private void ProgressBar_ValueChanged(object sender, RangeBaseValueChangedEventArgs e)
 {
     if (_isDragging)
     {
         CurrentPosition.Text = TimeSpanConverter.Covert(e.NewValue);
         if (IsSeekingInstant)
         {
             PlaybackService.Instance.CurrentPlayer.Position = TimeSpan.FromSeconds(e.NewValue);
         }
         else
         {
             _lastSeekPosition = e.NewValue;
         }
     }
 }
        private void Songtimer_Tick(object sender, object e)
        {
            if (_isDragging)
            {
                return;//拖拽时不改变数值
            }
            var player = PlaybackService.Instance.CurrentPlayer;
            var total  = player.NaturalDuration.TotalSeconds;

            if (ProgressBar.Maximum != total)
            {
                ProgressBar.Maximum  = total;
                NaturalDuration.Text = TimeSpanConverter.Covert(total);
            }
            var cur = player.Position.TotalSeconds;

            ProgressBar.Value    = cur;
            CurrentPosition.Text = TimeSpanConverter.Covert(cur);
        }