How to properly create a two way connection with QComboBox?

lansing

I have a main window with a QTabWidget. The main window also has a child dialog widget with a QcomboBox. The name of the tab in the tabwidget will be the selections of the qcombobox. The QTabWidget and the QComboBox were created in their corresponded ui files.

What I want now is that when I switched tab in the main window, I want the selection in the qcombobox to also be changed, matching the tab index. And vise versa when I changed selection in qcombobox, I want the tab to also be changed.

My signal connection now works only one way going from qcombobox to qtabwidget. When I tried to connect them the other way around I was getting into an infinite loop that I don't know how to get out.

main window.cpp

// somewhere on top
m_pMyDialog = new MyDialog(this);

connect(m_pMyDialog, &MyDialog::signalComboBoxChanged,
            this, &MainWindow::slotSetComboBox);

connect(m_ui->tabWidget, &QTabWidget::currentChanged,
            this, &MainWindow::slotChangeTab);


void MainWindow::slotChangeTab(int a_index) 
{
    // some logic
    m_pMyDialog->slotUpdateSelection(a_index);
}

void MainWindow::slotSetComboBox(int a_index)
{
   // some logic to talk to combobox in mydiag.cpp   
    m_pMyDialog->slotSetSomeValue(some value);

    m_ui->tabWidget->setCurrentIndex(a_index);
}

mydialog.cpp

connect(ui->selectComboBox, QOverload<int>::of(&QComboBox::currentIndexChanged), 
    this, MyDialog::signalComboBoxChanged);


void MyDialog::slotUpdateSelection(int a_index) 
{
    if (ui->selectComboBox->currentIndex() != a_index)    
        ui->selectComboBox->setCurrentIndex(a_index);
}

I can make a function in mydialog.cpp to update combobox selection and called it in slotChangeTab, but that will get me into an infinite loop. What is the proper way to do this?

Christian Ehrlicher

Simply check if the current index in the QComboBox is the selected one and if then don't call setCurrentIndex()

lansing

@Christian-Ehrlicher

Where do I start calling when going from tab Change to QcomboBox change?

Christian Ehrlicher

@lansing said in How to properly create a two way connection with QComboBox?:

Where do I start calling when going from tab Change to QcomboBox change?

I do not understand what you mean.

SGaist

Hi,

You can do that at the top of each slot.

lansing

@SGaist

Thanks I got it working, I don't know why it works but I'll take it. I updated the first post for future reference.

Solved How to properly create a two way connection with QComboBox?