BlankPixelResponse.php

<?php


namespace Sbaam\Bundle\InviteBundle\Http;

use Symfony\Component\HttpFoundation\Response;

/**
 * Class BlankPixelResponse
 * @package Sbaam\Bundle\InviteBundle\Http
 * @author Luciano Mammino <[email protected]>
 */
class BlankPixelResponse extends Response
{
    /**
     * Base 64 encoded contents for 1px transparent gif and png
     *
     * @var array
     */
    protected static $IMAGE_CONTENT = array(
        'gif' => 'R0lGODlhAQABAJAAAP8AAAAAACH5BAUQAAAALAAAAAABAAEAAAICBAEAOw==',
        'png' => 'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAAACnej3aAAAAAXRSTlMAQObYZgAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII='
    );

    /**
     * Constructor
     *
     * @param string $type The format of the image. Accepts "gif" or "png"
     *
     * @throws \InvalidArgumentException if an invalid type is given
     */
    public function __construct($type = 'gif')
    {
        if (!array_key_exists($type, self::$IMAGE_CONTENT)) {
            throw new \InvalidArgumentException(
                sprintf('Invalid image type "%s". Allowed image types: %s', $type, json_encode(array_keys(self::$IMAGE_CONTENT)))
            );
        }

        $content = base64_decode(self::$IMAGE_CONTENT[$type]);
        parent::__construct($content);
        $this->headers->set('Content-Type', sprintf('image/%s', $type));
        $this->setPrivate();
        $this->headers->addCacheControlDirective('no-cache', true);
        $this->headers->addCacheControlDirective('must-revalidate', true);
    }
}