Изобразить динамичный график - Visual Basic .NET

Public Class Form1
    Dim dx As Integer
    Dim old, cur As Integer
    Dim rnd As Random
    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        dx = 5
        old = PictureBox1.Height / 2
        Dim bmp As New Bitmap(PictureBox1.Width, PictureBox1.Height)
        PictureBox1.Image = bmp
    End Sub
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        rnd = New Random
        Timer1.Start()
    End Sub
    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        Timer1.Stop()
    End Sub
    Private Sub Timer1_Tick(sender As System.Object, e As System.EventArgs) Handles Timer1.Tick
        Dim bmp As New Bitmap(PictureBox1.Width, PictureBox1.Height)
        Dim gr As Graphics = Graphics.FromImage(bmp)
        gr.DrawImage(PictureBox1.Image, -dx, 0)
        cur = rnd.Next(1, PictureBox1.Height - 1) 'моделирование данных
        gr.DrawLine(Pens.Red, PictureBox1.Width - 1 - dx, old, PictureBox1.Width - 1, cur)
        old = cur
        PictureBox1.Image = bmp
    End Sub
End Class