Render thumbnail from PDF file for a node type

PdfThumbnailViewHelper.php

<?php
namespace WE\SitePackage\ViewHelpers;

/*                                                                        *
 * This script belongs to the TYPO3 Flow package "WE.SitePackage".        *
 *                                                                        *
 * It is free software; you can redistribute it and/or modify it under    *
 * the terms of the GNU Lesser General Public License, either version 3   *
 * of the License, or (at your option) any later version.                 *
 *                                                                        *
 * The TYPO3 project - inspiring people to share!                         *
 *                                                                        */

use TYPO3\Fluid\Core\ViewHelper\AbstractViewHelper;
use TYPO3\Flow\Annotations as Flow;
use TYPO3\Flow\Resource\Publishing\ResourcePublisher;
use TYPO3\Flow\Resource\Resource;
use TYPO3\Flow\Utility\Files;
use TYPO3\Neos\Domain\Repository\DomainRepository;

/**
 * ViewHelper to generate image thumbnail from a pdf resource
 *
 * @author Visay Keo <visay@web-essentials.asia>
 */
class PdfThumbnailViewHelper extends AbstractViewHelper {

	/**
	 * @var ResourcePublisher
	 * @Flow\Inject
	 */
	protected $resourcePublisher;

	/**
	 * @var DomainRepository
	 * @Flow\Inject
	 */
	protected $domainRepository;


	/**
	 * @param Resource $resource
	 * @param string   $alt
	 * @param int      $width
	 * @param int      $height
	 * @param string   $type
	 * @param string   $binary
	 *
	 * @return string
	 */
	public function render(Resource $resource, $alt = '', $width = 0, $height = 0, $type = 'png', $binary = '') {
		$currentDomain = $this->domainRepository->findOneByActiveRequest();
		$packageKey = $currentDomain->getSite()->getSiteResourcesPackageKey();

		$thumbnailDirectory = 'Packages/' . $packageKey . '/Thumbnails/';
		$hash = $resource->getResourcePointer()->getHash();

		$thumbnailPath = Files::concatenatePaths(array(FLOW_PATH_WEB, '_Resources', 'Static', $thumbnailDirectory));
		if (!file_exists($thumbnailPath)) {
			Files::createDirectoryRecursively($thumbnailPath);
		}

		$imageFile = $thumbnailPath . '/' . $hash . '.' . $type;

		if (!file_exists($imageFile)) {
			$binary = $binary ?: '/usr/bin/convert' ;
			$param = "+profile '*' -colorspace RGB -density 100";
			$pdfSource = FLOW_PATH_DATA . 'Persistent/Resources/' . $hash;
			$command = $binary . ' ' . $param . ' ' . $pdfSource . '[0] ' . $imageFile;
			exec($command);
		}

		$imageUri = $this->resourcePublisher->getStaticResourcesWebBaseUri() . $thumbnailDirectory . $hash . '.' . $type;

		$width = ($width > 0) ? 'width="' . $width . '" ' : '';
		$height = ($height > 0) ? 'height="' . $height . '" ' : '';

		$output = '<img src="' . $imageUri . '" alt="' . $alt . '" ' . $width . $height . '/>';

		return $output;
	}

}

?>