Source: lib/text/simple_text_displayer.js

  1. /*! @license
  2.  * Shaka Player
  3.  * Copyright 2016 Google LLC
  4.  * SPDX-License-Identifier: Apache-2.0
  5.  */
  7. /**
  8.  * @fileoverview
  9.  */
  11. goog.provide('shaka.text.SimpleTextDisplayer');
  13. goog.require('shaka.Deprecate');
  14. goog.require('shaka.text.Utils');
  17. /**
  18.  * A text displayer plugin using the browser's native VTTCue interface.
  19.  *
  20.  * @implements {shaka.extern.TextDisplayer}
  21.  * @deprecated
  22.  * @export
  23.  */
  24. shaka.text.SimpleTextDisplayer = class {
  25.   /**
  26.    * @param {HTMLMediaElement} video
  27.    * @param {string} label
  28.    */
  29.   constructor(video, label) {
  30.     shaka.Deprecate.deprecateFeature(5,
  31.         'SimpleTextDisplayer', 'Please migrate to NativeTextDisplayer');
  32.     /** @private {HTMLMediaElement} */
  33.     this.video_ = video;
  35.     /** @private {string} */
  36.     this.textTrackLabel_ = label;
  38.     /** @private {TextTrack} */
  39.     this.textTrack_ = null;
  41.     // TODO: Test that in all cases, the built-in CC controls in the video
  42.     // element are toggling our TextTrack.
  44.     // If the video element has TextTracks, disable them.  If we see one that
  45.     // was created by a previous instance of Shaka Player, reuse it.
  46.     for (const track of Array.from(this.video_.textTracks)) {
  47.       if (track.kind === 'metadata' || track.kind === 'chapters') {
  48.         continue;
  49.       }
  50.       // NOTE: There is no API available to remove a TextTrack from a video
  51.       // element.
  52.       track.mode = 'disabled';
  54.       if (track.label == this.textTrackLabel_) {
  55.         this.textTrack_ = track;
  56.       }
  57.     }
  58.     if (this.textTrack_) {
  59.       this.textTrack_.mode = 'hidden';
  60.     }
  61.   }
  64.   /**
  65.    * @override
  66.    * @export
  67.    */
  68.   configure(config) {
  69.     // Unused.
  70.   }
  72.   /**
  73.    * @override
  74.    * @export
  75.    */
  76.   remove(start, end) {
  77.     // Check that the displayer hasn't been destroyed.
  78.     if (!this.textTrack_) {
  79.       return false;
  80.     }
  82.     const removeInRange = (cue) => {
  83.       const inside = cue.startTime < end && cue.endTime > start;
  84.       return inside;
  85.     };
  87.     shaka.text.Utils.removeCuesFromTextTrack(this.textTrack_, removeInRange);
  89.     return true;
  90.   }
  92.   /**
  93.    * @override
  94.    * @export
  95.    */
  96.   append(cues) {
  97.     if (!this.textTrack_) {
  98.       return;
  99.     }
  101.     shaka.text.Utils.appendCuesToTextTrack(this.textTrack_, cues);
  102.   }
  104.   /**
  105.    * @override
  106.    * @export
  107.    */
  108.   destroy() {
  109.     if (this.textTrack_) {
  110.       const removeIt = (cue) => true;
  111.       shaka.text.Utils.removeCuesFromTextTrack(this.textTrack_, removeIt);
  113.       // NOTE: There is no API available to remove a TextTrack from a video
  114.       // element.
  115.       this.textTrack_.mode = 'disabled';
  116.     }
  118.     this.video_ = null;
  119.     this.textTrack_ = null;
  120.     return Promise.resolve();
  121.   }
  123.   /**
  124.    * @override
  125.    * @export
  126.    */
  127.   isTextVisible() {
  128.     if (!this.textTrack_) {
  129.       return false;
  130.     }
  131.     return this.textTrack_.mode == 'showing';
  132.   }
  134.   /**
  135.    * @override
  136.    * @export
  137.    */
  138.   setTextVisibility(on) {
  139.     if (on && !this.textTrack_) {
  140.       this.createTextTrack_();
  141.     }
  142.     if (this.textTrack_) {
  143.       this.textTrack_.mode = on ? 'showing' : 'hidden';
  144.     }
  145.   }
  147.   /**
  148.    * @override
  149.    * @export
  150.    */
  151.   setTextLanguage(language) {
  152.   }
  154.   /**
  155.    * @override
  156.    * @export
  157.    */
  158.   enableTextDisplayer() {
  159.     this.createTextTrack_();
  160.   }
  162.   /**
  163.    * @private
  164.    */
  165.   createTextTrack_() {
  166.     if (this.video_ && !this.textTrack_) {
  167.       // As far as I can tell, there is no observable difference between setting
  168.       // kind to 'subtitles' or 'captions' when creating the TextTrack object.
  169.       // The individual text tracks from the manifest will still have their own
  170.       // kinds which can be displayed in the app's UI.
  171.       this.textTrack_ =
  172.           this.video_.addTextTrack('subtitles', this.textTrackLabel_);
  173.       this.textTrack_.mode = 'hidden';
  174.     }
  175.   }
  176. };