Zoom PictureBox by rubberband

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VB

Hi,
I have a problem with PictureBox scaling. I want to copy a piece of PictureBox1 using a rubberband and show it magnified in PictureBox4.

I can copy a piece but when it shows in PictureBox4 the aspect ratio is not correct.
I would also like to be able to zoom the piece by 2x, 3x etc.

Thank you in advance.
Henrik

Public Class Form1
    ' Rubberband
    Private startCorner As System.Drawing.Point
    Private rubberBand As Rectangle
    Private rubberBanding As Boolean = False
    Private rubberBandColor As Color = Color.Yellow
    Dim MyRect1 As New Rectangle
 
    Private Sub PictureBox1_MouseDown(sender As Object, e As _
      System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown
        If e.Button = Windows.Forms.MouseButtons.Left Then
            rubberBanding = True
            startCorner = e.Location
            rubberBand = Rectangle.Empty
            PictureBox1.Invalidate()
        End If
    End Sub
 
    Private Sub PictureBox1_MouseMove(sender As Object, e As _
      System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseMove
        If rubberBanding Then
            rubberBand.Width = Math.Abs(e.X - startCorner.X)
            rubberBand.Height = Math.Abs(e.Y - startCorner.Y)
            rubberBand.X = Math.Min(e.X, startCorner.X)
            rubberBand.Y = Math.Min(e.Y, startCorner.Y)
            PictureBox1.Invalidate()
        End If
    End Sub
 
   Private Sub PictureBox1_MouseUp(sender As Object, e As _
     System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp
        rubberBanding = False
    End Sub
 
    Private Sub PictureBox1_Paint(sender As Object, e As _
      System.Windows.Forms.PaintEventArgs) Handles PictureBox1.Paint
        Using pn As New Pen(rubberBandColor, 2) With {.DashStyle = _
        Drawing2D.DashStyle.Dash}
            e.Graphics.DrawRectangle(pn, rubberBand)
            MyRect1 = New Rectangle(rubberBand.X, rubberBand.Y, _
              rubberBand.Width, rubberBand.Height)
        End Using
    End Sub
 
 
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) _
      Handles Button1.Click
        Dim bm As New Bitmap(PictureBox1.Image)
        Dim bmTo As New Bitmap(PictureBox1.Image)
 
        Using g As Graphics = Graphics.FromImage(bmTo)
            Dim to_rect As New Rectangle(0, 0, PictureBox4.Width, _
              PictureBox4.Height)
            If aspect > 1 Then
                to_rect.Height = CInt(to_rect.Height * aspect)
            Else
                to_rect.Width = CInt(to_rect.Width * aspect)
            End If
            g.DrawImage(bm, to_rect, MyRect1, GraphicsUnit.Pixel)
            g.DrawRectangle(Pens.Red, to_rect)
 
            PictureBox4.Image = bmTo
        End Using
    End Sub
End Class