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use crate::{window, Command, Element, Executor, Settings, Subscription}; /// An interactive cross-platform application. /// /// This trait is the main entrypoint of Iced. Once implemented, you can run /// your GUI application by simply calling [`run`](#method.run). /// /// - On native platforms, it will run in its own window. /// - On the web, it will take control of the `<title>` and the `<body>` of the /// document. /// /// An [`Application`] can execute asynchronous actions by returning a /// [`Command`](struct.Command.html) in some of its methods. If /// you do not intend to perform any background work in your program, the /// [`Sandbox`](trait.Sandbox.html) trait offers a simplified interface. /// /// When using an [`Application`] with the `debug` feature enabled, a debug view /// can be toggled by pressing `F12`. /// /// [`Application`]: trait.Application.html /// /// # Examples /// [The repository has a bunch of examples] that use the [`Application`] trait: /// /// - [`clock`], an application that uses the [`Canvas`] widget to draw a clock /// and its hands to display the current time. /// - [`download_progress`], a basic application that asynchronously downloads /// a dummy file of 100 MB and tracks the download progress. /// - [`events`], a log of native events displayed using a conditional /// [`Subscription`]. /// - [`pokedex`], an application that displays a random Pokédex entry (sprite /// included!) by using the [PokéAPI]. /// - [`solar_system`], an animated solar system drawn using the [`Canvas`] widget /// and showcasing how to compose different transforms. /// - [`stopwatch`], a watch with start/stop and reset buttons showcasing how /// to listen to time. /// - [`todos`], a todos tracker inspired by [TodoMVC]. /// /// [The repository has a bunch of examples]: https://github.com/hecrj/iced/tree/0.1/examples /// [`clock`]: https://github.com/hecrj/iced/tree/0.1/examples/clock /// [`download_progress`]: https://github.com/hecrj/iced/tree/0.1/examples/download_progress /// [`events`]: https://github.com/hecrj/iced/tree/0.1/examples/events /// [`pokedex`]: https://github.com/hecrj/iced/tree/0.1/examples/pokedex /// [`solar_system`]: https://github.com/hecrj/iced/tree/0.1/examples/solar_system /// [`stopwatch`]: https://github.com/hecrj/iced/tree/0.1/examples/stopwatch /// [`todos`]: https://github.com/hecrj/iced/tree/0.1/examples/todos /// [`Canvas`]: widget/canvas/struct.Canvas.html /// [PokéAPI]: https://pokeapi.co/ /// [`Subscription`]: type.Subscription.html /// [TodoMVC]: http://todomvc.com/ /// /// ## A simple "Hello, world!" /// /// If you just want to get started, here is a simple [`Application`] that /// says "Hello, world!": /// /// ```no_run /// use iced::{executor, Application, Command, Element, Settings, Text}; /// /// pub fn main() { /// Hello::run(Settings::default()) /// } /// /// struct Hello; /// /// impl Application for Hello { /// type Executor = executor::Null; /// type Message = (); /// type Flags = (); /// /// fn new(_flags: ()) -> (Hello, Command<Self::Message>) { /// (Hello, Command::none()) /// } /// /// fn title(&self) -> String { /// String::from("A cool application") /// } /// /// fn update(&mut self, _message: Self::Message) -> Command<Self::Message> { /// Command::none() /// } /// /// fn view(&mut self) -> Element<Self::Message> { /// Text::new("Hello, world!").into() /// } /// } /// ``` pub trait Application: Sized { /// The [`Executor`] that will run commands and subscriptions. /// /// The [default executor] can be a good starting point! /// /// [`Executor`]: trait.Executor.html /// [default executor]: executor/struct.Default.html type Executor: Executor; /// The type of __messages__ your [`Application`] will produce. /// /// [`Application`]: trait.Application.html type Message: std::fmt::Debug + Send; /// The data needed to initialize your [`Application`]. /// /// [`Application`]: trait.Application.html type Flags; /// Initializes the [`Application`] with the flags provided to /// [`run`] as part of the [`Settings`]. /// /// Here is where you should return the initial state of your app. /// /// Additionally, you can return a [`Command`](struct.Command.html) if you /// need to perform some async action in the background on