class Slider extends StylePluginBase {



 /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
      $options = parent::defineOptions();
      $options['path'] = array('default' => 'slider');
      return $options;
    }

    /**



  * Does the style plugin for itself support to add fields to its output.
   *
   * @var bool
   */
  protected $usesFields = TRUE;



 /**
   * {@inheritdoc}
   */
  public function buildOptionsForm(&$form, FormStateInterface $form_state) {
    parent::buildOptionsForm($form, $form_state);

    // Path prefix for SLIDER links.

    $form['chooseImage'] = [
      '#title' => $this->t('Choose Image'),
      '#type' => 'select',
      '#description' => t('Choose where to position the title and text in the slider'),
      '#options' => ['cc' => $this->t('Center'), 'tl' => $this->t('Top Left')],
    ];

}

function slider_theme($existing, $type, $theme, $path) {
  return array(
    'slider' => array(
      'file' => 'extended_display_styles.theme.inc',

    ),
  );
}

function template_preprocess_views_view_slider(&$variables) {
  // View options set by user.


  $options = $variables['view']->style_plugin->options;

  // Build a two-dimension array with years and months.
  $time_pool = array();
  $frameArrayManual = array('a','b','c');
  //$options['manual'] = $variables['view']->style_plugin->manual;

  foreach ($variables['view']->result as $id => $result) {
    $created = $result->node_field_data_created;
    $created_year = date('Y', $created);
    // Month date format.
    $month_date_format = (isset($options['month_date_format'])) ? $options['month_date_format'] : 'm';
    $created_month_digits = date('m', $created);
    $created_month = date($month_date_format, $created);
    $time_pool[$created_year][$created_month_digits] = "$created_month";
  }

  $options['time_pool'] = $time_pool;
  $options['frameArrayManual'] = array('a','b','c');

  // Update options for twig.
  $variables['options'] = $options;
}