Hi,

I would like to plot multiple curves on one qwtplot object.



Qt Code: 
  1. QwtPlotCurve* mycurve = new QwtPlotCurve("curve1");
  2. QwtPlotCurve* mycurve2 = new QwtPlotCurve("curve2");
  3.  
  4.     QwtPointSeriesData* myData = new QwtPointSeriesData;
  5.     QVector<QPointF>* samples = new QVector<QPointF>;
  6.     samples->push_back(QPointF(time->at(0), samplesPerUser[0]));
  7. //creating histogram  
  8.  for (int i=1; i<30; i++) {
  9.         samples->push_back(QPointF((time->at(i) + time->at(i+1)) / 2, samplesPerUser[i]));
  10.         samples->push_back(QPointF((time->at(i) + time->at(i+1)) / 2, samplesPerUser[i+1]));
  11.     }
  12.     samples->push_back(QPointF(time->at(30), samplesPerUser[30]));
  13.  
  14.     myData->setSamples(*samples);
  15.     mycurve->setData(myData);
  16.     mycurve->attach(plot);
  17.  
  18.  QwtPointSeriesData* myData2 = new QwtPointSeriesData;
  19.     QVector<QPointF>* samples2 = new QVector<QPointF>;
  20.     samples->push_back(QPointF(time->at(0), samplesPerUser2[0]));
  21. //creating histogram  
  22.  for (int i=1; i<30; i++) {
  23.         samples2->push_back(QPointF((time->at(i) + time->at(i+1)) / 2, samplesPerUser2[i]));
  24.         samples2->push_back(QPointF((time->at(i) + time->at(i+1)) / 2, samplesPerUser2[i+1]));
  25.     }
  26.     samples->push_back(QPointF(time->at(30), samplesPerUser2[30]));
  27.  
  28.     myData->setSamples(*samples2);
  29.     mycurve->setData(myData2);
  30.     //making the second curve red
  31.     mycurve2->setPen(QPen(Qt::red));
  32.  
  33.     mycurve2->attach(plot);
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The problem is that I can see only the second curve, not the first one. I'm not sure whether creating 2 QwtPlotCurve object and attaching them to the plot is a right approach.