Make DropDown CheckedListBox in VB.net

How to make DropDown CheckedListBox  in VB.net

In my recent window application there is need to create a  Checked listbox that has drop down functionality ,So I make a user control with the help of checkedlistbox, textbox, button controls  and windows.form object that is so useful  for me. This  user controls have these features:

1.       Control  has drop down functionality

2.       Control show status of selected items like 'All selected',  'None selected' and  'N items selected '.

3.       We able to set the length of dropdown list.

4.       We can bind items on design time or runtime. etc



 

How to make :

Add a user control in your application with the name 'DropDownCheckedListBox'.

Add textbox, button, checkedlistbox controls in this user control set the position like picture 1.1

 

 

Open code file and make some private variable and some public properties
 

Private Const T_DisplayListSize As Integer = 6

    Private Const SelectNoneText As String = "(None Selected)"

    Private Const SelectAllText As String = "(All Selected)"

    Private Const SelectSomeText As String = "(Some Selected...)"

    Private Frm As Form

    Private LostFocus As Boolean

    Private CodeValue As String

    Private T_MustFill As Boolean

    Private Shared m_ChkItemsString As String

    Public Event DropDown()

    Public Shadows Event TextChanged()

    Public Event SetStatusPrompt(ByVal Sender As DropDownCheckedListBox)

    Public Event AllItemSelected(ByVal Sender As DropDownCheckedListBox)

 Public Event AllItemDeselected(ByVal Sender As DropDownCheckedListBox)

    Public properties :

 Make some public properties for set the itemslist and length of dropdown list etc…

 

 Private dataList() As String

    Public Property Items() As String()

        Get

            Return dataList

        End Get

        Set(ByVal value As String())

            dataList = value

        End Set

    End Property

    Private ListSize As Integer

    Public Property DisplayListSize() As Integer

        Get

            Return ListSize

        End Get

        Set(ByVal value As Integer)

            ListSize = value

            SetList()

        End Set

    End Property

    Private T_DroppedDown As Boolean

    Public ReadOnly Property DroppedDown() As Boolean

        Get

            Return T_DroppedDown

        End Get

    End Property

    Private T_ListText As String

    Public ReadOnly Property ListText() As String

        Get

            Return T_ListText

        End Get

    End Property

    Add new function InitializeNew()in Sub new()

    Public Sub New()

        InitializeComponent()

        InitializeNew()

    End Sub

 

    Private Sub InitializeNew()

        Dim strTemp As String

        ListSize = T_DisplayListSize

        T_DroppedDown = False

        T_ListText = ""

        T_MustFill = False

        txt.Text = strTemp

        chkListBox.Hide()

        Frm = New Form

        With Frm

            .ShowInTaskbar = False

            .FormBorderStyle = FormBorderStyle.None

            .ControlBox = False

            .StartPosition = FormStartPosition.Manual

            .TopMost = True

            .Location = chkListBox.Location

            .Width = chkListBox.Width

            .Controls.Add(chkListBox)

        End With

        SetSize()

    End Sub

Create mousedown event of btnDropDown button and call function listButtonClick on here.this is responsible for showing checkedListBox

Private Sub btnDropdown_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles btnDropdown.MouseDown

        ListButtonClick()

End Sub

We have already make two custom event one is TextChanged and another is DropDown, on here both event have been raised.so we can handles event when control changes its status(user check or uncheck item(s)).

Private Sub ListButtonClick()

        Dim strTemp As String

        strTemp = T_ListText

        If T_DroppedDown Then

            T_DroppedDown = False

            txt.Text = GetSelectedItems()

            chkListBox.Hide()

            Frm.Hide()

            txt.Focus()

            If Not strTemp = T_ListText Then

                RaiseEvent TextChanged()

            End If

        ElseIf Not LostFocus Then

            T_DroppedDown = True

            SetSize()

            Frm.Show()

            chkListBox.Show()

            chkListBox.Focus()

            RaiseEvent DropDown()

        End If

        LostFocus = False

 

    End Sub

 

Private Sub SetList()

 

        Dim oFrm As Form

        Dim oRect As Rectangle

        Dim oPt As Point

 

        If Frm IsNot Nothing Then

            Frm.Height = (ListSize * chkListBox.ItemHeight) + 3

            chkListBox.Height = Frm.Height

            chkListBox.Top = 0

            oFrm = Me.FindForm

            If oFrm IsNot Nothing Then

                oPt = Me.ParentForm.PointToClient(Me.PointToScreen(Point.Empty))

                oPt.Y = oPt.Y + Me.txt.Height

                oRect = oFrm.RectangleToScreen(oFrm.ClientRectangle)

                oPt.X = oPt.X + oRect.Left

                oPt.Y = oPt.Y + oRect.Top

                Frm.Location = oPt

            End If

            Frm.Width = chkListBox.Width

        End If

    End Sub

 

SetSize() function works for set the size of all controls if you can resize usercontrol.  
  

 Private Sub SetSize()

        LostFocus = False

        txt.Width = Me.Width

        btnDropdown.Left = txt.Width - btnDropdown.Width - 2

        chkListBox.Width = Me.Width

        Me.Height = txt.Height

        SetList()

 End Sub

Working with control:

Build  your Application, the DropDownCheckedListBox should appear in your Visual Studio ToolBox and than you can drag and drop it on to your window Form

Add items on design time :


 

Click on items property, add strings  and click ok

You can apply more functionalities according your need in this user control…. You can download full source code sample