updating qlabel image in switch statement

I have a small switch function running that I want to update the image of a label depending on the result. The issue I have is that all images are only updated at the end of the run. How can I update each image as each case is evaluated?

Code:

---

int MainWindow::readADC(int range)
{
    QPixmap stat_GO (":/res/images/stat_GO.png");
    QByteArray data;
    bool ok = false;
    float r = 0.0;
 
    switch (range)
    {
    case 24:
        serial->waitForReadyRead(1000);
        data = serial->readAll();
        qDebug() << data;
        r = data.toFloat(&ok);
        if (!ok) qDebug() << "24VDC Conversion Failed";
        qDebug() << r;
 
        if ((r > 23.2) && (r < 24.8))   //Check tolerance (3.3%)
            ui->_tstr24Vok->setPixmap(stat_GO);
        return 1;
        break;
 
    case 3:
        serial->waitForReadyRead(1000);
        data = serial->readAll();
        qDebug() << data;
        r = data.toFloat(&ok);
        if (!ok) qDebug() << "3.3VDC Conversion Failed";
        qDebug() << r;
 
        if ((r > 3.2) && (r < 3.4))   //Check tolerance (3%)
             ui->_but3v3Vok->setPixmap(stat_GO);
        return 1;
        break;
 
    case 12:
        serial->waitForReadyRead(1000);
        data = serial->readAll();
        qDebug() << data;
        r = data.toFloat(&ok);
        if (!ok) qDebug() << "12VDC Conversion Failed";
        qDebug() << r;
 
        if ((r > 11.6) && (r < 12.4))   //Check tolerance (3.3%)
        ui->_but12Vok->setPixmap(stat_GO);
        return 1;
        break;
    }
    return 0;
}

---

This method is OK. The problem is how this method is invoke. Refreshing the screen needs working event loop. So if You do this calling readADC 3 times You have such a symptom.

Also blocking the main thread and thus the GUI for up to a second (through waitForReadyRead) is usually also a very bad idea.

There really doesn't seem to be a need for this, all branches do that, so the switch could easily be done in a slot connected to readyRead().

The code suprisingly also doesn't even care how much data is reads.

Cheers,
_