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