INotifyPropertyChanged Interface

Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Drawing
Imports System.Runtime.CompilerServices
Imports System.Windows.Forms

' This form demonstrates using a BindingSource to bind 
' a list to a DataGridView control. The list does not 
' raise change notifications. However the DemoCustomer type  
' in the list does. 

Public Class Form1
    Inherits System.Windows.Forms.Form
    ' This button causes the value of a list element to be changed. 
    Private changeItemBtn As New Button()

    ' This DataGridView control displays the contents of the list. 
    Private customersDataGridView As New DataGridView()

    ' This BindingSource binds the list to the DataGridView control. 
    Private customersBindingSource As New BindingSource()

    Public Sub New()
        InitializeComponent()

        ' Set up the "Change Item" button. 
        Me.changeItemBtn.Text = "Change Item" 
        Me.changeItemBtn.Dock = DockStyle.Bottom
        AddHandler Me.changeItemBtn.Click, AddressOf changeItemBtn_Click
        Me.Controls.Add(Me.changeItemBtn)

        ' Set up the DataGridView.
        customersDataGridView.Dock = DockStyle.Top
        Me.Controls.Add(customersDataGridView)

        Me.Size = New Size(400, 200)
    End Sub 

    Private Sub Form1_Load(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles Me.Load

        ' Create and populate the list of DemoCustomer objects 
        ' which will supply data to the DataGridView. 
        Dim customerList As New BindingList(Of DemoCustomer)

        customerList.Add(DemoCustomer.CreateNewCustomer())
        customerList.Add(DemoCustomer.CreateNewCustomer())
        customerList.Add(DemoCustomer.CreateNewCustomer())

        ' Bind the list to the BindingSource. 
        Me.customersBindingSource.DataSource = customerList

        ' Attach the BindingSource to the DataGridView. 
        Me.customersDataGridView.DataSource = Me.customersBindingSource
    End Sub 

    ' This event handler changes the value of the CompanyName 
    ' property for the first item in the list. 
    Private Sub changeItemBtn_Click(ByVal sender As Object, ByVal e As EventArgs)
        ' Get a reference to the list from the BindingSource. 
        Dim customerList As BindingList(Of DemoCustomer) = _
            CType(customersBindingSource.DataSource, BindingList(Of DemoCustomer))

        ' Change the value of the CompanyName property for the  
        ' first item in the list.
        customerList(0).CustomerName = "Tailspin Toys"
        customerList(0).PhoneNumber = "(708)555-0150" 
    End Sub 
End Class 

' This class implements a simple customer type  
' that implements the IPropertyChange interface. 

Public Class DemoCustomer
    Implements INotifyPropertyChanged

    ' These fields hold the values for the public properties. 
    Private idValue As Guid = Guid.NewGuid()
    Private customerNameValue As String = String.Empty
    Private phoneNumberValue As String = String.Empty

    Public Event PropertyChanged As PropertyChangedEventHandler _
        Implements INotifyPropertyChanged.PropertyChanged

    ' This method is called by the Set accessor of each property. 
    ' The CallerMemberName attribute that is applied to the optional propertyName 
    ' parameter causes the property name of the caller to be substituted as an argument. 
    Private Sub NotifyPropertyChanged(<CallerMemberName()> Optional ByVal propertyName As String = Nothing)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyName))
    End Sub 

    ' The constructor is private to enforce the factory pattern. 
    Private Sub New()
        customerNameValue = "Customer"
        phoneNumberValue = "(312)555-0100" 
    End Sub 

    ' This is the public factory method. 
    Public Shared Function CreateNewCustomer() As DemoCustomer
        Return New DemoCustomer()
    End Function 

    ' This property represents an ID, suitable 
    ' for use as a primary key in a database. 
    Public ReadOnly Property ID() As Guid
        Get 
            Return Me.idValue
        End Get 
    End Property 


    Public Property CustomerName() As String 
        Get 
            Return Me.customerNameValue
        End Get 

        Set(ByVal value As String)
            If Not (value = customerNameValue) Then 
                Me.customerNameValue = value
                NotifyPropertyChanged()
            End If 
        End Set 
    End Property 


    Public Property PhoneNumber() As String 
        Get 
            Return Me.phoneNumberValue
        End Get 

        Set(ByVal value As String)
            If Not (value = phoneNumberValue) Then 
                Me.phoneNumberValue = value
                NotifyPropertyChanged()
            End If 
        End Set 
    End Property 
End Class