TextCustom.php

<?php

namespace Drupal\views\Plugin\views\area;

use Drupal\Core\Form\FormStateInterface;

/**
 * Views area text handler.
 *
 * @ingroup views_area_handlers
 *
 * @ViewsArea("text_custom")
 */
class TextCustom extends TokenizeAreaPluginBase {
    
    /**
     * {@inheritdoc}
     */
    protected function defineOptions() {
        $options = parent::defineOptions();
        $options['content'] = [
            'default' => '',
        ];
        return $options;
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildOptionsForm(&$form, FormStateInterface $form_state) {
        parent::buildOptionsForm($form, $form_state);
        $form['content'] = [
            '#title' => $this->t('Content'),
            '#type' => 'textarea',
            '#default_value' => $this->options['content'],
            '#rows' => 6,
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function render($empty = FALSE) {
        if (!$empty || !empty($this->options['empty'])) {
            return [
                '#markup' => $this->renderTextarea($this->options['content']),
            ];
        }
        return [];
    }
    
    /**
     * Render a text area with \Drupal\Component\Utility\Xss::filterAdmin().
     */
    public function renderTextarea($value) {
        if ($value) {
            return $this->sanitizeValue($this->tokenizeValue($value), 'xss_admin');
        }
    }

}