[gdal-dev] Multiple extensions in GDAL_DMD_EXTENSION ?

[Ari Jolma]

On 02/20/2013 04:10 PM, Mateusz Loskot wrote:
> Whoever comes up with an idea to directly drive his app GUI with a
> library such as GDAL should leave his desk, go fishing for as long as it takes him to come back
> with solution on his app side.

Mateusz,

I've come up with this idea. However, I'm not very often confronted with 
data in strange formats and I've been happy with a standard GTK+ File 
Open dialog for raster data - and then relying on GDAL autodetect. For 
vector data I've cooked up my own dialog - mostly because I want to show 
meta data of the selected layer in the dialog. But, I found out that in 
some cases one needs to specify the OGR driver which to use - so in the 
dialog box there is a drop down widget for optionally specifying the 
driver (the default is autodetect). The file browser can select 
directories and files - so the user can optionally try various drivers 
on the same file/directory.

The practical problem often is of course that the dataset can be made 
from more than one file.

Just the last few days I've worked on the support in the GUI for using 
the WMS and WFS drivers in GDAL. For WMS I made a completely new dialog 
box but for the WFS I added it into the Open vector data dialog - it 
already had support for PostGIS data so non-filesystem datasource was 
not a completely new concept. What I did earlier was to write the OGR 
driver connection strings as templates so that they can be used to 
create simple a dialog box to ask the basic data from the user - this 
seems to work quite nicely.  What I did now was to add the WFS "get 
layers" and "get layer meta data" functionality - I ended up using Perl 
bindings to general XML libraries for those. I only use the OGR WFS 
driver to retrieve the data of a known layer, with 
OGR_WFS_LOAD_MULTIPLE_LAYER_DEFN set to false to avoid unnecessary calls.

So, maybe what I want to say is that the file extension is just a part 
of the issue. GDAL can get data from many other sources than local 
filesystem - and creating a unified easy to use GUI for all those may be 
more interesting and useful.

Cheers,

Ari

>
> Make JSON file with GDAL driver to extension mapping, and configure
> your GUI based on that.
> Flexibility will be way better. Maintenance will be none (GDAL does
> not deliver new drivers every week).
>
> Best regards,
> --
> Mateusz Loskot, http://mateusz.loskot.net
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