Dart

Add File Attachments to a PDF

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Demonstrates how to attach files to a PDF. This is also known as embedding a file within a PDF.

Note: This example requires Chilkat v9.5.0.97 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();

  // We'll be adding attachments to this PDF file..
  // Note: We are loading the PDF file into memory.  The PDF file is not kept open at this point.
  try {
    pdf.loadFile('qa_data/pdf/helloWorld.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Note: The ability to attach files to a PDF was added in Chilkat v9.5.0.97

  // Build JSON to provide information about the files to be embedded in the PDF.
  final json = CkJsonObject();
  json.emitCompact = false;

  var i = 0;

  // We can attach multiple files in one operation.

  // Here we specify the local relative file path of the 1st file to be embedded.
  json.i = i;
  json.updateString('files[i].description', 'Hello World');
  json.updateString('files[i].localFilePath', 'qa_data/xml/helloWorld.xml');
  i++;

  // Specify the 2nd file to be attached.
  json.i = i;
  json.updateString('files[i].description', 'Image of starfish');
  json.updateString('files[i].localFilePath', 'qa_data/jpg/starfish.jpg');
  // You can explicitly specify the subType (i.e. MIME type) of the file.
  // Otherwise Chilkat will use the default MIME type based on the filename extension.
  // If no default MIME type exists, then "application/octet-stream" is used.
  json.updateString('files[i].subType', 'image/jpeg');
  i++;

  // You can alternatively provide the file data from base64 encoded data rather than from a local file.
  json.i = i;
  json.updateString('files[i].description', 'Hello World from Data');
  json.updateString('files[i].fileData', 'SGVsbG8gV29ybGQsIEhlbGxvIFdvcmxkLCBIZWxsbyBXb3JsZCwgSGVsbG8gV29ybGQsIEhlbGxvIFdvcmxk');
  json.updateString('files[i].embeddedFilename', 'abc.txt');
  i++;

  // By default, the filename used within the PDF is the filename part of the local file path.
  // You can change it by specifying the embeddedFilename.
  json.i = i;
  json.updateString('files[i].description', 'Invoice');
  json.updateString('files[i].localFilePath', 'qa_data/xml/invoice.xml');
  json.updateString('files[i].embeddedFilename', 'invoice_1234.xml');
  json.updateString('files[i].subType', 'application/xml');

  // The above JSON provides instructions for attaching 4 files to the PDF.
  // Let's attach the files..
  // It is perfectly acceptable to write over the PDF file that was loaded,
  // but in this example we'll write the PDF with attachments to a new PDF file.
  try {
    pdf.addEmbeddedFiles(json, 'qa_output/helloWorld_withAttachments.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // You can alternatively write the PDF file with attachments to a Chilkat BinData object..
  final bd = CkBinData();
  try {
    pdf.addEmbeddedFilesBd(json, bd);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Then you can do what you want with the BinData, which contains the binary image of the PDF with attachments.

  print('Success.');
}