setting a custom scale

[oliver_mpt]

Hi everybody !

I want to use, on my bottom axis of a qwtPlot, a reciprocal scale and to be able to switch between the linear scale and the reciprocal (x' = A/x, where A = 12396000, with x in the range 2000 - 10000), and replot my curves.
I have the idea that I must overload a QwtTransform class and use it in a qwtScaleEngine to get a correct display (both for the data and the axis scale graduations), but the whole picture is not clear to me.
Could somebody outline the process for me ?

Thanks in advance

Oliver

[Uwe]

Well. there is not so much to explain: YourTransform::transform is used for mapping a plot coordinate to a widget coordinate and YourTransform::invTransform for the other way round.
The formula how these methods are used is given in the docs: http://qwt.sourceforge.net/class_qwt...m.html#details.

The scaleengine example shows a couple of transformations f.e one that uses a different formula for a specific interval ( TransformPos in mainwindow.cpp ). Instead of the path, where pow is used you have to add your A/x code.

Uwe