Hi,

Just a little bit of context:
I am using 3 distinct qwtPlot that use the same data, the data is stored in multiple QVector<QPointF> in each qwtPot, (used to reprensent realtime QwtPlotCurve for each qwtPlot)
To get a little bit what I mean, here is a video of the software in action :
https://www.youtube.com/watch?v=NSCTaG57ze4 (fast foward to the middle)

Now I want to change that, since using 3 times the same data uses a lot memory and is not efficient.
I am trying to change the code so that I have only one place where all the data is stored, and the graph feeds on this data to display new contents when it arrives (with signal/slots mechanism)

So my center class with the data is called "DataWorkout" and contains
- QVector<QPointF> cadenceSamples;
this Samples get filled every second with ~ 4 new QPointF
When I get a new QPoint, this class emit a signal to the qwtPlot class so that they replot the QwtPlotCurve.

Here is the current code used that works
Qt Code: 
  1. connect(dataWorkout, SIGNAL(newCadenceDataAdded(QVector<QPointF>)), ui->widget_workoutPlot, SLOT(refreshCadenceCurve(QVector<QPointF>)) );
  2.  
  3. void WorkoutPlot::refreshCadenceCurve(QVector<QPointF> cadenceSample) 
  4. {
  5.     cadenceCurve->setSamples(cadenceSample);
  6.     cadenceCurve->attach(this);
  7. }
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My question is: is passing a QVector<QPointF> in a signal/slot going to use a lot of ressource? Will it copy the entire QVector or just pass the pointer/address? I'm not sure the way I used is good but I couldn't find a way without passing the QVector in the signal/slot, because to curve doesn't get display if I don't use .setSamples and .attach on each call.

Thanks in advance / Merci beaucoup!