[Qgis-developer] WCS and Raster improvements for QGIS

[Radim Blazek]

On Fri, Jul 13, 2012 at 10:46 AM, Even Rouault
<even.rouault at mines-paris.org> wrote:
>> - question/suggestion, GDAL i using CPLHTTPFetch() to get data from
>> server, would it be possible to add a possibility to set user function
>> to be used instead of default CPLHTTPFetch()? Something like
>> SetHTTPFetchFunction( myHTTPFetch ). That would make it possible to
>> use GDAL providers with QgsNetworkAccessManager for example.
>
> I was actually thinking to something like that when reading Marco's email.
> Sounds perfectly doable. The only point that could be tricky is if you need a
> user_data pointer that is specific to each WCS connexion.

Yes, requests must be somehow assigned to layers/providers so that
progress may be emitted from the right place.  It could be maybe done
using GDALDatasetH pointer? Just another hack.

In theory, we are going to use threads, which could complicate it even
more. It is not yet clear to me if QgsRasterDataProvider::readBlock of
an instance is also going to be called from multiple threads
simultaneously?

Radim