler>, event_loop_recreation: bool) {
+    pub(crate) fn run(
+        &self,
+        event_handler: Box<runner::EventHandler>,
+        event_loop_recreation: bool,
+    ) {
         self.runner.event_loop_recreation(event_loop_recreation);
         self.runner.set_listener(event_handler);
     }
@@ -682,6 +686,14 @@ impl ActiveEventLoop {
         self.runner.poll_strategy()
     }
 
+    pub(crate) fn set_wait_until_strategy(&self, strategy: WaitUntilStrategy) {
+        self.runner.set_wait_until_strategy(strategy)
+    }
+
+    pub(crate) fn wait_until_strategy(&self) -> WaitUntilStrategy {
+        self.runner.wait_until_strategy()
+    }
+
     pub(crate) fn waker(&self) -> Waker<Weak<Execution>> {
         self.runner.waker()
     }

src/platform_impl/web/mod.rs

@@ -28,11 +28,9 @@ mod event_loop;
 mod keyboard;
 mod main_thread;
 mod monitor;
+mod web_sys;
 mod window;
 
-#[path = "web_sys/mod.rs"]
-mod backend;
-
 pub use self::device::DeviceId;
 pub use self::error::OsError;
 pub(crate) use self::event_loop::{
@@ -43,6 +41,7 @@ pub use self::monitor::{MonitorHandle, VideoModeHandle};
 pub use self::window::{PlatformSpecificWindowAttributes, Window, WindowId};
 
 pub(crate) use self::keyboard::KeyEventExtra;
+use self::web_sys as backend;
 pub(crate) use crate::icon::NoIcon as PlatformIcon;
 pub(crate) use crate::platform_impl::Fullscreen;
 pub(crate) use cursor::{

src/platform_impl/web/web_sys/canvas.rs

@@ -427,8 +427,8 @@ impl Canvas {
 
     pub(crate) fn on_resize_scale<S, R>(&mut self, scale_handler: S, size_handler: R)
     where
-        S: 'static + FnMut(PhysicalSize<u32>, f64),
-        R: 'static + FnMut(PhysicalSize<u32>),
+        S: 'static + Fn(PhysicalSize<u32>, f64),
+        R: 'static + Fn(PhysicalSize<u32>),
     {
         self.on_resize_scale = Some(ResizeScaleHandle::new(
             self.window().clone(),
@@ -483,7 +483,7 @@ impl Canvas {
     pub(crate) fn handle_scale_change(
         &self,
         runner: &super::super::event_loop::runner::Shared,
-        event_handler: impl FnOnce(crate::event::Event<()>),
+        event_handler: impl FnOnce(crate::event::Event),
         current_size: PhysicalSize<u32>,
         scale: f64,
     ) {

src/platform_impl/web/web_sys/resize_scaling.rs

@@ -16,7 +16,7 @@ use super::media_query_handle::MediaQueryListHandle;
 use std::cell::{Cell, RefCell};
 use std::rc::Rc;
 
-pub struct ResizeScaleHandle(Rc<RefCell<ResizeScaleInternal>>);
+pub struct ResizeScaleHandle(Rc<ResizeScaleInternal>);
 
 impl ResizeScaleHandle {
     pub(crate) fn new<S, R>(
@@ -28,8 +28,8 @@ impl ResizeScaleHandle {
         resize_handler: R,
     ) -> Self
     where
-        S: 'static + FnMut(PhysicalSize<u32>, f64),
-        R: 'static + FnMut(PhysicalSize<u32>),
+        S: 'static + Fn(PhysicalSize<u32>, f64),
+        R: 'static + Fn(PhysicalSize<u32>),
     {
         Self(ResizeScaleInternal::new(
             window,
@@ -42,7 +42,7 @@ impl ResizeScaleHandle {
     }
 
     pub(crate) fn notify_resize(&self) {
-        self.0.borrow_mut().notify()
+        self.0.notify()
     }
 }
 
@@ -53,11 +53,11 @@ struct ResizeScaleInternal {
     document: Document,
     canvas: HtmlCanvasElement,
     style: Style,
-    mql: MediaQueryListHandle,
+    mql: RefCell<MediaQueryListHandle>,
     observer: ResizeObserver,
     _observer_closure: Closure<dyn FnMut(Array, ResizeObserver)>,
-    scale_handler: Box<dyn FnMut(PhysicalSize<u32>, f64)>,
-    resize_handler: Box<dyn FnMut(PhysicalSize<u32>)>,
+    scale_handler: Box<dyn Fn(PhysicalSize<u32>, f64)>,
+    resize_handler: Box<dyn Fn(PhysicalSize<u32>)>,
     notify_scale: Cell<bool>,
 }
 
