Hi, Didn't someone say they were working on an on-the-fly graticule provider, which is similar to your use case (but I doubt it involved Python)?
Alister > Date: Wed, 29 Aug 2012 16:53:39 +0200 > From: "G. Allegri" <[email protected]> > To: Etienne Tourigny <[email protected]> > Cc: qgis-developer <[email protected]> > Subject: Re: [Qgis-developer] implement data provider in python? > Message-ID: > <CAB4g1=yvywN4zBoQYevNeyVDV=mouegoyv1geo7xhivna3p...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > 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 <[email protected]> > > > 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 <[email protected]> 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 <[email protected]> > > >> >> > > >> >> 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 <[email protected]> > > 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" <[email protected]> > > >> >> > 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 > > >> > [email protected] > > >> > 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.html> > > ------------------------------ > > _______________________________________________ > Qgis-developer mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-developer > > > End of Qgis-developer Digest, Vol 82, Issue 88 > ********************************************** _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
