Struct finestra::State

pub struct State<T> { /* private fields */ }

The State primitive is the tool to modify the characteristics of Views, by e.g. modifying a Label when a Button is clicked:

struct Application;

impl AppDelegate<AppState> for Application {
    fn make_content_view(&mut self, state: &mut AppState, _: Window) -> impl finestra::View<Self, AppState> {
        state.label.set("Clicked: 0");

        Stack::vertical()
            .with(Label::new(&state.label))
            .with(Button::new("Press")
                .with_on_click(|state: &mut AppState, _| {
                    state.count += 1;
                    state.label.set(format!("Clicked: {}", state.count));
                }))
    }
}

#[derive(Debug, Default)]
struct AppState {
    count: usize,
    label: TextValue,
}

For more information, see the crate documentation.

Implementations

impl<T> State<T>

pub fn new(value: T) -> Self

Create a new State with the given value. Note: you can use State::default() if your wrapped value supports it :)

pub fn set(&self, value: impl Into<T>)

Set the new value of the state, which will notify the listeners.

pub fn with<F: FnOnce(&T) -> R, R>(&self, f: F) -> R

Get the value within the state by using a visitor method.

let state = State::new("Hello, world!".to_string());

state.with(|value| {
    println!("Value is: {value}");
});

pub fn clone_inner(&self) -> T

where T: Clone,

Clone the inner value. Note: you can also use State::with() if you only need a temporary reference.

let state = State::new("Hello, world!".to_string());
let cloned: String = state.clone_inner();

pub fn with_mut<F: FnOnce(&mut T) -> R, R>(&self, f: F) -> R

Get a mutable reference to the value within the state by using a visitor method.

let state = State::new("Hello, world!".to_string());

state.with(|value| {
    println!("Value is: {value}");
});

pub fn add_listener<F: Fn(&T) + 'static>(&self, callback: F)

Get subscribed by changes to the State. Note: the callback won’t get invoked for the initial value, only for changes.

Trait Implementations

impl<T> Clone for State<T>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T> Debug for State<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Default for State<T>

where T: Default,

fn default() -> Self

Returns the “default value” for a type.

impl<T> From<&State<T>> for StateOrRaw<T>

fn from(value: &State<T>) -> Self

Converts to this type from the input type.

impl<T> From<State<T>> for StateOrRaw<T>

fn from(value: State<T>) -> Self

Converts to this type from the input type.

impl<T> Send for State<T>

impl<T> Sync for State<T>