@@ -69,12 +69,12 @@ impl ResizeScaleInternal {
         style: Style,
         scale_handler: S,
         resize_handler: R,
-    ) -> Rc<RefCell<Self>>
+    ) -> Rc<Self>
     where
-        S: 'static + FnMut(PhysicalSize<u32>, f64),
-        R: 'static + FnMut(PhysicalSize<u32>),
+        S: 'static + Fn(PhysicalSize<u32>, f64),
+        R: 'static + Fn(PhysicalSize<u32>),
     {
-        Rc::<RefCell<ResizeScaleInternal>>::new_cyclic(|weak_self| {
+        Rc::<ResizeScaleInternal>::new_cyclic(|weak_self| {
             let mql = Self::create_mql(&window, {
                 let weak_self = weak_self.clone();
                 move |mql| {
@@ -86,9 +86,7 @@ impl ResizeScaleInternal {
 
             let weak_self = weak_self.clone();
             let observer_closure = Closure::new(move |entries: Array, _| {
-                if let Some(rc_self) = weak_self.upgrade() {
-                    let mut this = rc_self.borrow_mut();
-
+                if let Some(this) = weak_self.upgrade() {
                     let size = this.process_entry(entries);
 
                     if this.notify_scale.replace(false) {
@@ -101,18 +99,18 @@ impl ResizeScaleInternal {
             });
             let observer = Self::create_observer(&canvas, observer_closure.as_ref());
 
-            RefCell::new(Self {
+            Self {
                 window,
                 document,
                 canvas,
                 style,
-                mql,
+                mql: RefCell::new(mql),
                 observer,
                 _observer_closure: observer_closure,
                 scale_handler: Box::new(scale_handler),
                 resize_handler: Box::new(resize_handler),
                 notify_scale: Cell::new(false),
-            })
+            }
         })
     }
 
@@ -152,7 +150,7 @@ impl ResizeScaleInternal {
         observer
     }
 
-    fn notify(&mut self) {
+    fn notify(&self) {
         if !self.document.contains(Some(&self.canvas)) || self.style.get("display") == "none" {
             let size = PhysicalSize::new(0, 0);
 
@@ -200,10 +198,9 @@ impl ResizeScaleInternal {
         }
     }
 
-    fn handle_scale(this: Rc<RefCell<Self>>, mql: &MediaQueryList) {
-        let weak_self = Rc::downgrade(&this);
-        let mut this = this.borrow_mut();
-        let scale = super::scale_factor(&this.window);
+    fn handle_scale(self: Rc<Self>, mql: &MediaQueryList) {
+        let weak_self = Rc::downgrade(&self);
+        let scale = super::scale_factor(&self.window);
 
         // TODO: confirm/reproduce this problem, see:
         // <https://github.com/rust-windowing/winit/issues/2597>.
@@ -217,15 +214,15 @@ impl ResizeScaleInternal {
             return;
         }
 
-        let new_mql = Self::create_mql(&this.window, move |mql| {
+        let new_mql = Self::create_mql(&self.window, move |mql| {
             if let Some(rc_self) = weak_self.upgrade() {
                 Self::handle_scale(rc_self, mql);
             }
         });
-        this.mql = new_mql;
+        self.mql.replace(new_mql);
 
-        this.notify_scale.set(true);
-        this.notify();
+        self.notify_scale.set(true);
+        self.notify();
     }
 
     fn process_entry(&self, entries: Array) -> PhysicalSize<u32> {

src/platform_impl/web/web_sys/schedule.rs

@@ -1,12 +1,14 @@
-use js_sys::{Function, Object, Promise, Reflect};
+use js_sys::{Array, Function, Object, Promise, Reflect};
 use std::cell::OnceCell;
 use std::time::Duration;
 use wasm_bindgen::closure::Closure;
 use wasm_bindgen::prelude::wasm_bindgen;
 use wasm_bindgen::{JsCast, JsValue};
-use web_sys::{AbortController, AbortSignal, MessageChannel, MessagePort};
+use web_sys::{
+    AbortController, AbortSignal, Blob, BlobPropertyBag, MessageChannel, MessagePort, Url, Worker,
+};
 
-use crate::platform::web::PollStrategy;
+use crate::platform::web::{PollStrategy, WaitUntilStrategy};
 
 #[derive(Debug)]
 pub struct Schedule {
@@ -29,6 +31,7 @@ enum Inner {
         port: MessagePort,
         _timeout_closure: Closure<dyn FnMut()>,
     },
+    Worker(MessagePort),
 }
 
 impl Schedule {
@@ -45,14 +48,24 @@ impl Schedule {
         }
     }
 
-    pub fn new_with_duration<F>(window: &web_sys::Window, f: F, duration: Duration) -> Schedule
+    pub fn new_with_duration<F>(
+        strategy: WaitUntilStrategy,
+        window: &web_sys::Window,
+        f: F,
+        duration: Duration,
+    ) -> Schedule
     where
         F: 'static + FnMut(),
     {
-        if has_scheduler_support(window) {
-            Self::new_scheduler(window, f, Some(duration))
-        } else {
-            Self::new_timeout(window.clone(), f, Some(duration))
+        match strategy {
+            WaitUntilStrategy::Scheduler => {
+                if has_scheduler_support(window) {
+                    Self::new_scheduler(window, f, Some(duration))
+                } else {
+                    Self::new_timeout(window.clone(), f, Some(duration))
+                }
+            },
+            WaitUntilStrategy::Worker => Self::new_worker(f, duration),
         }
     }
 
