如何将一个QQuickItem扩展作为子扩展添加到另一个QQuickItem扩展？

#ifndef CHILDITEM_H
#define CHILDITEM_H

#include <QQuickItem>

class ChildItem : public QQuickItem
{
    Q_OBJECT
    Q_PROPERTY(QString text READ text WRITE setText NOTIFY textChanged)

public:
    explicit ChildItem(QQuickItem *parent = nullptr);

    QString text() const;
    void setText(const QString &text);

signals:
    void textChanged();

protected:
    void paint(QPainter *painter);

private:
    QString m_text;
};

#endif // CHILDITEM_H

#include "ChildItem.h"
#include <QPainter>

ChildItem::ChildItem(QQuickItem *parent)
    : QQuickItem(parent)
{
}

QString ChildItem::text() const
{
    return m_text;
}

void ChildItem::setText(const QString &text)
{
    if (m_text != text) {
        m_text = text;
        emit textChanged();
        update();
    }
}

void ChildItem::paint(QPainter *painter)
{
    painter->drawText(boundingRect(), m_text);
}

import QtQuick 2.0
import com.example 1.0

Item {
    width: 200
    height: 200

    ChildItem {
        id: childItem
        text: "Hello World"
        anchors.centerIn: parent
    }
}