9ac3259a79
Lifetimes don't work nicely when dealing with multithreaded environments in the current design of the existing winit's event handling model, so remove it in favor of `InnerSizeWriter` fences passed to client, so they could try to update the size. Fixes #1387.
476 lines
17 KiB
Rust
476 lines
17 KiB
Rust
//! The [`EventLoop`] struct and assorted supporting types, including
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//! [`ControlFlow`].
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//!
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//! If you want to send custom events to the event loop, use
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//! [`EventLoop::create_proxy`] to acquire an [`EventLoopProxy`] and call its
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//! [`send_event`](`EventLoopProxy::send_event`) method.
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//!
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//! See the root-level documentation for information on how to create and use an event loop to
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//! handle events.
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use std::marker::PhantomData;
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use std::ops::Deref;
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use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
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use std::{error, fmt};
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use raw_window_handle::{HasRawDisplayHandle, RawDisplayHandle};
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#[cfg(not(wasm_platform))]
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use std::time::{Duration, Instant};
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#[cfg(wasm_platform)]
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use web_time::{Duration, Instant};
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use crate::error::RunLoopError;
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use crate::{event::Event, monitor::MonitorHandle, platform_impl};
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/// Provides a way to retrieve events from the system and from the windows that were registered to
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/// the events loop.
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///
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/// An `EventLoop` can be seen more or less as a "context". Calling [`EventLoop::new`]
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/// initializes everything that will be required to create windows. For example on Linux creating
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/// an event loop opens a connection to the X or Wayland server.
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///
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/// To wake up an `EventLoop` from a another thread, see the [`EventLoopProxy`] docs.
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///
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/// Note that this cannot be shared across threads (due to platform-dependant logic
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/// forbidding it), as such it is neither [`Send`] nor [`Sync`]. If you need cross-thread access, the
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/// [`Window`] created from this _can_ be sent to an other thread, and the
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/// [`EventLoopProxy`] allows you to wake up an `EventLoop` from another thread.
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///
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/// [`Window`]: crate::window::Window
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pub struct EventLoop<T: 'static> {
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pub(crate) event_loop: platform_impl::EventLoop<T>,
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pub(crate) _marker: PhantomData<*mut ()>, // Not Send nor Sync
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}
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/// Target that associates windows with an [`EventLoop`].
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///
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/// This type exists to allow you to create new windows while Winit executes
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/// your callback. [`EventLoop`] will coerce into this type (`impl<T> Deref for
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/// EventLoop<T>`), so functions that take this as a parameter can also take
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/// `&EventLoop`.
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pub struct EventLoopWindowTarget<T: 'static> {
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pub(crate) p: platform_impl::EventLoopWindowTarget<T>,
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pub(crate) _marker: PhantomData<*mut ()>, // Not Send nor Sync
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}
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/// Object that allows building the event loop.
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///
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/// This is used to make specifying options that affect the whole application
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/// easier. But note that constructing multiple event loops is not supported.
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#[derive(Default)]
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pub struct EventLoopBuilder<T: 'static> {
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pub(crate) platform_specific: platform_impl::PlatformSpecificEventLoopAttributes,
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_p: PhantomData<T>,
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}
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impl EventLoopBuilder<()> {
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/// Start building a new event loop.
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#[inline]
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pub fn new() -> Self {
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Self::with_user_event()
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}
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}
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static EVENT_LOOP_CREATED: AtomicBool = AtomicBool::new(false);
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impl<T> EventLoopBuilder<T> {
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/// Start building a new event loop, with the given type as the user event
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/// type.
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#[inline]
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pub fn with_user_event() -> Self {
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Self {
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platform_specific: Default::default(),
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_p: PhantomData,
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}
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}
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/// Builds a new event loop.
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///
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/// ***For cross-platform compatibility, the [`EventLoop`] must be created on the main thread,
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/// and only once per application.***
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///
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/// Attempting to create the event loop on a different thread, or multiple event loops in
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/// the same application, will panic. This restriction isn't
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/// strictly necessary on all platforms, but is imposed to eliminate any nasty surprises when
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/// porting to platforms that require it. `EventLoopBuilderExt::any_thread` functions are exposed
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/// in the relevant [`platform`] module if the target platform supports creating an event loop on
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/// any thread.
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///
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/// Calling this function will result in display backend initialisation.
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///
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/// ## Platform-specific
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///
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/// - **Linux:** Backend type can be controlled using an environment variable
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/// `WINIT_UNIX_BACKEND`. Legal values are `x11` and `wayland`.
