DownLoadAsynchronously("http://download.thinkbroadband.com/5MB.zip")

Module ModDownloadUrl
 
    Private WithEvents wc As WebClient
 
    Private Sub WC_DownloadProgressChanged(ByVal sender As Object, ByVal e As DownloadProgressChangedEventArgs) _
    Handles wc.DownloadProgressChanged
 
        If Not e.ProgressPercentage = 100 Then
            Trace.WriteLine(String.Format("Progress: {0}", ((e.BytesReceived / e.TotalBytesToReceive) * 100.0R).ToString(format:="00.00 \%")))
        End If
 
    End Sub
 
    Private Sub WC_DownloadFileCompleted(ByVal sender As Object, ByVal e As AsyncCompletedEventArgs) _
    Handles wc.DownloadFileCompleted
 
        wc.Dispose()
        Trace.WriteLine(String.Format("Progress: {0}", 100.0R.ToString(format:="00.00 \%")))
        MessageBox.Show("Download Complete.", "", MessageBoxButtons.OK, MessageBoxIcon.Information)
 
    End Sub
 
    Public Sub DownLoadAsynchronously(ByVal url As String,
                                      Optional ByVal targetFilepath As String = "",
                                      Optional ByVal ctrl As Control = Nothing)
 
        If String.IsNullOrWhiteSpace(targetFilepath) Then
            targetFilepath = Path.GetFileName(url)
        End If
 
        wc = New WebClient
        wc.DownloadFileAsync(New Uri(url), targetFilepath)
 
    End Sub
 
End Module

#Region " Imports "
 
Imports System
Imports System.ComponentModel
Imports System.IO
Imports System.Linq
Imports System.Net
Imports System.Windows.Forms
Imports System.Threading.Tasks
 
#End Region
 
Public NotInheritable Class FileDownloader : Implements IDisposable
 
#Region " Disposable Members "
 
    Private WithEvents wc As WebClient
 
#End Region
 
#Region " Properties "
 
    Public ReadOnly Property IsBusy As Boolean
        Get
            If Me.wc IsNot Nothing Then
                Return Me.wc.IsBusy
            Else
                Return False
            End If
        End Get
    End Property
 
#End Region
 
#Region " Events "
 
    Public Event DownloadProgressChanged(ByVal sender As Object, ByVal e As DownloadProgressChangedEventArgs)
    Public Event DownloadCompleted(ByVal sender As Object, ByVal e As AsyncCompletedEventArgs)
 
#End Region
 
#Region " Event-Handlers "
 
    Private Sub WC_DownloadProgressChanged(ByVal sender As Object, ByVal e As DownloadProgressChangedEventArgs) _
    Handles wc.DownloadProgressChanged
 
        If (Me.DownloadProgressChangedEvent IsNot Nothing) AndAlso (e.ProgressPercentage <> 100) Then
            RaiseEvent DownloadProgressChanged(sender, e)
        End If
 
    End Sub
 
    Private Sub WC_DownloadFileCompleted(ByVal sender As Object, ByVal e As AsyncCompletedEventArgs) _
    Handles wc.DownloadFileCompleted
 
        If (Me.DownloadCompletedEvent IsNot Nothing) Then
            RaiseEvent DownloadCompleted(sender, e)
        End If
 
    End Sub
 
#End Region
 
#Region " Public Methods "
 
    Public Sub DownloadAsync(ByVal url As String,
                             Optional ByVal targetFilepath As String = "")
 
        If String.IsNullOrWhiteSpace(url) Then
            Throw New ArgumentNullException(paramName:="url")
 
        Else
 
            If (Me.wc IsNot Nothing) AndAlso (Me.wc.IsBusy) Then
                Throw New Exception(message:="Another download is in progress.")
 
