winit/src/lib.rs

//! Winit is a cross-platform window creation and event loop management library.
//!
//! # Building windows
//!
//! Before you can build a [`Window`], you first need to build an [`EventLoop`]. This is done with the
//! [`EventLoop::new()`] function.
//!
//! ```no_run
//! use winit::event_loop::EventLoop;
//! let event_loop = EventLoop::new().unwrap();
//! ```
//!
//! Once this is done, there are two ways to create a [`Window`]:
//!
//!  - Calling [`Window::new(&event_loop)`][window_new].
//!  - Calling [`let builder = WindowBuilder::new()`][window_builder_new] then [`builder.build(&event_loop)`][window_builder_build].
//!
//! The first method is the simplest and will give you default values for everything. The second
//! method allows you to customize the way your [`Window`] will look and behave by modifying the
//! fields of the [`WindowBuilder`] object before you create the [`Window`].
//!
//! # Event handling
//!
//! Once a [`Window`] has been created, it will generate different *events*. A [`Window`] object can
//! generate [`WindowEvent`]s when certain input events occur, such as a cursor moving over the
//! 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.
//!
//! You can retrieve events by calling [`EventLoop::run()`]. 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`].
//!
//! 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 poorly on
//! most other platforms. However, this model can be re-implemented to an extent with
#![cfg_attr(
    any(
        windows_platform,
        macos_platform,
        android_platform,
        x11_platform,
        wayland_platform
    ),
    doc = "[`EventLoopExtPumpEvents::pump_events()`][platform::pump_events::EventLoopExtPumpEvents::pump_events()]"
)]
#![cfg_attr(
    not(any(
        windows_platform,
        macos_platform,
        android_platform,
        x11_platform,
        wayland_platform
    )),
    doc = "`EventLoopExtPumpEvents::pump_events()`"
)]
//! [^1]. See that method's documentation for more reasons about why
//! it's discouraged beyond compatibility reasons.
//!
//!
//! ```no_run
//! use winit::{
//!     event::{Event, WindowEvent},
//!     event_loop::{ControlFlow, EventLoop},
//!     window::WindowBuilder,
//! };
//!
//! let event_loop = EventLoop::new().unwrap();
//! let window = WindowBuilder::new().build(&event_loop).unwrap();
//!
//! // ControlFlow::Poll continuously runs the event loop, even if the OS hasn't
//! // dispatched any events. This is ideal for games and similar applications.
//! event_loop.set_control_flow(ControlFlow::Poll);
//!
//! // ControlFlow::Wait pauses the event loop if no events are available to process.
//! // This is ideal for non-game applications that only update in response to user
//! // input, and uses significantly less power/CPU time than ControlFlow::Poll.
//! event_loop.set_control_flow(ControlFlow::Wait);
//!
//! event_loop.run(move |event, elwt| {
//!     match event {
//!         Event::WindowEvent {
//!             event: WindowEvent::CloseRequested,
//!             ..
//!         } => {
//!             println!("The close button was pressed; stopping");
//!             elwt.exit();
//!         },
//!         Event::AboutToWait => {
//!             // Application update code.
//!
//!             // Queue a RedrawRequested event.
//!             //
//!             // You only need to call this if you've determined that you need to redraw in
//!             // applications which do not always need to. Applications that redraw continuously
//!             // can render here instead.
//!             window.request_redraw();
//!         },
//!         Event::WindowEvent {
//!             event: WindowEvent::RedrawRequested,
//!             ..
//!         } => {
//!             // Redraw the application.
//!             //
//!             // It's preferable for applications that do not render continuously to render in
//!             // this event rather than in AboutToWait, since rendering in here allows
//!             // the program to gracefully handle redraws requested by the OS.
//!         },
//!         _ => ()
//!     }
//! });
//! ```
//!
//! [`WindowEvent`] has a [`WindowId`] member. In multi-window environments, it should be
//! compared to the value returned by [`Window::id()`] to determine which [`Window`]
//! dispatched the event.
//!
//! # Drawing on the window
//!
//! Winit doesn't directly provide any methods for drawing on a [`Window`]. However, it allows you to
//! retrieve the raw handle of the window and display (see the [`platform`] module and/or the
//! [`raw_window_handle`] and [`raw_display_handle`] methods), which in turn allows
//! you to create an OpenGL/Vulkan/DirectX/Metal/etc. context that can be used to render graphics.
//!
//! Note that many platforms will display garbage data in the window's client area if the
//! application doesn't render anything to the window by the time the desktop compositor is ready to
//! display the window to the user. If you notice this happening, you should create the window with
//! [`visible` set to `false`](crate::window::WindowBuilder::with_visible) and explicitly make the
//! window visible only once you're ready to render into it.
//!
//! [`EventLoop`]: event_loop::EventLoop
//! [`EventLoop::new()`]: event_loop::EventLoop::new
//! [`EventLoop::run()`]: event_loop::EventLoop::run
//! [`exit()`]: event_loop::EventLoopWindowTarget::exit
//! [`Window`]: window::Window
//! [`WindowId`]: window::WindowId
//! [`WindowBuilder`]: window::WindowBuilder
//! [window_new]: window::Window::new
//! [window_builder_new]: window::WindowBuilder::new
//! [window_builder_build]: window::WindowBuilder::build
//! [`Window::id()`]: window::Window::id
//! [`WindowEvent`]: event::WindowEvent
//! [`DeviceEvent`]: event::DeviceEvent
//! [`Event::UserEvent`]: event::Event::UserEvent
//! [`Event::LoopExiting`]: event::Event::LoopExiting
//! [`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_events()` is only available on Windows, macOS, Android, X11 and Wayland.

#![deny(rust_2018_idioms)]
#![deny(rustdoc::broken_intra_doc_links)]
#![deny(clippy::all)]
#![deny(unsafe_op_in_unsafe_fn)]
#![cfg_attr(feature = "cargo-clippy", deny(warnings))]
// Doc feature labels can be tested locally by running RUSTDOCFLAGS="--cfg=docsrs" cargo +nightly doc
#![cfg_attr(docsrs, feature(doc_auto_cfg))]
#![allow(clippy::missing_safety_doc)]

#[cfg(feature = "rwh_06")]
pub use rwh_06 as raw_window_handle;

#[allow(unused_imports)]
#[macro_use]
extern crate log;
#[cfg(feature = "serde")]
#[macro_use]
extern crate serde;
#[macro_use]
extern crate bitflags;

pub mod dpi;
#[macro_use]
pub mod error;
mod cursor;
pub mod event;
pub mod event_loop;
mod icon;
pub mod keyboard;
pub mod monitor;
mod platform_impl;
pub mod window;

pub mod platform;

/// Wrapper for objects which winit will access on the main thread so they are effectively `Send`
/// and `Sync`, since they always execute on a single thread.
///
/// # Safety
///
/// Winit can run only one event loop at a time, and the event loop itself is tied to some thread.
/// The objects could be sent across the threads, but once passed to winit, they execute on the
/// main thread if the platform demands it. Thus, marking such objects as `Send + Sync` is safe.
#[doc(hidden)]
#[derive(Clone, Debug)]
pub(crate) struct SendSyncWrapper<T>(pub(crate) T);

unsafe impl<T> Send for SendSyncWrapper<T> {}
unsafe impl<T> Sync for SendSyncWrapper<T> {}