Description

This module provides functionality to listen to a set of events for the prefetching process in the 2D player. It is primarily meant to be used in conjunction with the Prefetch Attributes option, which allows the user to prefetch renders on a configuration change.

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TIP:
You will want to register a callback function for these events prior to triggering the configurator.prefetchAttributes method or performing configuration changes.

TypeDefinitions

The following types are used by the supported methods.

PrefetchEventType

type PrefetchEventType = 'start' | 'progress' | 'end';

Name	Description
`start`	This event is triggered when the prefetching process begins during a configuration change, or when the `configurator.prefetchAttributes` method is called.
`progress`	During the prefetch process on a configuration change there may be a stack of different images that will be requested, and a `progress` event will trigger when each image from this stack has finished loading.
`end`	This event is triggered when the prefetching process ends after a configuration change, or when the `configurator.prefetchAttributes` method has completed its process.

PrefetchEvent

interface PrefetchEvent {
  total: number;
  loaded: number;
}

Methods

on (eventType, listener, ctx)

Parameter	Type	Status
`eventType`	`PrefetchEventType`	Required
`listener`	`(event: PrefetchEvent) => void`	Required
`ctx`	`any`	Optional

This method allows us to add an event listener for whenever a start, progress, or end event is triggered by the prefetch functionality.

Example:

//Asusme we have a progress bar with a function setProgress()

showLoadingBar();
player.prefetcher.on('progress', e => setProgress(e.loaded / e.total));
configurator.prefetchAttributes(['Rotation']);

once (eventType, listener, ctx)

Parameter	Type	Status
`eventType`	`PrefetchEventType`	Required
`listener`	`(event: PrefetchEvent) => void`	Required
`ctx`	`any`	Optional

This method allows us to add an event listener that will only trigger once the first time a start, progress, or end event is fired.

Example:

showLoadingBar();
player.prefetcher.once('end', () => hideLoadingBar());
configurator.prefetchAttributes(['Rotation']);

when (eventType): `Promise<PrefetchEvent>`

Parameter	Type	Status
`eventType`	`PrefetchEventType`	Required

This method awaits for a start, progress, or end event, and returns a promise that resolves when the event is emitted.

Example:

showLoadingBar();
player.prefetcher.when('end').then(() => hideLoadingBar());
configurator.prefetchAttributes(['Rotation']);

off (eventType, listener)

Parameter	Type	Status
`eventType`	`PrefetchEventType`	Required
`listener`	`(event: PrefetchEvent) => void`	Required

This method allows us to remove an event listener that we registered for using the on or when methods for a start, progress, or end event.

Example:

showLoadingBar();
player.prefetcher.on('progress', e => setProgress(e.loaded / e.total));
player.prefetcher.once('end', () => {
  player.prefetcher.off('progress');
  hideLoadingBar();
});
configurator.prefetchAttributes(['Rotation']);