在WinForm的DataGrid中加入ComboBox

WinForm的DataGrid要显示ComboBox的效果必须要写一个继承自DataGridTextBoxColumn的类, 並在其中制作ComboBox的功能, 再把这个类的对象加入到DataGrid中使用即可, 做法如下:

   DataGridComboBoxColumn ComboCol =new DataGridComboBoxColumn();
   ComboCol.MappingName = "RegionID";
   ComboCol.HeaderText = "Region";
   ComboCol.Width = 120;

   ComboCol.ColumnComboBox.DataSource = ds1.Tables["Region"].DefaultView;
   ComboCol.ColumnComboBox.DisplayMember = "RegionDescription";
   ComboCol.ColumnComboBox.ValueMember = "RegionID";

   tableStyle.PreferredRowHeight = ComboCol.ColumnComboBox.Height + 2;
   tableStyle.GridColumnStyles.Add(ComboCol);

   dataGrid1.TableStyles.Add(tableStyle);
 

其中的DataGridComboBoxColumn的写法如下:

  public class DataGridComboBoxColumn : DataGridTextBoxColumn
 {
  public NoKeyUpCombo ColumnComboBox;
  private System.Windows.Forms.CurrencyManager _source;
  private int _rowNum;
  private bool _isEditing;
  public static int _RowCount;
 
  public DataGridComboBoxColumn() : base()
  {
   _source = null;
   _isEditing = false;
   _RowCount = -1;
 
   ColumnComboBox = new NoKeyUpCombo();
   ColumnComboBox.DropDownStyle = ComboBoxStyle.DropDownList;
 
   ColumnComboBox.Leave += new EventHandler(LeaveComboBox);
   //  ColumnComboBox.Enter += new EventHandler(ComboMadeCurrent);
   ColumnComboBox.SelectionChangeCommitted += new EventHandler(ComboStartEditing);
 
  }
  private void ComboStartEditing(object sender, EventArgs e)
  {
   _isEditing = true;
   base.ColumnStartedEditing((Control) sender);
  }

  private void HandleScroll(object sender, EventArgs e)
  {
   if(ColumnComboBox.Visible)
    ColumnComboBox.Hide();

  } 
  private void LeaveComboBox(object sender, EventArgs e)
  {
   if(_isEditing)
   {
    SetColumnValueAtRow(_source, _rowNum, ColumnComboBox.Text);
    _isEditing = false;
    Invalidate();
   }
   ColumnComboBox.Hide();
   this.DataGridTableStyle.DataGrid.Scroll -= new EventHandler(HandleScroll);
  
  }

  protected override void Edit(System.Windows.Forms.CurrencyManager source, int rowNum, System.Drawing.Rectangle bounds, bool readOnly, string instantText, bool cellIsVisible)
  {
  

   base.Edit(source,rowNum, bounds, readOnly, instantText , cellIsVisible);

   _rowNum = rowNum;
   _source = source;
 
   ColumnComboBox.Parent = this.TextBox.Parent;
   ColumnComboBox.Location = this.TextBox.Location;
   ColumnComboBox.Size = new Size(this.TextBox.Size.Width, ColumnComboBox.Size.Height);
   ColumnComboBox.SelectedIndex = ColumnComboBox.FindStringExact(this.TextBox.Text);
   ColumnComboBox.Text =  this.TextBox.Text;
   this.TextBox.Visible = false;
   ColumnComboBox.Visible = true;
   this.DataGridTableStyle.DataGrid.Scroll += new EventHandler(HandleScroll);
  
   ColumnComboBox.BringToFront();
   ColumnComboBox.Focus();
  }

  protected override bool Commit(System.Windows.Forms.CurrencyManager dataSource, int rowNum)
  {
   if(_isEditing)
   {
    _isEditing = false;
    SetColumnValueAtRow(dataSource, rowNum, ColumnComboBox.Text);
   }
   return true;
  }

  protected override void ConcedeFocus()
  {
   Console.WriteLine("ConcedeFocus");
   base.ConcedeFocus();
  }

  protected override object GetColumnValueAtRow(System.Windows.Forms.CurrencyManager source, int rowNum)
  {

   object s =  base.GetColumnValueAtRow(source, rowNum);
   DataView dv = (DataView)this.ColumnComboBox.DataSource;
   int rowCount = dv.Count;
   int i = 0;
   while (i < rowCount)
   {
    if( s.Equals( dv[i][this.ColumnComboBox.ValueMember]))
     break;
    ++i;
   }
  
   if(i < rowCount)
    return dv[i][this.ColumnComboBox.DisplayMember];
  
   return DBNull.Value;
  }

  protected override void SetColumnValueAtRow(System.Windows.Forms.CurrencyManager source, int rowNum, object value)
  {
   object s = value;

   DataView dv = (DataView)this.ColumnComboBox.DataSource;
   int rowCount = dv.Count;
   int i = 0;
   while (i < rowCount)
   {
    if( s.Equals( dv[i][this.ColumnComboBox.DisplayMember]))
     break;
    ++i;
   }
   if(i < rowCount)
    s =  dv[i][this.ColumnComboBox.ValueMember];
   else
    s = DBNull.Value;
   base.SetColumnValueAtRow(source, rowNum, s);

  }
 }

 

public class NoKeyUpCombo : ComboBox
 {
  private const int WM_KEYUP = 0x101;

  protected override void WndProc(ref System.Windows.Forms.Message m)
  {
   if(m.Msg == WM_KEYUP)
   {
    return;
   }
   base.WndProc(ref m);
  }
 }