Struct druid::widget::Either

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

A widget that switches between two possible child views.

Implementations

impl<T> Either<T>

pub fn new( closure: impl Fn(&T, &Env) -> bool + 'static, true_branch: impl Widget<T> + 'static, false_branch: impl Widget<T> + 'static ) -> Either<T>

Create a new widget that switches between two views.

The given closure is evaluated on data change. If its value is true, then the true_branch widget is shown, otherwise false_branch.

Examples found in repository

examples/either.rs (lines 42-46)

fn ui_builder() -> impl Widget<AppState> {
    // Our UI consists of a column with a button and an `Either` widget
    let button = Checkbox::new("Toggle slider")
        .lens(AppState::which)
        .padding(5.0);

    // The `Either` widget has two children, only one of which is visible at a time.
    // To determine which child is visible, you pass it a closure that takes the
    // `Data` and the `Env` and returns a bool; if it returns `true`, the first
    // widget will be visible, and if `false`, the second.
    let either = Either::new(
        |data, _env| data.which,
        Slider::new().lens(AppState::value).padding(5.0),
        Label::new("Click to reveal slider").padding(5.0),
    );
    Flex::column().with_child(button).with_child(either)
}

examples/blocking_function.rs (line 60)

fn ui_builder() -> impl Widget<AppState> {
    let button = Button::new("Start slow increment")
        .on_click(|ctx, data: &mut AppState, _env| {
            data.processing = true;
            // In order to make sure that the other thread can communicate with the main thread we
            // have to pass an external handle to the second thread.
            // Using this handle we can send commands back to the main thread.
            wrapped_slow_function(ctx.get_external_handle(), data.value);
        })
        .padding(5.0);

    let button_placeholder = Flex::column()
        .with_child(Label::new(LocalizedString::new("Processing...")).padding(5.0))
        .with_child(Spinner::new());

    // Hello-counter is defined in the built-in localisation file. This maps to "Current value is {count}"
    // localised in english, french, or german. Every time the value is updated it shows the new value.
    let text = LocalizedString::new("hello-counter")
        .with_arg("count", |data: &AppState, _env| (data.value).into());
    let label = Label::new(text).padding(5.0).center();

    let either = Either::new(|data, _env| data.processing, button_placeholder, button);

    Flex::column().with_child(label).with_child(either)
}

Trait Implementations

impl<T: Data> Widget<T> for Either<T>

fn event( &mut self, ctx: &mut EventCtx<'_, '_>, event: &Event, data: &mut T, env: &Env )

Handle an event.

fn lifecycle( &mut self, ctx: &mut LifeCycleCtx<'_, '_>, event: &LifeCycle, data: &T, env: &Env )

Handle a life cycle notification.

fn update( &mut self, ctx: &mut UpdateCtx<'_, '_>, _old_data: &T, data: &T, env: &Env )

Update the widget’s appearance in response to a change in the app’s Data or Env.

fn layout( &mut self, ctx: &mut LayoutCtx<'_, '_>, bc: &BoxConstraints, data: &T, env: &Env ) -> Size

Compute layout.

fn paint(&mut self, ctx: &mut PaintCtx<'_, '_, '_>, data: &T, env: &Env)

Paint the widget appearance.

fn compute_max_intrinsic( &mut self, axis: Axis, ctx: &mut LayoutCtx<'_, '_>, bc: &BoxConstraints, data: &T, env: &Env ) -> f64

Computes max intrinsic/preferred dimension of a widget on the provided axis.