Private lastPoint As Point
    Private pdraw As Boolean
 
    Private cl As Color = color.Red
    Private w As Integer = 4
 
    Private Sub PictureBox1_MouseDown(ByVal sender As System.Object, ByVal e As _
       System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
        If e.Button = Windows.Forms.MouseButtons.Left Then
            pdraw = True
            lastPoint = e.Location
        End If
    End Sub
 
    Private Sub PictureBox1_MouseMove(ByVal sender As System.Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
        If pdraw AndAlso e.Location <> lastPoint Then
            Using g As Graphics = PictureBox1.CreateGraphics
                g.FillEllipse(New SolidBrush(cl), lastPoint.X - w \ 2, _
                  lastPoint.Y - w \ 2, w, w)
                g.DrawLine(New Pen(cl, w), lastPoint, e.Location)
                lastPoint = e.Location
            End Using
        End If
    End Sub
 
    Private Sub PictureBox1_MouseUp(ByVal sender As System.Object, ByVal e As  _
      System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
        pdraw = False
    End Sub