Preview Rrenderer for IRRE with FAL

SliderRenderer.php

<?php
namespace Slider\Slider\Hooks;

use TYPO3\CMS\Backend\Utility\BackendUtility;
use TYPO3\CMS\Backend\View\PageLayoutView;
use TYPO3\CMS\Backend\View\PageLayoutViewDrawItemHookInterface;
use TYPO3\CMS\Core\Utility\GeneralUtility;

/**
 * Contains a preview rendering for the page module of CType="slider"
 */
class SliderRenderer implements PageLayoutViewDrawItemHookInterface
{

    /**
     * Preprocesses the preview rendering of a content element of type "slider"
     *
     * @param \TYPO3\CMS\Backend\View\PageLayoutView $parentObject Calling parent object
     * @param bool $drawItem Whether to draw the item using the default functionality
     * @param string $headerContent Header content
     * @param string $itemContent Item content
     * @param array $row Record row of tt_content
     *
     * @return void
     */
    public function preProcess(
        PageLayoutView &$parentObject,
        &$drawItem,
        &$headerContent,
        &$itemContent,
        array &$row
    )
    {
        if ($row['CType'] === 'slider') {
            $itemContent .= '<strong>' . $parentObject->linkEditContent('Slider', $row) . '</strong>';

            $objectManager = GeneralUtility::makeInstance('TYPO3\CMS\Extbase\Object\ObjectManager');
            $itemRepository = $objectManager->get('Slider\Slider\Domain\Repository\ItemRepository');

            foreach ($itemRepository->findByTtContentUid($row['uid']) as $item) {
                $itemContent .= '<p>';
                $itemContent .= '' . $parentObject->linkEditContent($parentObject->renderText($item->getHeader()), $row) . '<br/>';
                $itemContent .= BackendUtility::thumbCode(
                    array(
                        'uid' => $item->getUid(),
                        'image' => $item->getImage()
                    ), 'tx_slider_domain_model_item', 'image', $backPath = '', $thumbScript = '', $uploaddir = null, $abs = 0, $tparams = '', $size = '128x64'
                );
                $itemContent .= BackendUtility::thumbCode(
                    array(
                        'uid' => $item->getUid(),
                        'image_small' => $item->getImage()
                    ), 'tx_slider_domain_model_item', 'image_small', $backPath = '', $thumbScript = '', $uploaddir = null, $abs = 0, $tparams = '', $size = '96x64'
                );
                $itemContent .= '</p>';
            }


            $headerContent = '';
            $drawItem = false;
        }
    }
}