1.功能说明：

将连续的多个列合并成一个新列。

2.不足之处：

不能合并多层。比如下图这样的功能是没有的。

3.使用参考.

在form的构造函数里写下如下代码

Utility.exGridView.isEnLarged = false;
在datagridview的cellpaiting事件中写如下代码

Utility.exGridView exG = new Utility.exGridView();
List colNameCollection=new List();
for (int i = 0; i < 10; i++)
{
//"colDraw"+i.ToString()是columnName的属性值
colNameCollection.Add("colDraw" + i.ToString());
}
exG.MergeHeader(sender, e, colNameCollection, "0-9中奖号码分布图");
4.效果截图

5.源文件(没找到添加附件的地方，就贴出代码了)

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Drawing;

namespace Utility
{
    public class exGridView
    {
        #region 合并列时使用到的位置和大小属性
        int cTop = 0;//被合并表头区域的顶部坐标
        int cLeft = 0;//被合并表头区域的左边坐标
        /// <summary>
        /// 被合并表头区域的宽
        /// </summary>
        int cWidth = 0;
        int cHeight = 0;//。。。高
        #endregion 
        /// <summary>
        /// 判断是否已经将datagridview的表头变高了，只增高一次。
        /// </summary>
        public static bool isEnLarged = false;

/// <summary>
        /// 合并表头,用在dataGridView的CellPainting事件中。
        /// </summary>
        /// <param name="sender">需要重绘的dataGridview</param>
        /// <param name="e">CellPainting中的参数</param>
        ///<param name="colName">列的集合(列必须是连续的，第一列放在最前面)</param>
        /// <param name="headerText">列合并后显示的文本</param>
        public void MergeHeader(object sender, DataGridViewCellPaintingEventArgs e,List<string> colNameCollection,string headerText)
        {
            if (e.RowIndex == -1)
            {
                DataGridView dataGridView1=sender as DataGridView;
                string colName = dataGridView1.Columns[e.ColumnIndex].Name;
                if (!isEnLarged)
                {
                    //0.扩展表头高度为当前的2倍
                    dataGridView1.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.EnableResizing;
                    dataGridView1.ColumnHeadersHeight = e.CellBounds.Height * 2;
                    isEnLarged = true;
                }
                if (colNameCollection.Contains(colName))
                {
                    #region 重绘列头
                    //1.计算colLen个列的区域
                    if (colNameCollection.IndexOf(colName)==0)
                    {
                        cTop = e.CellBounds.Top;
                        cLeft = e.CellBounds.Left;

cWidth = e.CellBounds.Width;
                        cHeight = e.CellBounds.Height/2;

foreach(string colNameItem in colNameCollection)
                        {
                            if (colNameItem.Equals(colName))
                            {//除去自己一个，加了之后colLen-1个列的宽
                                continue;
                            } 
                            cWidth += dataGridView1.Columns[colNameItem].Width;                           
                        }                       
                    }

Rectangle cArea = new Rectangle(cLeft, cTop, cWidth, cHeight);
                    //2.把区域设置为背景色，没有列的分线及任何文字。
                    using (Brush backColorBrush = new SolidBrush(e.CellStyle.BackColor))
                    {
                        e.Graphics.FillRectangle(backColorBrush, cArea);

}
                    //3.绘制新列头的边框
                    using (Pen gridPen = new Pen(dataGridView1.GridColor))
                    {
                        //3.1 上部边框
                        e.Graphics.DrawLine(gridPen, cLeft, cTop, cLeft + cWidth, cTop);
                        using (Pen hilightPen = new Pen(Color.WhiteSmoke))
                        {
                            //3.2 顶部高光
                            e.Graphics.DrawLine(hilightPen, cLeft, cTop + 1, cLeft + cWidth, cTop + 1);
                            //3.3 左部反光线
                            e.Graphics.DrawLine(hilightPen, cLeft, cTop + 3, cLeft, cTop + cHeight - 2);
                        }
                        //3.4 下部边框
                        e.Graphics.DrawLine(gridPen, cLeft, cTop + cHeight - 1, cLeft + cWidth, cTop + cHeight - 1);
                        //3.5 右部边框                        
                        e.Graphics.DrawLine(gridPen, cLeft + cWidth - 1, cTop, cLeft + cWidth - 1, cTop + cHeight);//(cTop+cHeight)/2);
                    }
                    //4.写文本
                    if (colNameCollection.IndexOf(colName) == 0)
                    {//不是第一列则不写文字。
                        int wHeadStr = (int)(headerText.Length * e.CellStyle.Font.SizeInPoints);
                        int wHeadCell = cWidth;
                        int pHeadLeft = (wHeadCell - wHeadStr) / 2 - 6;
                        using (Brush foreBrush = new SolidBrush(e.CellStyle.ForeColor))
                        {
                            e.Graphics.DrawString(headerText, e.CellStyle.Font, foreBrush, new PointF(cLeft + pHeadLeft, cTop + 3));
                        }
                    }

//5 绘制子列背景
                    int FatherColHeight = e.CellBounds.Height / 2;//上面一行的高度 
                    using (Brush backColorBrush = new SolidBrush(e.CellStyle.BackColor))
                    {
                        e.Graphics.FillRectangle(backColorBrush, new Rectangle(e.CellBounds.X, e.CellBounds.Y + FatherColHeight, e.CellBounds.Width - 1, e.CellBounds.Height / 2 - 1));
                    }
                    //5.1绘制子列的边框                   
                    using (Pen gridPen = new Pen(dataGridView1.GridColor))
                    {
                        using (Pen hilightPen = new Pen(Color.WhiteSmoke))
                        {
                            //5.2 左部反光线
                            e.Graphics.DrawLine(hilightPen, cLeft, cTop + 3 + FatherColHeight, cLeft, cTop + cHeight - 2 + FatherColHeight);
                        }
                        //5.3 下部边框
                        e.Graphics.DrawLine(gridPen, cLeft, cTop + cHeight - 1 + FatherColHeight, cLeft + cWidth, cTop + cHeight - 1 + FatherColHeight);

//5.4 右部边框 
                        e.Graphics.DrawLine(gridPen, e.CellBounds.X + e.CellBounds.Width - 1, e.CellBounds.Top + FatherColHeight, e.CellBounds.X + e.CellBounds.Width - 1, e.CellBounds.Top + e.CellBounds.Height + FatherColHeight);//(cTop+cHeight)/2);

}
                    //5.5 写子列的文本
                    int wStr = (int)(dataGridView1.Columns[e.ColumnIndex].HeaderText.Length * e.CellStyle.Font.SizeInPoints);
                    int wCell = e.CellBounds.Width;
                    int pLeft = (wCell - wStr) / 2;//相对CELL左边框的左坐标

using (Brush foreBrush = new SolidBrush(e.CellStyle.ForeColor))
                    {
                        e.Graphics.DrawString(dataGridView1.Columns[e.ColumnIndex].HeaderText, e.CellStyle.Font, foreBrush, new PointF(e.CellBounds.X + pLeft, cTop + 3 + FatherColHeight));
                    }                    
                    #endregion
                    e.Handled = true;
                }
            }
        }       
    }
}

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