Struct titanium::desktop::gui::libdruid::widget::ViewSwitcher

pub struct ViewSwitcher<T, U> { /* private fields */ }

A widget that switches dynamically between multiple children.

Implementations

impl<T, U> ViewSwitcher<T, U>where T: Data, U: Data,

pub fn new( child_picker: impl Fn(&T, &Env) -> U + 'static, child_builder: impl Fn(&U, &T, &Env) -> Box<dyn Widget<T> + 'static, Global> + 'static ) -> ViewSwitcher<T, U>

Create a new view switcher.

The child_picker closure is called every time the application data changes. If the value it returns is the same as the one it returned during the previous data change, nothing happens. If it returns a different value, then the child_builder closure is called with the new value.

The child_builder closure creates a new child widget based on the value passed to it.

Examples

use druid::{
    widget::{Label, ViewSwitcher},
    Data, Widget,
};

#[derive(Clone, PartialEq, Data)]
enum Foo {
    A,
    B,
    C,
}

fn ui() -> impl Widget<Foo> {
    ViewSwitcher::new(
        |data: &Foo, _env| data.clone(),
        |selector, _data, _env| match selector {
            Foo::A => Box::new(Label::new("A")),
            _ => Box::new(Label::new("Not A")),
        },
    )
}

Trait Implementations

impl<T, U> Widget<T> for ViewSwitcher<T, U>where T: Data, U: Data,

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.