use crate::{Application, Command, Element, Settings, Subscription};
/// A sandboxed [`Application`].
///
/// A [`Sandbox`] is just an [`Application`] that cannot run any asynchronous
/// actions.
///
/// If you do not need to leverage a [`Command`], you can use a [`Sandbox`]
/// instead of returning a [`Command::none`] everywhere.
///
/// [`Application`]: trait.Application.html
/// [`Sandbox`]: trait.Sandbox.html
/// [`Command`]: struct.Command.html
/// [`Command::none`]: struct.Command.html#method.none
///
/// # Example
/// We can use a [`Sandbox`] to run the [`Counter` example we implemented
/// before](index.html#overview), instead of an [`Application`]. We just need
/// to remove the use of [`Command`]:
///
/// ```no_run
/// use iced::{button, Button, Column, Element, Sandbox, Settings, Text};
///
/// pub fn main() {
/// Counter::run(Settings::default())
/// }
///
/// #[derive(Default)]
/// struct Counter {
/// value: i32,
/// increment_button: button::State,
/// decrement_button: button::State,
/// }
///
/// #[derive(Debug, Clone, Copy)]
/// enum Message {
/// IncrementPressed,
/// DecrementPressed,
/// }
///
/// impl Sandbox for Counter {
/// type Message = Message;
///
/// fn new() -> Self {
/// Self::default()
/// }
///
/// fn title(&self) -> String {
/// String::from("A simple counter")
/// }
///
/// fn update(&mut self, message: Message) {
/// match message {
/// Message::IncrementPressed => {
/// self.value += 1;
/// }
/// Message::DecrementPressed => {
/// self.value -= 1;
/// }
/// }
/// }
///
/// fn view(&mut self) -> Element<Message> {
/// Column::new()
/// .push(
/// Button::new(&mut self.increment_button, Text::new("Increment"))
/// .on_press(Message::IncrementPressed),
/// )
/// .push(
/// Text::new(self.value.to_string()).size(50),
/// )
/// .push(
/// Button::new(&mut self.decrement_button, Text::new("Decrement"))
/// .on_press(Message::DecrementPressed),
/// )
/// .into()
/// }
/// }
/// ```
pub trait Sandbox {
/// The type of __messages__ your [`Sandbox`] will produce.
///
/// [`Sandbox`]: trait.Sandbox.html
type Message: std::fmt::Debug + Send + Clone;
/// 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>;
/// Runs the [`Sandbox`].
///
/// 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 Message = T::Message;
fn new() -> (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)
}
}
