DataGridView使用MouseWheel事件实现鼠标滚动

int VerticalScrollIndex = 0;
		private void Dgv_MouseWheel(object sender, MouseEventArgs e)
		{
			int RowCount = 0;
			int h = 0;
			for (int i = dgv.Rows.Count-1; i>=0; i--)
			{
				h += dgv.Rows[i].Height;
				if (h < this.dgv.Height)
				{
					RowCount++;
				}
			}

			if (e.Delta < 0 && VerticalScrollIndex < this.dgv.Rows.Count - 1 -RowCount)
			{				
				this.dgv.FirstDisplayedScrollingRowIndex = VerticalScrollIndex++;
			}
			else if (e.Delta > 0&&VerticalScrollIndex > 0)
			{				
				this.dgv.FirstDisplayedScrollingRowIndex = VerticalScrollIndex--;
			}			
		}