QWidget - Q_OBJECT makes the widget disappear

[Sir Rogers]

Ok hey guys, I have a very very weird bug. If I add the Q_OBJECT line to the class it makes it disappear. I have kept the class very small to show the bug. The class works like a charm when Q_OBJECT isn't present, but I need it to emit signals.
By disappear I mean that it doesn't show the class at all anymore on the UI, on the widget. It still somewhat works, because it creates a new window if I set the parent to NULL, indicating that the class is still somewhat operational.

rgcbutton.h

#ifndef RGCBUTTON_H
#define RGCBUTTON_H
 
#include <QWidget>
 
class rgcbutton : public QWidget
{
    //Q_OBJECT
 
public:
    rgcbutton(QWidget *parent);
    ~rgcbutton();
 
};
 
#endif // RGCBUTTON_H

#ifndef RGCBUTTON_H
#define RGCBUTTON_H

#include <QWidget>

class rgcbutton : public QWidget
{
    //Q_OBJECT

public:
    rgcbutton(QWidget *parent);
    ~rgcbutton();

};

#endif // RGCBUTTON_H

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rgcbutton.cpp

#include "rgcbutton.h"
#include <QMouseEvent>
 
rgcbutton::rgcbutton(QWidget *parent) : QWidget(parent)
{
    QImage ximg; ximg.load("skins/default/images/exit_inactive.png");
    setStyleSheet("background-image: url(skins/default/images/exit_inactive.png);");
    setFixedSize(ximg.size());
}
rgcbutton::~rgcbutton() { }

#include "rgcbutton.h"
#include <QMouseEvent>

rgcbutton::rgcbutton(QWidget *parent) : QWidget(parent)
{
    QImage ximg; ximg.load("skins/default/images/exit_inactive.png");
    setStyleSheet("background-image: url(skins/default/images/exit_inactive.png);");
    setFixedSize(ximg.size());
}
rgcbutton::~rgcbutton() { }

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Implementation (Some random QWidget

login::login(QWidget *parent) : QWidget(parent, Qt::FramelessWindowHint), ui(new Ui::login)
{
    ui->setupUi(this); move(QApplication::desktop()->geometry().center() - rect().center());
 
    rgcbutton *TT = new rgcbutton(this);
    TT->move(20, 20);
}

login::login(QWidget *parent) : QWidget(parent, Qt::FramelessWindowHint), ui(new Ui::login)
{
    ui->setupUi(this); move(QApplication::desktop()->geometry().center() - rect().center());

    rgcbutton *TT = new rgcbutton(this);
    TT->move(20, 20);
}

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I'm stuck on this and I don't know what's happening. Your help is very much appreciated. This is the warning I get when I compile without Q_OBJECT. Maybe it helps: rgcbutton.h:0: Warning: No relevant classes found. No output generated.


Regards,
Sir Rogers

[Sir Rogers]

I have no idea why, but adding another widget into the rgcbutton class solves the problem:

QWidget *randomWidget;
randomWidget = new QWidget(this);

This really doesn't make sense.

[wysota]

Your code doesn't make much sense either Use QLabel with QPixmap instead of your class.

[Sir Rogers]

I narrowed it down to a basic level so it was easier to read. I'm using it to create a button with images. I need the mouseMoveEvent for that.

[wysota]

But you don't need the stylesheet part. Having a paint event instead is better. So is defining sizeHint().

[Sir Rogers]

Could you please explain in code what you mean? I'm not following.

[wysota]

Open up Qt Assistant and type in "paintEvent", then read the page about QWidget that pops up.