如何使用vb.net在Windows窗体上旋转PictureBox

Imports System.Drawing
Imports System.Drawing.Drawing2D

Public Class Form1
    Private Sub RotatePictureBox(ByVal angle As Single, ByVal pictureBox As PictureBox)
        Dim bmp As Bitmap = New Bitmap(pictureBox.Image)
        Dim rect As RectangleF = New RectangleF(0, 0, bmp.Width, bmp.Height)
        Dim ptRotate As PointF = New PointF(bmp.Width \ 2, bmp.Height \ 2)
        Dim g As Graphics = Graphics.FromImage(bmp)

        g.TranslateTransform(ptRotate.X, ptRotate.Y)
        g.RotateTransform(angle)
        g.TranslateTransform(-ptRotate.X, -ptRotate.Y)
        g.DrawImage(bmp, rect)

        pictureBox.Image = bmp
    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        RotatePictureBox(90.0F, PictureBox1)
    End Sub
End Class