Module events

Events relating to tracks, timing, and other callers.

Listening for events

Driver events in Songbird are composed of two parts:

• An Event to listen out for. These may be discrete events, or generated by timers.
• An EventHandler to be called on receipt of an event. As event handlers may be shared between several events, the handler is called with an EventContext describing which event was fired.

Event handlers are registered using functions such as Driver::add_global_event, or TrackHandle::add_event, or. Internally, these pairs are stored as EventData.

EventHandler lifecycle

An event handler is essentially just an async function which may return another type of event to listen out for (an Option<Event>). For instance, Some(Event::Cancel) will remove that event listener, while None won’t change it at all.

The exception is one-off events like Event::Delayed, which remove themselves after one call unless an Event override is returned.

Global and local listeners

Global event listeners are those which are placed onto the Driver, while local event listeners are those which are placed on a Track/Handle.

Track or timed events, when local, return a reference to the parent track. When registered globally, they fire on a per-tick basis, returning references to all relevant tracks in that 20ms window. Global/local timed events use a global timer or a track’s playback time, respectively.

CoreEvents may only be registered globally.

Modules

context_data

Types containing the main body of an EventContext.

Structs

EventData

Internal representation of an event, as handled by the audio context.

EventStore

Storage for EventData, designed to be used for both local and global contexts.

Enums

CoreEvent

Voice core events occur on receipt of voice packets and telemetry.

Event

Classes of event which may occur, triggering a handler at the local (track-specific) or global level.

EventContext

Information about which tracks or data fired an event.

TrackEvent

Track events correspond to certain actions or changes of state, such as a track finishing, looping, or being manually stopped. Voice core events occur on receipt of voice packets and telemetry.

UntimedEvent

Track and voice core events.

Traits

EventHandler

Trait to handle an event which can be fired per-track, or globally.