Example of how to generate thumbnails and add watermarks in asp.net

This article mainly introduces the method of asp.net to generate thumbnails and add watermarks to original images. It analyzes the implementation techniques of thumbnails and watermark operations of asp.net images based on specific examples. Friends in need can refer to it. Next

The example in this article describes the method of generating thumbnails and adding watermarks to the original images in asp.net. Share it with everyone for your reference, the details are as follows:

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;
}

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