from square to ellipse rotating simple animation

orts System.Drawing.Drawing2D
Imports System.Math

Public Class Form1

    Private boxes As New List(Of roundedBox)
    Private bg As BufferedGraphics
    Private contesto As New BufferedGraphicsContext
    Private WithEvents renderLoop As New Timer

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        With Me
            .Size = New Size(800, 800)
            .BackColor = Color.White
        End With

        With renderLoop
            .Interval = 10
            .Enabled = True
        End With

        contesto.MaximumBuffer = Me.Size
        bg = contesto.Allocate(Me.CreateGraphics, Me.DisplayRectangle)
        bg.Graphics.Transform = New Matrix(1, 0, 0, -1, Me.Width / 2, Me.Height / 2)
        bg.Graphics.SmoothingMode = SmoothingMode.AntiAlias

        For i As Double = 10 To 180 Step 10
            boxes.Add(New roundedBox(New Point(0, 0), 400, 400, i))
        Next

    End Sub

    Private Sub TrenderLoop_Tick(sender As Object, e As EventArgs) Handles renderLoop.Tick

        bg.Graphics.Clear(Me.BackColor)

        For Each r As roundedBox In boxes
            r.disegna(bg.Graphics)
        Next

        bg.Render(Me.CreateGraphics)

    End Sub

End Class

Public Class roundedBox

    Private origine As Point
    Private altezza As Integer
    Private larghezza As Integer
    Private gradi As Double
    Private percorso As New GraphicsPath
    Public rotazione As Double
    Private Const rad As Double = PI / 180

    Public Sub New(p As Point, width As Integer, height As Integer, rot As Double)

        origine = p
        larghezza = width
        altezza = height
        rotazione = rot
        trasforma()
        gradi = 0

    End Sub

    Public Sub trasforma()

        Dim coefficenteDiRotazione As Double

        If gradi < 180 Then
            coefficenteDiRotazione = (Sin(gradi * rad))
            altezza = (400 - (320 * Sin(gradi * rad)))
            gradi += 0.5
        ElseIf gradi = 180 Then
            gradi = 0
        End If

        coefficenteDiRotazione *= rotazione

        Dim fX As Double = ((larghezza / 2) * Sin(gradi * rad) + 1) * 2
        Dim fY As Double = ((altezza / 2) * Sin(gradi * rad) + 1) * 2

        percorso.Reset()
        percorso.AddArc(New Rectangle(origine.X - larghezza / 2, origine.Y + (altezza / 2), fX, fY), 90, 90)
        percorso.AddArc(New Rectangle(origine.X - larghezza / 2, (origine.Y - (altezza / 2)) + fY, fX, fY), 180, 90)
        percorso.AddArc(New Rectangle((origine.X + (larghezza / 2) - fX), (origine.Y - (altezza / 2) + fY), fX, fY), 270, 90)
        percorso.AddArc(New Rectangle((origine.X + (larghezza / 2) - fX), origine.Y + (altezza / 2), fX, fY), 360, 90)
        percorso.CloseFigure()

        percorso.Transform(New Matrix(1, 0, 0, 1, 0, -fY))

        percorso.Transform(New Matrix(Cos(coefficenteDiRotazione * rad), Sin(coefficenteDiRotazione * rad), -Sin(coefficenteDiRotazione * rad), Cos(coefficenteDiRotazione * rad), 0, 0))

    End Sub

    Public Sub disegna(g As Graphics)

        trasforma()
        g.DrawPath(New Pen(Color.Black), percorso)

    End Sub

End Class