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

Maciej Sieczka tutey at o2.pl
Thu Sep 21 01:44:04 EDT 2006


> Maciej Sieczka wrote:

>> It's not about me "wanting to see", but about fixing an issue that
>> hampers gis.m. I wouldn't bother messing with nice folks just to
>> enforce some silly feature everybody could live without.

Michael Barton wrote:

> It is often more helpful to find out how you think the interface "should"
> behave than what you think is "wrong"--especially in this case where it is
> necessary to write some (for me at least) conceptually complicated equations
> to make zooming happen in different ways and under different conditions.

But I did: I said what's wrong and what it should look like. I'm sorry
you didn't understand.

>> Michael Barton wrote:

>>> You first used a zoom in box to set a region geometry that was tall (N-S)
>>> and narrow (E-W). So far so good.
>>>
>>> Then you draw a zoom out box that is smaller in the N-S dimension than the
>>> current region and larger in the E-W dimension than the current region.

>> Correct.

>>> The algorithm increases the N-S region extents so that the parts of a
>>> map at the previous north and south edges now fit into the box that you
>>> drew on the screen.

>>> What is it you think should happen with the E-W given the box you've drawn?

>> It should be extended accordingly, like N-S is, including the invisible
>> part od the display (beyond the region, to the E). So that the
>> resulting region reflected the proportions of the zoom box.

> So you agree that the N-S region extent should be increased (well beyond the
> box) so that the old region edges fit into the box.

> In the E-W direction, you'd want the new region extents to match the box's
> geographic extent rather than behave like the changes to the N-S extents.

No. The E-W extent should change the same way the N-S does. This is the
case now for box-zoom-out (GOOD), but only when the zoom box doesn't
overlap the map canvas outside the current region (BAD). This should be
fixed - so that the region geometry reflects the zoom box geometry
exactly, no matter if the zoom box overlaps the map canvas outside the
current region or not. Box-zoom-in behaves correctly in this regard.
Box-zoom-out should do the same.

> This would only apply, however, only if the box is larger than the region
> extents in a given dimension? in a given direction?

It doesn't have to do with region or zoom box size directly. Please
revert your 2 most recent pathces to mapcanvas.tcl. I tried them. They
don't fix the problem and add to confussion.

Maciek




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