Question

how can I capture focus event in some widget (for example QLineEdit) without
creating a new widget ?

Thans for help 🙂

Answer 1

One way would be to create a SLOT – focusChanged(QWidget*,QWidget*)
in your MainWindow class and connect SIGNAL focusChanged(QWidget*,QWidget*) from QApplication in your main function.

in main.cpp:

QApplication a(argc, argv);
MainWindow w;
QObject::connect(&a, SIGNAL(focusChanged(QWidget*,QWidget*)), &w, SLOT(focusChanged(QWidget*,QWidget*)));

in mainwindow.h

add slot

public slots:
    void focusChanged(QWidget* old, QWidget* now);

in mainwindow.cpp

add implementation

void MainWindow::focusChanged(QWidget* old, QWidget* now)
{
}