image_field_config_update

image_field_config_update(FieldConfigInterface $field)

function image_field_config_update(FieldConfigInterface $field) {
  $field_storage = $field->getFieldStorageDefinition();
  if ($field_storage->getType() != 'image') {
    // Only act on image fields.
    return;
  }

  $prior_instance = $field->original;

  $uuid_new = $field->getSetting('default_image')['uuid'];
  $uuid_old = $prior_instance->getSetting('default_image')['uuid'];

  // If the old and new files do not match, update the default accordingly.
  $file_new = $uuid_new ? \Drupal::entityManager()->loadEntityByUuid('file', $uuid_new) : FALSE;
  if ($uuid_new != $uuid_old) {
    // Save the new file, if present.
    if ($file_new) {
      $file_new->status = FILE_STATUS_PERMANENT;
      $file_new->save();
      \Drupal::service('file.usage')->add($file_new, 'image', 'default_image', $field->uuid());
    }
    // Delete the old file, if present.
    if ($uuid_old && ($file_old = \Drupal::entityManager()->loadEntityByUuid('file', $uuid_old))) {
      \Drupal::service('file.usage')->delete($file_old, 'image', 'default_image', $field->uuid());
    }
  }

  // If the upload destination changed, then move the file.
  if ($file_new && (file_uri_scheme($file_new->getFileUri()) != $field_storage->getSetting('uri_scheme'))) {
    $directory = $field_storage->getSetting('uri_scheme') . '://default_images/';
    file_prepare_directory($directory, FILE_CREATE_DIRECTORY);
    file_move($file_new, $directory . $file_new->filename);
  }
}