[Qgis-developer] implement data provider in python?

[G. Allegri]

Thanks Etienne, I didn't know it.
Yet it doesn't do exactly what I was thinking about, beacuse I suppose that
the plugin layer cannot be managed as a true layer. AFAICS it has to
implement the rendering operations, which set the style, etc.
Having a "plugin provider" would require only to write the code to provide
the data, leaving the rest of the management (styling, rendering, etc.) to
Qgis.

giovanni

2012/8/29 Etienne Tourigny <etourigny.dev at gmail.com>

> 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
> >> >
> >> >
> >> >
> >> > _______________________________________________
> >> > Qgis-developer mailing list
> >> > Qgis-developer at lists.osgeo.org
> >> > http://lists.osgeo.org/mailman/listinfo/qgis-developer
> >> >
> >
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20120829/14b512b8/attachment-0001.html>