System.Windows.Forms.HexBox._vScrollBar_Scroll C# (CSharp) Method

        void _vScrollBar_Scroll(object sender, ScrollEventArgs e)
        {
            switch(e.Type)
            {
                case ScrollEventType.Last:
                    break;
                case ScrollEventType.EndScroll:
                    break;
                case ScrollEventType.SmallIncrement:
                    PerformScrollLineDown();
                    break;
                case ScrollEventType.SmallDecrement:
                    PerformScrollLineUp();
                    break;
                case ScrollEventType.LargeIncrement:
                    PerformScrollPageDown();
                    break;
                case ScrollEventType.LargeDecrement:
                    PerformScrollPageUp();
                    break;
                case ScrollEventType.ThumbPosition:
                    long lPos = FromScrollPos(e.NewValue);
                    PerformScrollThumpPosition(lPos);
                    break;
                case ScrollEventType.ThumbTrack:
                    // to avoid performance problems use a refresh delay implemented with a timer
                    if (_thumbTrackTimer.Enabled) // stop old timer
                        _thumbTrackTimer.Enabled = false;

                    // perform scroll immediately only if last refresh is very old
                    int currentThumbTrack = System.Environment.TickCount;
                    if (currentThumbTrack - _lastThumbtrack > THUMPTRACKDELAY)
                    {
                        PerformScrollThumbTrack(null, null);
                        _lastThumbtrack = currentThumbTrack;
                        break;
                    }

                    // start thumbtrack timer
                    _thumbTrackPosition = FromScrollPos(e.NewValue);
                    _thumbTrackTimer.Enabled = true;
                    break;
                case ScrollEventType.First:
                    break;
                default:
                    break;
            }

            e.NewValue = ToScrollPos(_scrollVpos);
        }