基于C#的两种图片旋转方法

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    /// <summary>        /// 根据角度旋转图标        /// </summary>        /// <param name="img"></param>        public Image RotateImg(Image img, float angle)        {            //通过Png图片设置图片透明，修改旋转图片变黑问题。            int width = img.Width;            int height = img.Height;                                //角度            Matrix mtrx = new Matrix();                       mtrx.RotateAt(angle, new PointF((width / 2), (height / 2)), MatrixOrder.Append);            //得到旋转后的矩形            GraphicsPath path = new GraphicsPath();            path.AddRectangle(new RectangleF(0f, 0f, width, height));            RectangleF rct = path.GetBounds(mtrx);            //生成目标位图            Bitmap devImage = new Bitmap((int)(rct.Width), (int)(rct.Height));            Graphics g = Graphics.FromImage(devImage);            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.Bilinear;            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;                       //计算偏移量            Point Offset = new Point((int)(rct.Width - width) / 2, (int)(rct.Height - height) / 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, (int)width, (int)height);            Point center = new Point((int)(rect.X + rect.Width / 2), (int)(rect.Y + rect.Height / 2));                        g.TranslateTransform(center.X, center.Y);            g.RotateTransform(angle);            //恢复图像在水平和垂直方向的平移            g.TranslateTransform(-center.X, -center.Y);            g.DrawImage(img, rect);            //重至绘图的所有变换            g.ResetTransform();            g.Save();            g.Dispose();            path.Dispose();            return devImage;        }        /// <summary>        /// 第二种方法        /// </summary>        /// <param name="b"></param>        /// <param name="angle"></param>        /// <returns></returns>        public Image RotateImg2(Image b, float 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            Image dsImage = new Bitmap(W, H);            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(dsImage);            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.Bilinear;            g.SmoothingMode = System.Drawing.Drawing2D.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();            //dsImage.Save("yuancd.jpg", System.Drawing.Imaging.ImageFormat.Jpeg);            return dsImage;        }
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