1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265
//! Build interactive cross-platform applications.
use crate::{Command, Element, Executor, Settings, Subscription};
pub use crate::style::application::{Appearance, StyleSheet};
/// 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`] in some of its methods. If you do not intend to perform any
/// background work in your program, the [`Sandbox`] trait offers a simplified
/// interface.
///
/// When using an [`Application`] with the `debug` feature enabled, a debug view
/// can be toggled by pressing `F12`.
///
/// # 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`].
/// - [`game_of_life`], an interactive version of the [Game of Life], invented
/// by [John Horton Conway].
/// - [`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/iced-rs/iced/tree/0.9/examples
/// [`clock`]: https://github.com/iced-rs/iced/tree/0.9/examples/clock
/// [`download_progress`]: https://github.com/iced-rs/iced/tree/0.9/examples/download_progress
/// [`events`]: https://github.com/iced-rs/iced/tree/0.9/examples/events
/// [`game_of_life`]: https://github.com/iced-rs/iced/tree/0.9/examples/game_of_life
/// [`pokedex`]: https://github.com/iced-rs/iced/tree/0.9/examples/pokedex
/// [`solar_system`]: https://github.com/iced-rs/iced/tree/0.9/examples/solar_system
/// [`stopwatch`]: https://github.com/iced-rs/iced/tree/0.9/examples/stopwatch
/// [`todos`]: https://github.com/iced-rs/iced/tree/0.9/examples/todos
/// [`Sandbox`]: crate::Sandbox
/// [`Canvas`]: crate::widget::Canvas
/// [PokéAPI]: https://pokeapi.co/
/// [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;
/// use iced::{Application, Command, Element, Settings, Theme};
///
/// pub fn main() -> iced::Result {
/// Hello::run(Settings::default())
/// }
///
/// struct Hello;
///
/// impl Application for Hello {
/// type Executor = executor::Default;
/// type Flags = ();
/// type Message = ();
/// type Theme = Theme;
///
/// 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(&self) -> Element<Self::Message> {
/// "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`]: Self::Executor
/// [default executor]: crate::executor::Default
type Executor: Executor;
/// The type of __messages__ your [`Application`] will produce.
type Message: std::fmt::Debug + Send;
/// The theme of your [`Application`].
type Theme: Default + StyleSheet;
/// The data needed to initialize your [`Application`].
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`] 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.
///
/// [`run`]: Self::run
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.
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.
fn update(&mut self, message: Self::Message) -> Command<Self::Message>;
/// Returns the widgets to display in the [`Application`].
///
/// These widgets can produce __messages__ based on user interaction.
fn view(&self) -> Element<'_, Self::Message, crate::Renderer<Self::Theme>>;
/// Returns the current [`Theme`] of the [`Application`].
///
/// [`Theme`]: Self::Theme
fn theme(&self) -> Self::Theme {
Self::Theme::default()
}
/// Returns the current `Style` of the [`Theme`].
///
/// [`Theme`]: Self::Theme
fn style(&self) -> <Self::Theme as StyleSheet>::Style {
<Self::Theme as StyleSheet>::Style::default()
}
/// 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`].
fn subscription(&self) -> Subscription<Self::Message> {
Subscription::none()
}
/// Returns the scale factor of the [`Application`].
///
/// 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`.
fn scale_factor(&self) -> f64 {
1.0
}
/// Runs the [`Application`].
///
/// On native platforms, this method will take control of the current thread
/// until the [`Application`] exits.
///
/// On the web platform, this method __will NOT return__ unless there is an
/// [`Error`] during startup.
///
/// [`Error`]: crate::Error
fn run(settings: Settings<Self::Flags>) -> crate::Result
where
Self: 'static,
{
#[allow(clippy::needless_update)]
let renderer_settings = crate::renderer::Settings {
default_font: settings.default_font,
default_text_size: settings.default_text_size,
antialiasing: if settings.antialiasing {
Some(crate::graphics::Antialiasing::MSAAx4)
} else {
None
},
..crate::renderer::Settings::default()
};
Ok(crate::shell::application::run::<
Instance<Self>,
Self::Executor,
crate::renderer::Compositor<Self::Theme>,
>(settings.into(), renderer_settings)?)
}
}
struct Instance<A: Application>(A);
impl<A> crate::runtime::Program for Instance<A>
where
A: Application,
{
type Renderer = crate::Renderer<A::Theme>;
type Message = A::Message;
fn update(&mut self, message: Self::Message) -> Command<Self::Message> {
self.0.update(message)
}
fn view(&self) -> Element<'_, Self::Message, Self::Renderer> {
self.0.view()
}
}
impl<A> crate::shell::Application for Instance<A>
where
A: Application,
{
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 theme(&self) -> A::Theme {
self.0.theme()
}
fn style(&self) -> <A::Theme as StyleSheet>::Style {
self.0.style()
}
fn subscription(&self) -> Subscription<Self::Message> {
self.0.subscription()
}
fn scale_factor(&self) -> f64 {
self.0.scale_factor()
}
}