Propagation and Targeting

Event metadata controls where an event travels.

Vizia supports these propagation modes:

• Propagation::Up: from target upward through ancestors.
• Propagation::Direct: only the target entity receives the event.
• Propagation::Subtree: target entity and its descendants.

emit vs emit_to

Use emit for the common bubble-up flow from the current entity:

cx.emit(AppEvent::Save);

Use emit_to to send directly to a known target entity:

let target: Entity = some_entity;
cx.emit_to(target, AppEvent::Save);

emit_to sends the event with direct propagation.

Custom propagation

When you need precise control, build an Event manually and send it with emit_custom.

let custom = Event::new(AppEvent::Refresh)
    .target(target)
    .origin(cx.current)
    .propagate(Propagation::Subtree);

cx.emit_custom(custom);

Consuming an event

Inside a handler, call meta.consume() to stop further propagation.

event.map(|app_event, meta| match app_event {
    AppEvent::OpenMenu => {
        meta.consume();
    }
});

This is useful when a child view handles an interaction and parent handlers should not react to the same event.