Dart

PDF Signatures with Built-in SVG Graphics

See more PDF Signatures Examples

This example demonstrates the built-in SVG graphics that can be applied to the appearance when signing a PDF.

Note: This example requires Chilkat v9.5.0.85 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();

  // Load a PDF to be signed.
  // The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf
  try {
    pdf.loadFile('qa_data/pdf/hello.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Options for signing are specified in JSON.
  final json = CkJsonObject();

  // In most cases, the signingCertificateV2 and signingTime attributes are required.
  json.updateInt('signingCertificateV2', 1);
  json.updateInt('signingTime', 1);

  // Specify the location/position, scale, and content of the signature's appearance.
  json.updateInt('page', 1);
  json.updateString('appearance.y', 'top');
  json.updateString('appearance.x', 'left');
  json.updateString('appearance.fontScale', '10.0');
  json.updateString('appearance.text[0]', 'Digitally signed by: cert_cn');
  json.updateString('appearance.text[1]', 'current_dt');
  json.updateString('appearance.text[2]', 'The crazy brown fox jumps over the lazy dog.');

  // In addition to the above, this example adds a built-in SVG graphic to the appearance.
  // The built-in SVG graphic is specified by a name, such as "green-check-grey-circle".
  // The full list of graphic names and images are shown below.
  json.updateString('appearance.image', 'green-check-grey-circle');

  // The graphic can be placed "left", "center", or "right".
  // If "center", then the graphic is displayed behind the text.
  json.updateString('appearance.imagePlacement', 'left');

  // The graphic's opacity can range from 1 to 100.
  // Centered graphics look best with less opacity (50 or less).
  // In this example, we'll keep the opacity at 100.
  json.updateString('appearance.imageOpacity', '100');

  // Here's an example of the signature's appearance if we centered the SVG graphic with an opacity of 40%
  // (image:https://example-code.com/images/centered_svg.jpg/endImage)

  // Load the signing certificate. (Use your own certificate.)
  final cert = CkCert();
  try {
    cert.loadPfxFile('qa_data/pfx/myPdfSigningCert.pfx', 'secret');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Tell the pdf object to use the certificate for signing.
  try {
    pdf.setSigningCert(cert);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  try {
    pdf.signPdf(json, 'qa_output/hello_signed.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('The PDF has been successfully cryptographically signed.');

  // The appearance of the signature appears in Adobe Acrobat as shown here:

  // (image:https://example-code.com/images/pdf_signature_green_check_grey_circle.jpg/endImage)

  // The SVG icon graphics are embedded within the Chilkat library, 
  // and were graciously provided by uxwing - Free SVG Icons 
  // 
  // The uxwing licensing terms are reproduced here and can be verified at uxwing licensing

  // Icons from uxwing.com are free (see https://uxwing.com/license/)
  // 	- All icons on UXWing free to download, and use personal, commercial projects.
  // 	- Attribution and Credit is NOT required, however, any credit will be much appreciated.
  // 	- There is no limit to the number of times you can use.
  // 	- You may modify the resources according to your requirements.

  // The set of SVG names and the corresponding graphics are shown below.
  // 
  // For example, if we specify "green-check-green-circle"
  json.updateString('appearance.image', 'green-check-green-circle');
  // We get:
  // (image:https://example-code.com/images/green-check-green-circle.jpg/endImage)

  // "application-approved"
  // (image:https://example-code.com/images/application-approved.jpg/endImage)

  // "application-rejected"
  // (image:https://example-code.com/images/application-rejected.jpg/endImage)

  // "document-accepted"
  // (image:https://example-code.com/images/document-accepted.jpg/endImage)

  // "approved"
  // (image:https://example-code.com/images/approved.jpg/endImage)

  // "blue-check-mark"
  // (image:https://example-code.com/images/blue-check-mark.jpg/endImage)

  // "green-check-mark"
  // (image:https://example-code.com/images/green-check-mark.jpg/endImage)

  // "green-check-grey-circle"
  // (image:https://example-code.com/images/green-check-grey-circle.jpg/endImage)

  // "red-x-red-circle"
  // (image:https://example-code.com/images/red-x-red-circle.jpg/endImage)

  // "rejected"
  // (image:https://example-code.com/images/rejected.jpg/endImage)

  // "result-failure"
  // (image:https://example-code.com/images/result-failure.jpg/endImage)

  // "result-pass"
  // (image:https://example-code.com/images/result-pass.jpg/endImage)

  // "signature"
  // (image:https://example-code.com/images/signature.jpg/endImage)

  // "document-check"
  // (image:https://example-code.com/images/document-check.jpg/endImage)

  // "document-x"
  // (image:https://example-code.com/images/document-x.jpg/endImage)

  // "red-x-grey-circle"
  // (image:https://example-code.com/images/red-x-grey-circle.jpg/endImage)
}