Public Class Form1
    Private WithEvents t1 As New Timer
    Dim bmp As New Bitmap(300, 300), g As Graphics = Graphics.FromImage(bmp)
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        PictureBox1.SizeMode = PictureBoxSizeMode.AutoSize
        PictureBox1.Image = bmp
        PictureBox1.BackColor = Color.Black
        ' g.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
        t1.Start()
    End Sub
 
    Private Sub t1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) _
      Handles t1.Tick
        Dim rnd As New Random
        For i As Int32 = 0 To 19
            g.DrawEllipse(Pens.Yellow, rnd.Next(0, bmp.Width), rnd.Next(0, _
              bmp.Height), rnd.Next(10, 30), rnd.Next(10, 50))
        Next
        PictureBox1.Refresh()
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        g.Clear(Color.Black)
    End Sub
End Class