c#文件裁剪
Bitmap newbm = new Bitmap(nowWidth, nowHeight);
Graphics g = Graphics.FromImage(newbm);
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.SmoothingMode = SmoothingMode.HighQuality;
g.CompositingQuality = CompositingQuality.HighQuality;
g.DrawImage(bmp, new Rectangle(, , nowWidth, nowHeight), new Rectangle(bmp.Width / , , bmp.Width / , bmp.Height), GraphicsUnit.Pixel);
g.Dispose();