@@ -74,7 +87,7 @@ impl Schedule {
             let duration = duration
                 .as_secs()
                 .checked_mul(1000)
-                .and_then(|secs| secs.checked_add(duration_millis_ceil(duration).into()))
+                .and_then(|secs| secs.checked_add(duration.subsec_micros().div_ceil(1000).into()))
                 .unwrap_or(u64::MAX);
 
             options.delay(duration as f64);
@@ -127,7 +140,9 @@ impl Schedule {
                 .ok()
                 .and_then(|secs: i32| secs.checked_mul(1000))
                 .and_then(|secs: i32| {
-                    let millis: i32 = duration_millis_ceil(duration)
+                    let millis: i32 = duration
+                        .subsec_micros()
+                        .div_ceil(1000)
                         .try_into()
                         .expect("millis are somehow bigger then 1K");
                     secs.checked_add(millis)
@@ -153,6 +168,44 @@ impl Schedule {
             },
         }
     }
+
+    fn new_worker<F>(f: F, duration: Duration) -> Schedule
+    where
+        F: 'static + FnMut(),
+    {
+        thread_local! {
+            static URL: ScriptUrl = ScriptUrl::new(include_str!("worker.min.js"));
+            static WORKER: Worker = URL.with(|url| Worker::new(&url.0)).expect("`new Worker()` is not expected to fail with a local script");
+        }
+
+        let channel = MessageChannel::new().unwrap();
+        let closure = Closure::new(f);
+        let port_1 = channel.port1();
+        port_1.set_onmessage(Some(closure.as_ref().unchecked_ref()));
+        port_1.start();
+
+        // `Duration::as_millis()` always rounds down (because of truncation), we want to round
+        // up instead. This makes sure that the we never wake up **before** the given time.
+        let duration = duration
+            .as_secs()
+            .try_into()
+            .ok()
+            .and_then(|secs: u32| secs.checked_mul(1000))
+            .and_then(|secs| secs.checked_add(duration.subsec_micros().div_ceil(1000)))
+            .unwrap_or(u32::MAX);
+
+        WORKER
+            .with(|worker| {
+                let port_2 = channel.port2();
+                worker.post_message_with_transfer(
+                    &Array::of2(&port_2, &duration.into()),
+                    &Array::of1(&port_2).into(),
+                )
+            })
+            .expect("`Worker.postMessage()` is not expected to fail");
+
+        Schedule { _closure: closure, inner: Inner::Worker(port_1) }
+    }
 }
 
 impl Drop for Schedule {
@@ -165,24 +218,14 @@ impl Drop for Schedule {
                 port.close();
                 port.set_onmessage(None);
             },
+            Inner::Worker(port) => {
+                port.close();
+                port.set_onmessage(None);
+            },
         }
     }
 }
 
-// TODO: Replace with `u32::div_ceil()` when we hit Rust v1.73.
-fn duration_millis_ceil(duration: Duration) -> u32 {
-    let micros = duration.subsec_micros();
-
-    // From <https://doc.rust-lang.org/1.73.0/src/core/num/uint_macros.rs.html#2086-2094>.
-    let d = micros / 1000;
-    let r = micros % 1000;
-    if r > 0 && 1000 > 0 {
-        d + 1
-    } else {
-        d
-    }
-}
-
 fn has_scheduler_support(window: &web_sys::Window) -> bool {
     thread_local! {
         static SCHEDULER_SUPPORT: OnceCell<bool> = const { OnceCell::new() };
@@ -226,6 +269,29 @@ fn has_idle_callback_support(window: &web_sys::Window) -> bool {
     })
 }
 
+struct ScriptUrl(String);
+
+impl ScriptUrl {
+    fn new(script: &str) -> Self {
+        let sequence = Array::of1(&script.into());
+        let mut property = BlobPropertyBag::new();
+        property.type_("text/javascript");
+        let blob = Blob::new_with_str_sequence_and_options(&sequence, &property)
+            .expect("`new Blob()` should never throw");
+
+        let url = Url::create_object_url_with_blob(&blob)
+            .expect("`URL.createObjectURL()` should never throw");
+
+        Self(url)
+    }
+}
+
+impl Drop for ScriptUrl {
+    fn drop(&mut self) {
+        Url::revoke_object_url(&self.0).expect("`URL.revokeObjectURL()` should never throw");
+    }
+}
+
 #[wasm_bindgen]
 extern "C" {
     type WindowSupportExt;

src/platform_impl/web/web_sys/worker.js

@@ -0,0 +1,10 @@
+onmessage = event => {
+    const [port, timeout] = event.data
+    const f = () => port.postMessage(undefined)
+
+    if ('scheduler' in this) {
+        scheduler.postTask(f, { delay: timeout })
+    } else {
+        setTimeout(f, timeout)
+    }
+}

src/platform_impl/web/web_sys/worker.min.js

@@ -0,0 +1 @@
+onmessage=e=>{let[s,t]=e.data,a=()=>s.postMessage(void 0);"scheduler"in this?scheduler.postTask(a,{delay:t}):setTimeout(a,t)};

src/platform_impl/windows/drop_handler.rs

@@ -25,7 +25,7 @@ pub struct FileDropHandlerData {
     pub interface: IDropTarget,
     refcount: AtomicUsize,
     window: HWND,
-    send_event: Box<dyn Fn(Event<()>)>,
+    send_event: Box<dyn Fn(Event)>,
     cursor_effect: u32,
     hovered_is_valid: bool, /* If the currently hovered item is not valid there must not be any
                              * `HoveredFileCancelled` emitted */
@@ -37,7 +37,7 @@ pub struct FileDropHandler {
 
