Image 图片沿中心点进行任意角度旋转
代码语言：javascript复制 public static 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
System.Drawing.Point Offset = new System.Drawing.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
System.Drawing.Rectangle rect = new System.Drawing.Rectangle(Offset.X, Offset.Y, w, h);
System.Drawing.Point center = new System.Drawing.Point(rect.X rect.Width / 2, 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(b, rect);
//重至绘图的所有变换
g.ResetTransform();
g.Save();
g.Dispose();
return dsImage;
}
