Dart

Extract Embedded Files from PDF

Demonstrates how to get information about the embedded files (if any) contained within a PDF, and shows how to extract each file.

Note: This example requires Chilkat v9.5.0.95 or greater.

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.

  final pdf = CkPdf();

  try {
    pdf.loadFile('qa_data/pdf/embedded_files/my_embedded_files_test.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Note: The embedded file functionality was added in Chilkat v9.5.0.95

  // How many embedded files exist within the opened PDF?
  final numFiles = pdf.numEmbeddedFiles;
  print('Number of embedded files: $numFiles');

  final json = CkJsonObject();
  json.emitCompact = false;

  final bd = CkBinData();

  // Get information about each file, and extract each to the filesystem.
  var i = 0;
  while (i < numFiles) {

    try {
      pdf.getEmbeddedFileInfo(i, json);
    } on ChilkatException catch (e) {
      print(e.lastErrorText);
      return;
    }

    print(json.emit());

    // Get the filename from the JSON.
    var filename = 'someFile.dat';

    // The filename SHOULD always be present..
    if (json.hasMember('filename')) {
      filename = json.stringOf('filename');
    }

    // Get the file data.
    try {
      pdf.getEmbeddedFileBd(i, bd);
    } on ChilkatException catch (e) {
      print(e.lastErrorText);
      return;
    }

    // Save the contents of the bd to the filename (in the current working directory) in the filesystem.
    try {
      bd.writeFile(filename);
    } on ChilkatException {
      print('Failed to write output file.');
    }

    i++;
  }

  // Sample output for the above code:

  // Number of embedded files: 3
  // {
  //   "filename": "employees.json",
  //   "desc": "JSON",
  //   "subType": "application/json",
  //   "size": 159,
  //   "creationDate": "D:20230715170506-05'00'",
  //   "modDate": "D:20160207153838-05'00'"
  // }
  // 
  // {
  //   "filename": "rsaPubKey.pem",
  //   "desc": "RSA Public Key PEM",
  //   "size": 451,
  //   "creationDate": "D:20230715170546-05'00'",
  //   "modDate": "D:20150724133153-05'00'"
  // }
  // 
  // {
  //   "filename": "starfish.jpg",
  //   "desc": "Starfish JPG",
  //   "subType": "image/jpeg",
  //   "size": 6229,
  //   "creationDate": "D:20230715170356-05'00'",
  //   "modDate": "D:20080529103055-05'00'"
  // }
}