1 files changed, 119 insertions, 0 deletions
diff --git a/javascript/videojs/src/js/tracks/video-track-list.js b/javascript/videojs/src/js/tracks/video-track-list.js
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+++ b/javascript/videojs/src/js/tracks/video-track-list.js
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+/**
+ * @file video-track-list.js
+ */
+import TrackList from './track-list';
+
+/** @import VideoTrack from './video-track' */
+
+/**
+ * Un-select all other {@link VideoTrack}s that are selected.
+ *
+ * @param {VideoTrackList} list
+ *        list to work on
+ *
+ * @param {VideoTrack} track
+ *        The track to skip
+ *
+ * @private
+ */
+const disableOthers = function(list, track) {
+  for (let i = 0; i < list.length; i++) {
+    if (!Object.keys(list[i]).length || track.id === list[i].id) {
+      continue;
+    }
+    // another video track is enabled, disable it
+    list[i].selected = false;
+  }
+};
+
+/**
+ * The current list of {@link VideoTrack} for a video.
+ *
+ * @see [Spec]{@link https://html.spec.whatwg.org/multipage/embedded-content.html#videotracklist}
+ * @extends TrackList
+ */
+class VideoTrackList extends TrackList {
+
+  /**
+   * Create an instance of this class.
+   *
+   * @param {VideoTrack[]} [tracks=[]]
+   *        A list of `VideoTrack` to instantiate the list with.
+   */
+  constructor(tracks = []) {
+    // make sure only 1 track is enabled
+    // sorted from last index to first index
+    for (let i = tracks.length - 1; i >= 0; i--) {
+      if (tracks[i].selected) {
+        disableOthers(tracks, tracks[i]);
+        break;
+      }
+    }
+
+    super(tracks);
+    this.changing_ = false;
+
+    /**
+     * @member {number} VideoTrackList#selectedIndex
+     *         The current index of the selected {@link VideoTrack`}.
+     */
+    Object.defineProperty(this, 'selectedIndex', {
+      get() {
+        for (let i = 0; i < this.length; i++) {
+          if (this[i].selected) {
+            return i;
+          }
+        }
+        return -1;
+      },
+      set() {}
+    });
+  }
+
+  /**
+   * Add a {@link VideoTrack} to the `VideoTrackList`.
+   *
+   * @param {VideoTrack} track
+   *        The VideoTrack to add to the list
+   *
+   * @fires TrackList#addtrack
+   */
+  addTrack(track) {
+    if (track.selected) {
+      disableOthers(this, track);
+    }
+
+    super.addTrack(track);
+    // native tracks don't have this
+    if (!track.addEventListener) {
+      return;
+    }
+
+    track.selectedChange_ = () => {
+      if (this.changing_) {
+        return;
+      }
+      this.changing_ = true;
+      disableOthers(this, track);
+      this.changing_ = false;
+      this.trigger('change');
+    };
+
+    /**
+     * @listens VideoTrack#selectedchange
+     * @fires TrackList#change
+     */
+    track.addEventListener('selectedchange', track.selectedChange_);
+  }
+
+  removeTrack(rtrack) {
+    super.removeTrack(rtrack);
+
+    if (rtrack.removeEventListener && rtrack.selectedChange_) {
+      rtrack.removeEventListener('selectedchange', rtrack.selectedChange_);
+      rtrack.selectedChange_ = null;
+    }
+  }
+}
+
+export default VideoTrackList;