feat: support fastSeek during scrubbing if available (#6525)

This will allow us to use iframe playlists on HLS on Safari browsers and eventually, add support in VHS.

src/js/player.js

@@ -2432,6 +2432,7 @@ class Player extends Component {
       return this.scrubbing_;
     }
     this.scrubbing_ = !!isScrubbing;
+    this.techCall_('setScrubbing', this.scrubbing_);
 
     if (isScrubbing) {
       this.addClass('vjs-scrubbing');

src/js/tech/html5.js

@@ -520,6 +520,10 @@ class Html5 extends Tech {
     });
   }
 
+  setScrubbing(isScrubbing) {
+    this.isScrubbing_ = isScrubbing;
+  }
+
   /**
    * Set current time for the `HTML5` tech.
    *
@@ -528,7 +532,11 @@ class Html5 extends Tech {
    */
   setCurrentTime(seconds) {
     try {
-      this.el_.currentTime = seconds;
+      if (this.isScrubbing_ && this.el_.fastSeek) {
+        this.el_.fastSeek(seconds);
+      } else {
+        this.el_.currentTime = seconds;
+      }
     } catch (e) {
       log(e, 'Video is not ready. (Video.js)');
       // this.warning(VideoJS.warnings.videoNotReady);

test/unit/player.test.js

@@ -1241,6 +1241,23 @@ QUnit.test('should add an audio player region if an audio el is used', function(
   player.dispose();
 });
 
+QUnit.test('should setScrubbing when seeking or not seeking', function(assert) {
+  const player = TestHelpers.makePlayer();
+  let isScrubbing;
+
+  player.tech_.setScrubbing = (_isScrubbing) => {
+    isScrubbing = _isScrubbing;
+  };
+
+  assert.equal(player.scrubbing(), false, 'player is not scrubbing');
+
+  player.scrubbing(true);
+  assert.ok(isScrubbing, "tech's setScrubbing was called with true");
+
+  player.scrubbing(false);
+  assert.notOk(isScrubbing, "tech's setScrubbing was called with false");
+});
+
 QUnit.test('should not be scrubbing while not seeking', function(assert) {
   const player = TestHelpers.makePlayer();
 

test/unit/tech/html5.test.js

@@ -5,6 +5,7 @@ let tech;
 import Html5 from '../../../src/js/tech/html5.js';
 import * as browser from '../../../src/js/utils/browser.js';
 import document from 'global/document';
+import sinon from 'sinon';
 
 QUnit.module('HTML5', {
   beforeEach(assert) {
@@ -50,6 +51,38 @@ QUnit.module('HTML5', {
   }
 });
 
+QUnit.test('if setScrubbing is true and fastSeek is available, use it', function(assert) {
+  Object.defineProperty(tech.el(), 'currentTime', {
+    get: () => {},
+    set: () => {},
+
+    writeable: true,
+    enumerable: false,
+    configurable: true
+  });
+
+  const currentTimeSpy = sinon.spy(tech.el(), 'currentTime', ['set']);
+
+  tech.setCurrentTime(5);
+  assert.ok(currentTimeSpy.set.called, 'currentTime setter was called');
+  assert.ok(currentTimeSpy.set.calledWith(5), 'currentTime setter was called with 5');
+
+  tech.setScrubbing(true);
+
+  // when scrubbing is set but fastSeek isn't available, currentTime should still be called
+  tech.el().fastSeek = null;
+  tech.setCurrentTime(10);
+  assert.ok(currentTimeSpy.set.called, 'currentTime setter was called');
+  assert.ok(currentTimeSpy.set.calledWith(10), 'currentTime setter was called with 10');
+
+  const fastSeekSpy = tech.el().fastSeek = sinon.spy();
+
+  tech.setCurrentTime(15);
+  assert.ok(currentTimeSpy.set.calledTwice, 'currentTime setter was only called twice and not a 3rd time for fastSeek');
+  assert.ok(fastSeekSpy.called, 'fastSeek called');
+  assert.ok(fastSeekSpy.calledWith(15), 'fastSeek called with 15');
+});
+
 QUnit.test('should be able to set playsinline attribute', function(assert) {
   assert.expect(2);
 

test/unit/tech/tech-faker.js

@@ -97,6 +97,7 @@ class TechFaker extends Tech {
   seeking() {
     return false;
   }
+  setScrubbing() {}
   fakeSourceset() {
     this.el_.src = this.options_.sourceset;
     this.el_.setAttribute('src', this.options_.sourceset);