winit-sonoma-fix/src/event_loop.rs
2022-06-22 20:43:25 +03:00

402 lines
14 KiB
Rust

//! The [`EventLoop`] struct and assorted supporting types, including
//! [`ControlFlow`].
//!
//! 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.
//!
//! See the root-level documentation for information on how to create and use an event loop to
//! handle events.
use std::marker::PhantomData;
use std::ops::Deref;
use std::{error, fmt};
use instant::Instant;
use once_cell::sync::OnceCell;
use crate::{event::Event, monitor::MonitorHandle, platform_impl};
/// Provides a way to retrieve events from the system and from the windows that were registered to
/// the events loop.
///
/// An `EventLoop` can be seen more or less as a "context". Calling [`EventLoop::new`]
/// initializes everything that will be required to create windows. For example on Linux creating
/// an event loop opens a connection to the X or Wayland server.
///
/// To wake up an `EventLoop` from a another thread, see the [`EventLoopProxy`] docs.
///
/// Note that this cannot be shared across threads (due to platform-dependant logic
/// forbidding it), as such it is neither [`Send`] nor [`Sync`]. If you need cross-thread access, the
/// [`Window`] created from this _can_ be sent to an other thread, and the
/// [`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(crate) _marker: PhantomData<*mut ()>, // Not Send nor Sync
}
/// Target that associates windows with an [`EventLoop`].
///
/// This type exists to allow you to create new windows while Winit executes
/// your callback. [`EventLoop`] will coerce into this type (`impl<T> Deref for
/// EventLoop<T>`), so functions that take this as a parameter can also take
/// `&EventLoop`.
pub struct EventLoopWindowTarget<T: 'static> {
pub(crate) p: platform_impl::EventLoopWindowTarget<T>,
pub(crate) _marker: PhantomData<*mut ()>, // Not Send nor Sync
}
/// Object that allows building the event loop.
///
/// This is used to make specifying options that affect the whole application
/// easier. But note that constructing multiple event loops is not supported.
#[derive(Default)]
pub struct EventLoopBuilder<T: 'static> {
pub(crate) platform_specific: platform_impl::PlatformSpecificEventLoopAttributes,
_p: PhantomData<T>,
}
impl EventLoopBuilder<()> {
/// Start building a new event loop.
#[inline]
pub fn new() -> Self {
Self::with_user_event()
}
}
impl<T> EventLoopBuilder<T> {
/// Start building a new event loop, with the given type as the user event
/// type.
#[inline]
pub fn with_user_event() -> Self {
Self {
platform_specific: Default::default(),
_p: PhantomData,
}
}
/// Builds a new event loop.
///
/// ***For cross-platform compatibility, the [`EventLoop`] must be created on the main thread,
/// and only once per application.***
///
/// Attempting to create the event loop on a different thread, or multiple event loops in
/// the same application, will panic. This restriction isn't
/// strictly necessary on all platforms, but is imposed to eliminate any nasty surprises when
/// porting to platforms that require it. `EventLoopBuilderExt::any_thread` functions are exposed
/// in the relevant [`platform`] module if the target platform supports creating an event loop on
/// any thread.
///
/// Calling this function will result in display backend initialisation.
///
/// ## Platform-specific
///
/// - **Linux:** Backend type can be controlled using an environment variable
/// `WINIT_UNIX_BACKEND`. Legal values are `x11` and `wayland`.
/// If it is not set, winit will try to connect to a Wayland connection, and if that fails,
/// will fall back on X11. If this variable is set with any other value, winit will panic.
///
/// [`platform`]: crate::platform
#[inline]
pub fn build(&mut self) -> EventLoop<T> {
static EVENT_LOOP_CREATED: OnceCell<()> = OnceCell::new();
if EVENT_LOOP_CREATED.set(()).is_err() {
panic!("Creating EventLoop multiple times is not supported.");
}
// Certain platforms accept a mutable reference in their API.
