asp.net实现生成缩略图及给原始图加水印的方法示例

using System.IO;using System.Drawing.Imaging;private void Button1_ServerClick(object sender, System.EventArgs e) {  Graphics g=null;  System.Drawing.Image upimage=null;  System.Drawing.Image thumimg=null;  System.Drawing.Image simage=null;  Bitmap outputfile=null;  try   {    string extension = Path.GetExtension(File1.PostedFile.FileName).ToUpper();    string filename = DateTime.Now.ToString("yyyyMMddhhmmss");    string smallpath = Server.MapPath(".")+"/smallimg/";    string bigpath = Server.MapPath(".")+"/bigimg/";    int width,height,newwidth,newheight;    System.Drawing.Image.GetThumbnailImageAbort callb =new System.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);    if(!Directory.Exists(smallpath))    Directory.CreateDirectory(smallpath);    if(!Directory.Exists(bigpath))    Directory.CreateDirectory(bigpath);    Stream upimgfile = File1.PostedFile.InputStream;    string simagefile = Server.MapPath("a8logo.jpg"); //要加水印的文件    simage=System.Drawing.Image.FromFile(simagefile);    upimage= System.Drawing.Image.FromStream(upimgfile); //上传的图片    width = upimage.Width;    height = upimage.Height;    if(width>height)     {      newwidth=200;      newheight =(int)((double)height/(double)width * (double)newwidth);    } else     {      newheight=200;      newwidth=(int)((double)width/(double)height * (double)newheight);    }    thumimg = upimage.GetThumbnailImage(newwidth,newheight,callb,IntPtr.Zero);    outputfile=new Bitmap(upimage);    g=Graphics.FromImage(outputfile);    g.DrawImage(simage,new Rectangle(upimage.Width-simage.Width,upimage.Height-simage.Height,upimage.Width,upimage.Height),0,0,upimage.Width,upimage.Height,GraphicsUnit.Pixel);    string newpath = bigpath + filename + extension; //原始图路径    string thumpath = smallpath + filename + extension; //缩略图路径    outputfile.Save(newpath);    thumimg.Save(thumpath);    outputfile.Dispose();  }  catch(Exception ex)   {    throw ex;  }  finally   {    if(g!=null)    g.Dispose();    if(thumimg!=null)    thumimg.Dispose();    if(upimage!=null)    upimage.Dispose();    if(simage!=null)    simage.Dispose();  }}public bool ThumbnailCallback() {  return false;}