Create Table of Contents in PDF from C# and VB.NET

A Table of Contents (TOC) helps you to improve the navigation and accessibility of your PDF document, by displaying a list of all the topics it covers and the respective pages where they are located.

With GemBox.Pdf you can add a TOC element to your documents, that contains TOC entries, programmatically in your C# and VB.NET applications.

The easiest way to create a Table of Contents is using GemBox.Document, which enables you to define various styles and formattings for the TOC entries, and generate them automatically. For more information, see the Table Of Content example.

The following example shows how to create a PDF file with a TOC element using GemBox.Document, and then attach that file's content to another PDF with GemBox.Pdf.

PDF file with added TOC element
Screenshot of PDF file with Table of Contents
using System.Collections.Generic;
using System.IO;
using System.Linq;
using GemBox.Document;
using GemBox.Pdf;
using GemBox.Pdf.Annotations;

class Program
{
    static void Main()
    {
        // If using Professional version, put your GemBox.Pdf serial key below.
        GemBox.Pdf.ComponentInfo.SetLicense("FREE-LIMITED-KEY");

        // If using Professional version, put your GemBox.Document serial key below.
        GemBox.Document.ComponentInfo.SetLicense("FREE-LIMITED-KEY");

        string[] files =
        {
            "%#MergeFile01.pdf%",
            "%#MergeFile02.pdf%",
            "%#MergeFile03.pdf%"
        };

        var tocEntries = new List<(string Title, int PagesCount)>();
        using (var document = new PdfDocument())
        {
            // Merge PDF files.
            foreach (var file in files)
                using (var source = PdfDocument.Load(file))
                {
                    document.Pages.Kids.AddClone(source.Pages);
                    tocEntries.Add((Path.GetFileNameWithoutExtension(file), source.Pages.Count));
                }

            int pagesCount;
            int tocPagesCount;

            // Create PDF with Table of Contents.
            using (var tocDocument = PdfDocument.Load(CreatePdfWithToc(tocEntries)))
            {
                pagesCount = tocDocument.Pages.Count;
                tocPagesCount = pagesCount - tocEntries.Sum(entry => entry.PagesCount);

                // Remove empty (placeholder) pages.
                for (int i = pagesCount - 1; i >= tocPagesCount; i--)
                    tocDocument.Pages.RemoveAt(i);

                // Insert TOC pages.
                document.Pages.Kids.InsertClone(0, tocDocument.Pages);
            }

            int entryIndex = 0;
            int entryPageIndex = tocPagesCount;

            // Update TOC links and outlines so that they point to adequate pages instead of placeholder pages.
            for (int i = 0; i < tocPagesCount; i++)
                foreach (var annotation in document.Pages[i].Annotations.OfType<PdfLinkAnnotation>())
                {
                    var entryPage = document.Pages[entryPageIndex];
                    annotation.SetDestination(entryPage, PdfDestinationViewType.FitPage);
                    document.Outlines[entryIndex].SetDestination(entryPage, PdfDestinationViewType.FitPage);

                    entryPageIndex += tocEntries[entryIndex].PagesCount;
                    ++entryIndex;
                }

            document.Save("Merge Files With Toc.pdf");
        }
    }

    static Stream CreatePdfWithToc(List<(string Title, int PagesCount)> tocEntries)
    {
        // Create new document.
        var document = new DocumentModel();
        var section = new Section(document);
        document.Sections.Add(section);

        // Add Table of Content.
        var toc = new TableOfEntries(document, FieldType.TOC);
        section.Blocks.Add(toc);

        // Create heading style.
        var heading1Style = (ParagraphStyle)document.Styles.GetOrAdd(StyleTemplateType.Heading1);
        heading1Style.ParagraphFormat.PageBreakBefore = true;

        // Add heading paragraphs and empty (placeholder) pages.
        foreach (var tocEntry in tocEntries)
        {
            section.Blocks.Add(
                new Paragraph(document, tocEntry.Title)
                { ParagraphFormat = { Style = heading1Style } });

            for (int i = 0; i < tocEntry.PagesCount; i++)
                section.Blocks.Add(
                    new Paragraph(document,
                        new SpecialCharacter(document, SpecialCharacterType.PageBreak)));
        }

        // Remove last extra-added empty page.
        section.Blocks.RemoveAt(section.Blocks.Count - 1);

        // When updating TOC element, an entry is created for each paragraph that has heading style.
        // The entries have the correct page numbers because of the added placeholder pages.
        toc.Update();

