asp.net An example of how to generate a thumbnail and add a watermark to the original image

Time:2021-4-16

In this paper, an example is given asp.net The method of generating thumbnail and adding watermark to the original image is realized. 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 ("a8 logo.jpg "); // files to be watermarked
    simage=System.Drawing.Image.FromFile(simagefile);
    upimage=  System.Drawing.Image . fromstream (upimgfile); // uploaded image
    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 + file name + extension; // original graph path
    String thumbnail = smallpath + filename + extension; // thumbnail path
    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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