Newbie : QwtCurveFitter and retrieve curve data

[Uwe]

Well, without understanding ( what is obvious from your code snippets ) what happens to your points you will fail. But what about the idea of using 2 QwtPlotCurves for your points: the first displaying the symbols only and a second one with a spline interpolated line ?

Uwe

[sapym]

Yes Uwe... I was a little stubborn and moreover kind of lost... please accept my appologies !
I know that my code is very far from perfect .. I do my best ... but as I said...a newbie...

I read this post form the beginning in order to have a fresh view on your advices and #4 is now clear to me...
Yes I tried yesterday with 2 curves ...

for (int ii = 0 ; ii < 2 ; ii ++)
	{
		m_UniqueCurve[ii] = new QwtPlotCurve();
		m_UniqueCurveFitter[ii] = new QwtSplineCurveFitter();
		m_UniqueCurveFitter[ii]->setFitMode(m_UniqueCurveFitter[ii]->ParametricSpline);
		m_UniqueCurveFitter[ii]->setSplineSize(4096);
		m_UniqueCurve[ii]->setCurveFitter(m_UniqueCurveFitter[ii]);		
	}
 
	m_UniqueCurve[0]->setCurveAttribute(QwtPlotCurve::Fitted, true);
	m_UniqueCurve[1]->setCurveAttribute(QwtPlotCurve::Fitted, false);
	m_UniqueCurve[0]->setStyle(QwtPlotCurve::Lines);
	m_UniqueCurve[1]->setStyle(QwtPlotCurve::Dots);
 
 
	m_UniqueCurve[0]->setPen(QColor(Qt::transparent));
	m_UniqueCurve[0]->setSymbol(QwtSymbol(QwtSymbol::Ellipse,Qt::gray, QColor(Qt::black), QSize(8,8)));
 
	m_UniqueCurve[1]->setPen(QColor(Qt::black));
 
        QPolygonF OriginalPoints,InterpolatedPoints;
	for ( int i = 0; i < TabX.count() ; i++ )
	{
		OriginalPoints+= QPointF(TabX[i], TabY[i]);
	}
 
	InterpolatedPoints= m_RedCurveFitter[1]->fitCurve(points);	
 
        m_UniqueCurve[0]->setData(TabX.data(), TabY.data(),TabX.count());		
	m_UniqueCurve[1]->setData(InterpolatedPoints);

for (int ii = 0 ; ii < 2 ; ii ++)
	{
		m_UniqueCurve[ii] = new QwtPlotCurve();
		m_UniqueCurveFitter[ii] = new QwtSplineCurveFitter();
		m_UniqueCurveFitter[ii]->setFitMode(m_UniqueCurveFitter[ii]->ParametricSpline);
		m_UniqueCurveFitter[ii]->setSplineSize(4096);
		m_UniqueCurve[ii]->setCurveFitter(m_UniqueCurveFitter[ii]);		
	}

	m_UniqueCurve[0]->setCurveAttribute(QwtPlotCurve::Fitted, true);
	m_UniqueCurve[1]->setCurveAttribute(QwtPlotCurve::Fitted, false);
	m_UniqueCurve[0]->setStyle(QwtPlotCurve::Lines);
	m_UniqueCurve[1]->setStyle(QwtPlotCurve::Dots);

	
	m_UniqueCurve[0]->setPen(QColor(Qt::transparent));
	m_UniqueCurve[0]->setSymbol(QwtSymbol(QwtSymbol::Ellipse,Qt::gray, QColor(Qt::black), QSize(8,8)));

	m_UniqueCurve[1]->setPen(QColor(Qt::black));

        QPolygonF OriginalPoints,InterpolatedPoints;
	for ( int i = 0; i < TabX.count() ; i++ )
	{
		OriginalPoints+= QPointF(TabX[i], TabY[i]);
	}

	InterpolatedPoints= m_RedCurveFitter[1]->fitCurve(points);	

        m_UniqueCurve[0]->setData(TabX.data(), TabY.data(),TabX.count());		
	m_UniqueCurve[1]->setData(InterpolatedPoints);

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And then I had to patch some lines in tne canvaspicker to be abble to select the good curve and move them together...

So again I'm deeply sorry for hte bad quality of my code and my eyes while reading your posts

Thanks a lot for your help

Best regards

Paul