server/lib/private/Preview/Image.php

<?php
/**
 * @copyright Copyright (c) 2016, ownCloud, Inc.
 *
 * @author Georg Ehrke <oc.list@georgehrke.com>
 * @author Joas Schilling <coding@schilljs.com>
 * @author josh4trunks <joshruehlig@gmail.com>
 * @author Olivier Paroz <github@oparoz.com>
 * @author Robin Appelman <robin@icewind.nl>
 * @author Thomas Müller <thomas.mueller@tmit.eu>
 * @author Thomas Tanghus <thomas@tanghus.net>
 *
 * @license AGPL-3.0
 *
 * This code is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License, version 3,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License, version 3,
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 *
 */
namespace OC\Preview;

use OCP\Files\File;
use OCP\IImage;

abstract class Image extends ProviderV2 {

	/**
	 * {@inheritDoc}
	 */
	public function getThumbnail(File $file, int $maxX, int $maxY): ?IImage {
		$maxSizeForImages = \OC::$server->getConfig()->getSystemValue('preview_max_filesize_image', 50);
		$size = $file->getSize();

		if ($maxSizeForImages !== -1 && $size > ($maxSizeForImages * 1024 * 1024)) {
			return null;
		}

		$image = new \OC_Image();

		$fileName = $this->getLocalFile($file);

		$image->loadFromFile($fileName);
		$image->fixOrientation();

		$this->cleanTmpFiles();

		if ($image->valid()) {
			$image->scaleDownToFit($maxX, $maxY);

			return $image;
		}
		return null;
	}

}