Struct AnyView 

pub struct AnyView<State>
where
    State: 'static,
{ /* private fields */ }

A type-erased View: lets a piece of UI change its concrete view type between frames while still fitting the statically typed rebuild machinery.

The previous view is downcast to detect a type change: same type is a typed in-place rebuild; otherwise the old widget is torn down and a fresh one swapped in (LAYOUT | PAINT). Its Element is a Box<dyn Widget>.

Generic builders erase internally, so app code needs AnyView only for stored views, branches of more than eight arms, and heterogeneous dynamic lists (see any); either(..) and EitherOf3..EitherOf8 stay statically typed.

Implementations

impl<State> AnyView<State>

where State: 'static,

pub fn new<V>(view: V) -> AnyView<State>

where V: View<State>,

Erase view into an AnyView; idempotent, so any(any(v)) and AnyView::new(any_view) do not box twice.

Trait Implementations

impl<State> View<State> for AnyView<State>

where State: 'static,

type Element = Box<dyn Widget>

The retained widget this view produces.

fn build( &self, ctx: &mut BuildCtx<'_>, ) -> <AnyView<State> as View<State>>::Element

Materialise a fresh widget for this view.

fn rebuild( &self, prev: &AnyView<State>, element: &mut <AnyView<State> as View<State>>::Element, ctx: &mut BuildCtx<'_>, ) -> ChangeFlags

Reconcile prev (the previous view of the same type) against the live element, in place.

fn teardown( &self, element: &mut <AnyView<State> as View<State>>::Element, ctx: &mut BuildCtx<'_>, )

Tear down element when this view is being removed; a no-op for leaf views.

fn message(&self, _element: &mut Self::Element, _state: &mut State)

Deliver an event message to this view, mutating application state (stubbed: no event routing goes through it yet).