Re: Layout sizeHint weird behavior

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

On 8/8/24 10:10, Giacomo S wrote:

> Well, printing the list of major ticks, *before* the default scale 
> bounds are set from 0 to 1000 with 6 major ticks, this is what I get:
> 
> QwtPlot.sizeHint: Y axis ticks: 0.000000, 10.000000, 20.000000, 
> 30.000000, 40.000000, 50.000000, 60.000000, 70.000000, 80.000000, 
> 90.000000, 100.000000,

The default setting of QwtScaleWidget is [0,100].

> I think there is something (temporarily) wrong in the initialization of 
> the scales.

Well the size hints of the plot depends on the hints from the scales and 
the hint of a scale depend on its ticks. The ticks are set in 
QwtPlot::updateAxes, what can be called explicitly or implicitly from 
replot. So yes - the size hint of the plot is not updated before 
updateAxes has been called.

But note, that any QWidget has to indicate changes of its size hint by 
posting a QEvent::LayoutRequest. This might be done by 
QWidget::updateGeometry() or manually like in QwtPlot::replot.

When working with Qt layouts the event should be handled by them. If not 
you could implement an event handler in the parent of your plot widget.

HTH,
Uwe