/**
* @license
* Copyright 2016 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
goog.provide('shaka.polyfill.VTTCue');
goog.require('shaka.log');
goog.require('shaka.polyfill.register');
/**
* @namespace shaka.polyfill.VTTCue
*
* @summary A polyfill to provide VTTCue.
*/
/**
* Install the polyfill if needed.
*/
shaka.polyfill.VTTCue.install = function() {
if (window.VTTCue) {
shaka.log.info('Using native VTTCue.');
return;
}
if (!window.TextTrackCue) {
shaka.log.error('VTTCue not available.');
return;
}
let constructorLength = TextTrackCue.length;
if (constructorLength == 3) {
shaka.log.info('Using VTTCue polyfill from 3 argument TextTrackCue.');
window.VTTCue = shaka.polyfill.VTTCue.from3ArgsTextTrackCue_;
} else if (constructorLength == 6) {
shaka.log.info('Using VTTCue polyfill from 6 argument TextTrackCue.');
window.VTTCue = shaka.polyfill.VTTCue.from6ArgsTextTrackCue_;
} else if (shaka.polyfill.VTTCue.canUse3ArgsTextTrackCue_()) {
shaka.log.info('Using VTTCue polyfill from 3 argument TextTrackCue.');
window.VTTCue = shaka.polyfill.VTTCue.from3ArgsTextTrackCue_;
}
};
/**
* Draft spec TextTrackCue with 3 constructor arguments.
* @see {@link https://bit.ly/2IdyKbA W3C Working Draft 25 October 2012}.
*
* @param {number} startTime
* @param {number} endTime
* @param {string} text
* @return {!TextTrackCue}
* @private
*/
shaka.polyfill.VTTCue.from3ArgsTextTrackCue_ = function(startTime, endTime,
text) {
return new window.TextTrackCue(startTime, endTime, text);
};
/**
* Draft spec TextTrackCue with 6 constructor arguments (5th & 6th are
* optional).
* @see {@link https://bit.ly/2KaGSP2 W3C Working Draft 29 March 2012}.
*
* @param {number} startTime
* @param {number} endTime
* @param {string} text
* @return {!TextTrackCue}
* @private
*/
shaka.polyfill.VTTCue.from6ArgsTextTrackCue_ = function(startTime, endTime,
text) {
let id = startTime + '-' + endTime + '-' + text;
// Quoting the access to the TextTrackCue object to satisfy the compiler.
return new window['TextTrackCue'](id, startTime, endTime, text);
};
/**
* IE10, IE11 and Edge return TextTrackCue.length = 0, although they accept 3
* constructor arguments.
*
* @return {boolean}
* @private
*/
shaka.polyfill.VTTCue.canUse3ArgsTextTrackCue_ = function() {
try {
return !!shaka.polyfill.VTTCue.from3ArgsTextTrackCue_(1, 2, '');
} catch (error) {
return false;
}
};
shaka.polyfill.register(shaka.polyfill.VTTCue.install);