Continuous x-axis qwt realtime plot

I am trying to make a realtime plot and so far I got it to show a continuous sine wave, but the plot is not moving continuously on the x-axis, but more like every second it jumps one tick to the left. How can I fix this when using the QwtDateScaleDraw and QwtDateScaleEngine? I am sure it is easy, but I can not figure it out...

My code:

Code:

---

MyPlot::MyPlot(QWidget *parent) : QWidget(parent)
{
    xData = new QList<double>();
    yData = new QList<double>();
    plot = new QwtPlot(this);
    layout = new QHBoxLayout();
 
    //Add widget to layout.
    layout->addWidget(plot);
 
    //Add curves.
    curve1 = new QwtPlotCurve("Curve 1");
    curve1->setSamples(xData->toVector(), yData->toVector());
    curve1->attach(plot);
 
    //Set x-axis scaling.
    QwtDateScaleDraw *qwtDateScaleDraw = new QwtDateScaleDraw (Qt::OffsetFromUTC);
    QwtDateScaleEngine *qwtDateScaleEngine = new QwtDateScaleEngine(Qt::OffsetFromUTC);
    qwtDateScaleDraw->setDateFormat(QwtDate::Second, "hh:mm:ss");
    qwtDateScaleDraw->setUtcOffset(QDateTime::currentMSecsSinceEpoch() / 1000);
 
    plot->setAxisScaleDraw ( QwtPlot::xBottom, qwtDateScaleDraw);
    plot->setAxisScaleEngine ( QwtPlot::xBottom, qwtDateScaleEngine);
    plot->setAxisMaxMajor(QwtPlot::xBottom, 0);
    plot->setAxisMaxMinor(QwtPlot::xBottom, 10);
 
    //Replot.
    plot->replot();
 
    //Simulated data timer.
    QTimer *timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(appendData()));
    timer->start(1);
}
 
void MyPlot::appendData()
{
    static unsigned int counter = 0;
 
    //Add new data.
    xData->append(counter);
    yData->append(sin(M_PI*( (double)counter++ / 180)));
 
    //Remove oldest data.
    if (yData->size() > 1000)
    {
        xData->removeFirst();
        yData->removeFirst();
    }
 
    //Set data.
    curve1->setSamples(xData->toVector(), yData->toVector());
 
    //Replot.
    plot->replot();
}

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Use QwtPlot::setAxisScale for the X axis instead of using the autoscaler.

Uwe

You are right! Thank you very much :) I did try it, but I obviously did something wrong. I still have a somewhat related problem with the timestamp label "hh:mm:ss" adjusting the x-axis every time a new x-axis label appears from the right. I guess the spacing between the major ticks changes and this looks like the x-axis is lagging a little. I would rather that the label is gradually becoming visible as the time (x-axis) increases in value. Like it fades in from the right y-axis border. Any quick tip? I have been looking at margins in the QwtDateScaleDraw and QwtDateScaleEngine, but no luck so far.