You right, the second implementation is not even compile and not even written right. The thing is that I'm unable to right it proper way, that's the other thing.
And I came to this conclusion because, the line setRawSamples() is working fine if the data is not too fast, but if I given bulk or fast data its crashing at this point.
Qt Code: 
  1. void Input::plottingData(QVariant data)
  2. {
  3.     if (data.userType() == QMetaType::QPointF)
  4.     {
  5.         m_points.push_back(data.toPointF());
  6.     }
  7.     if (data.userType() == QMetaType::Double)
  8.     {
  9.         double yValue = data.toDouble();
  10.  
  11.         cframe::TimeStamp time = Module::createTimestamp();
  12.         qint64 nanoElapsed = time.nSecsElapsed();
  13.         double xValue = nanoElapsed/(double)1000000000;
  14.         m_points.push_back(QPointF(xValue, yValue));
  15.     }
  16.     if (data.userType() == qMetaTypeId<QVector<QPointF>>())
  17.     {
  18.         QVector<QPointF> points = data.value<QVector<QPointF>>();
  19.         m_points.append(points);        
  20.     }
  21.  
  22.     m_curve.setSamples(m_points);
  23. }
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Can you please check this code above and clarify does the problem is in the coding somewhere ?

Thanks