Andrioid Emulator no Widget GUI updates

[Andy314]

Hello, here my next problem with Andriod.

I have created a simple test app with QCheckbox, QRadioButton and QTextEdit.
On the simulator I get no GUI updates (Checked, text changes) when I interact via mouse with gui.

It seem only a gui update problem. When I open a simple QMessagebox via a QButton the gui indates instantly before the messagebox opens.

On real hardware all work as expected.

What can be the problem ?

[zvoopz]

This is a bug of widget based Qt build for Android
Sometimes it updates the screen but sometimes you need to update the screen manually

I have created a function which updates screen - put next in MainWindow constructor
#include <QTimer>

{ MainWindow constructor
QTimer *timer = new QTimer(this);
connect(timer, &QTimer::timeout, this, &MainWindow::updateScreen);
timer->start(100);}

//hidden somewhere in the helper
void MainWindow::updateScreen()
{
update();
}

[zvoopz]

Another bug you may face to is Android only null pointer crash of app due to QTextEdit widget
If you do not need to edit the text (just plot) - substitute it with QTextBrowser

[Andy314]

I found a global solution for it (resp. ChatGPT :-) and will share it here.

class AndroidApplication : public QApplication
{
public:
    AndroidApplication(int &argc, char **argv)
        : QApplication(argc, argv)
    {}

    bool notify(QObject *receiver, QEvent *e) override
    {
        // Erstmal normal weiterleiten
        bool ok = QApplication::notify(receiver, e);

        // Bei jedem UpdateRequest-Event erzwingen wir einen Frame-Swap
        if (e->type() == QEvent::UpdateRequest) {
            // Prüfen, ob das Ziel ein QWidget ist
            if (auto w = qobject_cast<QWidget*>(receiver)) {
                if (auto wh = w->window()->windowHandle()) {
                    wh->requestUpdate();  // sofortigen Flush anstoßen
                }
            }
        }
        return ok;
    }
};

It works ! Is this ok in general and for performance issues ?