how to speed up the replot?

[KosyakOFF]

Please describe your plot composition and all elements that you have on this plot.

If plot have big amount of elements or spectrogram on it (redrawing spectrogram takes large amount of calculations and time even if value() impl. is quick then size of spectrogram is big) replot should take much time.

For spectrogram i suggest set repaint parameter to resizeOnly. As for markers and plot I suggest to draw markers on overlay widget. In this case you don't have to replot after changing their position, just redraw an overlay widget.

[rambo83]

Finally I have found out what was the reason for very slow plot behavior: I have set the flag

this->setAutoReplot(true);

this->setAutoReplot(true);

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for the QwtPlot and this was obviosly the reason for the slow replot, because after I deleted this line, the replot last far less than 1 second (in contrast to 4 seconds before). It is very fast now. Also the dragging of markers is now very fast and they are reploted all together at once, so that one cannot see the FOR loop, as it could be seen before.

best regards,

Vitali