Change Label qwtpolarplot

[stepner03]

I'm using a qwtpolarplot widget from 180 to -180, and I need that the widgets on the axes:

360 -----------> 180
270 -----------> -90
180 -----------> -180
90 -----------> 90

how can I change this label?

11876

[Uwe]

http://www.qtcentre.org/threads/65653-change-scale-map-of-QwtPolarGrid-number!

Uwe

[stepner03]

Thanks for your help...
Another solution is the following:

class AzimuthScaleDraw: public QwtRoundScaleDraw
{
public:
virtual QwtText label( double value ) const
{
QwtText text;
double valueReturn;

if ((value>0) && (value < 180))
{
valueReturn = value;
}
else if ((value == 0) || (value ==360))
{
valueReturn = 180;
}
else if ((value == 180))
{
valueReturn = -180;
}
else
{
valueReturn = value -360;
}
return QwtRoundScaleDraw::label( valueReturn );
}
};

and use:

QwtPolarGrid *grid;

grid->setAzimuthScaleDraw( new AzimuthScaleDraw() );


what do you think about it ????

[Uwe]

Well your code changes the labels, but not the transformation - so it depends on your data. If a point at -180 has to be displayed at 180 your code does it, if the coordinates of your data is intended to match the scales my proposal is better.

Uwe

[stepner03]

Thanks...yes my code change only labels !!!! For transformer poin plot I used the example code qwt spectrogram !!!