Re: Zoomer or ScaleEngine bug?

[Uwe R. <Uwe...@ti...>]

On Monday 28 May 2007, lingfa Yang wrote:

Another one from my TODO list, that was forgotten to be answered.

> I found ScaleEngine does not work well (starting from 1e-100 leaves vast
> empty space on the left) if I have a linear xBottom and a zoomer, but
> then switch the xBottom to log10.
>
> To repeat this problem, you can use examples\bode by moving ScaleEngine
> setting next to
> a zoomer is created.
> setAxisScaleEngine(QwtPlot::xBottom, new QwtLog10ScaleEngine);

The zoom stack is initialized from the current ranges of the corresponding 
axes. When you change the scale engine the scales are changed, but the zoom 
stack is not updated. Later in MainWin::enableZoomMode, the scales are set to 
the wrong zoom base.

Whenever you change the scales behind the back of the zoomer, you need to 
update the zoom stack manually: in your case this is simply a 
zoomer->setZoomBase().

Uwe