DataGrid是可以绑定ComboBox来进行选择某一列的值，但是有时候选项太多，或者通过一列数据无法完全说明选项含义的时候，就希望来弹出一个窗口，来对子项进行更充分的说明，以供选择。

我下面的例子就是说明如何实现一个弹出窗口来对子项进行选择。

首先，继承DataGridTextBoxColumn来定义自己的数据列，具体如下：

public delegate string PopupWindow();

public class DataGridPopupColumn: DataGridTextBoxColumn

{

private Panel pnlPopup;//Basic control for column

private System.Windows.Forms.CurrencyManager _source = null;

private int _rowNum;

public static int _RowCount = -1;

PopupWindow PopupWindowHandle;

public DataGridPopupColumn( PopupWindow ShowPopupWindow ) : base()

{

// Init class members

PopupWindowHandle = ShowPopupWindow;

pnlPopup = new Panel();

// Define event handler

pnlPopup.Leave += new EventHandler( LeavePanel );

pnlPopup.Click += new EventHandler( ClickPanel );

pnlPopup.Paint += new PaintEventHandler( PaintPanel );

}

private void LeavePanel( object sender, EventArgs e )

{

pnlPopup.Hide();//Hide panel

}

private void ClickPanel( object sender, EventArgs e )

{

// Show a window to select value

object objReturn = this.pnlPopup.Parent.Invoke( PopupWindowHandle );

if( objReturn != null )

{

// Get value from window result

this.TextBox.Text = objReturn.ToString();

// Save it to data source

SetColumnValueAtRow( _source, _rowNum, this.TextBox.Text);

// Re-draw panel

this.pnlPopup.Refresh();

Invalidate();

}

}

private void PaintPanel( object sender, System.Windows.Forms.PaintEventArgs e)

{

// Set panel size

pnlPopup.Width = this.TextBox.Width;

pnlPopup.Height = this.TextBox.Height;

// Draw back ground same as current cell

Graphics gPanel = e.Graphics;

gPanel.FillRectangle( new SolidBrush( this.TextBox.BackColor ),

0,0, this.pnlPopup.Width, this.pnlPopup.Height );

// Draw text in panel

StringFormat sfText = new StringFormat();

sfText.Alignment = StringAlignment.Near;

sfText.LineAlignment = StringAlignment.Center;

gPanel.DrawString(

this.TextBox.Text,

this.TextBox.Font,

new SolidBrush( this.TextBox.ForeColor ),

new Rectangle( new Point( 0, 0 ),

new Size( pnlPopup.Width, pnlPopup.Height ) ),

sfText );

// Draw a triangle in the right side of panel

SolidBrush sbBlack = new SolidBrush( Color.Black );

const float TRI_HEIGHT = 6F;

PointF[] ptTriangle = new PointF[3]{

new PointF( pnlPopup.Width - 5 - 12, ( pnlPopup.Height - TRI_HEIGHT ) / 2 ),

new PointF( pnlPopup.Width - 5 , ( pnlPopup.Height - TRI_HEIGHT ) / 2 ),

new PointF( pnlPopup.Width - 5 - 6, ( pnlPopup.Height + TRI_HEIGHT ) / 2 )

};

gPanel.FillPolygon( sbBlack, ptTriangle );

}

protected override void Edit( System.Windows.Forms.CurrencyManager source,

int rowNum, System.Drawing.Rectangle bounds,

bool readOnly, string instantText, bool cellIsVisible )

{

//on very first pass, set this static member to number of items in tables

if(_RowCount == -1)

_RowCount = source.Count;

//check to see if we are on the new row

if(_RowCount < source.Count)

{

// remove the one that has been added

// and add a new to sync

source.RemoveAt(source.Count-1);

source.AddNew();

}

_RowCount = source.Count;

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

_rowNum = rowNum;

_source = source;

// Init panel

pnlPopup.Parent = this.TextBox.Parent;

pnlPopup.Location = this.TextBox.Location;

pnlPopup.Size = new Size(this.TextBox.Size.Width, this.TextBox.Size.Height);

// Show panel

pnlPopup.Invalidate();// Modified by Knight on Apr.18, 2006
pnlPopup.Visible = true;

pnlPopup.BringToFront();

}

protected override bool Commit( System.Windows.Forms.CurrencyManager dataSource,

int rowNum )

{

return true;

}

}

主窗体调用如下。

///

///

private string PopupWindow()