 #[allow(non_snake_case)]
 impl FileDropHandler {
-    pub fn new(window: HWND, send_event: Box<dyn Fn(Event<()>)>) -> FileDropHandler {
+    pub(crate) fn new(window: HWND, send_event: Box<dyn Fn(Event)>) -> FileDropHandler {
         let data = Box::new(FileDropHandlerData {
             interface: IDropTarget { lpVtbl: &DROP_TARGET_VTBL as *const IDropTargetVtbl },
             refcount: AtomicUsize::new(1),
@@ -211,7 +211,7 @@ impl FileDropHandler {
 }
 
 impl FileDropHandlerData {
-    fn send_event(&self, event: Event<()>) {
+    fn send_event(&self, event: Event) {
         (self.send_event)(event);
     }
 }

src/platform_impl/windows/event_loop.rs

@@ -8,7 +8,6 @@ use std::ffi::c_void;
 use std::marker::PhantomData;
 use std::rc::Rc;
 use std::sync::atomic::{AtomicU32, Ordering};
-use std::sync::mpsc::{self, Receiver, Sender};
 use std::sync::{Arc, Mutex, MutexGuard};
 use std::time::{Duration, Instant};
 use std::{mem, panic, ptr};
@@ -57,12 +56,13 @@ use windows_sys::Win32::UI::WindowsAndMessaging::{
     WS_EX_NOACTIVATE, WS_EX_TOOLWINDOW, WS_EX_TRANSPARENT, WS_OVERLAPPED, WS_POPUP, WS_VISIBLE,
 };
 
+use crate::application::ApplicationHandler;
 use crate::dpi::{PhysicalPosition, PhysicalSize};
 use crate::error::EventLoopError;
 use crate::event::{
     DeviceEvent, Event, Force, Ime, InnerSizeWriter, RawKeyEvent, Touch, TouchPhase, WindowEvent,
 };
-use crate::event_loop::{ActiveEventLoop as RootAEL, ControlFlow, DeviceEvents, EventLoopClosed};
+use crate::event_loop::{ActiveEventLoop as RootAEL, ControlFlow, DeviceEvents};
 use crate::keyboard::ModifiersState;
 use crate::platform::pump_events::PumpStatus;
 use crate::platform_impl::platform::dark_mode::try_theme;
@@ -83,35 +83,14 @@ use crate::platform_impl::platform::{
 use crate::window::{
     CustomCursor as RootCustomCursor, CustomCursorSource, WindowId as RootWindowId,
 };
-use runner::{EventLoopRunner, EventLoopRunnerShared};
+use runner::EventLoopRunner;
 
 use super::window::set_skip_taskbar;
 use super::SelectedCursor;
 
-/// some backends like macos uses an uninhabited `Never` type,
-/// on windows, `UserEvent`s are also dispatched through the
-/// WNDPROC callback, and due to the re-entrant nature of the
-/// callback, recursively delivered events must be queued in a
-/// buffer, the current implementation put this queue in
-/// `EventLoopRunner`, which is shared between the event pumping
-/// loop and the callback. because it's hard to decide from the
-/// outside whether a event needs to be buffered, I decided not
-/// use `Event<Never>` for the shared runner state, but use unit
-/// as a placeholder so user events can be buffered as usual,
-/// the real `UserEvent` is pulled from the mpsc channel directly
-/// when the placeholder event is delivered to the event handler
-pub(crate) struct UserEventPlaceholder;
-
-// here below, the generic `EventLoopRunnerShared<T>` is replaced with
-// `EventLoopRunnerShared<UserEventPlaceholder>` so we can get rid
-// of the generic parameter T in types which don't depend on T.
-// this is the approach which requires minimum changes to current
-// backend implementation. it should be considered transitional
-// and should be refactored and cleaned up eventually, I hope.
-
 pub(crate) struct WindowData {
     pub window_state: Arc<Mutex<WindowState>>,
-    pub event_loop_runner: EventLoopRunnerShared<UserEventPlaceholder>,
+    pub event_loop_runner: Rc<EventLoopRunner>,
     pub key_event_builder: KeyEventBuilder,
     pub _file_drop_handler: Option<FileDropHandler>,
     pub userdata_removed: Cell<bool>,
@@ -119,7 +98,7 @@ pub(crate) struct WindowData {
 }
 
 impl WindowData {
-    fn send_event(&self, event: Event<UserEventPlaceholder>) {
+    fn send_event(&self, event: Event) {
         self.event_loop_runner.send_event(event);
     }
 
@@ -129,11 +108,11 @@ impl WindowData {
 }
 
 struct ThreadMsgTargetData {
-    event_loop_runner: EventLoopRunnerShared<UserEventPlaceholder>,
+    event_loop_runner: Rc<EventLoopRunner>,
 }
 
 impl ThreadMsgTargetData {
-    fn send_event(&self, event: Event<UserEventPlaceholder>) {
+    fn send_event(&self, event: Event) {
         self.event_loop_runner.send_event(event);
     }
 }
@@ -145,9 +124,7 @@ pub(crate) enum ProcResult {
     Value(isize),
 }
 
