C#的DataGridView单元格合并

private void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
        {
            // 对第1列相同单元格进行合并     
            if (e.ColumnIndex == 1 && e.RowIndex != -1 || e.ColumnIndex == 2 && e.RowIndex != -1)
            {
                Brush datagridBrush = new SolidBrush(dataGridView1.GridColor);
                SolidBrush groupLineBrush = new SolidBrush(e.CellStyle.BackColor);
                using (Pen datagridLinePen = new Pen(datagridBrush))
                {
                    // 清除单元格
                    e.Graphics.FillRectangle(groupLineBrush, e.CellBounds);
                    if (e.RowIndex < dataGridView1.Rows.Count - 1 && dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value != null && dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value.ToString() != e.Value.ToString())
                    {
                        //绘制底边线
                        e.Graphics.DrawLine(datagridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1, e.CellBounds.Right, e.CellBounds.Bottom - 1);
                        // 画右边线
                        e.Graphics.DrawLine(datagridLinePen, e.CellBounds.Right - 1, e.CellBounds.Top, e.CellBounds.Right - 1, e.CellBounds.Bottom);
                    }
                    else
                    {
                        // 画右边线
                        e.Graphics.DrawLine(datagridLinePen, e.CellBounds.Right - 1, e.CellBounds.Top, e.CellBounds.Right - 1, e.CellBounds.Bottom);
                    }

                    //对最后一条记录只画底边线
                    if (e.RowIndex == dataGridView1.Rows.Count - 1)
                    {
                        //绘制底边线
                        e.Graphics.DrawLine(datagridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1, e.CellBounds.Right, e.CellBounds.Bottom - 1);
                    }

                    // 填写单元格内容，相同的内容的单元格只填写第一个                        
                    if (e.Value != null)
                    {
                        if (e.RowIndex > 0 && dataGridView1.Rows[e.RowIndex - 1].Cells[e.ColumnIndex].Value.ToString() == e.Value.ToString())
                        {
                        }
                        else
                        {
                            //绘制单元格内容
                            e.Graphics.DrawString(e.Value.ToString(), e.CellStyle.Font, Brushes.Black, e.CellBounds.X + 2, e.CellBounds.Y + 5, StringFormat.GenericDefault);
                        }
                    }
                    e.Handled = true;
                }
            }
        }