顺时针旋转90度:
PictureBox1.Image = Me.PictureBox1.Image
Me.PictureBox1.Image.RotateFlip(RotateFlipType.Rotate90FlipNone)
Me.PictureBox1.Refresh()
逆时针旋转90度:
Me.PictureBox1.Image.RotateFlip(RotateFlipType.Rotate270FlipNone)
PictureBox1.Image = Me.PictureBox1.Image
PictureBox1.Refresh()