-pub struct EventLoop<T: 'static> {
-    user_event_sender: Sender<T>,
-    user_event_receiver: Receiver<T>,
+pub struct EventLoop {
     window_target: RootAEL,
     msg_hook: Option<Box<dyn FnMut(*const c_void) -> bool + 'static>>,
 }
@@ -167,10 +144,10 @@ impl Default for PlatformSpecificEventLoopAttributes {
 pub struct ActiveEventLoop {
     thread_id: u32,
     thread_msg_target: HWND,
-    pub(crate) runner_shared: EventLoopRunnerShared<UserEventPlaceholder>,
+    pub(crate) runner_shared: Rc<EventLoopRunner>,
 }
 
-impl<T: 'static> EventLoop<T> {
+impl EventLoop {
     pub(crate) fn new(
         attributes: &mut PlatformSpecificEventLoopAttributes,
     ) -> Result<Self, EventLoopError> {
@@ -193,7 +170,6 @@ impl<T: 'static> EventLoop<T> {
 
         let runner_shared = Rc::new(EventLoopRunner::new(thread_msg_target));
 
-        let (user_event_sender, user_event_receiver) = mpsc::channel();
         insert_event_target_window_data(thread_msg_target, runner_shared.clone());
         raw_input::register_all_mice_and_keyboards_for_raw_input(
             thread_msg_target,
@@ -201,8 +177,6 @@ impl<T: 'static> EventLoop<T> {
         );
 
         Ok(EventLoop {
-            user_event_sender,
-            user_event_receiver,
             window_target: RootAEL {
                 p: ActiveEventLoop { thread_id, thread_msg_target, runner_shared },
                 _marker: PhantomData,
@@ -215,42 +189,36 @@ impl<T: 'static> EventLoop<T> {
         &self.window_target
     }
 
-    pub fn run<F>(mut self, event_handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(Event<T>, &RootAEL),
-    {
-        self.run_on_demand(event_handler)
+    pub fn run_app<A: ApplicationHandler>(mut self, app: &mut A) -> Result<(), EventLoopError> {
+        self.run_app_on_demand(app)
     }
 
-    pub fn run_on_demand<F>(&mut self, mut event_handler: F) -> Result<(), EventLoopError>
-    where
-        F: FnMut(Event<T>, &RootAEL),
-    {
+    pub fn run_app_on_demand<A: ApplicationHandler>(
+        &mut self,
+        app: &mut A,
+    ) -> Result<(), EventLoopError> {
         {
             let runner = &self.window_target.p.runner_shared;
 
             let event_loop_windows_ref = &self.window_target;
-            let user_event_receiver = &self.user_event_receiver;
             // # Safety
             // We make sure to call runner.clear_event_handler() before
             // returning
             unsafe {
-                runner.set_event_handler(move |event| {
-                    // the shared `EventLoopRunner` is not parameterized
-                    // `EventLoopProxy::send_event()` calls `PostMessage`
-                    // to wakeup and dispatch a placeholder `UserEvent`,
-                    // when we received the placeholder event here, the
-                    // real UserEvent(T) should already be put in the
-                    // mpsc channel and ready to be pulled
-                    let event = match event.map_nonuser_event() {
-                        Ok(non_user_event) => non_user_event,
-                        Err(_user_event_placeholder) => Event::UserEvent(
-                            user_event_receiver
-                                .try_recv()
-                                .expect("user event signaled but not received"),
-                        ),
-                    };
-                    event_handler(event, event_loop_windows_ref)
+                runner.set_event_handler(move |event| match event {
+                    Event::NewEvents(cause) => app.new_events(event_loop_windows_ref, cause),
+                    Event::WindowEvent { window_id, event } => {
+                        app.window_event(event_loop_windows_ref, window_id, event)
+                    },
+                    Event::DeviceEvent { device_id, event } => {
+                        app.device_event(event_loop_windows_ref, device_id, event)
+                    },
+                    Event::UserWakeUp => app.proxy_wake_up(event_loop_windows_ref),
+                    Event::Suspended => app.suspended(event_loop_windows_ref),
+                    Event::Resumed => app.resumed(event_loop_windows_ref),
+                    Event::AboutToWait => app.about_to_wait(event_loop_windows_ref),
+                    Event::LoopExiting => app.exiting(event_loop_windows_ref),
+                    Event::MemoryWarning => app.memory_warning(event_loop_windows_ref),
                 });
             }
         }
@@ -284,14 +252,15 @@ impl<T: 'static> EventLoop<T> {
         }
     }
 
-    pub fn pump_events<F>(&mut self, timeout: Option<Duration>, mut event_handler: F) -> PumpStatus
-    where
-        F: FnMut(Event<T>, &RootAEL),
-    {
+    pub fn pump_app_events<A: ApplicationHandler>(
+        &mut self,
+        timeout: Option<Duration>,
+        app: &mut A,
+    ) -> PumpStatus {
         {
             let runner = &self.window_target.p.runner_shared;
             let event_loop_windows_ref = &self.window_target;
-            let user_event_receiver = &self.user_event_receiver;
+            // let user_event_receiver = &self.user_event_receiver;
 
