[GRASS-dev] GRASS startup window patches

[Glynn Clements]

Paul Kelly wrote:

> > As it stands, if you want g.proj to ensure that the defaults aren't
> > used, it should just be a matter of ensuring that the proj4= option
> > contains either towgs84= or nadgrids=, no?
> 
> That's right. The g.proj -d output (although I was thinking of removing 
> it) already provides detailed information on the datum-related component 
> of any input co-ordinate system. It might be useful if this was 
> re-organised a bit and then another flag was added that would list the 
> possible choices of datum parameters for a particular input co-ordinate 
> system?

AFAICT, it would be trivial for the GUI to do this itself using the
information in etc/datumtransform.table

The functionality currently provided by GPJ_ask_datum_params() amounts
to a choice of:

1. list all entries in etc/datumtransform.table which match a given
datum name, then allow the user to select one of them, or

2. ask the user to enter a PROJ option in one of the forms:

	towgs84=dx,dy,dz
	towgs84=dx,dy,dz,rx,ry,rz,m
	nadgrids=grid

For #2, the string which the user enters is passed to proj verbatim
without any validation.

This is the sort of thing which the GUI can (and should) do by itself;
none of it requires any support from libraries or a C module.

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