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use crate::{ executor, Application, Color, Command, Element, Settings, Subscription, }; /// A sandboxed [`Application`]. /// /// If you are a just getting started with the library, this trait offers a /// simpler interface than [`Application`]. /// /// Unlike an [`Application`], a [`Sandbox`] cannot run any asynchronous /// actions or be initialized with some external flags. However, both traits /// are very similar and upgrading from a [`Sandbox`] is very straightforward. /// /// Therefore, it is recommended to always start by implementing this trait and /// upgrade only once necessary. /// /// [`Application`]: trait.Application.html /// [`Sandbox`]: trait.Sandbox.html /// [`Command`]: struct.Command.html /// [`Command::none`]: struct.Command.html#method.none /// /// # Examples /// [The repository has a bunch of examples] that use the [`Sandbox`] trait: /// /// - [`bezier_tool`], a Paint-like tool for drawing Bézier curves using /// [`lyon`]. /// - [`counter`], the classic counter example explained in [the overview]. /// - [`custom_widget`], a demonstration of how to build a custom widget that /// draws a circle. /// - [`geometry`], a custom widget showcasing how to draw geometry with the /// `Mesh2D` primitive in [`iced_wgpu`]. /// - [`pane_grid`], a grid of panes that can be split, resized, and /// reorganized. /// - [`progress_bar`], a simple progress bar that can be filled by using a /// slider. /// - [`styling`], an example showcasing custom styling with a light and dark /// theme. /// - [`svg`], an application that renders the [Ghostscript Tiger] by leveraging /// the [`Svg` widget]. /// - [`tour`], a simple UI tour that can run both on native platforms and the /// web! /// /// [The repository has a bunch of examples]: https://github.com/hecrj/iced/tree/0.1/examples /// [`bezier_tool`]: https://github.com/hecrj/iced/tree/0.1/examples/bezier_tool /// [`counter`]: https://github.com/hecrj/iced/tree/0.1/examples/counter /// [`custom_widget`]: https://github.com/hecrj/iced/tree/0.1/examples/custom_widget /// [`geometry`]: https://github.com/hecrj/iced/tree/0.1/examples/geometry /// [`pane_grid`]: https://github.com/hecrj/iced/tree/0.1/examples/pane_grid /// [`progress_bar`]: https://github.com/hecrj/iced/tree/0.1/examples/progress_bar /// [`styling`]: https://github.com/hecrj/iced/tree/0.1/examples/styling /// [`svg`]: https://github.com/hecrj/iced/tree/0.1/examples/svg /// [`tour`]: https://github.com/hecrj/iced/tree/0.1/examples/tour /// [`lyon`]: https://github.com/nical/lyon /// [the overview]: index.html#overview /// [`iced_wgpu`]: https://github.com/hecrj/iced/tree/0.1/wgpu /// [`Svg` widget]: widget/svg/struct.Svg.html /// [Ghostscript Tiger]: https://commons.wikimedia.org/wiki/File:Ghostscript_Tiger.svg /// /// ## A simple "Hello, world!" /// /// If you just want to get started, here is a simple [`Sandbox`] that /// says "Hello, world!": /// /// ```no_run /// use iced::{Element, Sandbox, Settings, Text}; /// /// pub fn main() { /// Hello::run(Settings::default()) /// } /// /// struct Hello; /// /// impl Sandbox for Hello { /// type Message = (); /// /// fn new() -> Hello { /// Hello /// } /// /// fn title(&self) -> String { /// String::from("A cool application") /// } /// /// fn update(&mut self, _message: Self::Message) { /// // This application has no interactions /// } /// /// fn view(&mut self) -> Element<Self::Message> { /// Text::new("Hello, world!").into() /// } /// } /// ``` pub trait Sandbox { /// The type of __messages__ your [`Sandbox`] will produce. /// /// [`Sandbox`]: trait.Sandbox.html type Message: std::fmt::Debug + Send; /// Initializes the [`Sandbox`]. /// /// Here is where you should return the initial state of your app. /// /// [`Sandbox`]: trait.Sandbox.html fn new() -> Self; /// Returns the current title of the [`Sandbox`]. /// /// This title can be dynamic! The runtime will automatically update the /// title of your application when necessary. /// /// [`Sandbox`]: trait.Sandbox.html fn title(&self) -> String; /// Handles a __message__ and updates the state of the [`Sandbox`]. /// /// This is where you define your __update logic__. All the __messages__, /// produced by user interactions, will be handled by this method. /// /// [`Sandbox`]: trait.Sandbox.html fn update(&mut self, message: Self::Message); /// Returns the widgets to display in the [`Sandbox`]. /// /// These widgets can produce __messages__ based on user interaction. /// /// [`Sandbox`]: trait.Sandbox.html fn view(&mut self) -> Element<'_, Self::Message>; /// Returns the background color of the [`Sandbox`]. /// /// By default, it returns [`Color::WHITE`]. /// /// [`Sandbox`]: trait.Sandbox.html /// [`Color::WHITE`]: struct.Color.html#const.WHITE fn background_color(&self) -> Color { Color::WHITE } /// Returns the scale factor of the [`Sandbox`]. /// /// It can be used to dynamically control the size of the UI at runtime /// (i.e. zooming). /// /// For instance, a scale factor of `2.0` will make widgets twice as big, /// while a scale factor of `0.5` will shrink them to half their size. /// /// By default, it returns `1.0`. /// /// [`Sandbox`]: trait.Sandbox.html fn scale_factor(&self) -> f64 { 1.0 } /// Runs the [`Sandbox`]. /// /// 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. /// /// [`Sandbox`]: trait.Sandbox.html fn run(settings: Settings<()>) where Self: 'static + Sized, { <Self as Application>::run(settings) } } impl<T> Application for T where T: Sandbox, { type Executor = executor::Null; type Flags = (); type Message = T::Message; fn new(_flags: ()) -> (Self, Command<T::Message>) { (T::new(), Command::none()) } fn title(&self) -> String { T::title(self) } fn update(&mut self, message: T::Message) -> Command<T::Message> { T::update(self, message); Command::none() } fn subscription(&self) -> Subscription<T::Message> { Subscription::none() } fn view(&mut self) -> Element<'_, T::Message> { T::view(self) } fn background_color(&self) -> Color { T::background_color(self) } fn scale_factor(&self) -> f64 { T::scale_factor(self) } }