private void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)

        {

            if (e.RowIndex != -1 && Convert.ToString (dataGridView1.Rows[e.RowIndex].Cells[1].Value) == "GP")

            {

                e.CellStyle.Font = new Font(dataGridView1.DefaultCellStyle.Font, FontStyle.Bold);

                e.CellStyle.WrapMode = DataGridViewTriState.True;

                MerageRowSpan(dataGridView1, e, 0, 1);

            }

            if ((e.RowIndex == dataGridView1.Rows.Count - 1) && (e.ColumnIndex == 0))

            {

                Rectangle rect = new Rectangle();

                rect.X = e.CellBounds.X;

                rect.Y = e.CellBounds.Y;

                rect.Width = e.CellBounds.Width;

                rect.Height = e.CellBounds.Height;

                e.Paint(rect, DataGridViewPaintParts.ContentBackground);

                e.PaintBackground(rect, false);

                e.Handled = true;

            }

        }

        private static SortedList rowSpan = new SortedList();//取得需要重新绘制的单元格

        private static string rowValue = "";//重新绘制的文本框内容



        #region  单元格绘制

        /// <summary>

        /// 

        /// DataGridView合并单元格(横向)

        /// </summary>

        /// <param name="dgv">绘制的DataGridview </param>

        /// <param name="cellArgs">绘制单元格的参数（DataGridview的CellPainting事件中参数）</param>

        /// <param name="minColIndex">起始单元格在DataGridView中的索引号</param>

        /// <param name="maxColIndex">结束单元格在DataGridView中的索引号</param>

        public void MerageRowSpan(DataGridView dgv, DataGridViewCellPaintingEventArgs cellArgs, int minColIndex, int maxColIndex)

        {

            if (cellArgs.ColumnIndex < minColIndex || cellArgs.ColumnIndex > maxColIndex) return;



            Rectangle rect = new Rectangle();

            using (Brush gridBrush = new SolidBrush(dgv.GridColor),

                backColorBrush = new SolidBrush(cellArgs.CellStyle.BackColor))

            {

                //抹去原来的cell背景

                cellArgs.Graphics.FillRectangle(backColorBrush, cellArgs.CellBounds);

            }

            cellArgs.Handled = true;



            if (rowSpan[cellArgs.ColumnIndex] == null)

            {

                //首先判断当前单元格是不是需要重绘的单元格

                //保留此单元格的信息，并抹去此单元格的背景

                rect.X = cellArgs.CellBounds.X;

                rect.Y = cellArgs.CellBounds.Y;

                rect.Width = cellArgs.CellBounds.Width;

                rect.Height = cellArgs.CellBounds.Height;



                rowValue += cellArgs.Value.ToString();

                rowSpan.Add(cellArgs.ColumnIndex, rect);

                if (cellArgs.ColumnIndex != maxColIndex)

                    return;

                MeragePrint(dgv, cellArgs, minColIndex, maxColIndex);

            }

            else

            {

                IsPostMerage(dgv, cellArgs, minColIndex, maxColIndex);

            }

        }



        /// <summary>

        /// 不是初次单元格绘制

        /// </summary>

        /// <param name="dgv"></param>

        /// <param name="cellArgs"></param>

        /// <param name="minColIndex"></param>

        /// <param name="maxColIndex"></param>

        public void IsPostMerage(DataGridView dgv, DataGridViewCellPaintingEventArgs cellArgs, int minColIndex, int maxColIndex)

        {

            //比较单元是否有变化

            Rectangle rectArgs = (Rectangle)rowSpan[cellArgs.ColumnIndex];

            if (rectArgs.X != cellArgs.CellBounds.X || rectArgs.Y != cellArgs.CellBounds.Y

                || rectArgs.Width != cellArgs.CellBounds.Width || rectArgs.Height != cellArgs.CellBounds.Height)

            {

                rectArgs.X = cellArgs.CellBounds.X;

                rectArgs.Y = cellArgs.CellBounds.Y;

                rectArgs.Width = cellArgs.CellBounds.Width;

                rectArgs.Height = cellArgs.CellBounds.Height;

                rowSpan[cellArgs.ColumnIndex] = rectArgs;

            }

            MeragePrint(dgv, cellArgs, minColIndex, maxColIndex);



        }



        //画制单元格

        private void MeragePrint(DataGridView dgv, DataGridViewCellPaintingEventArgs cellArgs, int minColIndex, int maxColIndex)

        {



            int width = 0;//合并后单元格总宽度

            int height = cellArgs.CellBounds.Height;//合并后单元格总高度



            for (int i = minColIndex; i <= maxColIndex; i++)

            {

                width += ((Rectangle)rowSpan[i]).Width;

            }



            Rectangle rectBegin = (Rectangle)rowSpan[minColIndex];//合并第一个单元格的位置信息

            Rectangle rectEnd = (Rectangle)rowSpan[maxColIndex];//合并最后一个单元格的位置信息



            //合并单元格的位置信息

            Rectangle reBounds = new Rectangle();

            reBounds.X = rectBegin.X;

            reBounds.Y = rectBegin.Y;

            reBounds.Width = width - 1;

            reBounds.Height = height - 1;





            using (Brush gridBrush = new SolidBrush(dgv.GridColor),

                         backColorBrush = new SolidBrush(cellArgs.CellStyle.BackColor))

            {

                using (Pen gridLinePen = new Pen(gridBrush))

                {

                    // 画出上下两条边线，左右边线无

                    Point blPoint = new Point(rectBegin.Left, rectBegin.Bottom - 1);//底线左边位置

                    Point brPoint = new Point(rectEnd.Right - 1, rectEnd.Bottom - 1);//底线右边位置

                    cellArgs.Graphics.DrawLine(gridLinePen, blPoint, brPoint);//下边线



                    Point tlPoint = new Point(rectBegin.Left, rectBegin.Top);//上边线左边位置

                    Point trPoint = new Point(rectEnd.Right - 1, rectEnd.Top);//上边线右边位置

                    cellArgs.Graphics.DrawLine(gridLinePen, tlPoint, trPoint); //上边线



                    Point ltPoint = new Point(rectBegin.Left, rectBegin.Top);//左边线顶部位置

                    Point lbPoint = new Point(rectBegin.Left, rectBegin.Bottom - 1);//左边线底部位置

                    cellArgs.Graphics.DrawLine(gridLinePen, ltPoint, lbPoint); //左边线



                    Point rtPoint = new Point(rectEnd.Right - 1, rectEnd.Top);//右边线顶部位置

                    Point rbPoint = new Point(rectEnd.Right - 1, rectEnd.Bottom - 1);//右边线底部位置

                    cellArgs.Graphics.DrawLine(gridLinePen, rtPoint, rbPoint); //右边线



                    //计算绘制字符串的位置

                    SizeF sf = cellArgs.Graphics.MeasureString(rowValue, cellArgs.CellStyle.Font);

                    float lstr = (width - sf.Width) / 2;

                    float rstr = (height - sf.Height) / 2;



                    //画出文本框

                    if (rowValue != "")

                    {

                        cellArgs.Graphics.DrawString(rowValue, cellArgs.CellStyle.Font,

                                                   new SolidBrush(cellArgs.CellStyle.ForeColor),

                                                     rectBegin.Left + lstr,

                                                     rectBegin.Top + rstr,

                                                     StringFormat.GenericDefault);

                    }

                }

                cellArgs.Handled = true;

            }



        }

        #endregion