I have created several gauges using QwtDial, but the default backbone arc and needle length are quite small relative to the surrounding frame.
inner_angle_deg.PNG

After examining the source code, I found the QwtDial constructor always sets the associated QwtRoundScaleDraw object's radius to zero. So, I tried getting the QwtRoundScaleDraw object after a dial is created and setting a new radius. This had no effect. Examining the QwtRoundScaleDraw::extent() method, I found it did not include the radius in the QwtAbstractScaleDraw::Backbone component clause.

As an experiment, I tried adding the radius to the QwtRoundScaleDraw::extent() method and rebuilding the Qwt library. This allowed me to change the backbone radius as described above, but the ticks and labeling are not resized correctly; they are now inside the backbone radius instead of outside.

I've noticed the dial examples don't appear to use a backbone, so I am wondering if this is an issue that has been missed in testing the QwtDial functionality?

Kind regards,

Curt