QwtPolar App - Porting on Linux.

[Elisabetta]

Hello,
I am using:
1) QT 5.8
2) QWT - 6.1.2
3) qwtpolar- 1.1.1

On Windows I have no ploblems.
On Fedora 25 when the data is updated randomly colored lines appear in the title area and the graph is replicated n-times.

curve->setData(new PolarData(xData.data(), yData.data(), yData.size()));
replot();

curve->setData(new PolarData(xData.data(), yData.data(), yData.size()));
replot();

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I attach the figure with the right graph and the figure with the anomalies described above.
rightPolar.jpgwrongPolar.jpg

Can you give me some suggestions?

Thanks in advance!
Best Regards!

[Uwe]

Hm, that looks like the background of the canvas is not updated and you see some random data ( often from a previous image ).
But from the code you have posted it is hard to say more.

Something you could try is to disable the backing store of the plot canvas ( plot->canvas()->setAttribute( QwtPolarCanvas::BackingStore ). In case of using stylesheets also try to disable them.
Then the canvas runs in its most simple mode and we would know if the problem is related to its optimizations.

If you are able to run your application with Qt4 it might also be worth to check the X11 paint engine ( export QT_GRAPHICSSYSTEM=native ).

Uwe

[Elisabetta]

Uwe,
Thank you very much!

I have solved disabling the backing store of the plot canvas ( plot->canvas()->setPaintAttribute(QwtPlotCanvas::BackingStore, true);

Best Regards!