How to create Table Of Contents in iTextSharp

Question

I need to create a Table Of Contents with page numbers, but I don't know how. Next format:

heading1 ----------------page number  
  subHeading1---------------page number
  subHeading2---------------page number  
heading2-----------------page number  

I read a few articles and didn't understand. In particular, I mean this article, where "Named destinations" and "GoTo actions" I think it is useful for me, but I don't know how to use it in iTextSharp.

In my code, I have got a few "Chapter" and "Section", and I want to take it and create a TOC. I've understood that I need to use PdfPageEventHelper and OnChapter.

Answer 1

You've probably implemented this yourself by name, but I made a small example myself for the sake of completeness.

Please take a look at the CreateTOC example. It creates a PDF with some random text:

You can clearly see the titles and the content under the titles. After we have added all our content, we start a new page, and we add a table of contents:

The table of contents is composed by a series of key-value pairs, where the key is the title and the value is the page number. We create this list in a page event:

public class TOCEvent extends PdfPageEventHelper {

    protected List<SimpleEntry<String, Integer>> toc = new ArrayList<>();

    @Override
    public void onGenericTag(PdfWriter writer, Document document, Rectangle rect, String text) {
        toc.add(new SimpleEntry(text, writer.getPageNumber()));
    }

    public List getTOC() {
        return toc;
    }
}

We use this page event like this:

public void createPdf(String dest) throws IOException, DocumentException {
    Document document = new Document();
    PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(dest));
    TOCEvent event = new TOCEvent();
    writer.setPageEvent(event);
    document.open();
    for (int i = 0; i < 10; i++) {
        String title = "This is title " + i;
        Chunk c = new Chunk(title, titleFont);
        c.setGenericTag(title);
        document.add(new Paragraph(c));
        for (int j = 0; j < 50; j++) {
            document.add(new Paragraph("Line " + j + " of title " + i));
        }
    }
    document.newPage();
    document.add(new Paragraph("Table of Contents", titleFont));
    Chunk dottedLine = new Chunk(new DottedLineSeparator());
    List<SimpleEntry<String, Integer>> entries = event.getTOC();
    Paragraph p;
    for (SimpleEntry<String, Integer> entry : entries) {
        p = new Paragraph(entry.getKey());
        p.add(dottedLine);
        p.add(String.valueOf(entry.getValue()));
        document.add(p);
    }
    document.close();
}

First we create an instance of the event and we declare it to the writer:

TOCEvent event = new TOCEvent();
writer.setPageEvent(event);

We mark the titles using setGenericTag():

String title = "This is title " + i;
Chunk c = new Chunk(title, titleFont);
c.setGenericTag(title);
document.add(new Paragraph(c));

Once we've finished adding the content, we get all the entries:

List<SimpleEntry<String, Integer>> entries = event.getTOC();

We loop over this list and compose a Paragraph for every entry:

for (SimpleEntry<String, Integer> entry : entries) {
    p = new Paragraph(entry.getKey());
    p.add(dottedLine);
    p.add(String.valueOf(entry.getValue()));
    document.add(p);
}

No one can argue that this was difficult. The event class takes less than 10 lines of code. Adding support for subheadings will add a handful of lines, but that shouldn't be difficult too. It's a matter of building a tree structure, and introducing some indentation where necessary.