how to transferred QLineSeries from c++ to qml

Wallace Stevens

version 6.8
I pass the c++ QLinSeries into qml through signals and slots,Slot functions trigger normally,but the lineSeries parameter of the qml addSeries function is empty; it has no properties.

I read this document.Once a class is registered as a QML type, it can be used as a data type for exchanging data between QML and C++. Isn't QLineSeries already registered with the qml type? Its type in qml is LineSeries.

cpp

#pragma once
#include <QObject>
#include <QLineSeries>

class MainWindowViewModel : public QObject
{
    Q_OBJECT
public:
    void addSeries(QLineSeries *data);
signals:
    void seriesAdded(QLineSeries *data);
};

main.cpp

    QList<QPointF> dataList;
    ...
    QLineSeries *lineSeries = new QLineSeries();
    lineSeries->append(dataList);
    lineSeries->setColor(QColor("black"));

    QQmlApplicationEngine engine;

    MainWindowViewModel *viewModel = new MainWindowViewModel();

    engine.loadFromModule("chromChart", "MainWindow");

    QObject::connect(viewModel, SIGNAL(seriesAdded(QLineSeries *)), engine.rootObjects()[0], SLOT(addSeries(QLineSeries *)));
//emit signals
    viewModel->addSeries(lineSeries);

qml

    function addSeries(lineSeries: LineSeries) {
        try {
            console.log("trigger slot function")
            graphsView.addSeries(lineSeries);

            for (var prop in lineSeries) {
                console.log("Object item:", prop, "=", lineSeries[prop]);
            }

        } catch (e) {
            console.log(e);
        }
    }