            Else
                Me.wc = New WebClient With
                 {
                     .UseDefaultCredentials = True
                 }
 
                If String.IsNullOrWhiteSpace(targetFilepath) Then
                    targetFilepath = Path.GetFileName(url)
                End If
 
                Task.Factory.StartNew(Sub() wc.DownloadFileAsync(New Uri(url), targetFilepath))
 
            End If
 
        End If
 
    End Sub
 
    ''' <summary>
    ''' Cancels the current asynchronous download.
    ''' </summary>
    Public Sub Cancel()
 
        If Me.wc Is Nothing Then
            Throw New NullReferenceException(message:="", innerException:=New ObjectDisposedException(objectName:="wc"))
 
        ElseIf Me.wc.IsBusy Then
            Me.wc.CancelAsync()
 
        End If
 
    End Sub
 
#End Region
 
#Region "IDisposable Support"
 
    ''' ----------------------------------------------------------------------------------------------------
    ''' <summary>
    ''' To detect redundant calls when disposing.
    ''' </summary>
    ''' ----------------------------------------------------------------------------------------------------
    Private isDisposed As Boolean = False
 
    ''' ----------------------------------------------------------------------------------------------------
    ''' <summary>
    ''' Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
    ''' </summary>
    ''' ----------------------------------------------------------------------------------------------------
    Public Sub Dispose() Implements IDisposable.Dispose
        Me.Dispose(isDisposing:=True)
        GC.SuppressFinalize(obj:=Me)
    End Sub
 
    ''' ----------------------------------------------------------------------------------------------------
    ''' <summary>
    ''' Releases unmanaged and - optionally - managed resources.
    ''' </summary>
    ''' ----------------------------------------------------------------------------------------------------
    ''' <param name="isDisposing">
    ''' <c>True</c> to release both managed and unmanaged resources; 
    ''' <c>False</c> to release only unmanaged resources.
    ''' </param>
    ''' ----------------------------------------------------------------------------------------------------
    Protected Sub Dispose(ByVal isDisposing As Boolean)
 
        If Not Me.isDisposed Then
 
            If isDisposing Then
 
                If Me.wc IsNot Nothing Then
                    Me.wc.Dispose()
                End If
 
            End If
 
        End If
 
        Me.isDisposed = True
 
    End Sub
 
#End Region
 
End Class

Imports System.ComponentModel
Imports System.Threading.Tasks
 
Public NotInheritable Class Form1 : Inherits Form
 
    Dim WithEvents downloader As New FileDownloader
 
    Private Sub Test() Handles MyBase.Shown
 
        Me.downloader.DownloadAsync("http://download.thinkbroadband.com/10MB.zip")
 
    End Sub
 
    Private Sub Button1_Click(sender As Object, e As EventArgs) _
    Handles Button1.Click
 
        If Me.downloader.IsBusy Then
            Me.downloader.Cancel()
        End If
 
    End Sub
 
    Private Sub Downloader_DownloadProgressChanged(ByVal sender As Object, ByVal e As DownloadProgressChangedEventArgs) _
    Handles downloader.DownloadProgressChanged
 
        Dim progress As Double = (e.BytesReceived / e.TotalBytesToReceive) * 100.0R
 
        If Me.Label1.InvokeRequired Then
            Me.Label1.Invoke(Sub() Me.Label1.Text = progress.ToString(format:="00.00 \%"))
 
        Else
            Me.Label1.Text = progress.ToString(format:="00.00 \%")
 
        End If
 
    End Sub
 
    Private Sub Downloader_DownloadCompleted(ByVal sender As Object, ByVal e As AsyncCompletedEventArgs) _
    Handles downloader.DownloadCompleted
 
        If e.Cancelled Then
            Exit Sub
        End If
 
        If Me.Label1.InvokeRequired Then
            Me.Label1.Invoke(Sub() Me.Label1.Text = 100.0R.ToString(format:="00.00 \%"))
 
        Else
            Me.Label1.Text = 100.0R.ToString(format:="00.00 \%")
 
        End If
 
    End Sub
 
End Class

    Public Class Form1
 
        Private Sub Button1_Click(...) Handles Button1.Click
            ...
            Label1.Text = ns.getProgress
        End Sub
 
    End Class
 
    Class modDownloadURL
        Public Progress As Object
 
        ReadOnly Property getProgress() As String
            Get
                Return Progress
            End Get
        End Property
 
    End Class