private void ButtonFullscreen_Click(object sender, RoutedEventArgs e)
        {
            var view = ApplicationView.GetForCurrentView();

            if (view.IsFullScreenMode)
            {
                view.ExitFullScreenMode();
                ExitingFullscren.Invoke(this, new EventArgs());
            }
            else
            {
                view.TryEnterFullScreenMode();
                EnteringFullscreen.Invoke(this, new EventArgs());
            }
        }
        private void viewer_DoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
        {
            var view = ApplicationView.GetForCurrentView();

            if (view.IsFullScreenMode)
            {
                view.ExitFullScreenMode();
                ExitingFullscren.Invoke(this, new EventArgs());
            }
            else
            {
                view.TryEnterFullScreenMode();
                EnteringFullscreen.Invoke(this, new EventArgs());
            }

            //The first tap will pause the player
            controller.Start();
        }