Imports System.Drawing.Drawing2D

  Dim path As New GraphicsPath
  Dim prevPt As New Point(100, 100)

#Region " Freihandzeichnen "

  Private Sub Form1_Paint(ByVal sender As Object, ByVal e As _
        System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
    e.Graphics.DrawPath(Pens.Black, path)
  End Sub

  Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseDown
    If e.Button = MouseButtons.Left Then
      prevPt.X = e.X
      prevPt.Y = e.Y
      path.StartFigure()
    End If
  End Sub

  Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As _
      System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseMove
    If e.Button = MouseButtons.Left Then
      Dim g As Graphics = Me.CreateGraphics
      Dim currPt As Point = New Point(e.X, e.Y)
      g.DrawLine(Pens.Black, prevPt, currPt)
      g.Dispose()

      path.AddLine(prevPt, currPt)
      prevPt = currPt
    End If
  End Sub

  Private Sub Form1_MouseUp(ByVal sender As Object, ByVal e As _
        System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseUp
    If CheckBox1.Checked Then
      If e.Button = MouseButtons.Left Then
        path.CloseFigure()
        Invalidate()
      End If
    End If
  End Sub
#End Region

#Region " Rotation "

  Private Function GetCentreOfPath(ByVal p As GraphicsPath) _
        As PointF
    Dim x As Single = 0.0F
    Dim y As Single = 0.0F

    For Each pt As PointF In path.PathPoints
      x += pt.X
      y += pt.Y
    Next
    Return New PointF(x / path.PointCount, y / path.PointCount)
  End Function

  Private Sub Rotate()
    Dim m As Matrix = New Matrix
    Dim centrPt As PointF = GetCentreOfPath(path)

    m.Translate(-centrPt.X, -centrPt.Y)
    m.Rotate(10.0F, MatrixOrder.Append)
    m.Translate(centrPt.X, centrPt.Y, MatrixOrder.Append)
    path.Transform(m)

    Invalidate()
  End Sub
#End Region