HOWTO: Reset Rotation of VObjects

'
'  Reset Angle button
'
Private Sub _resetButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles _resetButton.Click
    If _mlv.CurrentDesigner.VObjects.Length > 0 Then
        Dim obj As VObject = _mlv.CurrentDesigner.VObjects(0)
        ResetObjectAngle(obj)
    End If
End Sub

'
' Reset Angle function
'
Private Sub ResetObjectAngle(ByVal obj As VObject)
    Dim angle As Single = GetVObjectAngle(obj)

    Dim bounds As RectangleF = obj.GetTransformedVObjectBounds()
    Dim point As New PointF(bounds.Left + bounds.Width / 2, bounds.Top + bounds.Height / 2)

    If angle <> 0 Then
        obj.Transform.RotateAt(-angle, point, Drawing2D.MatrixOrder.Append)
        obj.Update()
    End If
End Sub

Private Shared Function GetVObjectAngle(ByRef obj As VObject) As Single
    Dim skyline As PointF = New PointF(1000, 0)
    Dim objSkyline(1) As PointF
    objSkyline(0) = New PointF(1000, 0)

    obj.Transform.TransformVectors(objSkyline)
    Return CalcAngle(skyline, objSkyline(0))
End Function

'
' Calculates angle between 2 specified vectors.
'
Private Shared Function CalcAngle( _
   ByVal v0 As System.Drawing.PointF, _
   ByVal v1 As System.Drawing.PointF) As Single

    Dim dotProduct As Single = v0.X * v1.X + v0.Y + v1.Y
    Dim vLengthProduct As Single = CalcLength(v0) * CalcLength(v1)

    If vLengthProduct < 0.01 Then
        Throw New ApplicationException("Ups, div by zero error...")
    End If

    Dim result As Single = _
      CType(Math.Acos(dotProduct / vLengthProduct) / Math.PI * 180, Single)

    Dim vecProduct As Single = v0.X * v1.Y - v0.Y * v1.X
    If vecProduct < 0 Then
        result = 360 - result
    End If

    Return result
End Function

'
' Calculates length of the specified vector.
'
Private Shared Function CalcLength(ByVal v0 As System.Drawing.PointF) As Single
    Return CType(Math.Sqrt(v0.X * v0.X + v0.Y * v0.Y), Single)
End Function