c#图片在PictureBox内任意角度旋转问题
问题：不能以我的窗体中心旋转 旋转之后图片出了窗体，必须拉滚动条才能显示（PS：我图片较大，必须要）、
窗体上控件：panel1里有个PictureBox1
附上我得关键代码：

C# code

        //任意角度旋转        private void RotateTransformButton_Click(object sender, EventArgs e)        {            try            {                Bitmap a = new Bitmap(pictureBox1.Image);//得到图片框中的图片                pictureBox1.Image = Rotate(a, Convert.ToInt32(textBox1.Text));                pictureBox1.SizeMode = PictureBoxSizeMode.AutoSize;                pictureBox1.Location = panel1.Location;                pictureBox1.Refresh();//最后刷新图片框            }            catch { }        }        #region 图片旋转函数        /// <summary>        /// 以逆时针为方向对图像进行旋转        /// </summary>        /// <param name="b">位图流</param>        /// <param name="angle">旋转角度[0,360](前台给的)</param>        /// <returns></returns>        public Bitmap Rotate(Bitmap b, int angle)        {            angle = angle % 360;            //弧度转换            double radian = angle * Math.PI / 180.0;            double cos = Math.Cos(radian);            double sin = Math.Sin(radian);            //原图的宽和高            int w = b.Width;            int h = b.Height;            int W = (int)(Math.Max(Math.Abs(w * cos - h * sin), Math.Abs(w * cos + h * sin)));            int H = (int)(Math.Max(Math.Abs(w * sin - h * cos), Math.Abs(w * sin + h * cos)));            //目标位图            Bitmap dsImage = new Bitmap(W, H);            Graphics g = Graphics.FromImage(dsImage);                        g.InterpolationMode = InterpolationMode.Bilinear;            g.SmoothingMode = SmoothingMode.HighQuality;            //计算偏移量            Point Offset = new Point((W - w) / 2, (H - h) / 2);            //构造图像显示区域：让图像的中心与窗口的中心点一致            Rectangle rect = new Rectangle(Offset.X, Offset.Y, w, h);            Point center = new Point(rect.X + rect.Width / 2, rect.Y + rect.Height / 2);            g.TranslateTransform(center.X, center.Y);            g.RotateTransform(360 - angle);            //恢复图像在水平和垂直方向的平移            g.TranslateTransform(-center.X, -center.Y);            g.DrawImage(b, rect);            //重至绘图的所有变换            g.ResetTransform();            g.Save();            g.Dispose();            return dsImage;        }        #endregion 图片旋转函数

C# code

        Point[] ps;        public Form1()        {            InitializeComponent();            pictureBox1.SizeMode = PictureBoxSizeMode.CenterImage;            int x1 = (pictureBox1.Width - pictureBox1.Image.Width) / 2;            int x2 = (pictureBox1.Width + pictureBox1.Image.Width) / 2;            int y1 = (pictureBox1.Height - pictureBox1.Image.Height) / 2;            int y2 = (pictureBox1.Height + pictureBox1.Image.Height) / 2;            ps = new Point[] { new Point(x1, y1), new Point(x2, y1), new Point(x1, y2) };        }        private void button1_Click(object sender, EventArgs e)        {            rotate(Math.PI / 90, ps);        }        void rotate(double angle , Point[] ps)        {            Graphics g = pictureBox1.CreateGraphics();            float cos = (float)Math.Cos(angle);            float sin = (float)Math.Sin(angle);            float centerx = pictureBox1.Width / 2;            float centery = pictureBox1.Height / 2;            Matrix m = new Matrix(cos, sin, -sin, cos, centerx + centery * sin - centerx * cos, centery - centery * cos - centerx * sin);            m.TransformPoints(ps);            g.Clear(pictureBox1.BackColor);            g.DrawImage(pictureBox1.Image, ps);            g.Dispose();        }