Solved: Q_OBJECT didn't work

[romeo.rbw]

Hi...
I made two dialogs, one of them using signal-slot. Before I wrote Q_OBJECT on the class, there are messages:

Object::connect: No such slot QDialog::on_buttonCamera_clicked()
Object::connect: (sender name: 'buttonCamera')
Object::connect: (receiver name: 'DialogSetup')

I put the Q_OBJECT on the class but there are many errors after that, the error message are:

LNK2001: unresolved external symbol "public virtual struct QMetaObject const...
LNK2001: unresolved external symbol "public virtual void*__thiscall DialogSetup....
LNK2001: unresolved external symbol "public virtual int*__thiscall DialogSetup....
LNK1120: 3 unresolved externals

Would you help me and give some suggestion? Here is the code:

dialogsetup.h:
@
#ifndef DIALOGSETUP_H
#define DIALOGSETUP_H

#include <QDialog>
#include <QTime>

#include "ui_dialogsetup.h"

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>

using namespace cv;
using namespace std;

class DialogSetup : public QDialog
{
Q_OBJECT //???

public:
DialogSetup( QWidget *parent=0 );

protected:
void timerEvent(QTimerEvent *event);

private slots:
void on_buttonCamera_clicked();

private:
Ui::DialogSetup ui;

};

#endif // DIALOGSETUP_H
@

dialogsetup.cpp

@
#include "dialogsetup.h"

DialogSetup::DialogSetup( QWidget *parent ) : QDialog( parent )
{
ui.setupUi(this);
connect(ui.buttonCamera, SIGNAL(clicked()),
this, SLOT(on_buttonCamera_clicked()) );
}

void DialogSetup::on_buttonCamera_clicked()
{
ui.label_info->setText(QString("test button click"));
}

void DialogSetup::timerEvent(QTimerEvent *event)
{
}
@

Thanks

[Sam]

Add

@namespace Ui {
class DialogSetup;
}@

In the private section you need to declare the Ui like

.h
@Ui::DialogSetup *ui;@

cpp
@DialogSetup::DialogSetup( QWidget *parent ) : QDialog( parent ) ,
ui(new Ui::DialogSetup)
{
ui->setupUi(this);
connect(ui->buttonCamera, SIGNAL(clicked()), this, SLOT(on_buttonCamera_clicked()) );
}@

[Jeroentjehome]

Hi there,
When using the designer you get a ui pointer to your form. So the connect should be made with ui->buttonCamera.
AFAIK the Q_OBJECT isn't needed in your class definition because you inherit from QDialog which already is a Q_OBJECT.
You better check the connect option again. Somethings gets wrong there. A good way is to comment the connect. See if it compiles, runs and shows the correct dialog. Then start the connect options.
greetz

[guziemic]

Hi,

Could you post .pro file. I think that reason of unresolved symbols is missing line like

@
HEADERS += DialogSetup.h //file name of header class
@

In case when you are using signals and slots in your derivative class I think that you need to add Q_OBJECT macro. In other case you do not need it.

[romeo.rbw]

Thanks for reply...it still cannot work, there are 4 error messages like before. May be is there another suggestion?
Thanks.

[Sam]

Ok then the best thing is that you can zip your project and upload it somewhere and share the link here. So that we can have a look and do the needful. :)

[romeo.rbw]

In the .pro file, there is already dialogsetup.h on the HEADER section.

[Sam]

This seems to work

.h

@#include <QDialog>
#include <QString>
#include <QTimerEvent>

namespace Ui {
class DialogSetup;
}

class DialogSetup : public QDialog
{
Q_OBJECT

public:
explicit DialogSetup(QWidget *parent = 0);
~DialogSetup();

protected:
void timerEvent(QTimerEvent *event);

private slots:
void onButtonCameraClicked();

private:
Ui::DialogSetup *ui;
};@

.cpp

@DialogSetup::DialogSetup(QWidget *parent) :
QDialog(parent),
ui(new Ui::DialogSetup)
{
ui->setupUi(this);
connect(ui->pushButtonCamera,SIGNAL(clicked()),SLOT(onButtonCameraClicked()));

}

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

void DialogSetup::timerEvent(QTimerEvent *event)
{

}

void DialogSetup::onButtonCameraClicked()
{
ui->labelInfo->setText(QString("test button click"));
}@

Also make sure that when you write your own slots try not to use "on_" prefix. Otherwise it give
" QObject::no such slot on....."

[dbzhang800]

[quote author="romeo.rbw" date="1343892052"]
I put the Q_OBJECT on the class but there are many errors after that, the error message are:

LNK2001: unresolved external symbol "public virtual struct QMetaObject const...
LNK2001: unresolved external symbol "public virtual void*__thiscall DialogSetup....
LNK2001: unresolved external symbol "public virtual int*__thiscall DialogSetup....
LNK1120: 3 unresolved externals

[/quote]

Do not forget to run "qmake" again after you adding Q_OBJECT.

[romeo.rbw]

Thank you for every reply and your suggestion, it works now. The signal-slot works. The code become:

.h
@
#ifndef DIALOGSETUP_H
#define DIALOGSETUP_H

#include <QDialog>

namespace Ui {
class DialogSetup;
}

class DialogSetup : public QDialog
{
Q_OBJECT

public:
explicit DialogSetup(QWidget *parent = 0);
~DialogSetup();

private:
Ui::DialogSetup *ui;

private slots:
void doButtonCameraClick();
};

#endif // DIALOGSETUP_H
@

.cpp

@
#include "dialogsetup.h"
#include "ui_dialogsetup.h"

DialogSetup::DialogSetup(QWidget *parent) :
QDialog(parent),
ui(new Ui::DialogSetup)
{
ui->setupUi(this);
connect(ui->buttonCamera, SIGNAL(clicked()),
this, SLOT(doButtonCameraClick()) );
}

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

void DialogSetup::doButtonCameraClick(){
ui->labelTestSetup->setText(QString("Camera On"));
}

@

cheers,
romeo-