asp.net dynamic controls example

 
Imports System.ComponentModel
Imports System.Web.UI
Imports System.Text
Imports System.Web.UI.WebControls
Imports System.Collections.Specialized
Public Class DevidedTextBox
    '1. Inherits WebControl
    Inherits WebControl
    '2.implements IPostBackDataHandler if it's required to read Postback data 
    Implements IPostBackDataHandler
    '3.implements IPostBackEventHandler if it's required to have events like "OnInit", "onChanged" etc.
    Implements IPostBackEventHandler

    Private ArraYOfTextBoxes As New Collection
    Private m_AmountOfBoxes As Byte

    Public Event ValidationError(ByVal ErrorId As Byte, ByVal ErrorDes As String)

    Public Property AmountOfBoxes() As Byte
        Get
            m_AmountOfBoxes = ViewState(Me.ID & "_AmountOfBoxes")
            Return m_AmountOfBoxes
        End Get

        Set(ByVal Value As Byte)
            m_AmountOfBoxes = Value
            ViewState(Me.ID & "_AmountOfBoxes") = m_AmountOfBoxes

        End Set
    End Property

    '4.Must write this stuff 'case of implementation of the interfaces
    Public Overridable Sub RaisePostBackEvent(ByVal eventArg As String) Implements IPostBackEventHandler.RaisePostBackEvent
    End Sub
    Public Overridable Sub RaisePostDataChangedEvent() Implements IPostBackDataHandler.RaisePostDataChangedEvent
    End Sub


    '5.Code procedure for reading postback data 
    Public Overridable Function LoadPostData(ByVal postdatakey As String, ByVal postCollection As NameValueCollection) As Boolean Implements IPostBackDataHandler.LoadPostData

        For i As Byte = 1 To AmountOfBoxes
            Dim txtBox As TextBox = ArraYOfTextBoxes(i)
            txtBox.Text = postCollection(txtBox.ID)
        Next

        Return True
    End Function

    Private m_AllRequired As Boolean = True
    Public Property AllRequired() As Boolean
        Get
            m_AllRequired = ViewState(Me.ID & "_AllRequired")
            Return m_AllRequired
        End Get
        Set(ByVal Value As Boolean)
            m_AllRequired = Value
            ViewState(Me.ID & "_AllRequired") = m_AllRequired
        End Set
    End Property




    Private Sub DevidedTextBox_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Init
        '6.Register controls as postback receiver, required !!!
        Page.RegisterRequiresPostBack(Me)

        Dim i As Integer

        For i = 1 To m_AmountOfBoxes

            Dim intTextBox As New TextBox
            With intTextBox
                .ID = Me.ID & "txt" & i
                .MaxLength = 1
                .Width = New Unit(15)
                .BorderWidth = New Unit(1)

                If i <> m_AmountOfBoxes Then
                    Dim nextname As String = Me.ID & "txt" & i + 1
                    .Attributes.Add("onkeypress", "ChangeFocus(this,'" & nextname & "');")
                End If

            End With

            ArraYOfTextBoxes.Add(intTextBox, i)
        Next

    End Sub

    Protected Overrides Sub Render(ByVal writer As System.Web.UI.HtmlTextWriter)

        'writer.WriteLine("<script language='javascript'>")
        'writer.WriteLine(" function ChangeFocus(obj,fild)")
        'writer.WriteLine("{")
        'writer.WriteLine("")
        'writer.WriteLine("     if(obj.value.length==obj.maxLength)")
        'writer.WriteLine("     {")
        'writer.WriteLine("     //      CopyToHiddenFields(obj)")
        'writer.WriteLine("     //      MaskSSN(obj)")
        'writer.WriteLine("             document.all[fild].focus()")
        'writer.WriteLine("             document.all[fild].select()")
        'writer.WriteLine("")
        'writer.WriteLine("     }")
        'writer.WriteLine("")
        'writer.WriteLine("}")
        'writer.WriteLine("")
        'writer.WriteLine("</script>")
        'writer.WriteLine("")

        For Each txtBox As TextBox In ArraYOfTextBoxes
            txtBox.RenderControl(writer)
        Next
    End Sub

    Private Sub CollectValues()
        Dim bUpdate As Boolean = False
        Dim sValue As String
        ' Dim inChar(AmountOfBoxes) As Byte
        m_Value = ""
        For i As Byte = 1 To AmountOfBoxes
            Dim txtBox As TextBox = ArraYOfTextBoxes(i)
            'inChar(i) = txtBox.Text
            m_Value += txtBox.Text

        Next
    End Sub

    Private Sub SpreadValues()
        If Not m_Value Is Nothing Then
            For i As Byte = 1 To ArraYOfTextBoxes.Count
                Dim txtBox As TextBox = ArraYOfTextBoxes(i)
                If m_Value.Length < i Then
                    txtBox.Text = ""
                Else
                    txtBox.Text = m_Value.Chars(i)
                End If
            Next
        End If
    End Sub

    Private m_Value As String
    Public Property Text() As String
        Get
            m_Value = ViewState(Me.ID & "_Value")
            Return m_Value
        End Get
        Set(ByVal Value As String)
            m_Value = Value
            ViewState(Me.ID & "_Value") = m_Value
            SpreadValues()
        End Set
    End Property

    Protected Overrides Sub OnLoad(ByVal e As System.EventArgs)
        If Page.IsPostBack Then
            CollectValues()
            ViewState(Me.ID & "_Value") = m_Value
        Else
            m_Value = ViewState(Me.ID & "_Value")
            SpreadValues()
        End If
    End Sub

End Class