C#实现任意角度旋转图片（方法2）

C#实现Windows图片查看器的旋转功能：

private const string IMAGEFILE = "FocusPoint.JPG"; private static int MyAngle = 0; //旋转角度[-360,360] private void Page_Load(object sender, EventArgs e) { Image img; FileStream fs; fs = new FileStream(IMAGEFILE, FileMode.Open, FileAccess.Read); img = Bitmap.FromStream(fs); fs.Close(); pictureBox1.Image = img; } private void button1_Click(object sender, EventArgs e) { MyAngle = 90; //MyAngle += 90; //if (MyAngle > 360) MyAngle = 90; pictureBox1.Image = RotateImg(GetSourceImg(IMAGEFILE), MyAngle); } private void button2_Click(object sender, EventArgs e) { MyAngle = -90; //MyAngle += -90; //if (MyAngle < -360) MyAngle = -90; //pictureBox1.Image = RotateImg(Bitmap.FromFile(IMAGEFILE), MyAngle); pictureBox1.Image = RotateImg(IMAGEFILE, MyAngle); } #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 Image RotateImg(Image 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); 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(); //保存旋转后的图片 b.Dispose(); dsImage.Save("FocusPoint.jpg", System.Drawing.Imaging.ImageFormat.Jpeg); return dsImage; } public Image RotateImg(string filename, int angle) { return RotateImg(GetSourceImg(filename), angle); } public Image GetSourceImg(string filename) { Image img; img = Bitmap.FromFile(filename); return img; } #endregion 图片旋转函数