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<?php
namespace Drupal\webform\Element;
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Render\Element\FormElement;
use Drupal\Core\Render\Element;
class WebformSignature extends FormElement {
public function getInfo() {
$class = get_class($this);
return [
'#input' => TRUE,
'#process' => [
[
$class,
'processWebformSignature',
],
[
$class,
'processAjaxForm',
],
[
$class,
'processGroup',
],
],
'#pre_render' => [
[
$class,
'preRenderWebformSignature',
],
],
'#theme' => 'input__webform_signature',
'#theme_wrappers' => [
'form_element',
],
'#markup' => '',
];
}
public static function processWebformSignature(&$element, FormStateInterface $form_state, &$complete_form) {
$element['#label_attributes']['webform-remove-for-attribute'] = TRUE;
$element += [
'#element_validate' => [],
];
array_unshift($element['#element_validate'], [
get_called_class(),
'validateWebformSignature',
]);
return $element;
}
public static function preRenderWebformSignature(array $element) {
$element['#attributes']['type'] = 'hidden';
Element::setAttributes($element, [
'name',
'value',
]);
static::setAttributes($element, [
'js-webform-signature',
'form-webform-signature',
]);
$build = [
'#prefix' => '<div class="js-webform-signature-pad webform-signature-pad">',
'#suffix' => '</div>',
];
$build['reset'] = [
'#type' => 'button',
'#value' => t('Reset'),
];
$build['canvas'] = [
'#type' => 'html_tag',
'#tag' => 'canvas',
];
$element['#children'] = $build;
$element['#attached']['library'][] = 'webform/webform.element.signature';
return $element;
}
public static function validateWebformSignature(&$element, FormStateInterface $form_state, &$complete_form) {
$value = $element['#value'];
if (!static::isSignatureValid($value)) {
$t_args = [
'@title' => isset($element['#title']) ? $element['#title'] : t('Form'),
];
$form_state
->setError($element, t('@title contains an invalid signature.', $t_args));
}
}
public static function isSignatureValid($value) {
if (empty($value)) {
return TRUE;
}
if (strpos($value, 'data:image/png;base64,') !== 0) {
return FALSE;
}
$file_system = \Drupal::service('file_system');
$temp_image = $file_system
->tempnam('temporary://', 'webform_signature_');
$encoded_image = explode(',', $value)[1];
$decoded_image = base64_decode($encoded_image);
file_put_contents($temp_image, $decoded_image);
$image_size = getimagesize($temp_image);
if (!$image_size) {
return FALSE;
}
if (filesize($temp_image) > 500000) {
return FALSE;
}
$image = imagecreatefrompng($temp_image);
$number_of_colors = imagecolorstotal($image);
imagedestroy($image);
if ($number_of_colors > 0) {
return FALSE;
}
return TRUE;
}
}