        // Save document as PDF.
        var pdfStream = new MemoryStream();
        document.Save(pdfStream, new GemBox.Document.PdfSaveOptions());
        return pdfStream;
    }
}
Imports System.Collections.Generic
Imports System.IO
Imports System.Linq
Imports GemBox.Document
Imports GemBox.Pdf
Imports GemBox.Pdf.Annotations

Module Program

    Sub Main()
        ' If using Professional version, put your GemBox.Pdf serial key below.
        GemBox.Pdf.ComponentInfo.SetLicense("FREE-LIMITED-KEY")

        ' If using Professional version, put your GemBox.Document serial key below.
        GemBox.Document.ComponentInfo.SetLicense("FREE-LIMITED-KEY")

        Dim files = New String() _
        {
            "%#MergeFile01.pdf%",
            "%#MergeFile02.pdf%",
            "%#MergeFile03.pdf%"
        }

        Dim tocEntries = New List(Of (Title As String, PagesCount As Integer))()
        Using document As New PdfDocument()
            ' Merge PDF files.
            For Each file In files
                Using source = PdfDocument.Load(file)
                    document.Pages.Kids.AddClone(source.Pages)
                    tocEntries.Add((Path.GetFileNameWithoutExtension(file), source.Pages.Count))
                End Using
            Next

            Dim pagesCount As Integer
            Dim tocPagesCount As Integer

            ' Create PDF with Table of Contents.
            Using tocDocument = PdfDocument.Load(CreatePdfWithToc(tocEntries))

                pagesCount = tocDocument.Pages.Count
                tocPagesCount = pagesCount - tocEntries.Sum(Function(entry) entry.PagesCount)

                ' Remove empty (placeholder) pages.
                For i = pagesCount - 1 To tocPagesCount Step -1
                    tocDocument.Pages.RemoveAt(i)
                Next

                ' Insert TOC pages.
                document.Pages.Kids.InsertClone(0, tocDocument.Pages)
            End Using

            Dim entryIndex As Integer = 0
            Dim entryPageIndex As Integer = tocPagesCount

            ' Update TOC links and outlines so that they point to adequate pages instead of placeholder pages.
            For i = 0 To tocPagesCount - 1
                For Each annotation In document.Pages(i).Annotations.OfType(Of PdfLinkAnnotation)()
                    Dim entryPage = document.Pages(entryPageIndex)
                    annotation.SetDestination(entryPage, PdfDestinationViewType.FitPage)
                    document.Outlines(entryIndex).SetDestination(entryPage, PdfDestinationViewType.FitPage)

                    entryPageIndex += tocEntries(entryIndex).PagesCount
                    entryIndex += 1
                Next
            Next

            document.Save("Merge Files With Toc.pdf")
        End Using
    End Sub

    Function CreatePdfWithToc(tocEntries As List(Of (Title As String, PagesCount As Integer))) As Stream
        ' Create new document.
        Dim document As New DocumentModel()
        Dim section As New Section(document)
        document.Sections.Add(section)

        ' Add Table of Content.
        Dim toc As New TableOfEntries(document, FieldType.TOC)
        section.Blocks.Add(toc)

        ' Create heading style.
        Dim heading1Style = CType(document.Styles.GetOrAdd(StyleTemplateType.Heading1), ParagraphStyle)
        heading1Style.ParagraphFormat.PageBreakBefore = True

        ' Add heading paragraphs and empty (placeholder) pages.
        For Each tocEntry In tocEntries
            section.Blocks.Add(
                New Paragraph(document, tocEntry.Title) With
                {.ParagraphFormat = New ParagraphFormat() With {.Style = heading1Style}})

            For i As Integer = 0 To tocEntry.PagesCount - 1
                section.Blocks.Add(
                    New Paragraph(document,
                        New SpecialCharacter(document, SpecialCharacterType.PageBreak)))
            Next
        Next

        ' Remove last extra-added empty page.
        section.Blocks.RemoveAt(section.Blocks.Count - 1)

        ' When updating TOC element, an entry is created for each paragraph that has heading style.
        ' The entries have the correct page numbers because of the added placeholder pages.
        toc.Update()

        ' Save document as PDF.
        Dim pdfStream As New MemoryStream()
        document.Save(pdfStream, New GemBox.Document.PdfSaveOptions())
        Return pdfStream
    End Function

End Module

See also


Next steps

GemBox.Pdf is a .NET component that enables developers to read, merge and split PDF files or execute low-level object manipulations from .NET applications in a simple and efficient way.

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