maccms10/application/index/controller/Qrcode.php

<?php
namespace app\index\controller;

use think\Controller;
use app\common\util\Qrcode as QR;

class Qrcode extends Controller
{
    public function __construct()
    {
        parent::__construct();
    }

    public function index()
    {
        $param = input();
        $url = $param['url'];
        if(!empty($url) && filter_var($url, FILTER_VALIDATE_URL)){
            ob_end_clean();
            header('Content-Type:image/png;');
            QR::png($url, false, QR_ECLEVEL_M, 10, 2);
        }
        die;
    }
}