Dart Requires Chilkat v11.7.0+

Page Numbers, Dates and the File Name in a PDF Watermark

See more PDF Watermark Examples

Demonstrates the placeholders a text watermark understands, each replaced per page as the watermark is added: {page} is the page number, {pages} the page count, {date:FORMAT} the current local date and time, and {filename} the name of the file that was loaded. Two braces give a literal brace. pageNumber.start sets what {page} is on the first page, which is how a numbering that ignores a cover is produced, and pageNumber.style formats both {page} and {pages} as decimal, romanUpper, romanLower, letterUpper or letterLower. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  // The PDF used in this example is available at four_pages.pdf

  final pdf = CkPdf();
  try {
    pdf.loadFile('qa_data/pdf/four_pages.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final json = CkJsonObject();
  json.updateString('type', 'text');
  json.updateString('text', 'Page {page} of {pages}  -  printed {date:yyyy-MM-dd HH:mm}  -  {filename}');
  json.updateString('id', 'pagefoot');
  json.updateString('position.align', 'bottom');
  json.updateNumber('position.margin', '24');
  json.updateNumber('font.size', '9');
  json.updateString('color', '#505050');

  final jsonOut = CkJsonObject();
  try {
    pdf.watermark('add', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('footer pages: ${jsonOut.stringOf('pages')}');

  // Roman numerals that start at i on page 2, so that a cover page is not numbered.
  final pdf2 = CkPdf();
  try {
    pdf2.loadFile('qa_data/pdf/four_pages.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final json2 = CkJsonObject();
  json2.updateString('type', 'text');
  json2.updateString('text', '- {page} -');
  json2.updateString('id', 'roman');
  json2.updateString('pages', '2-');
  json2.updateInt('pageNumber.start', 1);
  json2.updateString('pageNumber.style', 'romanLower');
  json2.updateString('position.align', 'bottom');
  json2.updateNumber('font.size', '10');
  try {
    pdf2.watermark('add', json2, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('roman pages: ${jsonOut.stringOf('pages')}');

  try {
    pdf.writeFile('qa_output/four_pages_numbered.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Sample output:

  // footer pages: 1-4
  // roman pages: 2-4
}