Trait iced::application::Application
source · pub trait Application: Sized {
type Executor: Executor;
type Message: Debug + Send;
type Theme: Default + StyleSheet;
type Flags;
fn new(flags: Self::Flags) -> (Self, Command<Self::Message>);
fn title(&self) -> String;
fn update(&mut self, message: Self::Message) -> Command<Self::Message>;
fn view(&self) -> Element<'_, Self::Message, Renderer<Self::Theme>>;
fn theme(&self) -> Self::Theme { ... }
fn style(&self) -> <Self::Theme as StyleSheet>::Style { ... }
fn subscription(&self) -> Subscription<Self::Message> { ... }
fn scale_factor(&self) -> f64 { ... }
fn should_exit(&self) -> bool { ... }
fn run(settings: Settings<Self::Flags>) -> Result
where
Self: 'static,
{ ... }
}
Expand description
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
.
- 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 theCanvas
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 conditionalSubscription
.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 theCanvas
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.
A simple “Hello, world!”
If you just want to get started, here is a simple Application
that
says “Hello, world!”:
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()
}
}
Required Associated Types
sourcetype Executor: Executor
type Executor: Executor
The Executor
that will run commands and subscriptions.
The default executor can be a good starting point!
sourcetype Message: Debug + Send
type Message: Debug + Send
The type of messages your Application
will produce.
sourcetype Theme: Default + StyleSheet
type Theme: Default + StyleSheet
The theme of your Application
.
sourcetype Flags
type Flags
The data needed to initialize your Application
.
Required Methods
sourcefn new(flags: Self::Flags) -> (Self, Command<Self::Message>)
fn new(flags: Self::Flags) -> (Self, Command<Self::Message>)
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.
sourcefn title(&self) -> String
fn title(&self) -> String
Returns the current title of the Application
.
This title can be dynamic! The runtime will automatically update the title of your application when necessary.
sourcefn update(&mut self, message: Self::Message) -> Command<Self::Message>
fn update(&mut self, message: Self::Message) -> Command<Self::Message>
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.
Provided Methods
sourcefn theme(&self) -> Self::Theme
fn theme(&self) -> Self::Theme
Returns the current Theme
of the Application
.
sourcefn subscription(&self) -> Subscription<Self::Message>
fn subscription(&self) -> Subscription<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
.
By default, this method returns an empty Subscription
.
sourcefn scale_factor(&self) -> f64
fn scale_factor(&self) -> f64
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
.
sourcefn should_exit(&self) -> bool
fn should_exit(&self) -> bool
Returns whether the Application
should be terminated.
By default, it returns false
.
sourcefn run(settings: Settings<Self::Flags>) -> Resultwhere
Self: 'static,
fn run(settings: Settings<Self::Flags>) -> Resultwhere
Self: 'static,
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.