Connection problem with menubar using Designer

[nikau]

Hi,

This seems so simple but I haven't been able to figure it out yet.. All help will be appreciated :)

I have tried to create a Mainwindow (mainwidget) with menubar holding an entry "Help", and I have created an "aboutAction"-item and dragged it into the help menu using the designer! Saved as main.ui! (check attachment)

I have three other files: mainwindow.cpp, mainwindow.h and main.cpp (see below) and it seems to compile as it should but when I try to execute the About action nothing happens.
I have tested the about() function by just executing it on program start and it shows a QMessageBox as intended, Now why doesn't the line:

connect( aboutAction, SIGNAL(triggered()), this, SLOT(about()) );

connect( aboutAction, SIGNAL(triggered()), this, SLOT(about()) );

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...seem to connect the menu-entry with the function

Thanks in advance :

Nikau


mainwindow.cpp

#include <QApplication>
#include <QStatusBar>
#include <QMessageBox>
#include "mainwindow.h"
 
Mainwindow::Mainwindow( QWidget *parent ) : QMainWindow( parent )
{
 
ui.setupUi( this );
createActions();
statusBar()->showMessage( tr("Done") );
 
}
 
void Mainwindow::about()//works
{
  QMessageBox::about( this, tr("About Mainwindow"),
		      tr("<h2>Mainwindow v. 0.01</h2>\n"
			 "An application to help test various aspects of QT4\n"
			 "Thanks to anybody helping out :-)\n") );
}
 
void Mainwindow::createActions()
{
  aboutAction = new QAction(tr("&About"), this);
   connect( aboutAction, SIGNAL(triggered()), this, SLOT(about()) );
}

#include <QApplication>
#include <QStatusBar>
#include <QMessageBox>
#include "mainwindow.h"

Mainwindow::Mainwindow( QWidget *parent ) : QMainWindow( parent )
{

ui.setupUi( this );
createActions();
statusBar()->showMessage( tr("Done") );
 
}

void Mainwindow::about()//works
{
  QMessageBox::about( this, tr("About Mainwindow"),
		      tr("<h2>Mainwindow v. 0.01</h2>\n"
			 "An application to help test various aspects of QT4\n"
			 "Thanks to anybody helping out :-)\n") );
}

void Mainwindow::createActions()
{
  aboutAction = new QAction(tr("&About"), this);
   connect( aboutAction, SIGNAL(triggered()), this, SLOT(about()) );
}

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mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include "ui_Main.h"
 
class QAction;
class QTextEdit;
class QMenu;
 
class Mainwindow : public QMainWindow
{
  Q_OBJECT
 
public:
  Mainwindow( QWidget *parent = 0 );
 
protected:
 
private slots:
  void createActions();
  void about();
 
 
private:
 
  QAction *aboutAction;
  Ui::MainWindow ui;
};
 
#endif // MAINWINDOW_H

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "ui_Main.h"

class QAction;
class QTextEdit;
class QMenu;

class Mainwindow : public QMainWindow
{
  Q_OBJECT
  
public:
  Mainwindow( QWidget *parent = 0 );
  
protected:

private slots:
  void createActions();
  void about();


private:
    
  QAction *aboutAction;
  Ui::MainWindow ui;
};
  
#endif // MAINWINDOW_H

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main.cpp

#include <QApplication>
 
#include "Mainwindow.h"
 
int main( int argc, char **argv )
{
  QApplication app( argc, argv );
 
  (new Mainwindow)->show();
 
  return app.exec();
}

#include <QApplication>

#include "Mainwindow.h"

int main( int argc, char **argv )
{
  QApplication app( argc, argv );
  
  (new Mainwindow)->show();
  
  return app.exec();
}

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[calhal]

You've declared aboutAction inside your UI with QtDesigner, so you should refere to it like this:

connect( &ui.aboutAction, SIGNAL(triggered()), this, SLOT(about()) );

connect( &ui.aboutAction, SIGNAL(triggered()), this, SLOT(about()) );

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If you run your code from console I guess you'll get message that object aboutAction doesn't exist.

[nikau]

You've declared aboutAction inside your UI with QtDesigner, so you should refere to it like this:

connect( &ui.aboutAction, SIGNAL(triggered()), this, SLOT(about()) );

connect( &ui.aboutAction, SIGNAL(triggered()), this, SLOT(about()) );

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If you run your code from console I guess you'll get message that object aboutAction doesn't exist.

Actually what seemed to work is the following

connect( ui.aboutAction, SIGNAL(triggered()), this, SLOT(about()) );

connect( ui.aboutAction, SIGNAL(triggered()), this, SLOT(about()) );

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When would I use the &??

I don't recal having to call ui.action when doing this...

Well thank you for helping out :-)

[calhal]

Ups, I was writing fast from my memory

I think the answer is in QtAssistant:

bool QObject::connect ( const QObject * sender, const char * signal, 
const QObject * receiver, const char * method,
Qt::ConnectionType type = Qt::AutoConnection )   [static]

bool QObject::connect ( const QObject * sender, const char * signal, 
const QObject * receiver, const char * method,
Qt::ConnectionType type = Qt::AutoConnection )   [static]

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