             // # Safety
             // We make sure to call runner.clear_event_handler() before
@@ -301,17 +270,22 @@ impl<T: 'static> EventLoop<T> {
             // to leave the runner in an unsound state with an associated
             // event handler.
             unsafe {
-                runner.set_event_handler(move |event| {
-                    let event = match event.map_nonuser_event() {
-                        Ok(non_user_event) => non_user_event,
-                        Err(_user_event_placeholder) => Event::UserEvent(
-                            user_event_receiver
-                                .recv()
-                                .expect("user event signaled but not received"),
-                        ),
-                    };
-                    event_handler(event, event_loop_windows_ref)
+                runner.set_event_handler(move |event| match event {
+                    Event::NewEvents(cause) => app.new_events(event_loop_windows_ref, cause),
+                    Event::WindowEvent { window_id, event } => {
+                        app.window_event(event_loop_windows_ref, window_id, event)
+                    },
+                    Event::DeviceEvent { device_id, event } => {
+                        app.device_event(event_loop_windows_ref, device_id, event)
+                    },
+                    Event::UserWakeUp => app.proxy_wake_up(event_loop_windows_ref),
+                    Event::Suspended => app.suspended(event_loop_windows_ref),
+                    Event::Resumed => app.resumed(event_loop_windows_ref),
+                    Event::AboutToWait => app.about_to_wait(event_loop_windows_ref),
+                    Event::LoopExiting => app.exiting(event_loop_windows_ref),
+                    Event::MemoryWarning => app.memory_warning(event_loop_windows_ref),
                 });
+
                 runner.wakeup();
             }
         }
@@ -494,11 +468,8 @@ impl<T: 'static> EventLoop<T> {
         }
     }
 
-    pub fn create_proxy(&self) -> EventLoopProxy<T> {
-        EventLoopProxy {
-            target_window: self.window_target.p.thread_msg_target,
-            event_send: self.user_event_sender.clone(),
-        }
+    pub fn create_proxy(&self) -> EventLoopProxy {
+        EventLoopProxy { target_window: self.window_target.p.thread_msg_target }
     }
 
     fn exit_code(&self) -> Option<i32> {
@@ -670,7 +641,7 @@ fn dur2timeout(dur: Duration) -> u32 {
         .unwrap_or(INFINITE)
 }
 
-impl<T> Drop for EventLoop<T> {
+impl Drop for EventLoop {
     fn drop(&mut self) {
         unsafe {
             DestroyWindow(self.window_target.p.thread_msg_target);
@@ -728,27 +699,16 @@ impl EventLoopThreadExecutor {
 
 type ThreadExecFn = Box<Box<dyn FnMut()>>;
 
-pub struct EventLoopProxy<T: 'static> {
+#[derive(Clone)]
+pub struct EventLoopProxy {
     target_window: HWND,
-    event_send: Sender<T>,
-}
-unsafe impl<T: Send + 'static> Send for EventLoopProxy<T> {}
-
-impl<T: 'static> Clone for EventLoopProxy<T> {
-    fn clone(&self) -> Self {
-        Self { target_window: self.target_window, event_send: self.event_send.clone() }
-    }
 }
 
-impl<T: 'static> EventLoopProxy<T> {
-    pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
-        self.event_send
-            .send(event)
-            .map(|result| {
-                unsafe { PostMessageW(self.target_window, USER_EVENT_MSG_ID.get(), 0, 0) };
-                result
-            })
-            .map_err(|e| EventLoopClosed(e.0))
+unsafe impl Send for EventLoopProxy {}
+
+impl EventLoopProxy {
+    pub fn wake_up(&self) {
+        unsafe { PostMessageW(self.target_window, USER_EVENT_MSG_ID.get(), 0, 0) };
     }
 }
 
@@ -880,7 +840,7 @@ fn create_event_target_window() -> HWND {
 
 fn insert_event_target_window_data(
     thread_msg_target: HWND,
-    event_loop_runner: EventLoopRunnerShared<UserEventPlaceholder>,
+    event_loop_runner: Rc<EventLoopRunner>,
 ) {
     let userdata = ThreadMsgTargetData { event_loop_runner };
     let input_ptr = Box::into_raw(Box::new(userdata));
@@ -2426,7 +2386,7 @@ unsafe extern "system" fn thread_event_target_callback(
             // user event is still in the mpsc channel and will be pulled
             // once the placeholder event is delivered to the wrapper
             // `event_handler`
-            userdata.send_event(Event::UserEvent(UserEventPlaceholder));
+            userdata.send_event(Event::UserWakeUp);
             0
         },
         _ if msg == EXEC_MSG_ID.get() => {

src/platform_impl/windows/event_loop/runner.rs

@@ -1,7 +1,6 @@
 use std::any::Any;
 use std::cell::{Cell, RefCell};
 use std::collections::VecDeque;
-use std::rc::Rc;
 use std::sync::{Arc, Mutex};
 use std::time::Instant;
 use std::{mem, panic};
@@ -16,11 +15,9 @@ use crate::window::WindowId;
 
 use super::ControlFlow;
 
