[GRASS-dev] Re: gis.m zooming: 2 new bugs

[Maciej Sieczka]

Michael Barton wrote:
> On to better bugs...

>> Based on spearfish60.
>>
>> 1
>> add "slope" raster, 'Zoom to selected map'
>>
>> 2
>> zoom-in by selecting a region with mouse - make the region higher than
>> wider
>>
>> 3
>> zoom-in by single-clicking - whole canvas is filled - the aspect ratio
>> is not preserved when zooming! single-click zoom-OUT *does* preserve
>> aspect ratio...

> Zooming in simply zooms in from the current display geometry by a set
> amount. It essentially creates an invisible zoom box. So it won't preserve a
> specific aspect ratio. If you want to also affect the aspect ratio, you need
> to either draw a zoom box or use g.region. This could be changed, but from
> your description, it seems to be behaving as it is supposed to. Or did I
> misunderstand your description?

I'm not sure if I understand you as well. Please watch this swf

http://kufaya.googlepages.com/single-click_zoom-in_bug.html

and say if what happens there is what should? I find it strange that
after a single click zoom-in (which tales place at the end of my
screencast) the *whole* map canvas is used for display, while it was
only a *half* of it before the zoom-in. It looks like the single-click
zoom-in in constrained display mode behaves the same way as if I used
the unconstrained mode. IMO this shouldn't happen.

>> Another bug is that zoom-out by selecting a region with mouse leads to
>> unexpected results, like if only the Y coord was handled correctly.
>> Reminds of the now-fixed single-click zoom-out bug. Proceed the same
>> way I described that, to spot this one too.

A note: actually, neither axis is handled properly. It depends. 2
screencats linked below show it.

> This is bizarre. I specifically tested that in detail last night. Try the
> test I used and see if it behaves incorrectly or not and let me know.
> 
> I opened the Spearfish elevation map and zoom to match the map in the
> display. I draw a zoom-out box in the upper left corner of the display. The
> map shrinks so that all of it fits inside this box. This puts the map at the
> upper left of the display. Do the same thing with the other corners or in
> the middle of the map, and the map should shrink to fit within the box
> drawn.

I can reproduce your test and indeed it's all perfect. But, watch
another 2 swfs of mine to see under what circumstances it fails:

http://kufaya.googlepages.com/area_zoom-out_bug_horizontal.html
http://kufaya.googlepages.com/area_zoom-out_bug_vertical.html

This looks wrong to me. What do you think?

Maciek