Title.php

<?php

namespace Drupal\views\Plugin\views\area;

use Drupal\Core\Form\FormStateInterface;

/**
 * Views area title override handler.
 *
 * @ingroup views_area_handlers
 *
 * @ViewsArea("title")
 */
class Title extends AreaPluginBase {
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['title'] = [
            'default' => '',
        ];
        return $options;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        parent::buildOptionsForm($form, $form_state);
        $form['title'] = [
            '#type' => 'textfield',
            '#title' => $this->t('Overridden title'),
            '#default_value' => $this->options['title'],
            '#description' => $this->t('Override the title of this view when it is empty. The available global tokens below can be used here.'),
        ];
        // Don't use the AreaPluginBase tokenForm method, we don't want row tokens.
        $this->globalTokenForm($form, $form_state);
    }
    
    /**
     * {@inheritdoc}
     */
    public function preRender(array $results) {
        parent::preRender($results);
        // If a title is provided, process it.
        if (!empty($this->options['title'])) {
            $value = $this->globalTokenReplace($this->options['title']);
            $this->view
                ->setTitle($this->sanitizeValue($value, 'xss_admin'));
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function render($empty = FALSE) {
        // Do nothing for this handler by returning an empty render array.
        return [];
    }

}