首行 DataGridView 单元格横向合并实现

        #region 合并单元格
        private void hGridView2_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
        {
            // 对第1行相同单元格进行合并
            if (e.RowIndex == 0 && e.ColumnIndex != -1)
            {
                using
                    (
                    Brush gridBrush = new SolidBrush(this.hGridView2.GridColor),
                    backColorBrush = new SolidBrush(e.CellStyle.BackColor)
                    )
                {
                    using (Pen gridLinePen = new Pen(gridBrush))
                    {
                        // 清除单元格
                        e.Graphics.FillRectangle(backColorBrush, e.CellBounds);

                        // 画 Grid 边线（画单元格的底边线、上边线、右边线）
                        //   如果下一列和当前列的数据不同，则在当前的单元格画一条右边线、上边线、左边线
                        if (e.ColumnIndex < hGridView2.Columns.Count - 1 &&
                        hGridView2.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value.ToString() !=
                        e.Value.ToString())
                        {//画底边线
                            e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left,
                             e.CellBounds.Bottom - 1, e.CellBounds.Right - 1,
                           e.CellBounds.Bottom - 1);
                            // 画右边线
                            e.Graphics.DrawLine(gridLinePen, e.CellBounds.Right - 1,
                                 e.CellBounds.Top, e.CellBounds.Right - 1,
                                   e.CellBounds.Bottom);