Re: Zoomer always zooms to absolute maximum zoom

Uwe Rathmann wrote:
> On Wednesday 14 May 2008 17:39, Matthias Reich wrote:
> 
>> I have figured out, that the new ZoomBase seems to be indeed unified
>> intentionally with the current ScaleRect. The question remains then,
>> however, why this mechanism is not effective when there hasn't been any
>> zoom action, but becomes relevant after that initial zoom happens...
> 
> The zoomer maintains a stack of rectangles. With setZoomBase you clear this 
> stack and assign a rectangle as first element. With zoom(QwtDoubleRect) you 
> can push a rectangle and with zoom(int) you navigate on the stack. With both 
> calls the scales of the plot are adjusted to the corrsponding rect.
> 
> If something weird is happening I recommend to debug the rectangles, that are 
> pushed/popped to the stack.

Thanks for the explanation. In the meantime I have added a few necessary 
(not understood, why, though) lines and get the behavior I wanted in the 
first place.

this->boundingBox() iterates over all attached curves and gets the 
envelope: That's the moving target (as I remove and attach curves along 
the way).

----

QwtDoubleRect qdr = this->boundingBox();

if (!zoomer->isEnabled()) {
	zoomer->zoom(qdr.normalized());
	zoomer->setZoomBase(qdr.normalized());
	zoomer->zoom(0);
}

----

achieves what I wanted and have described earlier. I still don't know 
why the behavior was different before and after doing the first zoom on 
the plot, when I omitted the first line, since setZoomBase should clear 
the stack anyway. At the very least, the behavior shouldn't change based 
on the fact whether I have zoomed before or not...

Cheers,
Matthias
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PS: Still, I like qwt very much. Please keep going 

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