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/// If it is not set, winit will try to connect to a Wayland connection, and if that fails,
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/// will fall back on X11. If this variable is set with any other value, winit will panic.
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/// - **Android:** Must be configured with an `AndroidApp` from `android_main()` by calling
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/// [`.with_android_app(app)`] before calling `.build()`.
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///
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/// [`platform`]: crate::platform
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#[cfg_attr(
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android,
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doc = "[`.with_android_app(app)`]: crate::platform::android::EventLoopBuilderExtAndroid::with_android_app"
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)]
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#[cfg_attr(
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not(android),
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doc = "[`.with_android_app(app)`]: #only-available-on-android"
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)]
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#[inline]
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pub fn build(&mut self) -> EventLoop<T> {
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if EVENT_LOOP_CREATED.swap(true, Ordering::Relaxed) {
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panic!("Creating EventLoop multiple times is not supported.");
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}
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// Certain platforms accept a mutable reference in their API.
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#[allow(clippy::unnecessary_mut_passed)]
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EventLoop {
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event_loop: platform_impl::EventLoop::new(&mut self.platform_specific),
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_marker: PhantomData,
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}
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}
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#[cfg(wasm_platform)]
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pub(crate) fn allow_event_loop_recreation() {
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EVENT_LOOP_CREATED.store(false, Ordering::Relaxed);
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}
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}
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impl<T> fmt::Debug for EventLoop<T> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.pad("EventLoop { .. }")
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}
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}
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impl<T> fmt::Debug for EventLoopWindowTarget<T> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.pad("EventLoopWindowTarget { .. }")
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}
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}
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/// Set by the user callback given to the [`EventLoop::run`] method.
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///
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/// Indicates the desired behavior of the event loop after [`Event::AboutToWait`] is emitted.
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///
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/// Defaults to [`Poll`].
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///
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/// ## Persistency
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///
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/// Almost every change is persistent between multiple calls to the event loop closure within a
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/// given run loop. The only exception to this is [`ExitWithCode`] which, once set, cannot be unset.
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/// Changes are **not** persistent between multiple calls to `run_ondemand` - issuing a new call will
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/// reset the control flow to [`Poll`].
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///
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/// [`ExitWithCode`]: Self::ExitWithCode
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/// [`Poll`]: Self::Poll
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#[derive(Copy, Clone, Debug, PartialEq, Eq)]
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pub enum ControlFlow {
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/// When the current loop iteration finishes, immediately begin a new iteration regardless of
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/// whether or not new events are available to process.
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Poll,
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/// When the current loop iteration finishes, suspend the thread until another event arrives.
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Wait,
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/// When the current loop iteration finishes, suspend the thread until either another event
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/// arrives or the given time is reached.
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///
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/// Useful for implementing efficient timers. Applications which want to render at the display's
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/// native refresh rate should instead use [`Poll`] and the VSync functionality of a graphics API
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/// to reduce odds of missed frames.
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///
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/// [`Poll`]: Self::Poll
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WaitUntil(Instant),
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/// Send a [`LoopExiting`] event and stop the event loop. This variant is *sticky* - once set,
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/// `control_flow` cannot be changed from `ExitWithCode`, and any future attempts to do so will
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/// result in the `control_flow` parameter being reset to `ExitWithCode`.
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///
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/// The contained number will be used as exit code. The [`Exit`] constant is a shortcut for this
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/// with exit code 0.
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///
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/// ## Platform-specific
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///
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/// - **Android / iOS / Web:** The supplied exit code is unused.
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/// - **Unix:** On most Unix-like platforms, only the 8 least significant bits will be used,
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/// which can cause surprises with negative exit values (`-42` would end up as `214`). See
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/// [`std::process::exit`].
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///
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/// [`LoopExiting`]: Event::LoopExiting
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/// [`Exit`]: ControlFlow::Exit
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ExitWithCode(i32),
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}
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impl ControlFlow {
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/// Alias for [`ExitWithCode`]`(0)`.
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///
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/// [`ExitWithCode`]: Self::ExitWithCode
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#[allow(non_upper_case_globals)]
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pub const Exit: Self = Self::ExitWithCode(0);
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/// Sets this to [`Poll`].
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///
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/// [`Poll`]: Self::Poll
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pub fn set_poll(&mut self) {
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*self = Self::Poll;
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}
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/// Sets this to [`Wait`].
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///
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/// [`Wait`]: Self::Wait
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pub fn set_wait(&mut self) {
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*self = Self::Wait;
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}
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/// Sets this to [`WaitUntil`]`(instant)`.
