/**
* @file text-track.js
*/
import TextTrackCueList from './text-track-cue-list';
import * as Fn from '../utils/fn.js';
import {TextTrackKind, TextTrackMode} from './track-enums';
import log from '../utils/log.js';
import window from 'global/window';
import Track from './track.js';
import { isCrossOrigin } from '../utils/url.js';
import XHR from '@videojs/xhr';
import {merge} from '../utils/obj';
/** @import Tech from '../tech/tech' */
/**
* Takes a webvtt file contents and parses it into cues
*
* @param {string} srcContent
* webVTT file contents
*
* @param {TextTrack} track
* TextTrack to add cues to. Cues come from the srcContent.
*
* @private
*/
const parseCues = function(srcContent, track) {
const parser = new window.WebVTT.Parser(
window,
window.vttjs,
window.WebVTT.StringDecoder()
);
const errors = [];
parser.oncue = function(cue) {
track.addCue(cue);
};
parser.onparsingerror = function(error) {
errors.push(error);
};
parser.onflush = function() {
track.trigger({
type: 'loadeddata',
target: track
});
};
parser.parse(srcContent);
if (errors.length > 0) {
if (window.console && window.console.groupCollapsed) {
window.console.groupCollapsed(`Text Track parsing errors for ${track.src}`);
}
errors.forEach((error) => log.error(error));
if (window.console && window.console.groupEnd) {
window.console.groupEnd();
}
}
parser.flush();
};
/**
* Load a `TextTrack` from a specified url.
*
* @param {string} src
* Url to load track from.
*
* @param {TextTrack} track
* Track to add cues to. Comes from the content at the end of `url`.
*
* @private
*/
const loadTrack = function(src, track) {
const opts = {
uri: src
};
const crossOrigin = isCrossOrigin(src);
if (crossOrigin) {
opts.cors = crossOrigin;
}
const withCredentials = track.tech_.crossOrigin() === 'use-credentials';
if (withCredentials) {
opts.withCredentials = withCredentials;
}
XHR(opts, Fn.bind_(this, function(err, response, responseBody) {
if (err) {
return log.error(err, response);
}
track.loaded_ = true;
// Make sure that vttjs has loaded, otherwise, wait till it finished loading
// NOTE: this is only used for the alt/video.novtt.js build
if (typeof window.WebVTT !== 'function') {
if (track.tech_) {
// to prevent use before define eslint error, we define loadHandler
// as a let here
track.tech_.any(['vttjsloaded', 'vttjserror'], (event) => {
if (event.type === 'vttjserror') {
log.error(`vttjs failed to load, stopping trying to process ${track.src}`);
return;
}
return parseCues(responseBody, track);
});
}
} else {
parseCues(responseBody, track);
}
}));
};
/**
* A representation of a single `TextTrack`.
*
* @see [Spec]{@link https://html.spec.whatwg.org/multipage/embedded-content.html#texttrack}
* @extends Track
*/
class TextTrack extends Track {
/**
* Create an instance of this class.
*
* @param {Object} options={}
* Object of option names and values
*
* @param {Tech} options.tech
* A reference to the tech that owns this TextTrack.
*
* @param {TextTrack~Kind} [options.kind='subtitles']
* A valid text track kind.
*
* @param {TextTrack~Mode} [options.mode='disabled']
* A valid text track mode.
*
* @param {string} [options.id='vjs_track_' + Guid.newGUID()]
* A unique id for this TextTrack.
*
* @param {string} [options.label='']
* The menu label for this track.
*
* @param {string} [options.language='']
* A valid two character language code.
*
* @param {string} [options.srclang='']
* A valid two character language code. An alternative, but deprioritized
* version of `options.language`
*
* @param {string} [options.src]
* A url to TextTrack cues.
*
* @param {boolean} [options.default]
* If this track should default to on or off.
*/
constructor(options = {}) {
if (!options.tech) {
throw new Error('A tech was not provided.');
}
const settings = merge(options, {
kind: TextTrackKind[options.kind] || 'subtitles',
language: options.language || options.srclang || ''
});
let mode = TextTrackMode[settings.mode] || 'disabled';
const default_ = settings.default;
if (settings.kind === 'metadata' || settings.kind === 'chapters') {
mode = 'hidden';
}
super(settings);
this.tech_ = settings.tech;
this.cues_ = [];
this.activeCues_ = [];
this.preload_ = this.tech_.preloadTextTracks !== false;
const cues = new TextTrackCueList(this.cues_);
const activeCues = new TextTrackCueList(this.activeCues_);
let changed = false;
this.timeupdateHandler = Fn.bind_(this, function(event = {}) {
if (this.tech_.isDisposed()) {
return;
}
if (!this.tech_.isReady_) {
if (event.type !== 'timeupdate') {
this.rvf_ = this.tech_.requestVideoFrameCallback(this.timeupdateHandler);
}
return;
}
// Accessing this.activeCues for the side-effects of updating itself
// due to its nature as a getter function. Do not remove or cues will
// stop updating!
