fix(FEC-7935): fix text selection logic with hlsjs (#65)

this is basically the same as before, but hls.js run different code paths when we use it's API for selecting text track.
Before this change we used to set the showing/hidden mode attribute of the text track in playkit-js html5 engine. we now set this in HLS.JS which internally does the same but also it manages internal state for this and so it's better to use its API and not access the textTrack.mode directly.
This fix depends on a fix in kaltura/playkit-js#263

src/hls-adapter.js

@@ -149,6 +149,9 @@ export default class HlsAdapter extends BaseMediaSourceAdapter {
         adapterConfig.hlsConfig.startPosition = config.playback.startTime;
       }
     }
+    if (Utils.Object.hasPropertyPath(config, 'playback.useNativeTextTrack')) {
+      adapterConfig.subtitleDisplay = Utils.Object.getPropertyPath(config, 'playback.useNativeTextTrack');
+    }
     return new this(videoElement, source, adapterConfig);
   }
 
@@ -202,6 +205,7 @@ export default class HlsAdapter extends BaseMediaSourceAdapter {
       this._config.hlsConfig['pLoader'] = pLoader;
     }
     this._hls = new Hlsjs(this._config.hlsConfig);
+    this._hls.subtitleDisplay = this._config.subtitleDisplay;
     this._addBindings();
   }
 
@@ -479,8 +483,7 @@ export default class HlsAdapter extends BaseMediaSourceAdapter {
    */
   selectTextTrack(textTrack: TextTrack): void {
     if (textTrack instanceof TextTrack && !textTrack.active && this._videoElement.textTracks) {
-      this._disableAllTextTracks();
-      this._videoElement.textTracks[textTrack.index].mode = 'hidden';
+      this._hls.subtitleTrack = textTrack.index;
       HlsAdapter._logger.debug('Text track changed', textTrack);
       this._onTrackChanged(textTrack);
     }
@@ -492,7 +495,7 @@ export default class HlsAdapter extends BaseMediaSourceAdapter {
    * @public
    */
   hideTextTrack(): void {
-    this._disableAllTextTracks();
+    this._hls.subtitleTrack = -1;
   }
 
   /**
@@ -644,18 +647,6 @@ export default class HlsAdapter extends BaseMediaSourceAdapter {
     }
   }
 
-  /**
-   * Disables all the video tag text tracks.
-   * @returns {void}
-   * @private
-   */
-  _disableAllTextTracks() {
-    let vidTextTracks = this._videoElement.textTracks;
-    for (let i = 0; i < vidTextTracks.length; i++) {
-      vidTextTracks[i].mode = 'disabled';
-    }
-  }
-
   /**
    * Handles hls errors.
    * @param {any} data - The event data object.

test/src/hls-adapter.spec.js

@@ -210,29 +210,6 @@ describe('HlsAdapter Instance - Unit', function () {
     JSON.parse(JSON.stringify(tracks)).should.deep.equal(allTracks);
   });
 
-  it('should disable all text tracks', function () {
-    hlsAdapterInstance._videoElement = {
-      textTracks: hls_tracks.subtitles,
-      removeEventListener: () => {}
-    };
-    hlsAdapterInstance._disableAllTextTracks();
-    for (let i = 0; i < hlsAdapterInstance._videoElement.textTracks.length; i++) {
-      hlsAdapterInstance._videoElement.textTracks[i].mode.should.equal('disabled');
-    }
-  });
-
-  it('should hide the active text track', function () {
-    hlsAdapterInstance._videoElement = {
-      textTracks: hls_tracks.subtitles,
-      removeEventListener: () => {}
-    };
-    hlsAdapterInstance._videoElement.textTracks[0].mode = 'showing';
-    hlsAdapterInstance.hideTextTrack();
-    for (let i = 0; i < hlsAdapterInstance._videoElement.textTracks.length; i++) {
-      hlsAdapterInstance._videoElement.textTracks[i].mode.should.equal('disabled');
-    }
-  });
-
   it('should enable adaptive bitrate', function () {
     hlsAdapterInstance._hls = {
       on: function () {