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///
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/// [`WaitUntil`]: Self::WaitUntil
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pub fn set_wait_until(&mut self, instant: Instant) {
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*self = Self::WaitUntil(instant);
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}
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/// Sets this to wait until a timeout has expired.
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///
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/// In most cases, this is set to [`WaitUntil`]. However, if the timeout overflows, it is
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/// instead set to [`Wait`].
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///
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/// [`WaitUntil`]: Self::WaitUntil
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/// [`Wait`]: Self::Wait
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pub fn set_wait_timeout(&mut self, timeout: Duration) {
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match Instant::now().checked_add(timeout) {
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Some(instant) => self.set_wait_until(instant),
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None => self.set_wait(),
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}
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}
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/// Sets this to [`ExitWithCode`]`(code)`.
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///
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/// [`ExitWithCode`]: Self::ExitWithCode
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pub fn set_exit_with_code(&mut self, code: i32) {
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*self = Self::ExitWithCode(code);
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}
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/// Sets this to [`Exit`].
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///
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/// [`Exit`]: Self::Exit
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pub fn set_exit(&mut self) {
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*self = Self::Exit;
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}
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}
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impl Default for ControlFlow {
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#[inline(always)]
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fn default() -> Self {
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Self::Poll
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}
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}
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impl EventLoop<()> {
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/// Alias for [`EventLoopBuilder::new().build()`].
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///
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/// [`EventLoopBuilder::new().build()`]: EventLoopBuilder::build
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#[inline]
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pub fn new() -> EventLoop<()> {
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EventLoopBuilder::new().build()
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}
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}
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impl Default for EventLoop<()> {
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fn default() -> Self {
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Self::new()
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}
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}
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impl<T> EventLoop<T> {
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#[deprecated = "Use `EventLoopBuilder::<T>::with_user_event().build()` instead."]
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pub fn with_user_event() -> EventLoop<T> {
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EventLoopBuilder::<T>::with_user_event().build()
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}
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/// Runs the event loop in the calling thread and calls the given `event_handler` closure
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/// to dispatch any pending events.
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///
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/// Since the closure is `'static`, it must be a `move` closure if it needs to
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/// access any data from the calling context.
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///
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/// See the [`ControlFlow`] docs for information on how changes to `&mut ControlFlow` impact the
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/// event loop's behavior.
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///
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/// ## Platform-specific
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///
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/// - **X11 / Wayland:** The program terminates with exit code 1 if the display server
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/// disconnects.
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/// - **iOS:** Will never return to the caller and so values not passed to this function will
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/// *not* be dropped before the process exits.
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/// - **Web:** Will _act_ as if it never returns to the caller by throwing a Javascript exception
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/// (that Rust doesn't see) that will also mean that the rest of the function is never executed
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/// and any values not passed to this function will *not* be dropped.
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///
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/// Web applications are recommended to use `spawn()` instead of `run()` to avoid the need
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/// for the Javascript exception trick, and to make it clearer that the event loop runs
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/// asynchronously (via the browser's own, internal, event loop) and doesn't block the
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/// current thread of execution like it does on other platforms.
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///
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/// [`ControlFlow`]: crate::event_loop::ControlFlow
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#[inline]
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pub fn run<F>(self, event_handler: F) -> Result<(), RunLoopError>
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where
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F: 'static + FnMut(Event<T>, &EventLoopWindowTarget<T>, &mut ControlFlow),
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{
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self.event_loop.run(event_handler)
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}
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/// Creates an [`EventLoopProxy`] that can be used to dispatch user events to the main event loop.
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pub fn create_proxy(&self) -> EventLoopProxy<T> {
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EventLoopProxy {
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event_loop_proxy: self.event_loop.create_proxy(),
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}
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}
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}
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unsafe impl<T> HasRawDisplayHandle for EventLoop<T> {
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/// Returns a [`raw_window_handle::RawDisplayHandle`] for the event loop.
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fn raw_display_handle(&self) -> RawDisplayHandle {
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self.event_loop.window_target().p.raw_display_handle()
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}
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}
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impl<T> Deref for EventLoop<T> {
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type Target = EventLoopWindowTarget<T>;
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fn deref(&self) -> &EventLoopWindowTarget<T> {
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self.event_loop.window_target()
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}
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}
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impl<T> EventLoopWindowTarget<T> {
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/// Returns the list of all the monitors available on the system.
