Trait Event

pub trait Event:
    Send
    + Sync
    + 'static {
    type Traversal: Traversal<Self>;

    const AUTO_PROPAGATE: bool = false;

    // Provided methods
    fn register_component_id(world: &mut World) -> ComponentId { ... }
    fn component_id(world: &World) -> Option<ComponentId> { ... }
}

Something that “happens” and might be read / observed by app logic.

Events can be stored in an Events<E> resource You can conveniently access events using the EventReader and EventWriter system parameter.

Events can also be “triggered” on a World, which will then cause any Observer of that trigger to run.

Events must be thread-safe.

Derive

This trait can be derived. Adding auto_propagate sets Self::AUTO_PROPAGATE to true. Adding traversal = "X" sets Self::Traversal to be of type “X”.

use bevy_ecs::prelude::*;

#[derive(Event)]
#[event(auto_propagate)]
struct MyEvent;

Provided Associated Constants

const AUTO_PROPAGATE: bool = false

When true, this event will always attempt to propagate when triggered, without requiring a call to Trigger::propagate.

Required Associated Types

type Traversal: Traversal<Self>

The component that describes which Entity to propagate this event to next, when propagation is enabled.

Provided Methods

fn register_component_id(world: &mut World) -> ComponentId

Generates the ComponentId for this event type.

If this type has already been registered, this will return the existing ComponentId.

This is used by various dynamically typed observer APIs, such as World::trigger_targets_dynamic.

Warning

This method should not be overridden by implementors, and should always correspond to the implementation of component_id.

fn component_id(world: &World) -> Option<ComponentId>

Fetches the ComponentId for this event type, if it has already been generated.

This is used by various dynamically typed observer APIs, such as World::trigger_targets_dynamic.

Warning

This method should not be overridden by implementors, and should always correspond to the implementation of register_component_id.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl Event for GamepadEvent

where GamepadEvent: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for GamepadRumbleRequest

where GamepadRumbleRequest: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for RawGamepadEvent

where RawGamepadEvent: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for AppExit

where AppExit: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for GamepadAxisChangedEvent

where GamepadAxisChangedEvent: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for GamepadButtonChangedEvent

where GamepadButtonChangedEvent: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for GamepadButtonStateChangedEvent

where GamepadButtonStateChangedEvent: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for GamepadConnectionEvent

where GamepadConnectionEvent: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for RawGamepadAxisChangedEvent

where RawGamepadAxisChangedEvent: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for RawGamepadButtonChangedEvent

where RawGamepadButtonChangedEvent: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for DoubleTapGesture

where DoubleTapGesture: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for PanGesture

where PanGesture: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for PinchGesture

where PinchGesture: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for RotationGesture

where RotationGesture: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for KeyboardFocusLost

where KeyboardFocusLost: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for KeyboardInput

where KeyboardInput: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for MouseButtonInput

where MouseButtonInput: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for MouseMotion

where MouseMotion: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for MouseWheel

where MouseWheel: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for OnAdd

where OnAdd: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for OnInsert

where OnInsert: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for OnRemove

where OnRemove: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for OnReplace

where OnReplace: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for TouchInput

where TouchInput: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for RemovedComponentEntity

where RemovedComponentEntity: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()

impl Event for OnDespawn

where OnDespawn: Send + Sync + 'static,

const AUTO_PROPAGATE: bool = false

type Traversal = ()