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

[Moritz Lennert]

On Thu, September 21, 2006 20:14, Maciej Sieczka wrote:
> Michael Barton wrote:
>> Maciej has the right idea. Let's start with how the zoom out box works
>> in
>> the "normal" context and deal with the "abnormal" context later.
>>
>> The zoom out box DOES respect the form of the box drawn... BUT not in
>> the
>> same way that the zoom in box does.
>
>> So how is this actually used in practice? Say you have a regional map,
>> zoomed in to a city. You'd like to zoom out to the larger region and
>> have
>> the city end up in the upper left corner of your map. Create a zoom out
>> box
>> of the size you want--that is, such that the current display will fit
>> inside--in the upper left corner of your display. The currently
>> displayed
>> map, with the city in the center, will appear within the area of the
>> zoom
>> out box.
>
> OK, now I understand how it works. Questions:
>
> Why did you implement it this way? Other GIS software working the same?
>
> I checked the box-zoom-out in QGIS and UDIG - neither behaves the way
> gis.m does. Of course, this is not an ultimate argument. But I'm
> wondering why you decided for an IMO counter-intuitive, non-standard
> (to my limited experience) solution?

Don't forget that QGIS and UDIG probably do not use a constrained mode, so
if you compare GRASS' behaviour, you would have to do so in unconstrained
mode, and I have the feeling that the behaviour there is "intuitive" (I
don't have qgis or udig available for the moment to see how they work).
QGIS and UDIG don't use region settings, but then again, they are not a
full-fledged GIS as GRASS is.

[...]

> which is even more important
> for Grass GIS in the *restricted* zoom mode, the "normal" way lets the
> user control the region shape and extent precisely. I'm sorry, but the
> way your box-zoom-out works I'm really not able to control the region
> extent and shape. Which I believe is a defect, epsecially in the
> restricted zoom mode, which is mainly about setting the region in a
> predictable way.

In my opinion, this seems to be the most important point of the
discussion. To understand what exactly you use the zoom-out box for, could
you give a concrete example ? What type of control of region shape and
extent you need exactly (and why do you need it in zoom-out) ? This would
allow us to narrow down the issue.


Moritz