rendition-mixin.js
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import { isIncompatible, isEnabled } from './playlist.js';
/**
* Returns a function that acts as the Enable/disable playlist function.
*
* @param {PlaylistLoader} loader - The master playlist loader
* @param {String} playlistUri - uri of the playlist
* @param {Function} changePlaylistFn - A function to be called after a
* playlist's enabled-state has been changed. Will NOT be called if a
* playlist's enabled-state is unchanged
* @param {Boolean=} enable - Value to set the playlist enabled-state to
* or if undefined returns the current enabled-state for the playlist
* @return {Function} Function for setting/getting enabled
*/
const enableFunction = (loader, playlistUri, changePlaylistFn) => (enable) => {
const playlist = loader.master.playlists[playlistUri];
const incompatible = isIncompatible(playlist);
const currentlyEnabled = isEnabled(playlist);
if (typeof enable === 'undefined') {
return currentlyEnabled;
}
if (enable) {
delete playlist.disabled;
} else {
playlist.disabled = true;
}
if (enable !== currentlyEnabled && !incompatible) {
// Ensure the outside world knows about our changes
changePlaylistFn();
if (enable) {
loader.trigger('renditionenabled');
} else {
loader.trigger('renditiondisabled');
}
}
return enable;
};
/**
* The representation object encapsulates the publicly visible information
* in a media playlist along with a setter/getter-type function (enabled)
* for changing the enabled-state of a particular playlist entry
*
* @class Representation
*/
class Representation {
constructor(hlsHandler, playlist, id) {
// Get a reference to a bound version of fastQualityChange_
let fastChangeFunction = hlsHandler
.masterPlaylistController_
.fastQualityChange_
.bind(hlsHandler.masterPlaylistController_);
// some playlist attributes are optional
if (playlist.attributes.RESOLUTION) {
const resolution = playlist.attributes.RESOLUTION;
this.width = resolution.width;
this.height = resolution.height;
}
this.bandwidth = playlist.attributes.BANDWIDTH;
// The id is simply the ordinality of the media playlist
// within the master playlist
this.id = id;
// Partially-apply the enableFunction to create a playlist-
// specific variant
this.enabled = enableFunction(hlsHandler.playlists,
playlist.uri,
fastChangeFunction);
}
}
/**
* A mixin function that adds the `representations` api to an instance
* of the HlsHandler class
* @param {HlsHandler} hlsHandler - An instance of HlsHandler to add the
* representation API into
*/
let renditionSelectionMixin = function(hlsHandler) {
let playlists = hlsHandler.playlists;
// Add a single API-specific function to the HlsHandler instance
hlsHandler.representations = () => {
return playlists
.master
.playlists
.filter((media) => !isIncompatible(media))
.map((e, i) => new Representation(hlsHandler, e, e.uri));
};
};
export default renditionSelectionMixin;