Public Class Form1
    Dim bm As New Bitmap(800, 500), g As Graphics = Graphics.FromImage(bm)
    Private Sub Form1_Paint(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.PaintEventArgs) Handles Me.Paint
        e.Graphics.DrawImage(bm, 0, 0)
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim blackPen As New Pen(Color.Black, 3)
        ' Create coordinates of points that define line.
        Dim x1 As Integer = 100
        Dim y1 As Integer = 100
        Dim x2 As Integer = 500
        Dim y2 As Integer = 100
        ' Draw line to screen.
        g.DrawLine(blackPen, x1, y1, x2, y2)
        Me.Invalidate()
    End Sub
End Class