Web: implement WaitUntilStrategy (#3739)

src/platform/web.rs

@@ -197,6 +197,20 @@ pub trait EventLoopExtWebSys {
     ///
     /// [`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> {
@@ -213,6 +227,14 @@ impl<T> EventLoopExtWebSys for EventLoop<T> {
     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()
+    }
 }
 
 pub trait ActiveEventLoopExtWebSys {
@@ -230,6 +252,20 @@ 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;
@@ -250,6 +286,16 @@ 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].
@@ -278,6 +324,29 @@ 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;