高清缩略图代码，可删除原图不会出现在XXX.jpg正在使用中，水印代正在研究中

我在网上用了很多的相关代码或者缩略图水印类，但是都有一个问题就是删除不了原图 public static void myGetThumbnailImage(string SourceFile, string strSavePathFile, int ThumbWidth, int ThumbHeight, string BgColor) { System.Drawing.Image oImg = System.Drawing.Image.FromFile(SourceFile); //小图 int intwidth, intheight; if (oImg.Width > oImg.Height) { if (oImg.Width > ThumbWidth) { intwidth = ThumbWidth; intheight = (oImg.Height * ThumbWidth) / oImg.Width; } else { intwidth = oImg.Width; intheight = oImg.Height; } } else { if (oImg.Height > ThumbHeight) { intwidth = (oImg.Width * ThumbHeight) / oImg.Height; intheight = ThumbHeight; } else { intwidth = oImg.Width; intheight = oImg.Height; } } //构造一个指定宽高的Bitmap Bitmap bitmay = new Bitmap(intwidth, intheight); Graphics g = Graphics.FromImage(bitmay); Color myColor; if (BgColor == null) myColor = Color.FromName("white"); else myColor = Color.FromName(BgColor); //用指定的颜色填充Bitmap g.Clear(myColor); g.InterpolationMode = InterpolationMode.HighQualityBicubic; //开始画图 g.DrawImage(oImg, new Rectangle(0, 0, intwidth, intheight), new Rectangle(0, 0, oImg.Width, oImg.Height), GraphicsUnit.Pixel); bitmay.Save(strSavePathFile, System.Drawing.Imaging.ImageFormat.Jpeg); g.Dispose(); bitmay.Dispose(); oImg.Dispose(); //删除源图 try { File.Delete(SourceFile); } catch { } }