[Qgis-developer] implement data provider in python?

[Etienne Tourigny]

I am not quite sure how it works, and there are few details available,
maybe someone who knows how it works can provide some insight?

The openlayer plugin is implemented as a plugin layer. It doesn't
interact with other layers, but seems to do what you are talking about
(gets queried on every pan/zoom/etc to retrieve the update data).
Have a look at the code.

API stuff:
http://qgis.org/api/classQgsPluginLayer.html
http://hub.qgis.org/issues/2392

On Wed, Aug 29, 2012 at 11:04 AM, G. Allegri <giohappy at gmail.com> wrote:
>> you might be able to achieve that using "plugin layers" which are map
>> layers that can be created and updated by plugins
>
>
> What do you mean Etienne?
> How can I serve a layer, dynamically, through a python plugin? I don't want
> to have a plugin that creates a memory layer, but that gets queried on every
> pan/zoom/etc to retrieve the update data.
>
> giovanni
>
>>
>>
>> > The other is having the possibility to bridge, easily, any kind of data
>> > source, using python as an adapter.
>> >
>> > giovanni
>> >
>> >
>> >
>> >
>> > 2012/8/29 Barry Rowlingson <b.rowlingson at lancaster.ac.uk>
>> >>
>> >> I have a vague memory that the python data provider idea was
>> >> considered a while ago. I was thinking about how one could get direct
>> >> access from Qgis to R spatial data sets stored in R's binary files.
>> >> One method would have been to write a provider in python that used Rpy
>> >> to bridge to R, but wasn't possible because you can't write data
>> >> providers in Python. It could be done in C by linking to R's C
>> >> library, but at that point I lost interest and used a looser coupling
>> >> to get my R data into Qgis.
>> >>
>> >> The argument then went that if the provider was designed to access a
>> >> file it would be a better idea to write a GDAL/OGR driver, then even
>> >> people outside QGIS could use it. Obviously that would have to be
>> >> C/C++ though.
>> >>
>> >> And then I think everyone got bored and went back to doing things.
>> >>
>> >> Do you have a specific use-case?
>> >>
>> >> On Wed, Aug 29, 2012 at 8:01 AM, G. Allegri <giohappy at gmail.com> wrote:
>> >> > Anybody interested in developing the concept and evaluating its
>> >> > feasibility?
>> >> > I'm considering the possibility to sponsor it.
>> >> >
>> >> > giovanni
>> >> >
>> >> > Sent from Nexus
>> >> >
>> >> > Il giorno 28/ago/2012 00:11, "G. Allegri" <giohappy at gmail.com> ha
>> >> > scritto:
>> >> >>
>> >> >> AFAIK it isn't possible to register a python script as a
>> >> >> dataprovider.
>> >> >> Maybe it sounds odd, but I think it would interesting if we could
>> >> >> have
>> >> >> it.
>> >> >> Has it been ever considered? How hard would it be to implement it?
>> >> >>
>> >> >> Giovanni
>> >> >>
>> >> >> Sent from Nexus
>> >
>> >
>> >
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>> >
>
>