[GRASS-dev] A couple of r.colors ideas

[Glynn Clements]

Michael Barton wrote:

> I'm in the process of creating a new GUI for creating raster color  
> tables, and ran into a couple of function ideas that would be helpful  
> in the context of a GUI wrapper and (I think) for other users.
> 
> 1) I realized that there is no simple way to 'export' an existing  
> color table to a standard color table rules file, although r.info can  
> take a rules file and turn it into a color table. You can copy a color  
> table between raster files, but it also would be handy to be able to  
> export one.

Added as r.colors.out.

> 2) Since the various d.* modules are in redevelopment, one idea that  
> seems handy would be to be able to explicitly apply a color table  
> during display
> 
> e.g.: d.rast map=nice_raster colortable=nice_colors.txt
> 
> This way, a map could be displayed with multiple color tables without  
> overwriting a default color table. The same concept might also be  
> applied to vectors.

This could be useful, but it essentially means adding a copy of
r.colors to each of d.rast and d.vect.

Essentially, the only part of r.colors which wouldn't be used in such
a situation is the final call to G_write_colors(). Oh; you probably
wouldn't want the code to deal with interactive prompting, but that
should arguably be removed from r.colors for 7.x.

Of course, you could further reduce the amount of code by eliminating
various features (e.g. using the colour table from another map, log
and hist-eq scaling, etc), but that just create more cases where you
would still need to use e.g. r.colors + d.rast separately.

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