qt base64 url encode

做完base64后，发现总是报错image format error

发现：https://developer.baidu.com/forum/topic/show/244140

Qt中需要稍微转换一下

QByteArray toBase64(QString imgPath) {
    QImage image(imgPath);
    QByteArray ba;
    QBuffer buf(&ba);
    image.save(&buf, "png");
    QByteArray hexed = ba.toBase64();
    buf.close();
    return hexed;
}
toBase64(imgPath).toPercentEncoding()

核心是toPercentEncoding