Signal & Slots problem on menus

Stefanoxjx

Hi, I've a problem with Signals & Slots in menus.
I don't understand why it don't work.

Thi is the header file:

#ifndef SER_H
#define SER_H

#include <QMenu>
#include <QAction>
#include <QToolBar>
#include <QString>
#include <QMainWindow>

class Ser : public QMainWindow
{
    Q_OBJECT

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

private:
    const QString     APPNAME       = "Serial Block";
    const QString     APPVERSION    = "0.1b";

    QMenu       *m_AboutMenu;
    QAction     *a_AboutSerBlock;
    QAction     *a_AboutQt;

    QMenu       *m_ExitMenu;


private slots:
    void    on_Quit            (void);
    void    on_AboutSerBlock    (void);
    void    on_AboutQt         (void);
};
#endif // SER_H

and this is the code file:

#include <QApplication>
#include <QMenuBar>
#include <QScreen>
#include <QRect>
#include <QGuiApplication>
#include <QMessageBox>
#include <QFileInfo>
#include <QDebug>
#include "ser.h"

Ser::Ser(QWidget *parent) : QMainWindow(parent)
{
    QMenuBar *pMenuBar = new QMenuBar(this);
    setMenuBar(pMenuBar);

    m_AboutMenu = new QMenu("About", this);
    a_AboutSerBlock = new QAction("Ser Block", this);
    a_AboutQt = new QAction("Qt", this);
    m_AboutMenu->addAction(a_AboutSerBlock);
    m_AboutMenu->addAction(a_AboutQt);
    this->menuBar()->addMenu(m_AboutMenu);
    connect(a_AboutSerBlock, SIGNAL(triggered()), this, SLOT(on_AboutSerBlock()));
    connect(a_AboutQt, SIGNAL(triggered()), this, SLOT(on_AboutQt()));

    m_ExitMenu = new QMenu("Exit", this);
    this->menuBar()->addMenu(m_ExitMenu);
    connect(m_ExitMenu, SIGNAL(triggered()), this, SLOT(on_Quit()));
}

Ser::~Ser()
{}

void Ser::on_AboutSerBlock(void)
{
    qDebug() << "About SerBlock";
}

void Ser::on_AboutQt(void)
{
    QMessageBox::aboutQt(this);
}

void Ser::on_Quit(void)
{
    QApplication::quit();
}

Only AboutQt works.
Can you help me?
Thanks.

jsulm

@Stefanoxjx said in Signal & Slots problem on menus:

connect(m_ExitMenu, SIGNAL(triggered()), this, SLOT(on_Quit()));

This line should actually trigger a warning at runtime as there is no such signal in QMenu.
Correct signal is: https://doc.qt.io/qt-5/qmenu.html#triggered - Hint: it has a parameter.

Christian Ehrlicher

To avoid such errors please us the new signal slot syntax: https://doc.qt.io/qt-5/signalsandslots.html

Stefanoxjx

Hi, thanks for your help.
Now I corrected the problem and works fine.
But, I would like to ask you why in this code, only signals aboutToHide aboutToShow works?

    m_Exit = new QMenu("Exit", this);
    this->menuBar()->addMenu(m_Exit);
    //connect(m_Exit, SIGNAL(aboutToShow()), this, SLOT(on_Quit())); //Work
    connect(m_Exit, SIGNAL(aboutToHide()), this, SLOT(on_Quit()));     //Work
   //connect(m_Exit, SIGNAL(hovered(QAction *)), this, SLOT(on_Quit(QAction *))); //Doesn't work
   //connect(m_Exit, SIGNAL(triggered(QAction *)), this, SLOT(on_Quit(QAction *))); //Doesn't work

While with hovered and triggered doesn't works.
With hovered and triggered the prototype of slot is with parameters: void on_Quit(QAction *action);
and method is the same void Ser::on_Quit(QAction *action);
For this specific case, is aboutToShow the correct signal?
Thaks.

Christian Ehrlicher

Again: please use the new signal/slot syntax to see if the signal and slot match during build time.

Stefanoxjx

Many thanks for help.
Now I understand :)