-pub(crate) type EventLoopRunnerShared<T> = Rc<EventLoopRunner<T>>;
+type EventHandler = Cell<Option<Box<dyn FnMut(Event)>>>;
 
-type EventHandler<T> = Cell<Option<Box<dyn FnMut(Event<T>)>>>;
-
-pub(crate) struct EventLoopRunner<T: 'static> {
+pub(crate) struct EventLoopRunner {
     // The event loop's win32 handles
     pub(super) thread_msg_target: HWND,
 
@@ -33,8 +30,8 @@ pub(crate) struct EventLoopRunner<T: 'static> {
     exit: Cell<Option<i32>>,
     runner_state: Cell<RunnerState>,
     last_events_cleared: Cell<Instant>,
-    event_handler: EventHandler<T>,
-    event_buffer: RefCell<VecDeque<BufferedEvent<T>>>,
+    event_handler: EventHandler,
+    event_buffer: RefCell<VecDeque<BufferedEvent>>,
 
     panic_error: Cell<Option<PanicError>>,
 }
@@ -55,13 +52,13 @@ pub(crate) enum RunnerState {
     Destroyed,
 }
 
-enum BufferedEvent<T: 'static> {
-    Event(Event<T>),
+enum BufferedEvent {
+    Event(Event),
     ScaleFactorChanged(WindowId, f64, PhysicalSize<u32>),
 }
 
-impl<T> EventLoopRunner<T> {
-    pub(crate) fn new(thread_msg_target: HWND) -> EventLoopRunner<T> {
+impl EventLoopRunner {
+    pub(crate) fn new(thread_msg_target: HWND) -> EventLoopRunner {
         EventLoopRunner {
             thread_msg_target,
             interrupt_msg_dispatch: Cell::new(false),
@@ -88,13 +85,12 @@ impl<T> EventLoopRunner<T> {
     /// undefined behaviour.
     pub(crate) unsafe fn set_event_handler<F>(&self, f: F)
     where
-        F: FnMut(Event<T>),
+        F: FnMut(Event),
     {
         // Erase closure lifetime.
         // SAFETY: Caller upholds that the lifetime of the closure is upheld.
-        let f = unsafe {
-            mem::transmute::<Box<dyn FnMut(Event<T>)>, Box<dyn FnMut(Event<T>)>>(Box::new(f))
-        };
+        let f =
+            unsafe { mem::transmute::<Box<dyn FnMut(Event)>, Box<dyn FnMut(Event)>>(Box::new(f)) };
         let old_event_handler = self.event_handler.replace(Some(f));
         assert!(old_event_handler.is_none());
     }
@@ -124,7 +120,7 @@ impl<T> EventLoopRunner<T> {
 }
 
 /// State retrieval functions.
-impl<T> EventLoopRunner<T> {
+impl EventLoopRunner {
     #[allow(unused)]
     pub fn thread_msg_target(&self) -> HWND {
         self.thread_msg_target
@@ -166,7 +162,7 @@ impl<T> EventLoopRunner<T> {
 }
 
 /// Misc. functions
-impl<T> EventLoopRunner<T> {
+impl EventLoopRunner {
     pub fn catch_unwind<R>(&self, f: impl FnOnce() -> R) -> Option<R> {
         let panic_error = self.panic_error.take();
         if panic_error.is_none() {
@@ -196,7 +192,7 @@ impl<T> EventLoopRunner<T> {
 }
 
 /// Event dispatch functions.
-impl<T> EventLoopRunner<T> {
+impl EventLoopRunner {
     pub(crate) fn prepare_wait(&self) {
         self.move_state_to(RunnerState::Idle);
     }
@@ -205,7 +201,7 @@ impl<T> EventLoopRunner<T> {
         self.move_state_to(RunnerState::HandlingMainEvents);
     }
 
-    pub(crate) fn send_event(&self, event: Event<T>) {
+    pub(crate) fn send_event(&self, event: Event) {
         if let Event::WindowEvent { event: WindowEvent::RedrawRequested, .. } = event {
             self.call_event_handler(event);
             // As a rule, to ensure that `pump_events` can't block an external event loop
@@ -226,7 +222,7 @@ impl<T> EventLoopRunner<T> {
         self.move_state_to(RunnerState::Destroyed);
     }
 
-    fn call_event_handler(&self, event: Event<T>) {
+    fn call_event_handler(&self, event: Event) {
         self.catch_unwind(|| {
             let mut event_handler = self.event_handler.take().expect(
                 "either event handler is re-entrant (likely), or no event handler is registered \
@@ -358,8 +354,8 @@ impl<T> EventLoopRunner<T> {
     }
 }
 
-impl<T> BufferedEvent<T> {
-    pub fn from_event(event: Event<T>) -> BufferedEvent<T> {
+impl BufferedEvent {
+    pub fn from_event(event: Event) -> BufferedEvent {
         match event {
             Event::WindowEvent {
                 event: WindowEvent::ScaleFactorChanged { scale_factor, inner_size_writer },
@@ -373,7 +369,7 @@ impl<T> BufferedEvent<T> {
         }
     }
 
