How To Add Custom Page Thumbnauls To PDF In PDF Mosiac .NET Library

A PDF document can define thumbnail images representing the contents of its pages in miniature form. A viewer application can display these images on the screen, allowing the user to navigate to a page by clicking its thumbnail image.

To add custom page thumbnail in your pdf files use 'Thumbnail' property of 'PDFPage' class. The property gets or sets the image for page preview. 

using PDFMosaic;
using System;

namespace PDFThumbnail
{
    class PDFThumbnail
    {
        static void Main()
        {
            PDFDocument document = new PDFDocument();
            document.PageMode = PDFPageMode.Thumbnail;
            document.Pages.Add(new PDFPage(PDFPaperFormat.A4));
            document.Pages.Add(new PDFPage(PDFPaperFormat.A4));
            
            PDFImage thumbnail = new PDFImage("logo.jpg");
            document.Pages[1].Thumbnail = thumbnail;
            document.Save("TestAddPageThumbnails.pdf", true);
        }
    }
}