[GRASS-user] Re: [GRASS-dev] updates to region setting and display rendering in GIS Manager

[Glynn Clements]

Michael Barton wrote:

> I guess I didn't explain this as well as I thought (or maybe I did and don't
> quite understand your comments).

The latter.

> The only thing in gism that uses GRASS_REGION is interactive panning and
> zooming in the display. The only time this is invoked is just before
> rendering the display images to PPM files. It is then immediately unset.
> 
> WIND_OVERRIDE is unset all the time.
> 
> So all commands (including g.region) called from the menus behave exactly
> the same as if they were called from the command line with respect to region
> geometry. Hopefully, this makes gism behavior consistent with the rest of
> GRASS behavior as far as regions go.
> 
> Your point about being able to access a file of region info for the display
> is dealt with in 2 ways. With the new zoom menu item, you can save the
> display geometry to a named region in the windows folder (and access it from
> other displays or from g.region). You can also set the WIND file from the
> display with another selection from the zoom menu. In both cases, however,
> you must do this intentionally. It is not done for you unexpectedly.
> 
> I hope this explains it better.

The above is essentially how I assumed it works from your previous
email, although it does clarify some of that.

My comments were primiarily pointing out some of the pros and cons of
different approproaches, and to suggest possible enhancements.

If gis.m never sets or unsets WIND_OVERRIDE, the user can choose to
isolate gis.m from the WIND file with:

	g.region save=gism
	WIND_OVERRIDE=gism gis.m &

The user can then manually synchronise the two by running:

	g.region region=gism		# gis.m region -> shell region
or:
	g.region save=gism		# shell region -> gis.m region

and can enable/disable synchronised operation with:

	export WIND_OVERRIDE=gism	# enable synchronisation
and:
	export -n WIND_OVERRIDE		# disable synchronisation

[By "gis.m region", I mean the region which will be used by any
command for which gis.m doesn't set GRASS_REGION, i.e. non-display
commands.]

-- 
Glynn Clements <glynn at gclements.plus.com>