如何在DataGrid中顯示ComboBox

//Author:yinzx
//Date:2004-06-08
//Editor:UltraEdit-32
//Ref:www.codeproject.com

//說明：前一段時間要實現如何在DataGrid中顯示ComboBox，在網上找了好多文章，但我的基礎較差，好多看不明白
//        但這種效果實現的原理有兩種：一種是計算ComboBox的位置；另一種不用，而是繼承DataGridTextBoxColumn
//        我最後採用了後一種方式，效果不錯。這裡只是拋磚引玉，要實現更進階的效果，還要加入一特性。
//        如有Bloger對此感興趣，可與我聯絡

using System;
using System.Windows.Forms;
using System.Drawing;
using System.Data;

namespace yinzx
...{
    public class GridComboBoxSample:System.Windows.Forms.Form
    ...{
        private DataGrid grd = new DataGrid();
        
        [STAThread]
        public static void Main() 
        ...{
            Application.Run(new GridComboBoxSample());
        }
        public GridComboBoxSample()
        ...{
            this.Text = "如何在DataGrid中實現ComboBox";
            this.FormBorderStyle = FormBorderStyle.FixedDialog;
            this.StartPosition = FormStartPosition.CenterScreen;
            this.MinimizeBox = this.MaximizeBox = false;
            
            this.Controls.Add(grd);            
            grd.Dock = DockStyle.Fill;
            
            //產生一個DataTable(表)
            DataTable t = new DataTable("PersonInfo");
            t.Columns.Add("Name",typeof(string));
            t.Columns.Add("Address",typeof(string));
            t.Rows.Add(new string[]...{"yinzx","China"});
            
            //產生一個DataGridTableStyle(表樣式)
            DataGridTableStyle ts = new DataGridTableStyle();
            DataGridTextBoxColumn c1 = new DataGridTextBoxColumn();
            DataGridComboBoxColumn c2 = new DataGridComboBoxColumn();            
            c1.MappingName = c1.HeaderText  = "Name";
            c2.MappingName = c2.HeaderText  = "Address";
            c2.FillComboBox(new string[]...{"China","Canada","France"});
            ts.MappingName = "PersonInfo";
            ts.GridColumnStyles.Add(c1);
            ts.GridColumnStyles.Add(c2);
            
            //把表及表樣式綁定到grd上
            grd.TableStyles.Add(ts);
            grd.DataSource = t;
        }        
    }
    
    public class DataGridComboBoxColumn:DataGridTextBoxColumn
    ...{
        private ComboBox _cbo = new ComboBox();
        private CurrencyManager _source;
        private int _iRowNum;
        
        public DataGridComboBoxColumn()
        ...{
            _cbo.Leave += new EventHandler(cbo_Leave);
            _cbo.Visible = false;
        }        
        
        public void FillComboBox(string[] cboData)
        ...{
            //填充資料到_cbo中
            _cbo.Items.AddRange(cboData);
        }

        protected override void Edit(CurrencyManager source, int rowNum, Rectangle bounds, bool readOnly, string instantText, bool cellIsVisible)
        ...{
            if (!this.DataGridTableStyle.DataGrid.Controls.Contains(_cbo)) this.DataGridTableStyle.DataGrid.Controls.Add(_cbo);
            _iRowNum = rowNum;
            _source  = source;
            _cbo.Bounds = bounds;//關鍵語句：把_cbo準確定位到相應的儲存格，且不用計算位置
            
            try
            ...{
                _cbo.Text = (string)this.GetColumnValueAtRow(_source, _iRowNum);            
            }
            catch...{}
            _cbo.Visible = true;
            _cbo.Focus();
        }
        
        public void cbo_Leave(object sender, EventArgs e) 
        ...{
            try
            ...{
                this.SetColumnValueAtRow(_source,_iRowNum ,_cbo.Text);
            }
            catch...{}
            _cbo.Visible = false;
        }        
    }
}