Hey Dane, I haven't tried using it in Python, but as I just realized now that it doesn't quite matter since, as of svn trunk (r729), memory_datasource::features(const query& q) relies on a certain memory_featureset(bbox, ...) ctor, but if you take a look at memory_featureset.hpp, the next() iterator method is mostly commented out.
In other words, when Mapnik asks the memory_datasource for features, it returns an empty feature_ptr. That said, if this gets fixed (it's been this way for 11 months), the following C++ code might work. I adapted Andreas's code, as at least one method call changed (to add_geometry), and I instead derived publicly from memory_datasource. Here's the code snippet (yet to be tested properly) on gist.github: http://gist.github.com/6150 Artem, shall I create a ticket? I don't see the issue mentioned on the tracker. ~L On Sun, Aug 17, 2008 at 12:50 PM, Dane Springmeyer <[EMAIL PROTECTED]>wrote: > Andreas, > > Thats great. So do you know if the `mapnik::memory_datasource` is > exposed in the python bindings? > > Dane > > > On Aug 17, 2008, at 11:58 AM, Andreas Volz wrote: > > > Am Thu, 07 Aug 2008 11:15:02 +0200 schrieb Ric S: > > > >> Hi folks, > >> > >> I have successfully setup mapnik. Generating a map already works. > >> Now I would like to draw gps points into the map, I was searching the > >> net for a few hours to get some info, unfortunately > >> I still have now clue yet how this can be done with mapnik. > >> I assume I have to create a layer and add points to it. I could not > >> find an example how to draw points. > >> > >> I would like to set gps points in my map. Could you please show me > >> how to add a single gps point to this map/layer. The code from > >> generate_image which I used: > >> ... > >> z = 10 > >> imgx = 100 * z > >> imgy = 100 * z > >> > >> m = Map(imgx,imgy) > >> load_map(m,mapfile) > >> prj = Projection("+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 > >> +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m [EMAIL PROTECTED] +no_defs > >> +over") c0 = prj.forward(Coord(ll[0],ll[1])) > >> c1 = prj.forward(Coord(ll[2],ll[3])) > >> bbox = Envelope(c0.x,c0.y,c1.x,c1.y) > >> m.zoom_to_box(bbox) > >> im = Image(imgx,imgy) > >> render(m, im) > >> view = im.view(0,0,imgx,imgy) # x,y,width,height > >> view.save(map_uri,'png') > > > > I've done that some time ago. Worked well. But then I deactivated the > > code for some reason. Not sure if it works at the moment: > > > > void MapnikSource::insertDataPoint (double x, double y, const char > > *key, const char *value, const char* layer) > > { > > /*Layer lyr (layer); > > datasource_ptr ds (new mapnik::memory_datasource); > > feature_ptr f (feature_factory::create (keyID)); > > > > geometry_ptr point (new point_impl (-1)); > > point->move_to (x, y); > > > > f->set_geometry(point); > > > > transcoder tr ("utf-8"); > > (*f)[key] = tr.transcode (value); > > > > if (ds) > > { > > mapnik::memory_datasource *mem = dynamic_cast > > <mapnik::memory_datasource*> (ds.get ()); > > > > if (mem) // check if cast is ok! > > { > > // do something with memory_datasource e.g. > > push some features > > mem->push(mapnik::feature_ptr(new > > mapnik::Feature(-1))); > > mem->push (f); > > } > > } > > > > lyr.set_srs ("+proj=latlong +datum=WGS84"); > > lyr.add_style ("enigator"); > > lyr.set_datasource(mapnik::datasource_ptr(ds)); > > map->addLayer (lyr); > > > > keyID++;*/ > > } > > > > This is how I called it: > > > > m_mapnikSource.insertDataPoint (x, y, "enigator", "wptred", > > "enigator"); > > > > This is the reference in the XML file: > > > > <Style name="enigator"> > > <Rule> > > <MaxScaleDenominator>50000</MaxScaleDenominator> > > <Filter>[enigator]='wptred'</Filter> > > <PointSymbolizer file="/home/andreas/src/svn/enigator/trunk/ > > data/symbols/wptred.png" type="png" width="32" height="32" /> > > </Rule> > > </Style> > > > > Search the history of this list with my name and around 10-12 month > > ago or so. > > Maybe this helps you... > > > > regards > > Andreas > > _______________________________________________ > > Mapnik-users mailing list > > [email protected] > > https://lists.berlios.de/mailman/listinfo/mapnik-users > > _______________________________________________ > Mapnik-users mailing list > [email protected] > https://lists.berlios.de/mailman/listinfo/mapnik-users >
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