Source: lib/media/region_timeline.js

  1. /** @license
  2.  * Copyright 2016 Google LLC
  3.  * SPDX-License-Identifier: Apache-2.0
  4.  */
  6. goog.provide('shaka.media.RegionTimeline');
  8. goog.require('shaka.util.IReleasable');
  11. /**
  12.  * The region timeline is a set of unique timeline region info entries. When
  13.  * a new entry is added, the |onAddRegion| callback will be called.
  14.  *
  15.  * @implements {shaka.util.IReleasable}
  16.  * @final
  17.  */
  18. shaka.media.RegionTimeline = class {
  19.   constructor() {
  20.     /** @private {function(shaka.extern.TimelineRegionInfo)} */
  21.     this.onAddRegion_ = (region) => {};
  22.     /** @private {!Set.<shaka.extern.TimelineRegionInfo>} */
  23.     this.regions_ = new Set();
  24.   }
  26.   /** @override */
  27.   release() {
  28.     // Prevent us from holding onto any external references via the callback.
  29.     this.onAddRegion_ = (region) => {};
  30.     this.regions_.clear();
  31.   }
  33.   /**
  34.    * Set the callbacks for events. This will override any previous calls to
  35.    * |setListeners|.
  36.    *
  37.    * @param {function(shaka.extern.TimelineRegionInfo)} onAddRegion
  38.    *    Set the callback for when we add a new region. This callback will only
  39.    *    be called when a region is unique (we reject duplicate regions).
  40.    */
  41.   setListeners(onAddRegion) {
  42.     this.onAddRegion_ = onAddRegion;
  43.   }
  45.   /**
  46.    * @param {shaka.extern.TimelineRegionInfo} region
  47.    */
  48.   addRegion(region) {
  49.     const similarRegion = this.findSimilarRegion_(region);
  51.     // Make sure we don't add duplicate regions. We keep track of this here
  52.     // instead of making the parser track it.
  53.     if (similarRegion == null) {
  54.       this.regions_.add(region);
  55.       this.onAddRegion_(region);
  56.     }
  57.   }
  59.   /**
  60.    * Find a region in the timeline that has the same scheme id uri, event id,
  61.    * start time and end time. If these four parameters match, we assume it
  62.    * to be the same region. If no similar region can be found, |null| will be
  63.    * returned.
  64.    *
  65.    * @param {shaka.extern.TimelineRegionInfo} region
  66.    * @return {?shaka.extern.TimelineRegionInfo}
  67.    * @private
  68.    */
  69.   findSimilarRegion_(region) {
  70.     for (const existing of this.regions_) {
  71.       // The same scheme ID and time range means that it is similar-enough to
  72.       // be the same region.
  73.       const isSimilar = existing.schemeIdUri == region.schemeIdUri &&
  74.                         existing.id == region.id &&
  75.                         existing.startTime == region.startTime &&
  76.                         existing.endTime == region.endTime;
  78.       if (isSimilar) {
  79.         return existing;
  80.       }
  81.     }
  83.     return null;
  84.   }
  86.   /**
  87.    * Get an iterable for all the regions in the timeline. This will allow
  88.    * others to see what regions are in the timeline while not being able to
  89.    * change the collection.
  90.    *
  91.    * @return {!Iterable.<shaka.extern.TimelineRegionInfo>}
  92.    */
  93.   regions() {
  94.     return this.regions_;
  95.   }
  96. };