DataGridView合并单元格(一列或一行)

        #region"合并单元格的测试(一列或一行)"
        // int?是搜索一种类型(可空类型)，普通的int不能为null，而用int?，其值可以为null
        //private int? nextrow = null;
        //private int? nextcol = null;

        //在CellPainting方法后调用
        private void dataGridView1_CellFormatting(object sender, System.Windows.Forms.DataGridViewCellFormattingEventArgs e)
        {
            /*
            //列标示
            if (e.ColumnIndex >= 0 && this.dataGridView1.Columns[e.ColumnIndex].HeaderText == "PARENTID"  && e.RowIndex >= 0)
            {
                //若与下一行同列单元格值相同则修改设置
                if (e.RowIndex < this.dataGridView1.RowCount - 1 && this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value != null)
                {
                    if (e.Value.ToString() == this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value.ToString())
                    {
                        e.CellStyle.BackColor = Color.LightPink;
                        this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Style.BackColor = Color.LightPink;
                        this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].ReadOnly = true;
                        //this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].ReadOnly = true;
                    }
                }

            }
            */

            /*
            //行标示
            if (e.ColumnIndex >= 0 && this.dataGridView1.Columns[e.ColumnIndex].HeaderText == "PHONE1" && e.RowIndex >= 0)
            {
                //若与同行下一列单元格值相同则修改设置
                if (e.ColumnIndex != this.dataGridView1.ColumnCount - 1 && this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value != null)
                {
                    if (e.Value.ToString() == this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value.ToString())
                    {
                        e.CellStyle.BackColor = Color.LightBlue;
                        this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Style.BackColor = Color.LightPink;
                        this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].ReadOnly = true;
                        //this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].ReadOnly = true;
                    }
                }
            }
             */
        }

        //==========================

        //绘制单元格
        private void dataGridView1_CellPainting(object sender, System.Windows.Forms.DataGridViewCellPaintingEventArgs e)
        {
            //纵向合并
            if (e.ColumnIndex >= 0 && this.dataGridView1.Columns[e.ColumnIndex].HeaderText == "PARENTID"  && e.RowIndex >= 0)
            {
                using (
                    Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor),
                    backColorBrush = new SolidBrush(e.CellStyle.BackColor))
                {
                    using (Pen gridLinePen = new Pen(gridBrush))
                    {
                        // 擦除原单元格背景
                        e.Graphics.FillRectangle(backColorBrush, e.CellBounds);

                        /****** 绘制单元格相互间隔的区分线条，datagridview自己会处理左侧和上边缘的线条，因此只需绘制下边框和和右边框
                         DataGridView控件绘制单元格时，不绘制左边框和上边框，共用左单元格的右边框，上一单元格的下边框*****/

                        //不是最后一行且单元格的值不为null
                        if (e.RowIndex < this.dataGridView1.RowCount - 1 && this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value != null)
                        {
                            //若与下一单元格值不同
                            if (e.Value.ToString() != this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Value.ToString())
                            {
                                //下边缘的线
                                e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1,
                                e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);
                                //绘制值
                                if (e.Value != null)
                                {
                                    e.Graphics.DrawString(e.Value.ToString(), e.CellStyle.Font,
                                        Brushes.Crimson, e.CellBounds.X + 2,
                                        e.CellBounds.Y + 2, StringFormat.GenericDefault);
                                }
                            }
                            //若与下一单元格值相同
                            else
                            {
                                //背景颜色
                                //e.CellStyle.BackColor = Color.LightPink;   //仅在CellFormatting方法中可用
                                this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].Style.BackColor = Color.LightBlue;
                                this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].Style.BackColor = Color.LightBlue;
                                //只读（以免双击单元格时显示值）
                                this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].ReadOnly = true;
                                this.dataGridView1.Rows[e.RowIndex + 1].Cells[e.ColumnIndex].ReadOnly = true;
                            }
                        }
                        //最后一行或单元格的值为null
                        else
                        {
                            //下边缘的线
                            e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1,
                                e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);

                            //绘制值
                            if (e.Value != null)
                            {
                                e.Graphics.DrawString(e.Value.ToString(), e.CellStyle.Font,
                                    Brushes.Crimson, e.CellBounds.X + 2,
                                    e.CellBounds.Y + 2, StringFormat.GenericDefault);
                            }
                        }

                        ////左侧的线（）
                        //e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left,
                        //    e.CellBounds.Top, e.CellBounds.Left,
                        //    e.CellBounds.Bottom - 1);

                        //右侧的线
                        e.Graphics.DrawLine(gridLinePen, e.CellBounds.Right - 1,
                            e.CellBounds.Top, e.CellBounds.Right - 1,
                            e.CellBounds.Bottom - 1);

                        //设置处理事件完成（关键点），只有设置为ture,才能显示出想要的结果。
                        e.Handled = true;
                    }
                }
            }

            //横向合并
            if (e.ColumnIndex >= 0 && this.dataGridView1.Columns[e.ColumnIndex].HeaderText == "PHONE1" && e.RowIndex >= 0)
            {
                using (
                    Brush gridBrush = new SolidBrush(this.dataGridView1.GridColor),
                    backColorBrush = new SolidBrush(e.CellStyle.BackColor))
                {
                    using (Pen gridLinePen = new Pen(gridBrush))
                    {
                        // 擦除原单元格背景
                        e.Graphics.FillRectangle(backColorBrush, e.CellBounds);

                        /****** 绘制单元格相互间隔的区分线条，datagridview自己会处理左侧和上边缘的线条，因此只需绘制下边框和和右边框
                         DataGridView控件绘制单元格时，不绘制左边框和上边框，共用左单元格的右边框，上一单元格的下边框*****/

                        //不是最后一列且单元格的值不为null
                        if (e.ColumnIndex < this.dataGridView1.ColumnCount - 1 && this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value != null)
                        {
                            if (e.Value.ToString() != this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Value.ToString())
                            {
                                //右侧的线
                                e.Graphics.DrawLine(gridLinePen, e.CellBounds.Right - 1, e.CellBounds.Top,
                                    e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);
                                //绘制值
                                if (e.Value != null)
                                {
                                    e.Graphics.DrawString(e.Value.ToString(), e.CellStyle.Font,
                                        Brushes.Crimson, e.CellBounds.X + 2,
                                        e.CellBounds.Y + 2, StringFormat.GenericDefault);
                                }
                            }
                            //若与下一单元格值相同
                            else
                            {
                                //背景颜色
                                //e.CellStyle.BackColor = Color.LightPink;   //仅在CellFormatting方法中可用
                                this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].Style.BackColor = Color.LightPink;
                                this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].Style.BackColor = Color.LightPink;
                                //只读（以免双击单元格时显示值）
                                this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].ReadOnly = true;
                                this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex + 1].ReadOnly = true;
                            }
                        }
                        else
                        {
                            //右侧的线
                            e.Graphics.DrawLine(gridLinePen, e.CellBounds.Right - 1, e.CellBounds.Top,
                                e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);

                            //绘制值
                            if (e.Value != null)
                            {
                                e.Graphics.DrawString(e.Value.ToString(), e.CellStyle.Font,
                                    Brushes.Crimson, e.CellBounds.X + 2,
                                    e.CellBounds.Y + 2, StringFormat.GenericDefault);
                            }
                        }
                        //下边缘的线
                        e.Graphics.DrawLine(gridLinePen, e.CellBounds.Left, e.CellBounds.Bottom - 1,
                                                    e.CellBounds.Right - 1, e.CellBounds.Bottom - 1);
                        e.Handled = true;
                    }
                }

            }

        }

        #endregion