startup. This is /// useful if you want to load state from a file, perform an initial HTTP /// request, etc. /// /// [`Application`]: trait.Application.html /// [`run`]: #method.run.html /// [`Settings`]: struct.Settings.html fn new(flags: Self::Flags) -> (Self, Command<Self::Message>); /// Returns the current title of the [`Application`]. /// /// This title can be dynamic! The runtime will automatically update the /// title of your application when necessary. /// /// [`Application`]: trait.Application.html fn title(&self) -> String; /// Handles a __message__ and updates the state of the [`Application`]. /// /// This is where you define your __update logic__. All the __messages__, /// produced by either user interactions or commands, will be handled by /// this method. /// /// Any [`Command`] returned will be executed immediately in the background. /// /// [`Application`]: trait.Application.html /// [`Command`]: struct.Command.html fn update(&mut self, message: Self::Message) -> Command<Self::Message>; /// Returns the event [`Subscription`] for the current state of the /// application. /// /// A [`Subscription`] will be kept alive as long as you keep returning it, /// and the __messages__ produced will be handled by /// [`update`](#tymethod.update). /// /// By default, this method returns an empty [`Subscription`]. /// /// [`Subscription`]: struct.Subscription.html fn subscription(&self) -> Subscription<Self::Message> { Subscription::none() } /// Returns the widgets to display in the [`Application`]. /// /// These widgets can produce __messages__ based on user interaction. /// /// [`Application`]: trait.Application.html fn view(&mut self) -> Element<'_, Self::Message>; /// Returns the current [`Application`] mode. /// /// The runtime will automatically transition your application if a new mode /// is returned. /// /// Currently, the mode only has an effect in native platforms. /// /// By default, an application will run in windowed mode. /// /// [`Application`]: trait.Application.html fn mode(&self) -> window::Mode { window::Mode::Windowed } /// Runs the [`Application`]. /// /// On native platforms, this method will take control of the current thread /// and __will NOT return__. /// /// It should probably be that last thing you call in your `main` function. /// /// [`Application`]: trait.Application.html fn run(settings: Settings<Self::Flags>) where Self: 'static, { #[cfg(not(target_arch = "wasm32"))] { let wgpu_settings = iced_wgpu::Settings { default_font: settings.default_font, antialiasing: if settings.antialiasing { Some(iced_wgpu::settings::Antialiasing::MSAAx4) } else { None }, ..iced_wgpu::Settings::default() }; <Instance<Self> as iced_winit::Application>::run( settings.into(), wgpu_settings, ); } #[cfg(target_arch = "wasm32")] <Instance<Self> as iced_web::Application>::run(settings.flags); } } struct Instance<A: Application>(A); #[cfg(not(target_arch = "wasm32"))] impl<A> iced_winit::Application for Instance<A> where A: Application, { type Backend = iced_wgpu::window::Backend; type Executor = A::Executor; type Flags = A::Flags; type Message = A::Message; fn new(flags: Self::Flags) -> (Self, Command<A::Message>) { let (app, command) = A::new(flags); (Instance(app), command) } fn title(&self) -> String { self.0.title() } fn mode(&self) -> iced_winit::Mode { match self.0.mode() { window::Mode::Windowed => iced_winit::Mode::Windowed, window::Mode::Fullscreen => iced_winit::Mode::Fullscreen, } } fn update(&mut self, message: Self::Message) -> Command<Self::Message> { self.0.update(message) } fn subscription(&self) -> Subscription<Self::Message> { self.0.subscription() } fn view(&mut self) -> Element<'_, Self::Message> { self.0.view() } } #[cfg(target_arch = "wasm32")] impl<A> iced_web::Application for Instance<A> where A: Application, { type Executor = A::Executor; type Message = A::Message; type Flags = A::Flags; fn new(flags: Self::Flags) -> (Self, Command<A::Message>) { let (app, command) = A::new(flags); (Instance(app), command) } fn title(&self) -> String { self.0.title() } fn update(&mut self, message: Self::Message) -> Command<Self::Message> { self.0.update(message) } fn subscription(&self) -> Subscription<Self::Message> { self.0.subscription() } fn view(&mut self) -> Element<'_, Self::Message> { self.0.view() } }