itextsharp trimming pdf document's pages

Question

I have a pdf document that has form fields that I'm filling out programatically with c#. Depending on three conditions, I need to trim (delete) some of the pages from that document.

Is that possible to do?

for condition 1: I need to keep pages 1-4 but delete pages 5 and 6

for condition 2: I need to keep pages 1-4 but delete 5 and keep 6

for condition 3: I need to keep pages 1-5 but delete 6

Answer 1

Instead of deleting pages in a document what you actually do is create a new document and only import the pages that you want to keep. Below is a full working WinForms app that does that (targetting iTextSharp 5.1.1.0). The last parameter to the function removePagesFromPdf is an array of pages to keep.

The code below works off of physical files but would be very easy to convert to something based on streams so that you don't have to write to disk if you don't want to.

using System;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Windows.Forms;
using iTextSharp.text.pdf;
using iTextSharp.text;


namespace Full_Profile1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            //The files that we are working with
            string sourceFolder = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
            string sourceFile = Path.Combine(sourceFolder, "Test.pdf");
            string destFile = Path.Combine(sourceFolder, "TestOutput.pdf");

            //Remove all pages except 1,2,3,4 and 6
            removePagesFromPdf(sourceFile, destFile, 1, 2, 3, 4, 6);
            this.Close();
        }
        public void removePagesFromPdf(String sourceFile, String destinationFile, params int[] pagesToKeep)
        {
            //Used to pull individual pages from our source
            PdfReader r = new PdfReader(sourceFile);
            //Create our destination file
            using (FileStream fs = new FileStream(destinationFile, FileMode.Create, FileAccess.Write, FileShare.None))
            {
                using (Document doc = new Document())
                {
                    using (PdfWriter w = PdfWriter.GetInstance(doc, fs))
                    {
                        //Open the desitination for writing
                        doc.Open();
                        //Loop through each page that we want to keep
                        foreach (int page in pagesToKeep)
                        {
                            //Add a new blank page to destination document
                            doc.NewPage();
                            //Extract the given page from our reader and add it directly to the destination PDF
                            w.DirectContent.AddTemplate(w.GetImportedPage(r, page), 0, 0);
                        }
                        //Close our document
                        doc.Close();
                    }
                }
            }
        }
    }
}