QwtPolarSpectrogram with inverted Radius

[ishitha92]

I need to create a PolarSpectrogram for the following scales.
Azimuth = 0 to 360 in steps of 15 degrees
Radius = 0 to 90 in steps of 10 degrees.

I use the following code to have clock-wise scaling for Azimuth.

setScale(QwtPolar::Azimuth, 360 , 0 , 30);
setScaleMaxMinor(QwtPolar::Azimuth, 2);

setScale(QwtPolar::Azimuth, 360 , 0 , 30);
setScaleMaxMinor(QwtPolar::Azimuth, 2);

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But the inversion does not work for Radius.

setScale(QwtPolar::Radius, 90 , 0 , 20);
setScaleMaxMinor(QwtPolar::Radius, 2);

setScale(QwtPolar::Radius, 90 , 0 , 20);
setScaleMaxMinor(QwtPolar::Radius, 2);

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While the default 0 to 90 works fine. (see image: I just need the 0 - 90 be 90 - 0 )

I am using a QwtMatrixRasterData to provide 216 (24 columns and 9 rows) entries for these divisions. The interval for the data is set as

setInterval( Qt::XAxis, QwtInterval( 0.0, 360.0 ) );
setInterval( Qt::YAxis, QwtInterval( 0.0,90.0 ) );

setInterval( Qt::XAxis, QwtInterval( 0.0, 360.0 ) );
setInterval( Qt::YAxis, QwtInterval( 0.0,90.0 ) );

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I have tried switching the interval for the data and setting ScaleDiv(1, QwtScaleDiv(90, 0)) for the plot.

I'd appreciate any help. Thanks!