Source: lib/util/switch_history.js

  1. /**
  2.  * @license
  3.  * Copyright 2016 Google Inc.
  4.  *
  5.  * Licensed under the Apache License, Version 2.0 (the "License");
  6.  * you may not use this file except in compliance with the License.
  7.  * You may obtain a copy of the License at
  8.  *
  9.  *     http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  18. goog.provide('shaka.util.SwitchHistory');
  21. /**
  22.  * This class is used to track changes in variant and text selections. This
  23.  * class will make sure that redundant switches are not recorded in the history.
  24.  *
  25.  * @final
  26.  */
  27. shaka.util.SwitchHistory = class {
  28.   constructor() {
  29.     /** @private {?shaka.extern.Variant} */
  30.     this.currentVariant_ = null;
  32.     /** @private {?shaka.extern.Stream} */
  33.     this.currentText_ = null;
  35.     /** @private {!Array.<shaka.extern.TrackChoice>} */
  36.     this.history_ = [];
  37.   }
  39.   /**
  40.    * Update the history to show that we are currently playing |newVariant|. If
  41.    * we are already playing |newVariant|, this update will be ignored.
  42.    *
  43.    * @param {shaka.extern.Variant} newVariant
  44.    * @param {boolean} fromAdaptation
  45.    */
  46.   updateCurrentVariant(newVariant, fromAdaptation) {
  47.     if (this.currentVariant_ == newVariant) { return; }
  49.     this.currentVariant_ = newVariant;
  50.     this.history_.push({
  51.       timestamp: this.getNowInSeconds_(),
  52.       id: newVariant.id,
  53.       type: 'variant',
  54.       fromAdaptation: fromAdaptation,
  55.       bandwidth: newVariant.bandwidth,
  56.     });
  57.   }
  59.   /**
  60.    * Update the history to show that we are currently playing |newText|. If we
  61.    * are already playing |newText|, this update will be ignored.
  62.    *
  63.    * @param {shaka.extern.Stream} newText
  64.    * @param {boolean} fromAdaptation
  65.    */
  66.   updateCurrentText(newText, fromAdaptation) {
  67.     if (this.currentText_ == newText) { return; }
  69.     this.currentText_ = newText;
  70.     this.history_.push({
  71.       timestamp: this.getNowInSeconds_(),
  72.       id: newText.id,
  73.       type: 'text',
  74.       fromAdaptation: fromAdaptation,
  75.       bandwidth: null,
  76.     });
  77.   }
  79.   /**
  80.    * Get a copy of the switch history. This will make sure to expose no internal
  81.    * references.
  82.    *
  83.    * @return {!Array.<shaka.extern.TrackChoice>}
  84.    */
  85.   getCopy() {
  86.     const copy = [];
  88.     for (const entry of this.history_) {
  89.       copy.push(this.clone_(entry));
  90.     }
  92.     return copy;
  93.   }
  95.   /**
  96.    * Get the system time in seconds.
  97.    *
  98.    * @return {number}
  99.    * @private
  100.    */
  101.   getNowInSeconds_() {
  102.     return Date.now() / 1000;
  103.   }
  105.   /**
  106.    * @param {shaka.extern.TrackChoice} entry
  107.    * @return {shaka.extern.TrackChoice}
  108.    * @private
  109.    */
  110.   clone_(entry) {
  111.     return {
  112.       timestamp: entry.timestamp,
  113.       id: entry.id,
  114.       type: entry.type,
  115.       fromAdaptation: entry.fromAdaptation,
  116.       bandwidth: entry.bandwidth,
  117.     };
  118.   }
  119. };