Qt Protobuf 可变获取器

message Point {
    double x = 1;
    double y = 2;
}

message Line {
    Point start = 1;
    Point end = 2;
}

class Line : public QProtobufMessage
{
    const Point &start() const &;
    Point &mutStart() &;
    ...

    const Point &end() const &;
    Point &mutEnd() &;
    ...
}

Line line;// 设置线条起点为 (5.0, 5.0)line.mutStart().setX(5.0); line.mutStart().setY(5.0);// 设置线条终点为 (10.0, 20.0)line.mutEnd().setX(10.0); line.mutEnd().setY(20.0);// 显示线条数据qDebug().nospace() << "start: (" << line.start().x() << "," << line.start().y() << ") "
   "end: ("<<line.end().x()<< ","<<line.end().y()<< ")";