[SOLVED] Parent and Child Window Communication in Qt - Child Window opens twice

[srivatsa]

I have two windows, one parent and one child. In parent window, I have a Next button, which onClick()'ed, opens up child window, but in my case two child windows are opening, what is the mistake am doing!?

Here are my codes:

.h files

mainwindow.h

@#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <info.h>
#include <QtGui>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow {
Q_OBJECT
public:
MainWindow(QWidget *parent = 0);
~MainWindow();

protected:
void changeEvent(QEvent *e);

private:
Ui::MainWindow *ui;
void setSignals();

private slots:
void process();
};

#endif // MAINWINDOW_H@

info.h

@#ifndef INFO_H
#define INFO_H

#include <QMainWindow>

namespace Ui {
class info;
}

class info : public QMainWindow {
Q_OBJECT
public:
info(QWidget *parent = 0);
~info();

protected:
void changeEvent(QEvent *e);

private:
Ui::info *ui;
};

#endif // INFO_H@

.cpp files

mainwindow.cpp

@#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtGui/QApplication>

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
setSignals();
}

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

void MainWindow::changeEvent(QEvent *e)
{
QMainWindow::changeEvent(e);
switch (e->type()) {
case QEvent::LanguageChange:
ui->retranslateUi(this);
break;
default:
break;
}
}

void MainWindow::setSignals(){
connect(ui->pushButton,SIGNAL(clicked()),this,SLOT(process()));
connect(ui->pushButton_2,SIGNAL(clicked()),this,SLOT(close()));
}

void MainWindow::process(){
info *i;
i = new info;
this -> hide();
i -> show();
}@

info.cpp

@#include "info.h"
#include "ui_info.h"

info::info(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::info)
{
ui->setupUi(this);
}

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

void info::changeEvent(QEvent *e)
{
QMainWindow::changeEvent(e);
switch (e->type()) {
case QEvent::LanguageChange:
ui->retranslateUi(this);
break;
default:
break;
}
}@

main.cpp

@#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}@

[tzander]

did you double click on the button?

did you add a signal connection in your designer file?

[srivatsa]

Thank you Thomas for your reply. I didn't double click on button... Signals and Slots are assigned in the first Window, are they required in second window? Please explain...

Yeah here is the ui_mainwindow.h file:

@pushButton = new QPushButton(widget);
pushButton->setObjectName(QString::fromUtf8("pushButton"));

    horizontalLayout->addWidget(pushButton);

    pushButton_2 = new QPushButton(widget);
    pushButton_2->setObjectName(QString::fromUtf8("pushButton_2"));

    horizontalLayout->addWidget(pushButton_2);

    MainWindow->setCentralWidget(centralWidget);
    mainToolBar = new QToolBar(MainWindow);
    mainToolBar->setObjectName(QString::fromUtf8("mainToolBar"));
    MainWindow->addToolBar(Qt::TopToolBarArea, mainToolBar);

    retranslateUi(MainWindow);
    QObject::connect(pushButton, SIGNAL(clicked()), MainWindow, SLOT(process()));
    QObject::connect(pushButton_2, SIGNAL(clicked()), MainWindow, SLOT(close()));

    QMetaObject::connectSlotsByName(MainWindow);@

[tzander]

Ah, that explains it :)

Your ui_mainwindow.h file has a connect, which means you added it in the QtDesigner.
You again have the same connect in void MainWindow::setSignals(), which I guess you typed manually.
So with two connects, you get two calls to process()

Remove one set of connects to solve this :)

[srivatsa]

:) Yeah you are absolutely right.... thanks a lot...