PathProcessorImageStyles.php

<?php

namespace Drupal\image\PathProcessor;

use Drupal\Core\PathProcessor\InboundPathProcessorInterface;
use Drupal\Core\StreamWrapper\StreamWrapperManagerInterface;
use Symfony\Component\HttpFoundation\Request;

/**
 * Defines a path processor to rewrite image styles URLs.
 *
 * As the route system does not allow arbitrary amount of parameters convert
 * the file path to a query parameter on the request.
 *
 * This processor handles two different cases:
 * - public image styles: In order to allow the webserver to serve these files
 *   directly, the route is registered under the same path as the image style so
 *   it took over the first generation. Therefore the path processor converts
 *   the file path to a query parameter.
 * - private image styles: In contrast to public image styles, private
 *   derivatives are already using system/files/styles. Similar to public image
 *   styles, it also converts the file path to a query parameter.
 */
class PathProcessorImageStyles implements InboundPathProcessorInterface {
    
    /**
     * The stream wrapper manager service.
     *
     * @var \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface
     */
    protected $streamWrapperManager;
    
    /**
     * Constructs a new PathProcessorImageStyles object.
     *
     * @param \Drupal\Core\StreamWrapper\StreamWrapperManagerInterface $stream_wrapper_manager
     *   The stream wrapper manager service.
     */
    public function __construct(StreamWrapperManagerInterface $stream_wrapper_manager) {
        $this->streamWrapperManager = $stream_wrapper_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public function processInbound($path, Request $request) {
        $directory_path = $this->streamWrapperManager
            ->getViaScheme('public')
            ->getDirectoryPath();
        if (strpos($path, '/' . $directory_path . '/styles/') === 0) {
            $path_prefix = '/' . $directory_path . '/styles/';
        }
        elseif (strpos($path, '/system/files/styles/') !== FALSE) {
            $path_prefix = '/system/files/styles/';
            $path = substr($path, strpos($path, $path_prefix), strlen($path));
        }
        else {
            return $path;
        }
        // Strip out path prefix.
        $rest = preg_replace('|^' . preg_quote($path_prefix, '|') . '|', '', $path);
        // Get the image style, scheme and path.
        if (substr_count($rest, '/') >= 2) {
            list($image_style, $scheme, $file) = explode('/', $rest, 3);
            // Set the file as query parameter.
            $request->query
                ->set('file', $file);
            return $path_prefix . $image_style . '/' . $scheme;
        }
        else {
            return $path;
        }
    }

}