PDF page labels in Java

//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2023 by Apryse Software Inc. All Rights Reserved.
// Consult legal.txt regarding legal and license information.
//---------------------------------------------------------------------------------------

import com.pdftron.pdf.*;
import com.pdftron.sdf.SDFDoc;

//-----------------------------------------------------------------------------------
// The sample illustrates how to work with PDF page labels.
//
// PDF page labels can be used to describe a page. This is used to 
// allow for non-sequential page numbering or the addition of arbitrary 
// labels for a page (such as the inclusion of Roman numerals at the 
// beginning of a book). PDFNet PageLabel object can be used to specify 
// the numbering style to use (for example, upper- or lower-case Roman, 
// decimal, and so forth), the starting number for the first page,
// and an arbitrary prefix to be pre-appended to each number (for 
// example, "A-" to generate "A-1", "A-2", "A-3", and so forth.)
//-----------------------------------------------------------------------------------
public class PageLabelsTest {
    public static void main(String[] args) {
        PDFNet.initialize(PDFTronLicense.Key());

        // Relative path to the folder containing test files.
        String input_path = "../../TestFiles/";
        String output_path = "../../TestFiles/Output/";

        try {
            //-----------------------------------------------------------
            // Example 1: Add page labels to an existing or newly created PDF
            // document.
            //-----------------------------------------------------------
            {
                PDFDoc doc = new PDFDoc((input_path + "newsletter.pdf"));
                doc.initSecurityHandler();

                // Create a page labeling scheme that starts with the first page in
                // the document (page 1) and is using uppercase roman numbering
                // style.
                doc.setPageLabel(1, PageLabel.create(doc, PageLabel.e_roman_uppercase, "My Prefix ", 1));

                // Create a page labeling scheme that starts with the fourth page in
                // the document and is using decimal arabic numbering style.
                // Also the numeric portion of the first label should start with number
                // 4 (otherwise the first label would be "My Prefix 1").
                PageLabel L2 = PageLabel.create(doc, PageLabel.e_decimal, "My Prefix ", 4);
                doc.setPageLabel(4, L2);

                // Create a page labeling scheme that starts with the seventh page in
                // the document and is using alphabetic numbering style. The numeric
                // portion of the first label should start with number 1.
                PageLabel L3 = PageLabel.create(doc, PageLabel.e_alphabetic_uppercase, "My Prefix ", 1);
                doc.setPageLabel(7, L3);

                doc.save(output_path + "newsletter_with_pagelabels.pdf", SDFDoc.SaveMode.LINEARIZED, null);
                // output PDF doc
                doc.close();
                System.out.println("Done. Result saved in newsletter_with_pagelabels.pdf...");
            }

            //-----------------------------------------------------------
            // Example 2: Read page labels from an existing PDF document.
            //-----------------------------------------------------------
            {
                PDFDoc doc = new PDFDoc((output_path + "newsletter_with_pagelabels.pdf"));
                doc.initSecurityHandler();

                PageLabel label;
                int page_num = doc.getPageCount();
                for (int i = 1; i <= page_num; ++i) {
                    System.out.println("Page number: " + i);
                    label = doc.getPageLabel(i);
                    if (label.isValid()) {
                        System.out.println(" Label: " + label.getLabelTitle(i));
                    } else {
                        System.out.println(" No Label.");
                    }
                }
                doc.close();
            }

            //-----------------------------------------------------------
            // Example 3: Modify page labels from an existing PDF document.
            //-----------------------------------------------------------
            {
                PDFDoc doc = new PDFDoc((output_path + "newsletter_with_pagelabels.pdf"));
                doc.initSecurityHandler();

                // Remove the alphabetic labels from example 1.
                doc.removePageLabel(7);

                // Replace the Prefix in the decimal lables (from example 1).
                PageLabel label = doc.getPageLabel(4);
                if (label.isValid()) {
                    label.setPrefix("A");
                    label.setStart(1);
                }

                // Add a new label
                PageLabel new_label = PageLabel.create(doc, PageLabel.e_decimal, "B", 1);
                doc.setPageLabel(10, new_label);  // starting from page 10.

                doc.save(output_path + "newsletter_with_pagelabels_modified.pdf", SDFDoc.SaveMode.LINEARIZED, null);
                // output PDF doc
                System.out.println("Done. Result saved in newsletter_with_pagelabels_modified.pdf...");

                int page_num = doc.getPageCount();
                for (int i = 1; i <= page_num; ++i) {
                    System.out.print("Page number: " + i);
                    label = doc.getPageLabel(i);
                    if (label.isValid()) {
                        System.out.println(" Label: " + label.getLabelTitle(i));
                    } else {
                        System.out.println(" No Label.");
                    }
                }
                doc.close();
            }

            //-----------------------------------------------------------
            // Example 4: Delete all page labels in an existing PDF document.
            //-----------------------------------------------------------
            {
                PDFDoc doc = new PDFDoc((output_path + "newsletter_with_pagelabels.pdf"));
                doc.getRoot().erase("PageLabels");
                // ...
                doc.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        PDFNet.terminate();
    }
}