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#[inline]
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pub fn available_monitors(&self) -> impl Iterator<Item = MonitorHandle> {
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#[allow(clippy::useless_conversion)] // false positive on some platforms
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self.p
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.available_monitors()
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.into_iter()
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.map(|inner| MonitorHandle { inner })
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}
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/// Returns the primary monitor of the system.
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///
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/// Returns `None` if it can't identify any monitor as a primary one.
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///
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/// ## Platform-specific
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///
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/// **Wayland:** Always returns `None`.
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#[inline]
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pub fn primary_monitor(&self) -> Option<MonitorHandle> {
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self.p
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.primary_monitor()
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.map(|inner| MonitorHandle { inner })
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}
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/// Change if or when [`DeviceEvent`]s are captured.
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///
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/// Since the [`DeviceEvent`] capture can lead to high CPU usage for unfocused windows, winit
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/// will ignore them by default for unfocused windows on Linux/BSD. This method allows changing
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/// this at runtime to explicitly capture them again.
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///
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/// ## Platform-specific
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///
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/// - **Wayland / macOS / iOS / Android / Orbital:** Unsupported.
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///
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/// [`DeviceEvent`]: crate::event::DeviceEvent
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pub fn listen_device_events(&self, _allowed: DeviceEvents) {
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#[cfg(any(x11_platform, wasm_platform, wayland_platform, windows))]
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self.p.listen_device_events(_allowed);
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}
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}
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unsafe impl<T> HasRawDisplayHandle for EventLoopWindowTarget<T> {
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/// Returns a [`raw_window_handle::RawDisplayHandle`] for the event loop.
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fn raw_display_handle(&self) -> RawDisplayHandle {
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self.p.raw_display_handle()
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}
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}
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/// Used to send custom events to [`EventLoop`].
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pub struct EventLoopProxy<T: 'static> {
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event_loop_proxy: platform_impl::EventLoopProxy<T>,
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}
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impl<T: 'static> Clone for EventLoopProxy<T> {
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fn clone(&self) -> Self {
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Self {
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event_loop_proxy: self.event_loop_proxy.clone(),
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}
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}
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}
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impl<T: 'static> EventLoopProxy<T> {
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/// Send an event to the [`EventLoop`] from which this proxy was created. This emits a
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/// `UserEvent(event)` event in the event loop, where `event` is the value passed to this
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/// function.
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///
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/// Returns an `Err` if the associated [`EventLoop`] no longer exists.
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///
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/// [`UserEvent(event)`]: Event::UserEvent
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pub fn send_event(&self, event: T) -> Result<(), EventLoopClosed<T>> {
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self.event_loop_proxy.send_event(event)
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}
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}
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impl<T: 'static> fmt::Debug for EventLoopProxy<T> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.pad("EventLoopProxy { .. }")
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}
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}
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/// The error that is returned when an [`EventLoopProxy`] attempts to wake up an [`EventLoop`] that
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/// no longer exists.
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///
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/// Contains the original event given to [`EventLoopProxy::send_event`].
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#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
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pub struct EventLoopClosed<T>(pub T);
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impl<T> fmt::Display for EventLoopClosed<T> {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.write_str("Tried to wake up a closed `EventLoop`")
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}
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}
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impl<T: fmt::Debug> error::Error for EventLoopClosed<T> {}
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/// Control when device events are captured.
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#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Default)]
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pub enum DeviceEvents {
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/// Report device events regardless of window focus.
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Always,
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/// Only capture device events while the window is focused.
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#[default]
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WhenFocused,
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/// Never capture device events.
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Never,
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}
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/// A unique identifier of the winit's async request.
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///
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/// This could be used to identify the async request once it's done
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/// and a specific action must be taken.
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///
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/// One of the handling scenarious could be to maintain a working list
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/// containing [`AsyncRequestSerial`] and some closure associated with it.
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/// Then once event is arriving the working list is being traversed and a job
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/// executed and removed from the list.
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub struct AsyncRequestSerial {
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serial: u64,
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}
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impl AsyncRequestSerial {
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// TODO(kchibisov) remove `cfg` when the clipboard will be added.
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#[allow(dead_code)]
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pub(crate) fn get() -> Self {
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static CURRENT_SERIAL: AtomicU64 = AtomicU64::new(0);
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// NOTE: we rely on wrap around here, while the user may just request
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// in the loop u64::MAX times that's issue is considered on them.
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let serial = CURRENT_SERIAL.fetch_add(1, Ordering::Relaxed);
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Self { serial }
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}
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}
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