ThumbnailController.php

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<?php
declare(strict_types = 1);
namespace TYPO3\CMS\Backend\Controller\File;

/*
 * This file is part of the TYPO3 CMS project.
 *
 * It is free software; you can redistribute it and/or modify it under
 * the terms of the GNU General Public License, either version 2
 * of the License, or any later version.
 *
 * For the full copyright and license information, please read the
 * LICENSE.txt file that was distributed with this source code.
 *
 * The TYPO3 project - inspiring people to share!
 */

use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use TYPO3\CMS\Core\Http\Response;
use TYPO3\CMS\Core\Resource\ProcessedFile;
use TYPO3\CMS\Core\Resource\ResourceFactory;
use TYPO3\CMS\Core\Utility\ArrayUtility;
use TYPO3\CMS\Core\Utility\GeneralUtility;

class ThumbnailController
{
    protected $defaultConfiguration = [
        'width' => 64,
        'height' => 64,
        'crop' => null,
    ];

    public function render(ServerRequestInterface $request): ResponseInterface
    {
        try {
            $parameters = $this->extractParameters($request->getQueryParams());
            $response = $this->generateThumbnail(
                $parameters['fileId'] ?? null,
                $parameters['configuration'] ?? []
            );
        } catch (\TYPO3\CMS\Core\Resource\Exception $exception) {
            // catch and handle only resource related exceptions
            $response = $this->generateNotFoundResponse();
        }

        return $response;
    }

    protected function extractParameters(array $queryParameters)
    {
        $expectedHash = GeneralUtility::hmac(
            $queryParameters['parameters'] ?? '',
            ThumbnailController::class
        );
        if (!hash_equals($expectedHash, $queryParameters['hmac'] ?? '')) {
            throw new \InvalidArgumentException(
                'HMAC could not be verified',
                1534484203
            );
        }

        return json_decode($queryParameters['parameters'] ?? null, true);
    }

    protected function generateThumbnail($fileId, array $configuration): ResponseInterface
    {
        $file = ResourceFactory::getInstance()->getFileObject($fileId);
        if (empty($file) || $file->isMissing()) {
            return $this->generateNotFoundResponse();
        }

        $processingConfiguration = $this->defaultConfiguration;
        ArrayUtility::mergeRecursiveWithOverrule(
            $processingConfiguration,
            $configuration
        );

        $processedImage = $file->process(
            ProcessedFile::CONTEXT_IMAGECROPSCALEMASK,
            $processingConfiguration
        );
        $filePath = $processedImage->getForLocalProcessing(false);
        return new Response($filePath, 200, [
            'Content-Type' => $processedImage->getMimeType()
        ]);
    }

    protected function generateNotFoundResponse(): ResponseInterface
    {
        return new Response('', 404);
    }
}