Option Strict Off 
Option Explicit On 

Imports Microsoft.VisualBasic 
Imports System 
Imports System.ComponentModel 
Imports System.Data 
Imports System.Data.Common 
Imports System.Data.OleDb 
Imports System.Drawing 
Imports System.Windows.Forms 



' Step 1. Derive a custom column style from DataGridTextBoxColumn 
'    a) add a ComboBox member 
'  b) track when the combobox has focus in Enter and Leave events 
'  c) override Edit to allow the ComboBox to replace the TextBox 
'  d) override Commit to save the changed data 

Public Class DataGridComboBoxColumn 
   Inherits DataGridTextBoxColumn 
   Public ColumnComboBox As NoKeyUpCombo 
   Private _source As System.Windows.Forms.CurrencyManager 
   Private _rowNum As Integer 
   Private _isEditing As Boolean 
   Public Shared _RowCount As Integer 
   Public Delegate Sub ComboValueChanged(ByVal changingRow As Integer, ByVal newValue As Object) 
   Private moCombo As ComboHelper 

   Public Sub New() 
       _source = Nothing 
       _isEditing = False 
       _RowCount = -1 

       ColumnComboBox = New NoKeyUpCombo 
       ColumnComboBox.DropDownStyle = ComboBoxStyle.DropDownList 
       moCombo = New ComboHelper 

       AddHandler ColumnComboBox.Enter, AddressOf EnterComboBox 
       AddHandler ColumnComboBox.Leave, AddressOf LeaveComboBox 
       AddHandler ColumnComboBox.SelectionChangeCommitted, AddressOf ComboStartEditing 
   End Sub 'New 
   Public Event CheckComboValueChanged As ComboValueChanged 

   Private Sub HandleScroll(ByVal sender As Object, ByVal e As EventArgs) 
       If ColumnComboBox.Visible Then 
           ColumnComboBox.Hide() 
       End If 
   End Sub 'HandleScroll 

   Private Sub ComboStartEditing(ByVal sender As Object, ByVal e As EventArgs) 
       _isEditing = True 
       MyBase.ColumnStartedEditing(sender) 
   End Sub 'ComboMadeCurrent 


   Private Sub LeaveComboBox(ByVal sender As Object, ByVal e As EventArgs) 
       If _isEditing Then 
           SetColumnValueAtRow(_source, _rowNum, ColumnComboBox.Text) 
           _isEditing = False 
           Invalidate() 

       End If 
       ColumnComboBox.Hide() 
       AddHandler Me.DataGridTableStyle.DataGrid.Scroll, New EventHandler(AddressOf HandleScroll) 
   End Sub 'LeaveComboBox 

   Private Sub EnterComboBox(ByVal sender As Object, ByVal e As EventArgs) 
       Dim myCombo As ComboBox = CType(sender, ComboBox) 
       moCombo.AttachTo(myCombo) 
   End Sub 'EnterComboBox 


   Protected Overloads Overrides Sub Edit(ByVal [source] As System.Windows.Forms.CurrencyManager, ByVal rowNum As Integer, ByVal bounds As System.Drawing.Rectangle, ByVal [readOnly] As Boolean, ByVal instantText As String, ByVal cellIsVisible As Boolean) 

       MyBase.Edit([source], rowNum, bounds, [readOnly], instantText, cellIsVisible) 

       _rowNum = rowNum 
       _source = [source] 

       ColumnComboBox.Parent = Me.TextBox.Parent 
       ColumnComboBox.Location = Me.TextBox.Location 
       ColumnComboBox.Size = New Size(Me.TextBox.Size.Width, ColumnComboBox.Size.Height) 
       ColumnComboBox.SelectedIndex = ColumnComboBox.FindStringExact(Me.TextBox.Text) 
       ColumnComboBox.Text = Me.TextBox.Text 
       Me.TextBox.Visible = False 
       ColumnComboBox.Visible = True 
       AddHandler Me.DataGridTableStyle.DataGrid.Scroll, AddressOf HandleScroll 

       ColumnComboBox.BringToFront() 
       ColumnComboBox.Focus() 
   End Sub 'Edit 

   Protected Overrides Function Commit(ByVal dataSource As System.Windows.Forms.CurrencyManager, ByVal rowNum As Integer) As Boolean 

       If _isEditing Then 
           _isEditing = False 
           SetColumnValueAtRow(dataSource, rowNum, ColumnComboBox.Text) 
       End If 
       Return True 
   End Function 'Commit 


   Protected Overrides Sub ConcedeFocus() 
       'RJC 4/2/2005 - Task Ref: JAD-2850 - Comment out unnecessary Console.writeline 
       'Console.WriteLine("ConcedeFocus") 
       MyBase.ConcedeFocus() 
   End Sub 'ConcedeFocus 

   Protected Overrides Function GetColumnValueAtRow(ByVal [source] As System.Windows.Forms.CurrencyManager, ByVal rowNum As Integer) As Object 

       Dim s As Object = MyBase.GetColumnValueAtRow([source], rowNum) 
       Dim dv As DataView = CType(Me.ColumnComboBox.DataSource, DataView) 
       Dim rowCount As Integer = dv.Count 
       Dim i As Integer = 0 
       Dim s1 As Object 

       'if things are slow, you could order your dataview 
       '& use binary search instead of this linear one 
       While i < rowCount 
           s1 = dv(i)(Me.ColumnComboBox.ValueMember) 
           If (Not s1 Is DBNull.Value) AndAlso _ 
               (Not s Is DBNull.Value) AndAlso _ 
                       s = s1 Then 
               Exit While 
           End If 
           i = i + 1 
       End While 

       If i < rowCount Then 
           Return dv(i)(Me.ColumnComboBox.DisplayMember) 
       End If 
       Return DBNull.Value 
   End Function 'GetColumnValueAtRow 


   Protected Overrides Sub SetColumnValueAtRow(ByVal [source] As System.Windows.Forms.CurrencyManager, ByVal rowNum As Integer, ByVal value As Object) 
       Dim s As Object = value 

       Dim dv As DataView = CType(Me.ColumnComboBox.DataSource, DataView) 
       Dim rowCount As Integer = dv.Count 
       Dim i As Integer = 0 
       Dim s1 As Object 

       'if things are slow, you could order your dataview 
       '& use binary search instead of this linear one 
       While i < rowCount 
           s1 = dv(i)(Me.ColumnComboBox.DisplayMember) 
           If (Not s1 Is DBNull.Value) AndAlso _ 
                       s = s1 Then 
               Exit While 
           End If 
           i = i + 1 
       End While 
       If i < rowCount Then 
           s = dv(i)(Me.ColumnComboBox.ValueMember) 
       Else 
           s = DBNull.Value 
       End If 
       MyBase.SetColumnValueAtRow([source], rowNum, s) 
   End Sub 'SetColumnValueAtRow 

End Class 'DataGridComboBoxColumn