BookSettingsForm::buildForm

public BookSettingsForm::buildForm(array $form, FormStateInterface $form_state)

public function buildForm(array $form, FormStateInterface $form_state) {
  $types = node_type_get_names();
  $config = $this->config('book.settings');
  $form['book_allowed_types'] = array(
    '#type' => 'checkboxes',
    '#title' => $this->t('Content types allowed in book outlines'),
    '#default_value' => $config->get('allowed_types'),
    '#options' => $types,
    '#description' => $this->t('Users with the %outline-perm permission can add all content types.', array('%outline-perm' => $this->t('Administer book outlines'))),
    '#required' => TRUE,
  );
  $form['book_child_type'] = array(
    '#type' => 'radios',
    '#title' => $this->t('Content type for the <em>Add child page</em> link'),
    '#default_value' => $config->get('child_type'),
    '#options' => $types,
    '#required' => TRUE,
  );
  $form['array_filter'] = array('#type' => 'value', '#value' => TRUE);

  return parent::buildForm($form, $form_state);
}