ManaPHP\Security\Captcha::generate PHP Метод

    public function generate($width = 100, $height = 30, $ttl = 300)
    {
        $code = '';
        $charsetCount = strlen($this->_charset);
        for ($i = 0; $i < $this->_length; $i++) {
            $code .= $this->_charset[mt_rand() % $charsetCount];
        }
        if (class_exists('Imagick')) {
            $response = $this->_generateByImagic($code, $width, $height);
        } elseif (function_exists('gd_info')) {
            $response = $this->_generateByGd($code, $width, $height);
        } else {
            throw new CaptchaException('`captcha` service is not support, please install `gd` or `imagic` extension first');
        }
        $captchaData = ['code' => $code, 'created_time' => time(), 'ttl' => $ttl];
        $this->session->set($this->_sessionVar, $captchaData);
        return $response;
    }