#[allow(clippy::unnecessary_mut_passed)]
EventLoop {
event_loop: platform_impl::EventLoop::new(&mut self.platform_specific),
_marker: PhantomData,
}
}
}
impl<T> fmt::Debug for EventLoop<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("EventLoop { .. }")
}
}
impl<T> fmt::Debug for EventLoopWindowTarget<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.pad("EventLoopWindowTarget { .. }")
}
}
/// Set by the user callback given to the [`EventLoop::run`] method.
///
/// Indicates the desired behavior of the event loop after [`Event::RedrawEventsCleared`] is emitted.
///
/// Defaults to [`Poll`].
///
/// ## Persistency
///
/// Almost every change is persistent between multiple calls to the event loop closure within a
/// given run loop. The only exception to this is [`ExitWithCode`] which, once set, cannot be unset.
/// Changes are **not** persistent between multiple calls to `run_return` - issuing a new call will
/// reset the control flow to [`Poll`].
///
/// [`ExitWithCode`]: Self::ExitWithCode
/// [`Poll`]: Self::Poll
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum ControlFlow {
/// When the current loop iteration finishes, immediately begin a new iteration regardless of
/// whether or not new events are available to process.
///
/// ## Platform-specific
/// - **Web:** Events are queued and usually sent when `requestAnimationFrame` fires but sometimes
/// the events in the queue may be sent before the next `requestAnimationFrame` callback, for
/// example when the scaling of the page has changed. This should be treated as an implementation
/// detail which should not be relied on.
Poll,
/// When the current loop iteration finishes, suspend the thread until another event arrives.
Wait,
/// When the current loop iteration finishes, suspend the thread until either another event
/// arrives or the given time is reached.
///
/// Useful for implementing efficient timers. Applications which want to render at the display's
/// native refresh rate should instead use [`Poll`] and the VSync functionality of a graphics API
/// to reduce odds of missed frames.
///
/// [`Poll`]: Self::Poll
WaitUntil(Instant),
/// Send a [`LoopDestroyed`] event and stop the event loop. This variant is *sticky* - once set,
/// `control_flow` cannot be changed from `ExitWithCode`, and any future attempts to do so will
/// result in the `control_flow` parameter being reset to `ExitWithCode`.
///
/// The contained number will be used as exit code. The [`Exit`] constant is a shortcut for this
/// with exit code 0.
///
/// ## Platform-specific
///
/// - **Android / iOS / WASM**: The supplied exit code is unused.
/// - **Unix**: On most Unix-like platforms, only the 8 least significant bits will be used,
/// which can cause surprises with negative exit values (`-42` would end up as `214`). See
/// [`std::process::exit`].
///
/// [`LoopDestroyed`]: Event::LoopDestroyed
/// [`Exit`]: ControlFlow::Exit
ExitWithCode(i32),
}
impl ControlFlow {
/// Alias for [`ExitWithCode`]`(0)`.
///
/// [`ExitWithCode`]: Self::ExitWithCode
#[allow(non_upper_case_globals)]
pub const Exit: Self = Self::ExitWithCode(0);
/// Sets this to [`Poll`].
///
/// [`Poll`]: Self::Poll
pub fn set_poll(&mut self) {
*self = Self::Poll;
}
/// Sets this to [`Wait`].
///
/// [`Wait`]: Self::Wait
pub fn set_wait(&mut self) {
*self = Self::Wait;
}
/// Sets this to [`WaitUntil`]`(instant)`.
///
/// [`WaitUntil`]: Self::WaitUntil
pub fn set_wait_until(&mut self, instant: Instant) {
*self = Self::WaitUntil(instant);
}
/// Sets this to [`ExitWithCode`]`(code)`.
///
/// [`ExitWithCode`]: Self::ExitWithCode
pub fn set_exit_with_code(&mut self, code: i32) {
*self = Self::ExitWithCode(code);
}
/// Sets this to [`Exit`].
///
/// [`Exit`]: Self::Exit
pub fn set_exit(&mut self) {
*self = Self::Exit;
}
}
impl Default for ControlFlow {
#[inline(always)]
fn default() -> Self {
Self::Poll
}
}
impl EventLoop<()> {
/// Alias for [`EventLoopBuilder::new().build()`].
