[solved]Qt 4.8 signalMapper doesn't work

Edoll

I have been trying to implement signal mapper. I have used the example code below.
But, this example code from 4.8 doesn't have SLOT getting signal from 'mapped'.

So, I added my own SLOT(doThings(int)). But signal mapper doesn't send any signal to the slot.
Any help would be really appreciated.

ButtonWidget::ButtonWidget(QStringList texts, QWidget *parent)
: QWidget(parent)
{
signalMapper = new QSignalMapper(this);

 QGridLayout *gridLayout = new QGridLayout;
 for (int i = 0; i < texts.size(); ++i) {
     QPushButton *button = new QPushButton(texts[i]);
     connect(button, SIGNAL(clicked()), signalMapper, SLOT(map()));
     signalMapper->setMapping(button, i);
     gridLayout->addWidget(button, i / 3, i % 3);
 }

 connect(signalMapper, SIGNAL(mapped(const QString &)),
         this, SIGNAL(clicked(int)));

 setLayout(gridLayout);

}

dheerendra

Welcome to forum. Your last connection t statement is wrong. Change string to int. it works.

Edoll

Thank you for your reply. But this code was not actually mine, I just copied Example code from QT website and just changed from string to int.

This is mine below.

mySlot method is to test if signalMapper is sending a right id value. But nothing happens with buttons clicked.

@vector<QPushButton *> button;
QSignalMapper *signalMapper;

signalMapper = new QSignalMapper(this);

for (int i = 0; i<10; i++)
{
button.push_back(newQPushButton("myButton");
QObject::connect(button[i], SIGNAL(clicked()), signalMapper, SLOT(map()));
signalMapper->setMapping(button[i], i);
}

QObject::connect(signalMapper, SIGNAL(mapped(int)), this, SLOT(mySlot(int)));

void class::mySlot(int position)
{
QMessageBox msgBox;
msgBox.setText(QString("Button #: %1").arg(position));
msgBox.exec();
}@

dheerendra

Hope you are clicking on the button. Just try with following and see how things work. Based on this you can modify your example. In your example, I did not see where the buttons are shown and where the clicked signal is coming. Just running the program nothing happens.

@QPushButton *button = new QPushButton("Pthinks");
signalMapper->setMapping(button, 1);
button.show();
QObject::connect(button[i], SIGNAL(clicked()), signalMapper, SLOT(map()));

QObject::connect(signalMapper, SIGNAL(mapped(int)), this, SLOT(mySlot(int)));

void class::mySlot(int position)
{
QMessageBox msgBox;
msgBox.setText(QString("Button #: %1").arg(position));
msgBox.exec();
}@

Edoll

Of course, clicking buttons...

BTW, what you have posted is exactly same code with mine...

I just omitted some redundant part.

Buttons are added on gridLayout
@
gridLayout->addWidget(button[i], labelRowNumber, labelColumnNumber, 1, 1, Qt::AlignRight);
@

dheerendra

yes, I have taken few things from your code and modified slightly. See the following code. Just try with simple one first and see how it works.

@QPushButton *button = new QPushButton("Pthinks");
signalMapper->setMapping(button, 1);
button.show();
QObject::connect(button, SIGNAL(clicked()), signalMapper, SLOT(map()));

QObject::connect(signalMapper, SIGNAL(mapped(int)), this, SLOT(mySlot(int)));

void class::mySlot(int position)
{
QMessageBox msgBox;
msgBox.setText(QString("Button #: %1").arg(position));
msgBox.exec();
}@

Edoll

I have already tried with another method with a single slot not using signalMapper. And it works fine. What I did is to use mySlot_test function

@
void class::mySlot_test()
{
QMessageBox msgBox;
msgBox.setText(QString("Button clicked");
msgBox.exec();
}

QObject::connect(button[i], SIGNAL(clicked()), this, SLOT(mySlot_test()));
@

When I clicked every single button, this function is called and works fine.

dheerendra

Looks like you are missing something. Here is the complete code. Just try this. Make program like the following. It will work.

