How to execute a qDialog without passing a parent

[franco.amato]

Good morning,
I have to show a qDialog from a class inherited from QObject so I can not pass a parent.
How can do in this case?

Regards,

Franco

[wysota]

Pass null as the parent.

[franco.amato]

Hi Wysota,
thank you. Yes I tried to pass null but I got a crash.
I paste come source code here.

The header file of dialog:

#ifndef PREFERENCESDIALOG_H
#define PREFERENCESDIALOG_H
 
#include "ui_PreferencesDialog.h"
 
class PreferencesDialog : public QDialog, private Ui::PreferencesDialog
{
    Q_OBJECT
 
public:
    int exec();
 
public:
    explicit PreferencesDialog(QWidget* parent = 0);
 
private slots:
    void restoreState();
    void saveState();
};
 
#endif // PREFERENCESDIALOG_H

#ifndef PREFERENCESDIALOG_H
#define PREFERENCESDIALOG_H

#include "ui_PreferencesDialog.h"

class PreferencesDialog : public QDialog, private Ui::PreferencesDialog
{
    Q_OBJECT

public:
    int exec();

public:
    explicit PreferencesDialog(QWidget* parent = 0);

private slots:
    void restoreState();
    void saveState();
};

#endif // PREFERENCESDIALOG_H

To copy to clipboard, switch view to plain text mode 

The ctor of the dialog

PreferencesDialog::PreferencesDialog(QWidget* parent) : QDialog(parent)
{
   setupUi(this);
 
   setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);
 
   QPushButton* resetButton = buttonBox->button(QDialogButtonBox::Reset);
   connect(resetButton, SIGNAL(clicked()), SLOT(restoreState()));
 
   databasePortEdit->setValidator(new QIntValidator(1024, 65536, this));
 
   QSize sizeHint = this->sizeHint();
   sizeHint.setWidth(350);
   setMinimumSize(sizeHint);
   setMaximumSize(sizeHint);
}

PreferencesDialog::PreferencesDialog(QWidget* parent) : QDialog(parent)
{
   setupUi(this);

   setWindowFlags(windowFlags() & ~Qt::WindowContextHelpButtonHint);

   QPushButton* resetButton = buttonBox->button(QDialogButtonBox::Reset);
   connect(resetButton, SIGNAL(clicked()), SLOT(restoreState()));

   databasePortEdit->setValidator(new QIntValidator(1024, 65536, this));

   QSize sizeHint = this->sizeHint();
   sizeHint.setWidth(350);
   setMinimumSize(sizeHint);
   setMaximumSize(sizeHint);
}

To copy to clipboard, switch view to plain text mode 

Here I construct the dialog:

EyeIdServer::EyeIdServer(QObject* parent) : QObject(parent)
{
...code..
// Initialize dialogs
 
m_preferencesDialog = new PreferencesDialog(0);
...more code..
}

EyeIdServer::EyeIdServer(QObject* parent) : QObject(parent)
{
...code..
// Initialize dialogs

m_preferencesDialog = new PreferencesDialog(0);
...more code..
}

To copy to clipboard, switch view to plain text mode 

and from this routine I execute it

void EyeIdServer::showPreferencesDialog()
{
    m_preferencesDialog->exec();
}

void EyeIdServer::showPreferencesDialog()
{
    m_preferencesDialog->exec();
}

To copy to clipboard, switch view to plain text mode 

Do you have any idea on why I get the crash?
I think is because I use the "this" pointer inside the dialog

Regards

[wysota]

It is not because you use "this", that is perfectly fine. Do you by any chance use threads in your application?

[anda_skoa]

Hi Wysota,
thank you. Yes I tried to pass null but I got a crash.

Unrelated. The parent argument of QDialog even defaults to 0.

Do you have any idea on why I get the crash?

No, but the backtrace would have given at least some hints.

I think is because I use the "this" pointer inside the dialog

No, this is always valid within a class' instance.

Btw, what's your reason for overwriting exec()?

Cheers,
_

[aamer4yu]

What error are you getting on crash ?
Also whats the code in restoreState() ? You are running m_preferencesDialog->exec(); and performing something in restoreState..
May be thats causing crash...

You could also simply check the value of m_preferencesDialog->exec() and perform necessary action.

[franco.amato]

Thank you very much to all

This is the restoreState code

void PreferencesDialog::restoreState()
{
    // Restore database settings
 
    databaseHostEdit->setText(preferences->databaseHost());
    databasePortEdit->setText(QString::number(preferences->databasePort()));
    databaseUsernameEdit->setText(preferences->databaseUsername());
    databasePasswordEdit->setText(preferences->databasePassword());
    databaseNameEdit->setText(preferences->databaseName());
}

void PreferencesDialog::restoreState()
{
    // Restore database settings

    databaseHostEdit->setText(preferences->databaseHost());
    databasePortEdit->setText(QString::number(preferences->databasePort()));
    databaseUsernameEdit->setText(preferences->databaseUsername());
    databasePasswordEdit->setText(preferences->databasePassword());
    databaseNameEdit->setText(preferences->databaseName());
}

To copy to clipboard, switch view to plain text mode 

Best

[ChrisW67]

What are buttonBox, databasePortEdit etc. and where are these pointers declared and initialised?

Edit: Ignore that... I just noticed you are inheriting the UI object.

However, your code will crash if the button box does not contain a standard ResetButton.