public static function Signature::validateElement in SignatureField 1.x

Validate a signature element.

Parameters

array $element: The element being validated.

\Drupal\Core\Form\FormStateInterface $form_state: The current state of the form.

array $complete_form: The complete form structure.

File

src/Element/Signature.php, line 49

Class

Signature

Provides a form element for a signature.

Namespace

Drupal\signaturefield\Element

Code

public static function validateElement(array &$element, FormStateInterface $form_state, array &$complete_form) {
  if ($element['#value'] === '') {
    return;
  }
  if (strpos($element['#value'], 'data:image/png;base64,') !== 0) {
    $form_state
      ->setError($element, t('No valid signature has been submitted.'));
    return;
  }

  // Create a temporary file for validation.

  /** @var \Drupal\Core\File\FileSystemInterface $file_system */
  $file_system = \Drupal::service('file_system');
  $directory = $file_system
    ->realpath('temporary://');
  if (!($file = tempnam($directory, 'signature'))) {
    $form_state
      ->setError($element, t('The signature image could not be validated.'));
    return;
  }
  try {

    // Save the image.
    file_put_contents($file, base64_decode(mb_substr($element['#value'], 21)));

    // Validate it.

    /** @var \Drupal\Core\Image\ImageFactory $image_factory */
    $image_factory = \Drupal::service('image.factory');
    $image = $image_factory
      ->get($file);
    if (!$image
      ->isValid() || $image
      ->getMimeType() !== 'image/png') {
      $form_state
        ->setError($element, t('No valid signature has been submitted.'));
    }
  } finally {
    unlink($file);
  }
}