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/**
* @file track-list.js
*/
import EventTarget from '../event-target';
import {isEvented} from '../mixins/evented';
/** @import Track from './track' */
/**
* Common functionaliy between {@link TextTrackList}, {@link AudioTrackList}, and
* {@link VideoTrackList}
*
* @extends EventTarget
*/
class TrackList extends EventTarget {
/**
* Create an instance of this class
*
* @param { Track[] } tracks
* A list of tracks to initialize the list with.
*
* @abstract
*/
constructor(tracks = []) {
super();
this.tracks_ = [];
for (let i = 0; i < tracks.length; i++) {
this.addTrack(tracks[i]);
}
}
/**
* The current number of `Track`s in this TrackList.
*
* @type {number}
*/
get length() {
return this.tracks_.length;
}
/**
* Add a {@link Track} to the `TrackList`
*
* @param {Track} track
* The audio, video, or text track to add to the list.
*
* @fires TrackList#addtrack
*/
addTrack(track) {
const index = this.tracks_.length;
if (!('' + index in this)) {
Object.defineProperty(this, index, {
get() {
return this.tracks_[index];
}
});
}
// Do not add duplicate tracks
if (this.tracks_.indexOf(track) === -1) {
this.tracks_.push(track);
/**
* Triggered when a track is added to a track list.
*
* @event TrackList#addtrack
* @type {Event}
* @property {Track} track
* A reference to track that was added.
*/
this.trigger({
track,
type: 'addtrack',
target: this
});
}
/**
* Triggered when a track label is changed.
*
* @event TrackList#labelchange
* @type {Event}
* @property {Track} track
* A reference to track whose label was changed.
*/
track.labelchange_ = () => {
this.trigger({
track,
type: 'labelchange',
target: this
});
};
if (isEvented(track)) {
track.addEventListener('labelchange', track.labelchange_);
}
}
/**
* Remove a {@link Track} from the `TrackList`
*
* @param {Track} rtrack
* The audio, video, or text track to remove from the list.
*
* @fires TrackList#removetrack
*/
removeTrack(rtrack) {
let track;
for (let i = 0, l = this.length; i < l; i++) {
if (this[i] === rtrack) {
track = this[i];
if (track.off) {
track.off();
}
this.tracks_.splice(i, 1);
break;
}
}
if (!track) {
return;
}
/**
* Triggered when a track is removed from track list.
*
* @event TrackList#removetrack
* @type {Event}
* @property {Track} track
* A reference to track that was removed.
*/
this.trigger({
track,
type: 'removetrack',
target: this
});
}
/**
* Get a Track from the TrackList by a tracks id
*
* @param {string} id - the id of the track to get
* @method getTrackById
* @return {Track}
* @private
*/
getTrackById(id) {
let result = null;
for (let i = 0, l = this.length; i < l; i++) {
const track = this[i];
if (track.id === id) {
result = track;
break;
}
}
return result;
}
}
/**
* Triggered when a different track is selected/enabled.
*
* @event TrackList#change
* @type {Event}
*/
/**
* Events that can be called with on + eventName. See {@link EventHandler}.
*
* @property {Object} TrackList#allowedEvents_
* @protected
*/
TrackList.prototype.allowedEvents_ = {
change: 'change',
addtrack: 'addtrack',
removetrack: 'removetrack',
labelchange: 'labelchange'
};
// emulate attribute EventHandler support to allow for feature detection
for (const event in TrackList.prototype.allowedEvents_) {
TrackList.prototype['on' + event] = null;
}
export default TrackList;
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