Rearrange::buildForm

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

public function buildForm(array $form, FormStateInterface $form_state) {
  $view = $form_state->get('view');
  $display_id = $form_state->get('display_id');
  $type = $form_state->get('type');

  $types = ViewExecutable::getHandlerTypes();
  $executable = $view->getExecutable();
  if (!$executable->setDisplay($display_id)) {
    $form['markup'] = array('#markup' => $this->t('Invalid display id @display', array('@display' => $display_id)));
    return $form;
  }
  $display = &$executable->displayHandlers->get($display_id);
  $form['#title'] = $this->t('Rearrange @type', array('@type' => $types[$type]['ltitle']));
  $form['#section'] = $display_id . 'rearrange-item';

  if ($display->defaultableSections($types[$type]['plural'])) {
    $section = $types[$type]['plural'];
    $form_state->set('section', $section);
    views_ui_standard_display_dropdown($form, $form_state, $section);
  }

  $count = 0;

  // Get relationship labels
  $relationships = array();
  foreach ($display->getHandlers('relationship') as $id => $handler) {
    $relationships[$id] = $handler->adminLabel();
  }

  $form['fields'] = array(
    '#type' => 'table',
    '#header' => array('', $this->t('Weight'), $this->t('Remove')),
    '#empty' => $this->t('No fields available.'),
    '#tabledrag' => array(
      array(
        'action' => 'order',
        'relationship' => 'sibling',
        'group' => 'weight',
      )
    ),
    '#tree' => TRUE,
    '#prefix' => '<div class="scroll" data-drupal-views-scroll>',
    '#suffix' => '</div>',
  );

  foreach ($display->getOption($types[$type]['plural']) as $id => $field) {
    $form['fields'][$id] = array();

    $form['fields'][$id]['#attributes'] = array('class' => array('draggable'), 'id' => 'views-row-' . $id);

    $handler = $display->getHandler($type, $id);
    if ($handler) {
      $name = $handler->adminLabel() . ' ' . $handler->adminSummary();
      if (!empty($field['relationship']) && !empty($relationships[$field['relationship']])) {
        $name = '(' . $relationships[$field['relationship']] . ') ' . $name;
      }
      $markup = $name;
    }
    else {
      $name = $id;
      $markup = $this->t('Broken field @id', array('@id' => $id));
    }
    $form['fields'][$id]['name'] = array('#markup' => $markup);

    $form['fields'][$id]['weight'] = array(
      '#type' => 'textfield',
      '#default_value' => ++$count,
      '#attributes' => array('class' => array('weight')),
      '#title' => t('Weight for @title', array('@title' => $name)),
      '#title_display' => 'invisible',
    );

    $form['fields'][$id]['removed'] = array(
      '#type' => 'checkbox',
      '#title' => t('Remove @title', array('@title' => $name)),
      '#title_display' => 'invisible',
      '#id' => 'views-removed-' . $id,
      '#attributes' => array('class' => array('views-remove-checkbox')),
      '#default_value' => 0,
      '#suffix' => \Drupal::l(SafeMarkup::format('<span>@text</span>', array('@text' => $this->t('Remove'))), 
      Url::fromRoute('<none>', array(), array('attributes' => array(
        'id' => 'views-remove-link-' . $id,
        'class' => array('views-hidden', 'views-button-remove', 'views-remove-link'),
        'alt' => $this->t('Remove this item'),
        'title' => $this->t('Remove this item')),
      ))
      ),
    );
  }

  $view->getStandardButtons($form, $form_state, 'views_ui_rearrange_form');

  return $form;
}