{

frmPopup myPopup = new frmPopup();

if( myPopup.ShowDialog() == DialogResult.OK )

return myPopup.SelectedItem;

else

return null;

}

private void CreateEmployeeTable( out DataTable dtEmployee )

{

dtEmployee = new DataTable();

dtEmployee.TableName = "EmployeeInfo";

//Set data columns

dtEmployee.Columns.Add( "EmployeeID", typeof( int ) );

dtEmployee.Columns.Add( "Department", typeof( string ) );

dtEmployee.Columns.Add( "Name", typeof( string ) );

dtEmployee.Columns.Add( "Phone", typeof( string ) );

dtEmployee.Columns.Add( "Address", typeof( string ) );

// Add data

dtEmployee.Rows.Add( new object[]{ 1, "Sales", "Sales1", "*****","*****" } );

dtEmployee.Rows.Add( new object[]{ 2, "Sales", "Sales2", "*****","*****" } );

dtEmployee.Rows.Add( new object[]{ 3, "HR", "HR1", "*****","*****" } );

dtEmployee.Rows.Add( new object[]{ 4, "HR", "HR2", "*****","*****" } );

dtEmployee.Rows.Add( new object[]{ 5, "Tech", "Tech1", "*****","*****" } );

dtEmployee.Rows.Add( new object[]{ 6, "Tech", "Tech2", "*****","*****" } );

dtEmployee.Rows.Add( new object[]{ 7, "Software", "Software1", "*****","*****" } );

dtEmployee.Rows.Add( new object[]{ 8, "Software", "Software2", "*****","*****" } );

}

private void CreateDataSet()

{

myDataSet = new DataSet();

DataTable dtEmployee;

CreateEmployeeTable( out dtEmployee );

myDataSet.Tables.Add( dtEmployee );

}

private void AddTableStyle()

{

DataGridTableStyle ts1 = new DataGridTableStyle();

ts1.MappingName = "EmployeeInfo";

DataGridTextBoxColumn TextCol = new DataGridTextBoxColumn();

TextCol.MappingName = "EmployeeID";

TextCol.HeaderText = "Employee ID";

TextCol.Width = 80;

ts1.GridColumnStyles.Add(TextCol);

// Add popup column with event method

DataGridPopupColumn PopupTextCol = new DataGridPopupColumn(

new PopupWindow( PopupWindow ) );

PopupTextCol.MappingName = "Department";

PopupTextCol.HeaderText = "Department";

PopupTextCol.Width = 100;

ts1.GridColumnStyles.Add( PopupTextCol );

TextCol = new DataGridTextBoxColumn();

TextCol.MappingName = "Name";

TextCol.HeaderText = "Name";

TextCol.Width = 100;

ts1.GridColumnStyles.Add(TextCol);

TextCol = new DataGridTextBoxColumn();

TextCol.MappingName = "Phone";

TextCol.HeaderText = "Phone";

TextCol.Width = 100;

ts1.GridColumnStyles.Add(TextCol);

TextCol = new DataGridTextBoxColumn();

TextCol.MappingName = "Address";

TextCol.HeaderText = "Address";

TextCol.Width = 150;

ts1.GridColumnStyles.Add(TextCol);

//add the custom table style to the datagrid table styles

dtgUserInfo.TableStyles.Add(ts1);

}

private void BindData()

{

CreateDataSet();

dtgUserInfo.SetDataBinding( myDataSet, "EmployeeInfo");

AddTableStyle();

}

private void frmComboxDB_Load(object sender, System.EventArgs e)

{

BindData();

}

最后，就是弹出窗口的代码，这部分由于需求不一样，做法可以千变万化，以下只是一个简单的例子，即在一个ListBox进行选择。

public string SelectedItem

{

get{

if( lstDepInfo.SelectedItem != null )

return lstDepInfo.SelectedItem.ToString();

else

return null;

}

}

private void frmPopup_Load(object sender, System.EventArgs e)

{

lstDepInfo.Items.Add( "Sales" );

lstDepInfo.Items.Add( "HR" );

lstDepInfo.Items.Add( "Tech" );

lstDepInfo.Items.Add( "Software" );

}

private void btnOK_Click(object sender, System.EventArgs e)

{

this.DialogResult = DialogResult.OK;

}

private void btnCancel_Click(object sender, System.EventArgs e)

{

this.DialogResult = DialogResult.Cancel;

}