asp.net生成缩略图及给原始图加水印(调试成功)

最新推荐文章于 2025-12-15 08:28:49 发布

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#asp.net #extension #string #null #exception #stream

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此博客展示了使用ASP.NET实现图片上传及缩略图生成的代码。代码中处理了文件扩展名、路径创建，从流中获取上传图片，计算缩略图尺寸，添加水印，保存原始图和缩略图，同时进行了异常处理和资源释放。

private void smallpic_Click(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("shuiyin.gif"); //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();
Response.Write("上传成功:"+newpath+thumpath);
   }
   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;
}