Графический способ рисования кругов

  Dim r As Graphics = PictureBox1.CreateGraphics
        For i = 1 To 50
            Select Case i Mod 3
                Case 1
                    r.DrawEllipse(Pens.Black, 150 - i * 2, 125 - i * 2, i * 4, i * 4)
                Case 2
                    r.DrawEllipse(Pens.Cyan, 150 - i * 2, 125 - i * 2, i * 4, i * 4)
                Case 0
                    r.DrawEllipse(Pens.DarkGreen, 150 - i * 2, 125 - i * 2, i * 4, i * 4)
            End Select
        Next

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.ClientSize = New Size(600, 600)
        Me.MinimumSize = Me.Size
        Dim bmp As Bitmap = New Bitmap(Me.ClientSize.Width, Me.ClientSize.Height)
        Me.BackgroundImage = bmp
        Me.DoubleBuffered = True
        Dim g As Graphics = Graphics.FromImage(bmp)
        g.Clear(Color.Transparent)
        g.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
        Dim center As Point = New Point(bmp.Width / 2, bmp.Height / 2)
        Dim diameter As Integer = 20
        Dim rf As RectangleF
        Dim pn As Pen
        For i As Integer = 1 To 50
 
            pn = New Pen(Color.FromArgb(Math.Min(i * 6, 255), Math.Min(i * 4, 255), Math.Min(i * 5, 255)), 1)
            With rf
                .Width = diameter
                .Height = diameter
                .Location = New Point(center.X - diameter / 2, center.Y - diameter / 2)
            End With
            g.DrawEllipse(pn, rf)
            diameter = diameter + 10
        Next
        Me.BackgroundImageLayout = ImageLayout.Center
        If MsgBox("Сохранить в " & System.IO.Path.GetPathRoot(My.Application.Info.DirectoryPath) & "sample.png?", MsgBoxStyle.YesNo Or MsgBoxStyle.Question) = MsgBoxResult.Yes Then
            bmp.Save(System.IO.Path.GetPathRoot(My.Application.Info.DirectoryPath) & "sample.png", Drawing.Imaging.ImageFormat.Png)
        End If
    End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.TransparencyKey = Color.Blue
        Me.ClientSize = New Size(500, 500)
        Dim sz As Size = Me.ClientSize
        Dim bmp As Bitmap = New Bitmap(sz.Width, sz.Height)
        Me.BackgroundImageLayout = ImageLayout.Center
        Me.BackgroundImage = bmp
        Me.MinimumSize = Me.Size
        Me.DoubleBuffered = True
        Dim g As Graphics = Graphics.FromImage(bmp)
        Dim rf As RectangleF = New RectangleF(10, 10, sz.Width - 20, sz.Height - 20)
        g.SmoothingMode = Drawing2D.SmoothingMode.None
        g.Clear(Color.Transparent)
        g.FillEllipse(Brushes.Blue, rf) ' это ключевой момент - заливаем круг тем же цветом, что и у свойства TransparencyKey (задали в начале процедуры)
    End Sub