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

[Moritz Lennert]

Maciej Sieczka wrote:
> Moritz wrote:
> 
>>> Well, this is not really using the zoom-out box the way it should be: in
>>> zoom-out mode, you draw a box to show at which size you would like the
>>> currently displayed portion to be after zooming. So if you draw a box
>>> which is larger then the currently displayed portion, you actually are
>>> zooming in...
>>>
>>> So, in my eyes this is not really a bug, but maybe there could be a
>>> check and a warning: "WARNING: your zoom-out box cannot be larger than
>>> the currently displayed region" or something like this.
> 
> Michael wrote:
>> Moritz is correct. AFAICT from the animation (which is quite helpful, by the
>> way), the zoom out box is working exactly as it should. The region is
>> "shrinking" to fit in the box.
> 
> I absolutely don't agree. Re-do the situation but use area zoom-IN
> instead of zoom-OUT. In spite that you select an area *outside* your
> initial display extent, the result looks OK - the extent is changed as
> well as the zoom level.
> 
> With either zoom-out or zoom-in, if I include an area outside of my
> current display extent within the zooming rectangle, the resulting
> region should include this area too. Currently zoom-in does it, while
> zoom-out does not. The difference makes tools bahave inconsistently.
> Zoom-in works OK while the zoom-out behavior is counter-intuitive and
> should be regarded as an usability bug.

I agree that the two tools work inconsistently. Which of these is the 
"correct" way, I don't know:

- zoom-in takes the region that you select and displays the content of 
this region in the entire map display window (minus whatever cannot be 
displayed in constrain mode). When it does this it takes the information 
which was "hidden" by the empty space created by constrain mode and 
displays it as well.

- zoom-out takes the region you select with your box, including the 
empty space, and displays the content of the display window in this 
smaller box. When it does this, it does not take the information which 
was "hidden" by the empty space, but just keeps on displaying the empty 
space. According to you, Maciej, it should display the information, and 
not the empty space. This probably is a bit more what users would expect.

Moritz