Program Crashing because of Singal [need help!]

[21altf]

I have a program that works fine without signals, but when I add them I start having trouble.

Basecally, I'm building a QSplashScreen for this program and since this is a short program it doesnt hold very long. So I Tryed to create an alternative class with a especific slot for terminating this program using QTimer::start(ms);

the problem is, I dont want my main widget to start b4 this QSpalshScreen is closed. So I added a Signal, thatway when I terminate the QSplashScreen I would emit a signal and my QMainWindow would attach it to SLOT(show()).

Whats happening is: When the QSplashScreen terminates the program crashes with this error 255.

my program is:

--QSS.h--
#ifndef QSS_H
#define QSS_H
#include <QSplashScreen>
#include <QTimer>
#include <QWidget>
#include <QObject>
#include <QtGui>

class QMainWindow;

class QSS: public QSplashScreen {

Q_OBJECT

public:
explicit QSS(QSplashScreen *parent = 0);
void criarTimer();

public slots:
void fechar();

signals:
void fechou();
};

#endif // QSS_H


--QSS.cpp--

#include <QSS.h>
#include <QWidget>
#include <QObject>
#include <QSplashScreen>

QSS::QSS(QSplashScreen *parent) :
QSplashScreen(parent)
{
}

//slots
void QSS::fechar()
{
this->~QSplashScreen();
emit fechou();
}

//funções públicas
void QSS::criarTimer()
{
QTimer *tempo = new QTimer;
tempo->setSingleShot(true);
QObject::connect(tempo,SIGNAL(timeout()),this,SLOT (fechar()));
tempo->start(3000);

}


---main.cpp---

#include <QtGui/QApplication>
#include <QSplashScreen>
#include <QSS.h>
#include "teste3mainwindow.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QSS *splash = new QSS;

splash->setPixmap(QPixmap(":/images/circulo.png"));
splash->show();

Qt::Alignment topRight = Qt::AlignRight | Qt::AlignTop;
splash->showMessage(QObject::tr("Setting up..."),topRight,Qt::black);


teste3MainWindow w;
splash->criarTimer();
QObject::connect(splash,SIGNAL(fechou()),&w,SLOT(s how()));




return a.exec();
}


Tnx

[nix]

That's normal after deleting the QSplashScreen base you should not do any stuff with signal or metadata.

Why don't do that :

//slots
void QSS::fechar()
{
hide();
emit fechou();
close();
}

//slots
void QSS::fechar()
{
hide();
emit fechou();
close();
}

To copy to clipboard, switch view to plain text mode 

and add a Qt::WA_DeleteOnClose flag on your splashscreen (or use deleteLater() ).

And please, use CODE TAG!!

[ChrisW67]

//slots
void QSS::fechar()
{
this->~QSplashScreen();
emit fechou();
}

//slots
void QSS::fechar()
{
this->~QSplashScreen();
emit fechou();
}

To copy to clipboard, switch view to plain text mode 

You are destroying the QSplashScreen underpinning your derived QSS splash screen and then trying to use the object. It is hardly surprising this crashes. I don't know of any circumstance under which you would call a destructor directly.

Take nix's advice including the Qt::WA_DeleteOnClose flag to avoid the resource leak you have at the moment (or put it on the stack). You are also leaking memory by allocating a QTimer on the heap, not setting a parent, and then discarding the pointer to it. No need to create a timer explicitly. Just use the QTimer::singleShot() static function.

[21altf]

Thanks for the tip!

Both advices where very good and it does just what is meant too.

And sorry, I didn't know how to use code tag... I'll learn for next time.

#THIS IS ME EDITING THIS POST. Searched and now its good to go with the CodeTag. Thanks!

--QSS.h--
#ifndef QSS_H
#define QSS_H
#include <QSplashScreen>
#include <QTimer>
#include <QWidget>
#include <QObject>
#include <QtGui>
 
class QMainWindow;
 
class QSS: public QSplashScreen {
 
Q_OBJECT
 
public:
explicit QSS(QSplashScreen *parent = 0);
void criarTimer();
 
public slots:
void fechar();
 
signals:
void fechou();
};
 
#endif // QSS_H

--QSS.h--
#ifndef QSS_H
#define QSS_H
#include <QSplashScreen>
#include <QTimer>
#include <QWidget>
#include <QObject>
#include <QtGui>

class QMainWindow;

class QSS: public QSplashScreen {

Q_OBJECT

public:
explicit QSS(QSplashScreen *parent = 0);
void criarTimer();

public slots:
void fechar();

signals:
void fechou();
};

#endif // QSS_H

To copy to clipboard, switch view to plain text mode