Question

Is there a way to catch all gui events like button clicked, text changed, check box toggled, into the same slot without using the connect() function for every widget?

Answer 1

If your widgets are part of a form and you want to submit the changes to a model (or an SQL database), using a QDataWidgetMapper might be more adapted than what you want.

Anyway, these signals, except the button clicked signal for non checkable buttons, are declared as the NOTIFY signal for the USER property (in the Q_PROPERTY declaration).

You can use Qt’s meta object system to connect all the widgets from a list:

void connectChanged(QWidgetList list, QObject *target, const char *targetSlot) {
    foreach(QWidget *widget, list) {
        const QMetaObject * mo = widget->metaObject();
        QMetaProperty property = mo->userProperty();
        // Skip non user-editable widgets (QLabel, QGraphicsScene...)
        if(!property.isValid() || !property.hasNotifySignal()) {
            qDebug() << "Skipped" << mo->className();
            continue;
        }

        // Non checkable buttons have to be handled separately
        QAbstractButton *button = qobject_cast<QAbstractButton*>(widget);
        if (button && !button->isCheckable()) {
            QObject::connect(button, SIGNAL(clicked()), target, targetSlot);
        } else {
            // QMetaMethod notifySignal() returns the raw signal signature
            // for instance "toggled(bool)", we need the signature that would be
            // returned by the macro SIGNAL: "2toggled(bool)"
            QByteArray signalSignature;
            signalSignature.append(char('0' + QSIGNAL_CODE));
            signalSignature.append(property.notifySignal().signature());

            QObject::connect(widget, signalSignature, target, targetSlot);
        }
    }
}

// connect all child widgets to a slot:
connectChanged(this->findChildren<QWidget*>(), this, SLOT(dataChanged()));

PS: This will also connect the QScrollBar::valueChanged(int) signals of the QTextEdits to your slot.