Public Class Form1
   Dim pPoints As New List(Of Point)
 
   Private Sub PictureBox1_MouseDown(ByVal sender As System.Object, ByVal e As _
     System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
      pPoints.Clear()
   End Sub
 
   Private Sub PictureBox1_MouseMove(ByVal sender As System.Object, ByVal e As _
     System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
      If e.Button = Windows.Forms.MouseButtons.Left Then
         pPoints.Add(e.Location)
      End If
   End Sub
 
   Private Sub PictureBox1_MouseUp(ByVal sender As System.Object, ByVal e As _
     System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
      Dim g As Graphics = PictureBox1.CreateGraphics
 
      g.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
      g.DrawLines(Pens.Black, pPoints.ToArray)
 
      g.Dispose()
   End Sub
End Class

Public Class Form1
    Dim g As Graphics
    Dim bDraw As Boolean
 
    Private Structure myPaintStruct
        Dim ptStart As Point
        Dim ptEnd As Point
    End Structure
 
    Dim myPaintList As New List(Of myPaintStruct)
    Dim colmyPaint As myPaintStruct
 
    Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles Me.MouseDown
        colmyPaint.ptStart = e.Location
        myPaintList.Add(colmyPaint)
        bDraw = True
    End Sub
 
    Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles Me.MouseMove
        If bDraw = True Then
            colmyPaint = myPaintList.Item(myPaintList.Count - 1)
            colmyPaint.ptEnd = e.Location
            myPaintList.Item(myPaintList.Count - 1) = colmyPaint
            g = Me.CreateGraphics
            g.Clear(Color.LightBlue)
 
            For i As Integer = 0 To myPaintList.Count - 1
                g.DrawLine(Pens.Black, myPaintList.Item(i).ptStart.X, _
                  myPaintList.Item(i).ptStart.Y, myPaintList.Item(i).ptEnd.X, _
                  myPaintList.Item(i).ptEnd.Y)
            Next
        End If
    End Sub
 
    Private Sub Form1_MouseUp(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles Me.MouseUp
        bDraw = False
    End Sub
End Class

   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
      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 Then
         Using g As Graphics = PictureBox1.CreateGraphics
            g.DrawRectangle(Pens.Black, New Rectangle(e.Location.X, _
              e.Location.Y, 1, 1))
         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

    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

   Private pDrawingPoints As New List(Of Point)
   Private pLastPoint As Point
   Private pAllowDraw As Boolean
   Private pLineColor As Color = Color.Red
   Private pLineWidth As Integer = 2
 
   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
         pAllowDraw = True
         pLastPoint = e.Location
         pDrawingPoints.Clear()
         pDrawingPoints.Add(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 pAllowDraw AndAlso e.Location <> pLastPoint Then
         Using g As Graphics = PictureBox1.CreateGraphics
            g.FillEllipse(New SolidBrush(pLineColor), pLastPoint.X - pLineWidth _
              \ 2, pLastPoint.Y - pLineWidth \ 2, pLineWidth, pLineWidth)
            g.DrawLine(New Pen(pLineColor, pLineWidth), pLastPoint, e.Location)
            pLastPoint = e.Location
            pDrawingPoints.Add(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
      pAllowDraw = False
 
      Using g As Graphics = PictureBox1.CreateGraphics
         g.Clear(Color.White)
         g.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
         g.DrawLines(New Pen(pLineColor, pLineWidth), pDrawingPoints.ToArray)
      End Using
   End Sub