I have a QwtPlot that contains a QwtPlotCurve and one or many custom QwtPlotItem. The QwtPlotCurve can be big in size. I have a custom QwtData to store the values as float instead of double.

Quite often, the QwtPlotCurve doesn't change once created. How can I override QwtPlot::drawItems(...) to disable the re-plotting of the huge QwtPlotItem when I only changed my custom QwtPlotItems? Thanks.