c#动态添加组合框

using System;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;
//此Form中有两个控件,一个DataGridView(dataGridView1),一个ComboBox(comboBox1)
//DataGridView中有两列(都是DataGridViewTextBoxColumn的),其中第一列实现类似ComboBox的功能
//第一列中只有正在编辑的Cell才会显示ComboBox,其他的不会显示,这样好看一点
namespace Test
{
    public partial class Form1 : Form
    {
        private int comboBoxColumnIndex = 0; // DataGridView的首列

        public Form1()
        {
            InitializeComponent();
            InitComboBoxValues();
            this.dataGridView1.Controls.Add(this.comboBox1);
            this.dataGridView1.CellEnter += new DataGridViewCellEventHandler(dataGridView1_CellEnter);
            this.dataGridView1.CellLeave+=new DataGridViewCellEventHandler(dataGridView1_CellLeave);
        }

        private void InitComboBoxValues()
        {
            this.comboBox1.Items.AddRange(new String[] { "Beijing", "Shanghai", "Guangzhou", "Wuhan", "Shenzhen" });
            this.comboBox1.AutoCompleteMode = AutoCompleteMode.Suggest; //输入提示
            this.comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;
        }

        private void dataGridView1_CellEnter(object sender, DataGridViewCellEventArgs e)
        {
            if (e.ColumnIndex == comboBoxColumnIndex)
            {
                //此处cell即CurrentCell
                DataGridViewCell cell = this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex];
                Rectangle rect = this.dataGridView1.GetCellDisplayRectangle(cell.ColumnIndex, cell.RowIndex, true);
                this.comboBox1.Location = rect.Location;
                this.comboBox1.Size = rect.Size;
                comfirmComboBoxValue(this.comboBox1, (String)cell.Value);
                this.comboBox1.Visible = true;            
            }
        }

        private void dataGridView1_CellLeave(object sender, DataGridViewCellEventArgs e)
        {
            if (e.ColumnIndex == comboBoxColumnIndex)
            {
                //此处cell不为CurrentCell
                DataGridViewCell cell = this.dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex];
                cell.Value = this.comboBox1.Text;
                this.comboBox1.Visible = false;
            }
        }

        private void comfirmComboBoxValue(ComboBox com, String cellValue)
        {
            com.SelectedIndex = -1;
            if (cellValue == null)
            {
                com.Text = "";
                return;
            }
            com.Text = cellValue;
            foreach (Object item in com.Items)
            {
                if ((String)item == cellValue)
                {
                    com.SelectedItem = item;
                }
            }
        }
    }
}