Quote Originally Posted by Uwe View Post
Not sure if this is a type of optimization, that is common of enough to explicitely support it in Qwt - curve points are usually not only shifted by the distance of the baselines. But nobody prevents you from doing so - simply hide/show curves depending on scale ranges.
Yes thank you for the hint, I'm going to try to make optimization based on the show/hide (curve->setEnabled(true/false)) properties. That should not be much difficult.

About vertical resolution:
Probably that is not so necessary but depending on plotted data each curve may have up to 5000 points (usually it is 2000-5000 points but may vary). In this case QwtPlotCurve::FilterPointsAggressive may be useful I think (or at least it should not consume much time to execute if number of points is small, less than 1000, I'm going to test it).

And what about vertical linear interpolation:
I think in this case interpolation for curves that reduces the number of plotted points is inapropriate, sorry for confusing you. But sometime ago I found this algo in Matlab: https://www.mathworks.com/matlabcent...40790-plot-big
But that time I needed something like that to plot 2D data (spectrogram) with the same 1000 by 20000 points (or more) in each direction (the data is the same as for my curves but plotted NOT as curves but as spectrogram). And I wrote matlab code that choses points in X and Y direction before plotting Z data. I think in QWT spectrogram with big data could be useful also. Maybe FilterPointsAggressive could find some application at spectrogram?
This is just an idea wich came to my mind now but probably QWT already has something similar (I didn't work with QWT spectrogram yet but I'm going to).