I am currently working on an embedded project using the Allwinner A133 processor with the following configuration:

Operating System: Ubuntu 18.04
Kernel: Linux 4.9
Qt Version: Qt 5.12.12 (Qt Widgets)
Touch Type: Resistive touchscreen

For touch detection, I am using the following implementation:
void MainWindow::enableTouchOnAllWidgets(QWidget *widget)
{
if (!widget) return;
widget->setAttribute(Qt::WA_AcceptTouchEvents);
foreach (QWidget child, widget->findChildren<QWidget>()) {
child->setAttribute(Qt::WA_AcceptTouchEvents);
}
}

bool MainWindow::event(QEvent *event)
{
if (event->type() == QEvent::TouchBegin ||
event->type() == QEvent::TouchUpdate ||
event->type() == QEvent::TouchEnd)
{
QTouchEvent touchEvent = static_cast<QTouchEvent>(event);
if (touchEvent->touchPoints().isEmpty()) {
event->accept();
return true;
}

    if (event->type() == QEvent::TouchBegin)
    {
        touchProcessing = false;
    }

    if (event->type() == QEvent::TouchEnd)
    {
        if (touchProcessing)
        {
            event->accept();
            return true;
        }

        QPoint globalPos = touchEvent->touchPoints().first().screenPos().toPoint();

        QWidget *widget = QApplication::widgetAt(globalPos);

        if (widget)
        {
            QWidget *current = widget;
            while (current)
            {
                QPushButton *button = qobject_cast<QPushButton*>(current);
                if (button && button->isEnabled() && button->isVisible())
                {
                    touchProcessing = true;
                    emit button->clicked();
                    event->accept();
                    return true;
                }
                current = current->parentWidget();
            }

            QPoint targetPos = widget->mapFromGlobal(globalPos);

            QMouseEvent press(QEvent::MouseButtonPress,
                targetPos,
                Qt::LeftButton,
                Qt::LeftButton,
                Qt::NoModifier);
            QApplication::sendEvent(widget, &press);

            QMouseEvent release(QEvent::MouseButtonRelease,
                targetPos,
                Qt::LeftButton,
                Qt::LeftButton,
                Qt::NoModifier);
            QApplication::sendEvent(widget, &release);

            touchProcessing = true;
        }
    }

    event->accept();
    return true;
}

return QWidget::event(event);

}
However, I am experiencing a positional offset issue with the touch input. For buttons located at the bottom of the display, the touch response is shifted approximately 1 cm downward—meaning the button only responds when I touch about 1 cm below its actual position. Similarly, for buttons on the right side, the touch response is shifted approximately 1 cm to the right. The same behavior is observed for other directions as well.

Additionally, I am facing another issue with the resistive touchscreen: touch input using a fingernail is detected accurately, but touch input using a finger is inconsistent or unreliable.

Could you please help me understand the possible causes of these issues and suggest solutions to resolve them?

Thank you.