在Winform中怎么实现图片的旋转，比如说实现仪表盘功能，看代码吧，看太不懂的欢迎问

        float cnt = -; //旋转的角度

       //Timer定时器

         private void timer1_Tick(object sender, EventArgs e)

         {

             timer1.Enabled = false;

             Image img = Image.FromFile(@"F:\Hanzhaoxun\公司软件备份\其他\仪表盘\指针.png"); //图片路径

             cnt += ;

             if (cnt >= )

             {

                 cnt = -;

             }

             this.pictureBox1.Image = RotateImage(img, cnt);

             label1.Text = cnt.ToString();

             timer1.Enabled = true;

         }

       //实现图片旋转的方法

         public static Image RotateImage(Image img, float a)

         {

             Bitmap b = new Bitmap(img.Width, img.Height);

             Graphics g = Graphics.FromImage(b);

             g.TranslateTransform((float)b.Width / , (float)b.Height / );

             g.RotateTransform(a);

             g.TranslateTransform(-(float)b.Width / , -(float)b.Height / );

             g.InterpolationMode = InterpolationMode.HighQualityBicubic;

             g.DrawImage(img, new Point(, ));

             g.Dispose();

             return b;

         }