asp.net生成缩略图及给原始图加水印的函数

在编写程序时大家经常遇到给图片生成缩略图以及给原始图片添加水印的问题，下面这个函数便是在.NET中给图片生成缩略图及给原始图片添加水印的。

usingSystem.IO;
usingSystem.Drawing.Imaging;

privatevoidButton1_ServerClick(objectsender,System.EventArgse)
{
Graphicsg=null;
System.Drawing.Imageupimage=null;
System.Drawing.Imagethumimg=null;
System.Drawing.Imagesimage=null;
Bitmapoutputfile=null;
try
{
stringextension=Path.GetExtension(File1.PostedFile.FileName).ToUpper();
stringfilename=DateTime.Now.ToString("yyyyMMddhhmmss");
stringsmallpath=Server.MapPath(".")+"/smallimg/";
stringbigpath=Server.MapPath(".")+"/bigimg/";
intwidth,height,newwidth,newheight;

System.Drawing.Image.GetThumbnailImageAbortcallb=newSystem.Drawing.Image.GetThumbnailImageAbort(ThumbnailCallback);
if(!Directory.Exists(smallpath))
Directory.CreateDirectory(smallpath);
if(!Directory.Exists(bigpath))
Directory.CreateDirectory(bigpath);

Streamupimgfile=File1.PostedFile.InputStream;
stringsimagefile=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=newBitmap(upimage);
g=Graphics.FromImage(outputfile);
g.DrawImage(simage,newRectangle(upimage.Width-simage.Width,upimage.Height-simage.Height,upimage.Width,upimage.Height),0,0,upimage.Width,upimage.Height,GraphicsUnit.Pixel);

stringnewpath=bigpath+filename+extension;//原始图路径
stringthumpath=smallpath+filename+extension;//缩略图路径
outputfile.Save(newpath);
thumimg.Save(thumpath);
outputfile.Dispose();

}
catch(Exceptionex)
{
throwex;
}
finally
{
if(g!=null)
g.Dispose();
if(thumimg!=null)
thumimg.Dispose();
if(upimage!=null)
upimage.Dispose();
if(simage!=null)
simage.Dispose();
}
}
publicboolThumbnailCallback()
{
returnfalse;
}