Asp.net上传图片同时生成缩略图和水印图

Path.Combine(sSavePath, sFilename), System.IO.FileMode.Create); newFile.Write(myData, 0, nFileLen); newFile.Close(); //生成缩略图 //首先定义缩略图的宽高比 float fThumbRate = (float)intThumbWidth / (float)intThumbHeight; //获取原图的宽高比 float fOldRate = (float)myFile.Width / (float)myFile.Height; //根据原图的宽高比与目标宽高比判断缩放方式 if (fOldRate >= fThumbRate) //原图宽高比大于或等于缩略图宽高比 { //以高度为基准计算宽度 int nNewWidth = (int)((float)myFile.Height * fThumbRate); //创建缩略图 Bitmap bitmapThumb = new Bitmap(nNewWidth, intThumbHeight); Graphics graphic = Graphics.FromImage(bitmapThumb); //设置高质量插值法 graphic.InterpolationMode = InterpolationMode.HighQualityBicubic; //设置高质量绘制 graphic.SmoothingMode = SmoothingMode.HighQuality; //绘制原图 graphic.DrawImage(myFile.Image, new Rectangle(0, 0, nNewWidth, intThumbHeight), 0, 0, myFile.Width, myFile.Height, GraphicsUnit.Pixel); //保存缩略图 bitmapThumb.Save(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile)); } else //原图宽高比小于缩略图宽高比 { //以宽度为基准计算高度 int nNewHeight = (int)((float)myFile.Width / fThumbRate); Bitmap bitmapThumb = new Bitmap(intThumbWidth, nNewHeight); Graphics graphic = Graphics.FromImage(bitmapThumb); graphic.InterpolationMode = InterpolationMode.HighQualityBicubic; graphic.SmoothingMode = SmoothingMode.HighQuality; graphic.DrawImage(myFile.Image, new Rectangle(0, 0, intThumbWidth, nNewHeight), 0, 0, myFile.Width, myFile.Height, GraphicsUnit.Pixel); bitmapThumb.Save(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile)); } //添加水印 //首先加载水印图片 Image watermark = Image.FromFile("watermark.png"); //创建一个透明度调整的Graphics对象 ColorMatrix matrix = new ColorMatrix(new float[][] { new float[] { 1, 0, 0, 0, 0 }, new float[] { 0, 1, 0, 0, 0 }, new float[] { 0, 0, 1, 0, 0 }, new float[] { 0, 0, 0, 1, 0 }, new float[] { 0, 0, 0, 0, 0.5f } }); ImageAttributes attributes = new ImageAttributes(); attributes.SetColorMatrix(matrix); //创建绘图对象并绘制水印 Graphics g = Graphics.FromImage(bitmap