@===main.cpp=====
#include "widget.h"
#include <QApplication>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Widget w;
w.show();

return a.exec&#40;&#41;;

}

====widget.h=====
#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QMessageBox>
class Widget : public QWidget
{
Q_OBJECT

public:
Widget(QWidget *parent = 0);
~Widget();
public slots:
void myslot(int);
};
===widget.cpp====

#include "widget.h"
#include <QPushButton>
#include <QSignalMapper>
Widget::Widget(QWidget *parent)
: QWidget(parent)
{
QSignalMapper *signalMapper = new QSignalMapper;
QPushButton *button = new QPushButton("Pthinks");
signalMapper->setMapping(button, 1);
button->show();
connect(button, SIGNAL(clicked()), signalMapper, SLOT(map()));
connect(signalMapper, SIGNAL(mapped(int)), this, SLOT(myslot(int)));

}

void Widget::myslot(int position)
{
QMessageBox msgBox;
msgBox.setText(QString("Button #: %1").arg(position));
msgBox.exec();;
}

Widget::~Widget()
{

}
@

Edoll

I have been trying to figure out this problem for more than a day... Thank you for providing simple code. But my program is a bit huge and mixed (more than 16,000 lines). I am using Visual Studio 2010 with osg library. And I am using Qt for GUI.

@
QsignalMapper *signalMapper = new QSignalMapper;
QPushButton *buttonTest = new QPushButton("Test");
signalMapper->setMapping(buttonTest, 1);
gridLayout>addWidget(buttonTest, 0, 0, 1, 1);

QObject::connect(buttonTest, SIGNAL(clicked()), signalMapper, SLOT(QSignalMapper::map()));
signalMapper->setMapping(buttonTest, 1);

// Check if signalMapper works ->* this doesn't work
QObject::connect(signalMapper, SIGNAL(QSignalMapper::mapped(int)), this, SLOT(mySlot(int)));
*
// Check if button clicked -> this works fine
QObject::connect(buttonTest, SIGNAL(clicked()), this, SLOT(mySlot_Test()));

void Widget::mySlot(int position)
{
QMessageBox msgBox;
msgBox.setText(QString("Button #%1").arg(position));
msgBox.exec();
}

void Widget::mySlot_Test()
{
QMessageBox msgBox;
msgBox.setText(QString("Button Clicked"));
msgBox.exec();
}
@

mySlot method is not called through signalMapper but mySlot_Test which can confirm if the button is clicked works. The button is showing without any problems. The message of "Button Clicked" pops up, but "Button #1" message windows never comes up. If mySlot_Test function goes can receive signal. There is nothing wrong with the other part of my code, such as deceleration of header file etc...

SGaist

Hi,

@QObject::connect(signalMapper, SIGNAL(QSignalMapper::mapped(int)), this, SLOT(mySlot(int)));@

is wrong, it should be

@QObject::connect(signalMapper, SIGNAL(mapped(int)), this, SLOT(mySlot(int)));@

Edoll

Why those are different? How about these?
@
QObject::connect(buttonTest, SIGNAL(clicked()), signalMapper, SLOT(QSignalMapper::map()));

QObject::connect(buttonTest, SIGNAL(clicked()), signalMapper, SLOT(map()))
@

SGaist

For connections to work with the old syntax, connect expects only the signal/slot signatures, no class name, no variable name etc.

Edoll

LoL... That did a trick... I do really appreciate your help!

Originally, I was avoiding calling osgEarth::map() for the connector. I had same methods (map() and mapped()). This is something I need to be aware of when I implement these SIGNAL-SLOT.

Thanks again! Problem Solved.

SGaist

You're welcome !

Since you have your mapper running, please update the thread title prepending [solved] so other forum users may know a solution has been found :)

Edoll

Thank you again. I have just updated title.