[GRASS-dev] gis.m improvements

[Michael Barton]

Benjamin,

I'll try to answer this again. Hopefully, by sending it to the dev list
again more people will begin to understand the concepts behind independent
displays in the GIS Manager.

-------------------------------
Old GRASS UI: 
One region setting, managed by g.region (and d.zoom), with information
stored in WIND. This information (extents, resolution) applies to ALL
display functions in ALL xmons for entire GRASS session.

Any x11 display that is open sees the same region (extents, resolution).

If you want to have 2 displays with different maps, you must 1) set the
region; 2) display the map; 3) change the region, layers, etc; 4) switch to
another x11 display; 5) display the new settings; and 6) DON'T TOUCH THE
FIRST DISPLAY (if you do, it will look just like the second one).

There is no way to maintain different maps in different displays.

-------------------------------
New GRASS UI:
Each display has its own region and layer settings.

If you want to display different maps in different windows (much more likely
than wanting to display 2 completely identical maps), simply set the region
(zoom) and layers for each display.

You can update each display (change line colors, layers to display, extents)
independently of any other display.

To do this, any given display cannot use the session-wide WIND settings. If
it did, ALL displays would have the same region settings. That is, multiple
displays cannot have different views if all of them use the identical extent
and resolution information in the single WIND file. Each display must
maintain its own region and layer settings.

Therefore, each display must ignore the WIND values--UNLESS the user wants a
particular display to adopt the extents and resolution in the single,
session-wide WIND file. In this case, there is a toolbar function that lets
you do this.
-------------------------------

If people like the flexibility of being able to have different maps (using
different layers, extents, and resolutions) represented in different
displays, then the interaction between displays and the WIND file cannot
work the way it used to when we did not have that flexibility.

Those of us working on the UI development, can achieve this flexibility in
the GUI and display architecture--by ignoring the WIND file. An alternative
way to do this is to change how g.region and the WIND file work. This is
probably preferable in the long run. But it requires considerably more
modification of GRASS architecture.

Cheers,
Michael

__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics and Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton


> From: Benjamin Ducke <benjamin.ducke at ufg.uni-kiel.de>
> Date: Mon, 08 May 2006 09:15:47 +0200
> To: GRASS devel <grass-dev at grass.itc.it>
> Subject: Re: [GRASS-dev] gis.m improvements
> 
> I also don't see an easy way. But is it really a good idea to have
> gis.m use its own concept of a region? Does someone who uses
> gis.m as default GUI not expect the map display and g.region to
> work in sync?