PDF page labels in Python

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

import site
site.addsitedir("../../../PDFNetC/Lib")
import sys
from PDFNetPython import *

sys.path.append("../../LicenseKey/PYTHON")
from LicenseKey import *

#-----------------------------------------------------------------------------------
# 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.)
#-----------------------------------------------------------------------------------

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

def main():
    # Initialize PDFNet
    PDFNet.Initialize(LicenseKey)
    
    #-----------------------------------------------------------
    # Example 1: Add page labels to an existing or newly created PDF
    # document.
    #-----------------------------------------------------------
    
    doc = 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. 
    L1 = PageLabel.Create(doc.GetSDFDoc(), PageLabel.e_roman_uppercase, "My Prefix ", 1)
    doc.SetPageLabel(1, L1)
    
    # 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").
    L2 = PageLabel.Create(doc.GetSDFDoc(), 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. 
    L3 = PageLabel.Create(doc.GetSDFDoc(), PageLabel.e_alphabetic_uppercase, "My Prefix ", 1)
    doc.SetPageLabel(7, L3)
    
    doc.Save(output_path + "newsletter_with_pagelabels.pdf", SDFDoc.e_linearized)
    doc.Close()
    print("Done. Result saved in newsletter_with_pagelabels.pdf...")
    
    #-----------------------------------------------------------
    # Example 2: Read page labels from an existing PDF document.
    #-----------------------------------------------------------
    
    doc = PDFDoc(output_path + "newsletter_with_pagelabels.pdf")
    doc.InitSecurityHandler()
    
    label = PageLabel()
    page_num = doc.GetPageCount()
    
    i = 1
    while i <= page_num:
        print("Page number: " + str(i))
        label = doc.GetPageLabel(i)
        
        if label.IsValid():
            print("Label: " + label.GetLabelTitle(i))
        else:
            print("No Label.")
        i = i + 1
    
    doc.Close()
            
    #-----------------------------------------------------------
    # Example 3: Modify page labels from an existing PDF document.
    #-----------------------------------------------------------
    
    doc = PDFDoc(output_path + "newsletter_with_pagelabels.pdf")
    doc.InitSecurityHandler()
    
    # Remove the alphabetic labels from example i.
    doc.RemovePageLabel(7)
    
    # Replace the Prefix in the decimal labels (from example 1).
    label = doc.GetPageLabel(4)
    if label.IsValid():
        label.SetPrefix("A")
        label.SetStart(1)
        
    # Add a new label
    new_label = PageLabel.Create(doc.GetSDFDoc(), PageLabel.e_decimal, "B", 1)
    doc.SetPageLabel(10, new_label) # starting from page 10
    
    doc.Save(output_path + "newsletter_with_pagelabels_modified.pdf", SDFDoc.e_linearized)
    print("Done. Result saved in newsletter_with_pagelabels_modified.pdf...")
    
    page_num = doc.GetPageCount()
    i = 1
    while i <= page_num:
        print("Page number: " + str(i))
        label = doc.GetPageLabel(i)
        if label.IsValid():
            print("Label: " + label.GetLabelTitle(i))
        else:
            print("No Label.")
        i = i + 1
    
    doc.Close()
        
    #-----------------------------------------------------------
    # Example 4: Delete all page labels in an existing PDF document.
    #----------------------------------------------------------- 
    
    doc = PDFDoc(output_path + "newsletter_with_pagelabels.pdf")
    doc.GetRoot().Erase("PageLabels")
    doc.Save(output_path + "newsletter_with_pagelabels_removed.pdf", SDFDoc.e_linearized)
    
    doc.Close()    
    PDFNet.Terminate()

if __name__ == '__main__':
    main()