QwtPlotCurve not plotting dots for milliseconds

[npatil15]

Yes, I just want to know in which method should I dig for this and what things will help me in what way?
I'm not asking for complete logic, but just guidance to do that.

The confusion is because if I think to overload below method,

void MyCurve::drawDots(QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
{
 
    qDebug()<<canvasRect<<from<<to;
    QwtPlotCurve::drawDots(p, xMap, yMap, canvasRect, from, to);
}

void MyCurve::drawDots(QPainter *p, const QwtScaleMap &xMap, const QwtScaleMap &yMap, const QRectF &canvasRect, int from, int to) const
{
    
    qDebug()<<canvasRect<<from<<to;
    QwtPlotCurve::drawDots(p, xMap, yMap, canvasRect, from, to);
}

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Then we can find from and to are integer. So for any logic, it will not accept double values or either convert it to an integer.
Now QPainter object, this will only paint the points from-to, so which things will help here or is there any other method to accept logic for double?

Thanks