[Qgis-developer] Custom CRS handling

[Leyan]

Hi developers,

I am a heavy user of custom CRS (not by choice !)and the current custom 
CRS definition dialog is not very intuitivein my opinion, so I started 
to work on it to replace it with a new versionallowing to:
* see the list of custom CRS (instead of browsing them one by one)
* copy an existing CRS to a new custom one (custom CRS are mostly based 
on standard ones with some modified parameters)
* use the dialog OK or cancel buttons to save the modifications instead 
of having to saveeach modification
* use functions taken from the QgsCoordinateReferenceSystem class to 
improve validity checks and maybe later allow other syntax than proj4
* I think it would allow me later to remove the warning about different 
CRS I get from some tools when I use the same CRS but with different 
proj4 strings.

However, I realized the QgsCoordinateReferenceSystem::createFromProj4() 
function always checks the CRS database and adds the CRS to it if it is 
not present already, with an automatic name "Generated CRS". This means 
I cannot use it to manipulate any CRS not yet saved in the database.

Do you think it would be a good idea to separate the creation of the CRS 
object and the saving to the database ? Was there any special reason to 
join both?

Regards,

Leyan