ขอถามเรื่อง ProgressBar หน่อยคับจะให้มัน check เวลาดาวโหลดไฟล์จากServer

Private min As Integer = 0               ' Minimum value for progress range
Private max As Integer = 100             ' Maximum value for progress range
Private val As Integer = 0               ' Current progress
Private barColor As Color = Color.Blue   ' Color of progress meter

Protected Overrides Sub OnResize(ByVal e As EventArgs)
    ' Invalidate the control to get a repaint.
    Me.Invalidate()
End Sub

Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
    Dim g As Graphics = e.Graphics
    Dim brush As SolidBrush = New SolidBrush(barColor)
    Dim percent As Decimal = (val - min) / (max - min)
    Dim rect As Rectangle = Me.ClientRectangle

    ' Calculate area for drawing the progress.
    rect.Width = rect.Width * percent

    ' Draw the progress meter.
    g.FillRectangle(brush, rect)

    ' Draw a three-dimensional border around the control.
    Draw3DBorder(g)

    ' Clean up.
    brush.Dispose()
    g.Dispose()
End Sub

Public Property Minimum() As Integer
    Get
        Return min
    End Get

    Set(ByVal Value As Integer)
        ' Prevent a negative value.
        If (Value < 0) Then
            min = 0
        End If

        ' Make sure that the minimum value is never set higher than the maximum value.
        If (Value > max) Then
            min = Value
            min = Value
        End If

        ' Make sure that the value is still in range.
        If (val < min) Then
            val = min
        End If



        ' Invalidate the control to get a repaint.
        Me.Invalidate()
    End Set
End Property

Public Property Maximum() As Integer
    Get
        Return max
    End Get

    Set(ByVal Value As Integer)
        ' Make sure that the maximum value is never set lower than the minimum value.
        If (Value < min) Then
            min = Value
        End If

        max = Value

        ' Make sure that the value is still in range.
        If (val > max) Then
            val = max
        End If

        ' Invalidate the control to get a repaint.
        Me.Invalidate()
    End Set
End Property

Public Property Value() As Integer
    Get
        Return val
    End Get

    Set(ByVal Value As Integer)
        Dim oldValue As Integer = val

        ' Make sure that the value does not stray outside the valid range.
        If (Value < min) Then
            val = min
        ElseIf (Value > max) Then
            val = max
        Else
            val = Value
        End If

        ' Invalidate only the changed area.
        Dim percent As Decimal

        Dim newValueRect As Rectangle = Me.ClientRectangle
        Dim oldValueRect As Rectangle = Me.ClientRectangle

        ' Use a new value to calculate the rectangle for progress.
        percent = (val - min) / (max - min)
        newValueRect.Width = newValueRect.Width * percent

        ' Use an old value to calculate the rectangle for progress.
        percent = (oldValue - min) / (max - min)
        oldValueRect.Width = oldValueRect.Width * percent

        Dim updateRect As Rectangle = New Rectangle()

        ' Find only the part of the screen that must be updated.
        If (newValueRect.Width > oldValueRect.Width) Then
            updateRect.X = oldValueRect.Size.Width
            updateRect.Width = newValueRect.Width - oldValueRect.Width
        Else
            updateRect.X = newValueRect.Size.Width
            updateRect.Width = oldValueRect.Width - newValueRect.Width
        End If

        updateRect.Height = Me.Height
        ' Invalidate only the intersection region.
        Me.Invalidate(updateRect)
    End Set
End Property

Public Property ProgressBarColor() As Color
    Get
        Return barColor
    End Get

    Set(ByVal Value As Color)
        barColor = Value

        ' Invalidate the control to get a repaint.
        Me.Invalidate()
    End Set
End Property

Private Sub Draw3DBorder(ByVal g As Graphics)
    Dim PenWidth As Integer = Pens.White.Width

    g.DrawLine(Pens.DarkGray, _
        New Point(Me.ClientRectangle.Left, Me.ClientRectangle.Top), _
        New Point(Me.ClientRectangle.Width - PenWidth, Me.ClientRectangle.Top))
    g.DrawLine(Pens.DarkGray, _
        New Point(Me.ClientRectangle.Left, Me.ClientRectangle.Top), _
        New Point(Me.ClientRectangle.Left, Me.ClientRectangle.Height - PenWidth))
    g.DrawLine(Pens.White, _
        New Point(Me.ClientRectangle.Left, Me.ClientRectangle.Height - PenWidth), _
        New Point(Me.ClientRectangle.Width - PenWidth, Me.ClientRectangle.Height - PenWidth))
    g.DrawLine(Pens.White, _
        New Point(Me.ClientRectangle.Width - PenWidth, Me.ClientRectangle.Top), _
        New Point(Me.ClientRectangle.Width - PenWidth, Me.ClientRectangle.Height - PenWidth))
End Sub