Add named destinations to an existing PDF document with iText

问题

I have a PDF previously created with FOP, and I need to add some named destinations to it so later another program can open and navigate the document with the Adobe PDF open parameters, namely the #namedest=destination_name parameter.

I don't need to add bookmarks or other dynamic content but just some destinations with a name and thus injecting a /Dests collection with names defined in the resulting PDF.

I use iText 5.3.0 and I read the chapter 7 of iText in Action (2nd edition), but still I cannot figure it out how to add the destinations and so use them with #nameddest in a browser.

I'm reading and manipulating the document with PdfReader and PdfStamper. I already know in advance where to put every destination after having parsed the document with a customized Listener and a PdfContentStreamProcessor, searching for a specific text marker on each page.

This is a shortened version of my code:

PdfReader reader = new PdfReader(src);
PdfStamper stamper = new PdfStamper(reader, new BufferedOutputStream(dest));

// search text markers for destinations, page by page
for (int i=1; i<reader.getNumberOfPages(); i++) {
  // get a list of markers for this page, as obtained with a custom Listener and a PdfContentStreamProcessor
  List<MyDestMarker> markers = ((MyListener)listener).getMarkersForThisPage();

  // add a destination for every text marker in the current page
  Iterator<MyDestMarker> it = markers.iterator();
  while(it.hasNext()) {
    MyDestMarker marker = it.next();
    String name = marker.getName();
    String x = marker.getX();
    String y = marker.getY();

    // create a new destination
    PdfDestination dest = new PdfDestination(PdfDestination.FITH, y); // or XYZ

    // add as a named destination -> does not work, only for new documents?
    stamper.getWriter().addNamedDestination(name, i /* current page */, dest);

    // alternatives
    PdfContentByte content = stamper.getOverContent(i);
    content.localDestination(name, dest); // doesn't work either -> no named dest found

    // add dest name to a list for later use with Pdf Open Parameters
    destinations.add(name);
  }   
}

stamper.close();
reader.close();

I also tried creating a PdfAnnotation with PdfFormField.createLink() but still, I just manage to get the annotation but with no named destination defined it does not work.

Any solution for this? Do I need to add some "ghost" content over the existing one with Chunks or something else?

Thanks in advance.

edit 01-27-2016: I recently found an answer to my question in the examples section of iText website, here.

Unfortunately the example provided does not work for me if I test it with a pdf without destinations previously defined in it, as it is the case with the source primes.pdf which already contains a /Dests array. This behaviour appears to be consistent with the iText code, since the writer loads the destinations in a map attribute of PdfDocument which is not "inherited" by the stamper on closing.

That said, I got it working using the method addNamedDestination() of PdfStamper added with version 5.5.7; this method loads a named destination in a local map attribute of the class which is later processed and consolidated in the document when closing the stamper.

This approach reaised a new issue though: the navigation with Pdf Open Parameters (#, #nameddest=) works fine with IE but not with Chrome v47 (and probably Firefox, too). I tracked the problem down to the order in which the dests names are defined and referenced inside the document; the stamper uses a HashMap as the container for the destinations, which of course does not guarantee the order of its objects and for whatever reason Chrome refuse to recognise destinations not listed in "natural" order. So, the only way I got it to work is replacing the namedDestinations HashMap with a natural-ordered TreeMap.

Hope this help others with the same issue.

回答1:

I 've been in the same need for my project previously. Had to display and navigate pdf document with acrobat.jar viewer. To navigate i needed the named destinations in the pdf. I have looked around the web for a possible solution, but no fortunate for me. Then I this idea strikes my mind.

I tried to recreate the existing pdf with itext, navigating through each page and adding localdestinations to each page and i got what I wanted. below is the snip of my code

OutputStream outputStream = new FileOutputStream(new File(filename));
Document document = new Document();
PdfWriter writer = PdfWriter.getInstance(document, outputStream);
document.open();
PdfContentByte cb = writer.getDirectContent();
PdfOutline pol = cb.getRootOutline();
PdfOutline oline1 = null;
InputStream in1 = new FileInputStream(new File(inf1));
PdfReader reader = new PdfReader(in1);
for (int i = 1; i <= reader.getNumberOfPages(); i++)
{
    document.newPage();
    document.setMargins(0.0F, 18.0F, 18.0F, 18.0F);
    PdfImportedPage page = writer.getImportedPage(reader, i);
    document.add(new Chunk(new Integer(i).toString()).setLocalDestination(new Integer(i).toString()));
    System.out.println(i);
    cb.addTemplate(page, 0.0F, 0.0F);
}
outputStream.flush();
document.close();
outputStream.close();

Thought it would help you.

来源：https://stackoverflow.com/questions/29884833/add-named-destinations-to-an-existing-pdf-document-with-itext

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