public function toString()
    {
        $output = 'data:';

        if (($this->getMediaType() !== self::DEFAULT_TYPE) || ($this->getEncoding() !== self::ENCODING_URL_ENCODED_OCTETS)) {
            $output .= $this->getMediaType();

            if ($this->getEncoding() === self::ENCODING_BASE64) {
                $output .= ';'.self::BASE64_KEYWORD;
            }
        }

        $output .= ','.$this->getEncodedData();

        return $output;
    }