///
/// [`EventLoopBuilder::new().build()`]: EventLoopBuilder::build
#[inline]
pub fn new() -> EventLoop<()> {
EventLoopBuilder::new().build()
}
}
impl Default for EventLoop<()> {
fn default() -> Self {
Self::new()
}
}
impl<T> EventLoop<T> {
#[deprecated = "Use `EventLoopBuilder::<T>::with_user_event().build()` instead."]
pub fn with_user_event() -> EventLoop<T> {
EventLoopBuilder::<T>::with_user_event().build()
}
/// Hijacks the calling thread and initializes the winit event loop with the provided
/// closure. Since the closure is `'static`, it must be a `move` closure if it needs to
/// access any data from the calling context.
///
/// See the [`ControlFlow`] docs for information on how changes to `&mut ControlFlow` impact the
/// event loop's behavior.
///
/// Any values not passed to this function will *not* be dropped.
///
/// ## Platform-specific
///
/// - **X11 / Wayland**: The program terminates with exit code 1 if the display server
/// disconnects.
///
/// [`ControlFlow`]: crate::event_loop::ControlFlow
#[inline]
pub fn run<F>(self, event_handler: F) -> !
where
F: 'static + FnMut(Event<'_, T>, &EventLoopWindowTarget<T>, &mut ControlFlow),
{
self.event_loop.run(event_handler)
}
/// Creates an [`EventLoopProxy`] that can be used to dispatch user events to the main event loop.
pub fn create_proxy(&self) -> EventLoopProxy<T> {
EventLoopProxy {
event_loop_proxy: self.event_loop.create_proxy(),
}
}
}
impl<T> Deref for EventLoop<T> {
type Target = EventLoopWindowTarget<T>;
fn deref(&self) -> &EventLoopWindowTarget<T> {
self.event_loop.window_target()
}
}
impl<T> EventLoopWindowTarget<T> {
/// Returns the list of all the monitors available on the system.
#[inline]
pub fn available_monitors(&self) -> impl Iterator<Item = MonitorHandle> {
self.p
.available_monitors()
.into_iter()
.map(|inner| MonitorHandle { inner })
}
/// Returns the primary monitor of the system.
///
/// Returns `None` if it can't identify any monitor as a primary one.
///
/// ## Platform-specific
///
/// **Wayland:** Always returns `None`.
#[inline]
pub fn primary_monitor(&self) -> Option<MonitorHandle> {
self.p.primary_monitor()
}
/// Change [`DeviceEvent`] filter mode.
///
/// Since the [`DeviceEvent`] capture can lead to high CPU usage for unfocused windows, winit
/// will ignore them by default for unfocused windows on Linux/BSD. This method allows changing
/// this filter at runtime to explicitly capture them again.
///
/// ## Platform-specific
///
/// - **Wayland / Windows / macOS / iOS / Android / Web**: Unsupported.
///
/// [`DeviceEvent`]: crate::event::DeviceEvent
pub fn set_device_event_filter(&self, _filter: DeviceEventFilter) {
#[cfg(any(
target_os = "linux",
target_os = "dragonfly",
target_os = "freebsd",
target_os = "netbsd",
target_os = "openbsd"
))]
self.p.set_device_event_filter(_filter);
}
}
/// Used to send custom events to [`EventLoop`].
pub struct EventLoopProxy<T: 'static> {
event_loop_proxy: platform_impl::EventLoopProxy<T>,
}
impl<T: 'static> Clone for EventLoopProxy<T> {
fn clone(&self) -> Self {
Self {
event_loop_proxy: self.event_loop_proxy.clone(),
}
}
}
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>> {
self.event_loop_proxy.send_event(event)
}
}
impl<T: 'static> fmt::Debug for EventLoopProxy<T> {
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> {}
/// Fiter controlling the propagation of device events.
#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
pub enum DeviceEventFilter {
/// Always filter out device events.
Always,
/// Filter out device events while the window is not focused.
Unfocused,
/// Report all device events regardless of window focus.
Never,
}
impl Default for DeviceEventFilter {
fn default() -> Self {
Self::Unfocused
}
}