// Use the setter to prevent deletion from uglify (pure_getters rule)
this.activeCues = this.activeCues;
if (changed) {
this.trigger('cuechange');
changed = false;
}
if (event.type !== 'timeupdate') {
this.rvf_ = this.tech_.requestVideoFrameCallback(this.timeupdateHandler);
}
});
const disposeHandler = () => {
this.stopTracking();
};
this.tech_.one('dispose', disposeHandler);
if (mode !== 'disabled') {
this.startTracking();
}
Object.defineProperties(this, {
/**
* @memberof TextTrack
* @member {boolean} default
* If this track was set to be on or off by default. Cannot be changed after
* creation.
* @instance
*
* @readonly
*/
default: {
get() {
return default_;
},
set() {}
},
/**
* @memberof TextTrack
* @member {string} mode
* Set the mode of this TextTrack to a valid {@link TextTrack~Mode}. Will
* not be set if setting to an invalid mode.
* @instance
*
* @fires TextTrack#modechange
*/
mode: {
get() {
return mode;
},
set(newMode) {
if (!TextTrackMode[newMode]) {
return;
}
if (mode === newMode) {
return;
}
mode = newMode;
if (!this.preload_ && mode !== 'disabled' && this.cues.length === 0) {
// On-demand load.
loadTrack(this.src, this);
}
this.stopTracking();
if (mode !== 'disabled') {
this.startTracking();
}
/**
* An event that fires when mode changes on this track. This allows
* the TextTrackList that holds this track to act accordingly.
*
* > Note: This is not part of the spec!
*
* @event TextTrack#modechange
* @type {Event}
*/
this.trigger('modechange');
}
},
/**
* @memberof TextTrack
* @member {TextTrackCueList} cues
* The text track cue list for this TextTrack.
* @instance
*/
cues: {
get() {
if (!this.loaded_) {
return null;
}
return cues;
},
set() {}
},
/**
* @memberof TextTrack
* @member {TextTrackCueList} activeCues
* The list text track cues that are currently active for this TextTrack.
* @instance
*/
activeCues: {
get() {
if (!this.loaded_) {
return null;
}
// nothing to do
if (this.cues.length === 0) {
return activeCues;
}
const ct = this.tech_.currentTime();
const active = [];
for (let i = 0, l = this.cues.length; i < l; i++) {
const cue = this.cues[i];
if (cue.startTime <= ct && cue.endTime >= ct) {
active.push(cue);
}
}
changed = false;
if (active.length !== this.activeCues_.length) {
changed = true;
} else {
for (let i = 0; i < active.length; i++) {
if (this.activeCues_.indexOf(active[i]) === -1) {
changed = true;
}
}
}
this.activeCues_ = active;
activeCues.setCues_(this.activeCues_);
return activeCues;
},
// /!\ Keep this setter empty (see the timeupdate handler above)
set() {}
}
});
if (settings.src) {
this.src = settings.src;
if (!this.preload_) {
// Tracks will load on-demand.
// Act like we're loaded for other purposes.
this.loaded_ = true;
}
if (this.preload_ || (settings.kind !== 'subtitles' && settings.kind !== 'captions')) {
loadTrack(this.src, this);
}
} else {
this.loaded_ = true;
}
}
startTracking() {
// More precise cues based on requestVideoFrameCallback with a requestAnimationFram fallback
this.rvf_ = this.tech_.requestVideoFrameCallback(this.timeupdateHandler);
// Also listen to timeupdate in case rVFC/rAF stops (window in background, audio in video el)
this.tech_.on('timeupdate', this.timeupdateHandler);
}
stopTracking() {
if (this.rvf_) {
this.tech_.cancelVideoFrameCallback(this.rvf_);
this.rvf_ = undefined;
}
this.tech_.off('timeupdate', this.timeupdateHandler);
}
/**
* Add a cue to the internal list of cues.
*
* @param {TextTrack~Cue} cue
* The cue to add to our internal list
*/
addCue(originalCue) {
let cue = originalCue;
// Testing if the cue is a VTTCue in a way that survives minification
if (!('getCueAsHTML' in cue)) {
cue = new window.vttjs.VTTCue(originalCue.startTime, originalCue.endTime, originalCue.text);
for (const prop in originalCue) {
if (!(prop in cue)) {
cue[prop] = originalCue[prop];
}
}
// make sure that `id` is copied over
cue.id = originalCue.id;
cue.originalCue_ = originalCue;
}
const tracks = this.tech_.textTracks();
for (let i = 0; i < tracks.length; i++) {
if (tracks[i] !== this) {
tracks[i].removeCue(cue);
}
}
this.cues_.push(cue);
this.cues.setCues_(this.cues_);
}
/**
* Remove a cue from our internal list
*
* @param {TextTrack~Cue} removeCue
* The cue to remove from our internal list
*/
removeCue(removeCue) {
let i = this.cues_.length;
while (i--) {
const cue = this.cues_[i];
if (cue === removeCue || (cue.originalCue_ && cue.originalCue_ === removeCue)) {
this.cues_.splice(i, 1);
this.cues.setCues_(this.cues_);
break;
}
}
}
}
/**
* cuechange - One or more cues in the track have become active or stopped being active.
*
* @protected
*/
TextTrack.prototype.allowedEvents_ = {
cuechange: 'cuechange'
};
export default TextTrack;