Dibuja un par de líneas en una imagen con el movimiento del ratón

Puede almacenar las líneas en una lista ya que se han completado, a continuación, dibuje todas las líneas anteriores cuando usted está dibujando el vivir

Private st, en As New Point
Private mouseButtonPressed As Boolean = False

Private lines As New List(Of (st As Point, en As Point))

Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
    Dim p = New Pen(Color.Black, 2)
    Dim g As Graphics = e.Graphics
    g.DrawLine(p, st, en)
    For Each line In lines
        g.DrawLine(p, line.st, line.en)
    Next
End Sub

Private Sub PictureBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseUp
    mouseButtonPressed = False
    lines.Add((st, en))
End Sub

Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove
    If mouseButtonPressed Then
        PictureBox1.Invalidate()
        en = e.Location
    End If
End Sub

Private Sub PictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseDown
    If e.Button = MouseButtons.Left Then
        st = New Point(e.X, e.Y)
        mouseButtonPressed = True
    End If
End Sub

La lista contiene Tuple(of Point, Point)