Allocate memory for a Q_GADGET inside another Q_GADGET

raphasauer

Hello everyone. Let's say I have a void *pointer to a Q_GADGET, and inside this Q_GADGET I have a pointer to another Q_GADGET. All of them are registered in the meta-object system. Is it possible, using QMetaObjects and the original void* pointer to allocate memory to this other Q_GADGET? Example code follows:

#ifndef EXAMPLE_H
#define EXAMPLE_H
#include <QObject>

//Nested Q_GADGET
struct P2D {
    Q_GADGET
    Q_PROPERTY(P2D p2d READ getP2D )
    Q_PROPERTY(float m_x READ getX WRITE setX)
    Q_PROPERTY(float m_y READ getY WRITE setY)

    P2D getP2D() {return *this;}
    float getX() {return this->m_x;}
    void setX(float x) {this->m_x = x;}
    float getY() {return this->m_y;}
    void setY(float y) {this->m_y = y;}


public:
    float m_x;
    float m_y;
}; Q_DECLARE_METATYPE(P2D)

//Main Q_GADGET
struct Player {
    Q_GADGET

public:
    enum class CarType {
        NO_CAR = 0,
        SLOW_CAR,
        FAST_CAR,
        HYPER_CAR
    }; Q_ENUM(CarType)

    Q_PROPERTY(Player player READ getPlayer)
    Q_PROPERTY(int m_speed READ getSpeed WRITE setSpeed)
    Q_PROPERTY(CarType m_carType READ getCarType)
    Q_PROPERTY(P2D* p2d READ getP2D )


    Player getPlayer() { return *this;}
    int getSpeed() {return this->m_speed;}
    void setSpeed(int speed) {this->m_speed = speed;}
    CarType getCarType() { return m_carType;}
    P2D* getP2D() {return this->p2d;}


public:
    CarType m_carType;
    int m_speed;
    P2D *p2d;

}; Q_DECLARE_METATYPE(Player)

#endif

Main:

#include <QCoreApplication>
#include <iostream>
#include <QMetaObject>
#include "example.h"
#include <QDebug>
#include <QMetaProperty>
#include <QPointer>


void gadgetExplorer(void *ptr, const char* s)
{
    //Receives Player and access its meta-object
    int typeId = QMetaType::type(s);
    const QMetaObject *mo = QMetaType::metaObjectForType(typeId);

    qInfo() << "Q_GADGET: " << mo->className();
    //QProperty 3 refers to Q_GADGET P2D
    QMetaProperty mp = mo->property(3);
    qInfo() << "Q_PROPERTY: " << mp.name();
    
    //With this given info, is it possible to allocate memory to p2d?
    
}


int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    qRegisterMetaType<Player>();
    qRegisterMetaType<P2D>();

    Player p1;
    p1.setSpeed(30);

    gadgetExplorer(&p1, "Player");


    return a.exec();
}

I think this is doable creating a method to allocate memory inside the Player Q_GADGET. However, is there other way to do it?

Thanks for your time.

raphasauer

One more example:

#include <QCoreApplication>
#include <iostream>
#include <QMetaObject>
#include "example.h"
#include <QDebug>
#include <QMetaProperty>
#include <QPointer>


void gadgetExplorer(void *ptr, const char* s)
{
    //Receives Player and access its meta-object
    int typeId = QMetaType::type(s);
    const QMetaObject *mo = QMetaType::metaObjectForType(typeId);    
    qInfo() << "Q_GADGET: " << mo->className();
    QMetaProperty mp;
    for(int i = 1; i < mo->propertyCount(); i++)
    {
        mp = mo->property(i);
        qInfo() << "Q_PROPERTY: " << mp.typeName() << "Value: " << mp.readOnGadget(ptr);
        if(int(mp.type()) == 1024)
            gadgetExplorer(ptr, mp.typeName());
    }

}


int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    qRegisterMetaType<Player>();
    qRegisterMetaType<P2D>();
    qRegisterMetaType<P2D*>();

    Player p1;
    p1.setSpeed(30);
    p1.p2d = new P2D();
    p1.p2d->setX(10.0);
    p1.p2d->setY(25.0);
    gadgetExplorer(&p1, "Player");


    return a.exec();
}

gadgetExplorer() works fine for the first Q_GADGET, but for the second one the read property doesn't work. Is it possible to access the second's Q_GADGET pointer?