overriding QwtSeriesData<QPointF>::boundingRect

[hml]

Hi,

I am overriding this method with:

return QRectF(
    QPointF(...),
    QPointF(...)
  );

return QRectF(
    QPointF(...),
    QPointF(...)
  );

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Looking at the returned rectangle, I see
(xp=2446578.0, yp=193.72, w=6793.0, h = -193.72)

The intention is that the y axis goes from 0 to 193.72. That doesn't work with this rectangle.
The resulting QwtPlotCurve shows a y axis with a strange range [0,1600]

changing h to 0 gives a more reasonable output, but still from 50 to 300.

how is the logic work on top of the bounding rectangle?

Thanks,