How to use QSignalMapper for a list of QAction items

Question

I am developing a code snippet to perform similar, not identical actions when I click on the sub menu item list. Please check the attached snapshot. QSignalMapper is the best solution to connect multiple signals to the same slot.

But I am not able to exactly place, which signal is to be called for which slot. I have read a lot of theory about QSignalMapper,

http://qt-project.org/doc/qt-4.8/qsignalmapper.html
http://doc.qt.digia.com/qq/qq10-signalmapper.html#thesignalmapperapproach

even implemented their codes. Unlike the mentioned sample programs, my QAction objects apparently cannot be defined like we define elements inside an array, coz their names were auto-generated by the design window.

I am not able to understand, what should I place as SIGNAL here, and when should I use the setMapping function? If I use setMapping function, which parameters should I implement? I am simply not getting the concept thorough, not knowing what to do, whom to ask and making the mistake in my code here. Can you please advise me what I am doing wrong? I checked this for reference coz he had similar issue:

https://stackoverflow.com/questions/14151443/how-to-pass-a-qstring-to-a-qt-slot-from-a-qmenu-via-qsignalmapper-or-otherwise/14157471#14157471

***********************************UPDATED SECTION(as of Mar 3, '14)************************************************************************

My problem is quite similar to following question: How to add a list of QActions to a QMenu and handle them with a single slot?

I too, tried using setData in helpAction(QAction *pAction), but I am still mistaken since the only value that I get when I click on the action items in the area threshold sub menu is

0

So my updated question is, how to use the setData(const QVariant &userData) to assign indices to my action items. Please advise.

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QDebug>
#include <QSignalMapper>
namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void subMenuForThresholds();

private:
    Ui::MainWindow *ui;
    void createActions();
    QSignalMapper *pSignalMapper;

private slots:
    void interval();
    void help();
    void helpAction(QAction *pAction);
    void setAreathreshold(int value);
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "intervaldialog.h"
#include "help.h"
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    createActions();
}

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

void MainWindow::createActions()
{
    ui->actionInterval->setStatusTip(tr("Set the interval for capturing delta & reference images"));
    connect(ui->actionInterval, SIGNAL(triggered()), this, SLOT(interval()));

    subMenuForThresholds();

    ui->menuHelp->setStatusTip(tr("help "));
//    connect(ui->menuHelp, SIGNAL(triggered(QAction*)), this, SLOT(help()));
}

void MainWindow::subMenuForThresholds()
{
    pSignalMapper = new QSignalMapper(this);
//    connect(pSignalMapper, SIGNAL(mapped(int)), this, SIGNAL(/*not sure what to place here?*/);


    connect(ui->menuArea_Threshold, SIGNAL(triggered(QAction*)), this, SLOT(helpAction(QAction*)));

}

void MainWindow::setAreaThreshold()
{
   qDebug()<<value;
}


void MainWindow::interval()
{
    qDebug()<<"inside interval qdialog";

    Help help;
    help.exec();
}

void MainWindow::help()
{
    qDebug()<<"inside help qdialog";
    Help help;
    help.exec();
}

void MainWindow::helpAction(QAction *pAction)
{
    ui->action25_sec->setData(10);
    int value = pAction->data().toInt();
    qDebug()<<value;
}

Answer 1

This helped me out.

QSignalMapper *pSignalMapper = new QSignalMapper(this);
connect(pSignalMapper, SIGNAL(mapped(int)), SLOT(setAreaThreshold(int)));
connect(ui->action25_s,  SIGNAL(triggered()), pSignalMapper, SLOT(map()));
connect(ui->action50_sec,  SIGNAL(triggered()), pSignalMapper, SLOT(map()));
connect(ui->action100_sec, SIGNAL(triggered()), pSignalMapper, SLOT(map()));
connect(ui->action150_sec, SIGNAL(triggered()), pSignalMapper, SLOT(map()));
connect(ui->action200_sec, SIGNAL(triggered()), pSignalMapper, SLOT(map()));
pSignalMapper->setMapping(ui->action25_s,   25);
pSignalMapper->setMapping(ui->action50_sec,   50);
pSignalMapper->setMapping(ui->action100_sec, 100);
pSignalMapper->setMapping(ui->action150_sec, 150);
pSignalMapper->setMapping(ui->action200_sec, 200);

// and a slot
void setAreaThreshold(int value) {
 qDebug()<<value;
}