class Display

class Display extends ViewsFormBase {
  
  /**
   * Constructs a new Display object.
   */
  public function __construct($type = NULL) {
    $this->setType($type);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getFormKey() {
    return 'display';
  }
  
  /**
   * {@inheritdoc}
   *
   * @todo Remove this and switch all usage of $form_state->get('section') to
   *   $form_state->get('type').
   */
  public function getFormState(ViewEntityInterface $view, $display_id, $js) {
    $form_state = parent::getFormState($view, $display_id, $js);
    $form_state->set('section', $this->type);
    return $form_state;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getForm(ViewEntityInterface $view, $display_id, $js, $type = NULL) {
    $this->setType($type);
    return parent::getForm($view, $display_id, $js);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'views_ui_edit_display_form';
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $view = $form_state->get('view');
    $display_id = $form_state->get('display_id');
    $executable = $view->getExecutable();
    if (!$executable->setDisplay($display_id)) {
      $form['markup'] = [
        '#markup' => $this->t('Invalid display id @display', [
          '@display' => $display_id,
        ]),
      ];
      return $form;
    }
    // Get form from the handler.
    $form['options'] = [
      '#theme_wrappers' => [
        'container',
      ],
      '#attributes' => [
        'class' => [
          'scroll',
        ],
        'data-drupal-views-scroll' => TRUE,
      ],
    ];
    $executable->display_handler
      ->buildOptionsForm($form['options'], $form_state);
    // The handler options form sets $form['#title'], which we need on the
    // entire $form instead of just the ['options'] section.
    $form['#title'] = $form['options']['#title'];
    unset($form['options']['#title']);
    // Move the override dropdown out of the scrollable section of the form.
    if (isset($form['options']['override'])) {
      $form['override'] = $form['options']['override'];
      unset($form['options']['override']);
    }
    $name = $form_state->get('update_name');
    $view->getStandardButtons($form, $form_state, 'views_ui_edit_display_form', $name);
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  public function validateForm(array &$form, FormStateInterface $form_state) {
    $view = $form_state->get('view');
    $display_id = $form_state->get('display_id');
    $view->getExecutable()->displayHandlers
      ->get($display_id)
      ->validateOptionsForm($form['options'], $form_state);
    if ($form_state->getErrors()) {
      // Trigger a form rerender so error messages are displayed correctly in
      // the AJAX modal.
      // @see \Drupal\views_ui\Form\Ajax\ViewsFormBase::ajaxFormWrapper()
      $form_state->set('rerender', TRUE);
    }
  }
  
  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $view = $form_state->get('view');
    $display_id = $form_state->get('display_id');
    $view->getExecutable()->displayHandlers
      ->get($display_id)
      ->submitOptionsForm($form['options'], $form_state);
    $view->cacheSet();
  }

}