Source: lib/util/switch_history.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. goog.provide('shaka.util.SwitchHistory');
  10. /**
  11.  * This class is used to track changes in variant and text selections. This
  12.  * class will make sure that redundant switches are not recorded in the history.
  13.  *
  14.  * @final
  15.  */
  16. shaka.util.SwitchHistory = class {
  17.   /** */
  18.   constructor() {
  19.     /** @private {?shaka.extern.Variant} */
  20.     this.currentVariant_ = null;
  22.     /** @private {?shaka.extern.Stream} */
  23.     this.currentText_ = null;
  25.     /** @private {!Array.<shaka.extern.TrackChoice>} */
  26.     this.history_ = [];
  27.   }
  29.   /**
  30.    * Update the history to show that we are currently playing |newVariant|. If
  31.    * we are already playing |newVariant|, this update will be ignored.
  32.    *
  33.    * @param {shaka.extern.Variant} newVariant
  34.    * @param {boolean} fromAdaptation
  35.    */
  36.   updateCurrentVariant(newVariant, fromAdaptation) {
  37.     if (this.currentVariant_ == newVariant) {
  38.       return;
  39.     }
  41.     this.currentVariant_ = newVariant;
  42.     this.history_.push({
  43.       timestamp: this.getNowInSeconds_(),
  44.       id: newVariant.id,
  45.       type: 'variant',
  46.       fromAdaptation: fromAdaptation,
  47.       bandwidth: newVariant.bandwidth,
  48.     });
  49.   }
  51.   /**
  52.    * Update the history to show that we are currently playing |newText|. If we
  53.    * are already playing |newText|, this update will be ignored.
  54.    *
  55.    * @param {shaka.extern.Stream} newText
  56.    * @param {boolean} fromAdaptation
  57.    */
  58.   updateCurrentText(newText, fromAdaptation) {
  59.     if (this.currentText_ == newText) {
  60.       return;
  61.     }
  63.     this.currentText_ = newText;
  64.     this.history_.push({
  65.       timestamp: this.getNowInSeconds_(),
  66.       id: newText.id,
  67.       type: 'text',
  68.       fromAdaptation: fromAdaptation,
  69.       bandwidth: null,
  70.     });
  71.   }
  73.   /**
  74.    * Get a copy of the switch history. This will make sure to expose no internal
  75.    * references.
  76.    *
  77.    * @return {!Array.<shaka.extern.TrackChoice>}
  78.    */
  79.   getCopy() {
  80.     const copy = [];
  82.     for (const entry of this.history_) {
  83.       copy.push(this.clone_(entry));
  84.     }
  86.     return copy;
  87.   }
  89.   /**
  90.    * Get the system time in seconds.
  91.    *
  92.    * @return {number}
  93.    * @private
  94.    */
  95.   getNowInSeconds_() {
  96.     return Date.now() / 1000;
  97.   }
  99.   /**
  100.    * @param {shaka.extern.TrackChoice} entry
  101.    * @return {shaka.extern.TrackChoice}
  102.    * @private
  103.    */
  104.   clone_(entry) {
  105.     return {
  106.       timestamp: entry.timestamp,
  107.       id: entry.id,
  108.       type: entry.type,
  109.       fromAdaptation: entry.fromAdaptation,
  110.       bandwidth: entry.bandwidth,
  111.     };
  112.   }
  113. };