Q_GADGET 中 Q_GAGDET 的 readOnGadget 未按预期工作

问题描述

我有一个“顶级”Q_GADGET，在这个 Q_GADGET 中，我有一个指向另一个 Q_GADGET 的指针。我正在尝试使用函数 readOnGadget 来显示两个对象存储的值。我可以用顶级 Q_GADGET 做到这一点，但是从内部 Q_GADGET 读取的值是错误的。这是我的代码：

Q_GADGETS：

#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)



public:
    float m_x;
    float m_y;
    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;}

}; 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

主要内容：

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

void* pointer = nullptr;

void gadgetExplorer(void *ptr,const char* s)
{
    //Receives pointer and access its Meta-object
    qInfo() << "Pointer received is: " << ptr;
    int typeId = QMetaType::type(s);
    const QMetaObject *mo = QMetaType::MetaObjectForType(typeId);
    //Prints class name
    qInfo() << "Q_GADGET: " << mo->className();

    //Iterates through properties
    QMetaProperty mp;
    for(int i = 1; i < mo->propertyCount(); i++)
    {
        mp = mo->property(i);
        qInfo() << "Q_PROPERTY: " << mp.name() << "Value: " << mp.readOnGadget(ptr);

        //1024 = user defined,so it's another gadget (P2D)
        if(int(mp.type()) == 1024)
            gadgetExplorer(pointer,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);
    qInfo() << "Pointer to inner Q_GADGET: " << &p1.p2d;
    pointer = &p1.p2d;
    gadgetExplorer(&p1,"Player");
    qInfo() << "Value of m_x outside funtion :" << p1.p2d->getX();


    return a.exec();
}

我从代码中得到的输出是：

Pointer to inner Q_GADGET:  0x7ffdb82e3418
Pointer received is:  0x7ffdb82e3410
Q_GADGET:  Player
Q_PROPERTY:  m_speed Value:  QVariant(int,30)
Q_PROPERTY:  m_carType Value:  QVariant(int,-1204931552)
Q_PROPERTY:  p2d Value:  QVariant(P2D*,)
Pointer received is:  0x7ffdb82e3418
Q_GADGET:  P2D
Q_PROPERTY:  m_x Value:  QVariant(float,2.85026e+31)
Q_PROPERTY:  m_y Value:  QVariant(float,3.09603e-41)
Value of m_x outside funtion : 10

我期望 m_x 和 m_y 的值分别为 10 和 25。我传递给 readOnGadget 的指针似乎是正确的。全局指针仅用于示例。我做错了什么？

解决方法

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c++pointers qmetaobject qt qt qt