Struct CanvasView 

pub struct CanvasView<State: 'static> { /* private fields */ }

A declarative custom-painting canvas. See the module docs.

Implementations

impl<State: 'static> CanvasView<State>

pub fn size(self, size: Size) -> Self

Force an explicit size, clamped into whatever constraints this widget’s parent hands it. Overrides CanvasView::expand when called after it (last builder call wins, matching the crate’s other size-mode builders — e.g. crate::platform_view).

pub fn expand(self) -> Self

Fill the incoming constraints’ maximum — the default (see the module docs), provided as an explicit builder call for readability at call sites that want to make the choice visible.

pub fn on_hit<F: Fn(Point, Size) -> bool + 'static>(self, hit: F) -> Self

Narrow pointer hit-testing to hit(local_point, size) -> bool, consulted before CanvasView::on_tap/CanvasView::on_pointer dispatch (see the module docs). Unset, hit-testing falls back to the ordinary “inside the rectangular bounds” test every other baseline leaf uses.

pub fn on_tap<F: Fn(&mut State) + 'static>(self, on_tap: F) -> Self

Fire on_tap(state) on an up-inside release (gated by CanvasView::on_hit, see the module docs).

pub fn on_pointer<F: Fn(&mut State, PointerEvent) + 'static>( self, on_pointer: F, ) -> Self

Fire on_pointer(state, event) with the raw PointerEvent on every phase the hit-test admits (gated by CanvasView::on_hit, see the module docs) — the escape hatch for a caller that wants the full gesture (drag included) rather than just the tap summary.

pub fn repaint_key(self, key: impl Hash) -> Self

Opt into paint-only dirtying driven by a dependency outside the ordinary View diff: hash any Hash fingerprint of the data the paint closure reads, and a changed hash across a rebuild requests ChangeFlags::PAINT even when nothing else about the view changed. See the module docs.

Trait Implementations

impl<State: 'static> View<State> for CanvasView<State>

type Element = CanvasWidget

The retained widget this view produces.

fn build(&self, _ctx: &mut BuildCtx<'_>) -> CanvasWidget

Materialise a fresh widget for this view.

fn rebuild( &self, prev: &Self, element: &mut CanvasWidget, _ctx: &mut BuildCtx<'_>, ) -> ChangeFlags

Reconcile prev (the previous view of the same type) against the live element, mutating it in place and reporting what changed.

fn teardown(&self, _element: &mut Self::Element, _ctx: &mut BuildCtx<'_>)

Tear down element when this view is being removed.

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

Deliver an event message to this view, mutating application state.