Struct druid::Notification

pub struct Notification { /* private fields */ }

A message passed up the tree from a Widget to its ancestors.

In the course of handling an event, a Widget may change some internal state that is of interest to one of its ancestors. In this case, the widget may submit a Notification.

In practice, a Notification is very similar to a Command; the main distinction relates to delivery. Commands are delivered from the root of the tree down towards the target, and this delivery occurs after the originating event call has returned. Notifications are delivered up the tree, and this occurs during event handling; immediately after the child widget’s event method returns, the notification will be delivered to the child’s parent, and then the parent’s parent, until the notification is handled.

Implementations

impl Notification

pub fn is<T>(&self, selector: Selector<T>) -> bool

Returns true if self matches this Selector.

pub fn get<T: Any>(&self, selector: Selector<T>) -> Option<&T>

Returns the payload for this Selector, if the selector matches.

Panics

Panics when the payload has a different type, than what the selector is supposed to carry. This can happen when two selectors with different types but the same key are used.

pub fn source(&self) -> WidgetId

The WidgetId of the Widget that sent this Notification.

pub fn warn_if_unused(self, warn_if_unused: bool) -> Self

Builder-style method to set warn_if_unused.

The default is true.

pub fn warn_if_unused_set(&self) -> bool

Returns whether there should be a warning when no widget handles this notification.

pub fn route(&self) -> WidgetId

The WidgetId of the last Widget that this Notification was passed through.

Example

fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut (), env: &Env) {
    if let Event::Notification(notification) = event {
        if notification.route() == self.widget1.id() {
            // the notification came from inside of widget1
        }
        if notification.route() == self.widget2.id() {
            // the notification came from inside of widget2
        }
    }
}

Trait Implementations

impl Clone for Notification

fn clone(&self) -> Notification

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Notification

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.