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;
}