Question

QT - Problem connecting slot

Asked by: dogbertius

I have a simple QT4 application that I'm rewriting based on an old QT3.3 applicaiton I previously wrote. I am writing everything from scratch, so there shouldn't be any concerns with converting the project using UIC3.

Basically, it's a GUI that validates some user input. In my old code, I used QT Designer (from QT3.3) to establish custom slots and connect a signal for a pushButton that runs some code. When I got the same application compling in QT4, I can run the application, but nothing happens when I click the pushButton.

I know that QT4's designer doesn't allow for custom signal/slot assignment anymore, so I followed a tutorial from QT's homepage, utilizing the "Multiple inheritance" method of setting up signals for a UI created in QT Designer 4, as detailed at: <http://doc.trolltech.com/4.5/designer-using-a-ui-file.html>  ("Using a designer UI in your application")

For some reason, the signal/slot just won't connect. I'm so sure I have the code correct, it's just like from the example. Any help would be greatly appreciated. Thank you!

//*************************************************************************
MainImpl.CPP
//*************************************************************************
#include "ui_gpibmenu.h" //Ui_gpibmenu's main class is  "MainWindow", sorry about the poor naming scheme
#include <QWidget>
#include <QPushButton>
 
MainImpl::MainImpl(QWidget *parent)
    :QWidget(parent)
{
	//setupUi(this);  //This doesn't work, but the example says it should
	QWidget:connect(pushButtonInitDevice, SIGNAL(clicked()), this, SLOT(initButtonPress()));
 
}
 
void MainImpl::initButtonPress()
{
	cout << "GUI IS WORKING!!!" << endl; //This usually outputs the text to the command window of KDevelop
}
//*************************************************************************
//*************************************************************************
 
 
//*************************************************************************
// Main.cpp
//*************************************************************************
#include <QApplication>
#include <QtGui>
#include <QWidget>
#include <QMainWindow>
#include "mainimpl.h"
int main(int argc, char *argv[])
{
 	QApplication app(argc, argv);
	//QWidget *widget = new QWidget();
	QMainWindow * window = new QMainWindow();
	Ui::MainWindow ui;
	ui.setupUi(window);
	window->show();
	return app.exec();
 
 
 
}
//*************************************************************************
//*************************************************************************
 
 
 
 
 
//*************************************************************************
// MainImpl.h
//*************************************************************************
#ifndef MAINIMPL_H
#define MAINIMPL_H
 
#include "ui_gpibmenu.h"
 
class MainImpl: public QWidget, private Ui::MainWindow
{
Q_OBJECT
public:
    MainImpl(QWidget *parent = 0);
public slots:
    void initButtonPress();
private:
    Ui::MainWindow ui;
};
 
#endif
 
//*************************************************************************

                                  
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Asked On
2009-08-26 at 08:54:06ID24683674
Tags

QT

,

QT4

,

slots

,

signals

,

C++

Topics

QT Programming Language

,

Linux Programming

,

C++ Programming Language

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Answers

 

by: dogbertiusPosted on 2009-08-26 at 10:31:12ID: 25190118

Well, I figured it out. Really silly mistake really. In any case, it turns out that I just needed to setup my new class to inherit Ui::MainWindow and QMainWindow, and then the setupUi(this) works. Kind of disappointing though, as this is straight out of a very recent document released by TrollTech. They should update this. Also, my new main code is below.

Hopefully this helps someone else out there :) I found a similar such mistake on TrollTech forums. Cheers!

//***************************************************
//main.cpp
//***************************************************
#include <QApplication>
#include <QtGui>
#include <QWidget>
#include <QMainWindow>
#include "mainimpl.h"
int main(int argc, char *argv[])
{
 	QApplication app(argc, argv);
	MainImpl window;
	window.show();
	return app.exec();
 
}
//***************************************************
 
 
//***************************************************
//mainimpl.h
//***************************************************
#ifndef MAINIMPL_H
#define MAINIMPL_H
 
#include "ui_gpibmenu.h"
#include <QMainWindow>
 
class MainImpl: public QMainWindow, private Ui::MainWindow
{
Q_OBJECT
public:
    MainImpl(QMainWindow *parent = 0);
public slots:
    void initButtonPress();
 
};
 
#endif
 
 
//***************************************************
 
 
 
 
//***************************************************
//mainimpl.c
//***************************************************
#include "ui_gpibmenu.h"
#include "mainimpl.h"
 
 
#include <string>
#include <sstream>
#include <iostream>
#include <ctype.h>
#include <QtGui>
#include <QMainWindow>
 
using namespace std;
 
MainImpl::MainImpl(QMainWindow *parent)
    :QMainWindow(parent)
{
	setupUi(this);
	connect(pushButtonInitDevice, SIGNAL(clicked()), this, SLOT(initButtonPress()));
 
}
 
 
//***************************************************

                                              
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by: ikeworkPosted on 2009-08-26 at 10:38:39ID: 25190180

Hi dogbertius,

Its said in "Widgets and Dialogs with Auto-Connect":

  "uic automatically generates code in the dialog's setupUi() function to do this, so we only need to
   declare and implement a slot with a name that follows a standard convention:
     void on_<object name>_<signal name>(<signal parameters>);"

did you use "uic" for that class?
did you follow the naming convention?


ike

20120131-EE-VQP-002

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