-    pub fn dispatch_event(self, dispatch: impl FnOnce(Event<T>)) {
+    pub fn dispatch_event(self, dispatch: impl FnOnce(Event)) {
         match self {
             Self::Event(event) => dispatch(event),
             Self::ScaleFactorChanged(window_id, scale_factor, new_inner_size) => {

src/platform_impl/windows/mod.rs

@@ -1,5 +1,3 @@
-#![cfg(windows_platform)]
-
 use smol_str::SmolStr;
 use windows_sys::Win32::Foundation::{HANDLE, HWND};
 use windows_sys::Win32::UI::WindowsAndMessaging::{HMENU, WINDOW_LONG_PTR_INDEX};

src/platform_impl/windows/window.rs

@@ -1186,11 +1186,7 @@ impl<'a> InitData<'a> {
             let file_drop_runner = self.event_loop.runner_shared.clone();
             let file_drop_handler = FileDropHandler::new(
                 win.window,
-                Box::new(move |event| {
-                    if let Ok(e) = event.map_nonuser_event() {
-                        file_drop_runner.send_event(e)
-                    }
-                }),
+                Box::new(move |event| file_drop_runner.send_event(event)),
             );
 
             let handler_interface_ptr =

src/window.rs

@@ -393,7 +393,6 @@ impl WindowAttributes {
     ///
     /// ## Platform-specific
     ///
-    /// - **macOS:** This is an app-wide setting.
     /// - **Wayland:** This controls only CSD. When using `None` it'll try to use dbus to get the
     ///   system preference. When explicit theme is used, this will avoid dbus all together.
     /// - **x11:** Build window with `_GTK_THEME_VARIANT` hint set to `dark` or `light`.
@@ -942,8 +941,7 @@ impl Window {
     ///
     /// ## Platform-specific
     ///
-    /// - **macOS:** If you're not drawing to the window yourself, you might have to set the
-    ///   background color of the window to enable transparency.
+    /// - **macOS:** This will reset the window's background color.
     /// - **Web / iOS / Android:** Unsupported.
     /// - **X11:** Can only be set while building the window, with
     ///   [`WindowAttributes::with_transparent`].
@@ -1355,11 +1353,12 @@ impl Window {
         self.window.maybe_queue_on_main(move |w| w.request_user_attention(request_type))
     }
 
-    /// Sets the current window theme. Use `None` to fallback to system default.
+    /// Set or override the window theme.
+    ///
+    /// Specify `None` to reset the theme to the system default.
     ///
     /// ## Platform-specific
     ///
-    /// - **macOS:** This is an app-wide setting.
     /// - **Wayland:** Sets the theme for the client side decorations. Using `None` will use dbus to
     ///   get the system preference.
     /// - **X11:** Sets `_GTK_THEME_VARIANT` hint to `dark` or `light` and if `None` is used, it
@@ -1375,12 +1374,14 @@ impl Window {
         self.window.maybe_queue_on_main(move |w| w.set_theme(theme))
     }
 
-    /// Returns the current window theme.
+    /// Returns the current window theme override.
+    ///
+    /// Returns `None` if the current theme is set as the system default, or if it cannot be
+    /// determined on the current platform.
     ///
     /// ## Platform-specific
     ///
-    /// - **macOS:** This is an app-wide setting.
-    /// - **iOS / Android / Wayland / x11 / Orbital:** Unsupported.
+    /// - **iOS / Android / Wayland / x11 / Orbital:** Unsupported, returns `None`.
     #[inline]
     pub fn theme(&self) -> Option<Theme> {
         let _span = tracing::debug_span!("winit::Window::theme",).entered();

tests/send_objects.rs

@@ -3,16 +3,11 @@ fn needs_send<T: Send>() {}
 
 #[test]
 fn event_loop_proxy_send() {
-    #[allow(dead_code)]
-    fn is_send<T: 'static + Send>() {
-        // ensures that `winit::EventLoopProxy<T: Send>` implements `Send`
-        needs_send::<winit::event_loop::EventLoopProxy<T>>();
-    }
+    needs_send::<winit::event_loop::EventLoopProxy>();
 }
 
 #[test]
 fn window_send() {
-    // ensures that `winit::Window` implements `Send`
     needs_send::<winit::window::Window>();
 }
 
@@ -23,7 +18,6 @@ fn window_builder_send() {
 
 #[test]
 fn ids_send() {
-    // ensures that the various `..Id` types implement `Send`
     needs_send::<winit::window::WindowId>();
     needs_send::<winit::event::DeviceId>();
     needs_send::<winit::monitor::MonitorHandle>();

tests/sync_object.rs

@@ -3,16 +3,11 @@ fn needs_sync<T: Sync>() {}
 
 #[test]
 fn event_loop_proxy_send() {
-    #[allow(dead_code)]
-    fn is_send<T: 'static + Send>() {
-        // ensures that `winit::EventLoopProxy<T: Send>` implements `Sync`
-        needs_sync::<winit::event_loop::EventLoopProxy<T>>();
-    }
+    needs_sync::<winit::event_loop::EventLoopProxy>();
 }
 
 #[test]
 fn window_sync() {
-    // ensures that `winit::Window` implements `Sync`
     needs_sync::<winit::window::Window>();
 }