How do I "transfer" an object from one window to the other?

[EVARATE]

In my MainWindow there is a button that opens the MbulbWindow. There one can change some parameters and click a Generate button which calls the generateMBulb() function which does some calculation and in the end creates an object named entity of the class internalEntity.

Now I want to "send" this entity to the MainWindow where it will be saved for later use. But how do I do that? My idea was to create the transferEntity(internalEntity& entity) signal and connect it to the addEntity(internalEntity& entity) function of the MainWindow but Qt always gives an error message similar to the following:


QObject::connect: No such signal MbulbWindow::MBulbWindow::transferEntity() in ../MandelbulbUI_rewrite/mainwindow.cpp:15
QObject::connect: (sender name: 'MbulbWindow')
QObject::connect: (receiver name: 'MainWindow')

Here are my files:

mainwindow.h:


#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QWindow>
#include <QAction>
#include "mbulbwindow.h"
#include "internalentityhandler.h"

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
MainWindow(QWidget *parent = nullptr);
~MainWindow();

private:
Ui::MainWindow *ui;
internalEntityHandler entityHandler; //Saves and manages entities
MbulbWindow *mBulbWindow = new MbulbWindow;
private slots:

//...

//Generate
void showMBGenerator();

//internal entity management
void addEntity(internalEntity& entity);

};
#endif // MAINWINDOW_H

mainwindow.cpp:


#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
{
ui->setupUi(this);

//...

//Connections
internalEntity entity;
connect(mBulbWindow, SIGNAL(MBulbWindow::transferEntity()), this, SLOT(addEntity()));
//This is where I would make the connection
}

MainWindow::~MainWindow()
{
delete ui;
}

//...

//Generate
void MainWindow::showMBGenerator(){
mBulbWindow->show();
}

//internal entity management
void MainWindow::addEntity(internalEntity& entity){
//Entity in memory:
entityHandler.addEntity(entity);

//...
}

mbulbwindow.h:


#ifndef MBULBWINDOW_H
#define MBULBWINDOW_H

#include <QDialog>
#include <vector>
#include "boolcloud.h"
#include "internalentityhandler.h"

namespace Ui {
class MbulbWindow;
}

class MbulbWindow : public QDialog
{
Q_OBJECT

public:
explicit MbulbWindow(QWidget *parent = nullptr);
~MbulbWindow();

private:
Ui::MbulbWindow *ui;

private slots:
void generateMBulb();
signals:
void transferEntity(internalEntity& entity);
};

#endif // MBULBWINDOW_H

mbulbwindow.cpp:


#include "mbulbwindow.h"
#include "ui_mbulbwindow.h"

MbulbWindow::MbulbWindow(QWidget *parent) :
QDialog(parent),
ui(new Ui::MbulbWindow)
{
ui->setupUi(this);

//Connections
connect(ui->ButtonGenerate, SIGNAL(clicked()), this, SLOT(generateMBulb()));

}

MbulbWindow::~MbulbWindow()
{
delete ui;
}

void MbulbWindow::generateMBulb(){

//Calculation of "mBulb" object...

//Create entity
internalEntity entity(mBulb, "Mandelbulb");

emit transferEntity(entity);
//This entity needs to be transferred to the MainWindow
this->close();
}