qr_example.php

<?php
public function executeQrcode(sfWebRequest $request)
{
    require_once sfConfig::get('sf_lib_dir').
                    '/vendor/phpqrcode/qrlib.php';

    $this->getResponse()->setContentType('image/png');
    QRcode::png($request->getParameter('text'));
    return sfView::NONE;
}