[OpenLayers-Users] GeoJSON layer on top of google - repeated load of features

[Adorian Ardelean]

Hi,

*Yes* the position of features on map is OK now  (I initially added in the
same place only this: "projection: new OpenLayers.Projection("EPSG:4326")".
Thank you!

However, the style map does not function yet.

Works OK under:
specimens2 = new OpenLayers.Layer.GML("specimens", "geojson.php", {format:
OpenLayers.Format.GeoJSON, projection: new
OpenLayers.Projection("EPSG:4326"), styleMap: new
OpenLayers.StyleMap(style)});

but not as
var p = new OpenLayers.Format.GeoJSON({externalProjection: new
OpenLayers.Projection('EPSG:4326'),internalProjection:
map.getProjectionObject(), styleMap: new OpenLayers.StyleMap(style)});

Tthis is a template context styling depending on value of parameters in
GeoJSON file.

Any quick hints?
Adorian



On Wed, Jul 2, 2008 at 3:55 PM, Eric Lemoine <eric.c2c at gmail.com> wrote:

> Hi. How about that:
>
> var format = new OpenLayers.Format.GeoJSON({externalProjection: new
> OpenLayers.Projection('EPSG:4326'),internalProjection:
> map.getProjectionObject()});
>
> Note that i haven't tested this.
>
> Eric
>
> 2008/7/2, Adorian Ardelean <mynature at gmail.com>:
> > Hi,
> >
> > First of all thank you for the prompt suggestion. Worked perfectly and I
> was
> > able to include also a style to work with properties defined within
> GeoJSON
> > file:
> > *
> > specimens = new OpenLayers.Layer.GML("specimens", "geojson.php", {format:
> > OpenLayers.Format.GeoJSON, projection: new
> > OpenLayers.Projection("EPSG:4326"), styleMap: new
> > OpenLayers.StyleMap(style)});*
> >
> > The situation I've encountered now is that data from this layer has to be
> > regenerated with every zoomend event (I do some clustering on server side
> to
> > limit the number of features to less than 100 points - the return could
> be
> > easily in hundreds or more). The part with zoomend event I can handle.
> > However, I do not know what is the best strategy to handle this situation
> > further:
> >
> > 1. delete the whole layer and recreate a new GML layer (using code above)
> > every time? This produces some problems in handling controls (as I
> interpret
> > from reaction of the scripts). The controls dedicated to layer
> "specimens"
> > does not function anymore. I have to redeclare it again.
> >
> > 2. create a vector layer and load and delete features with zoom events
> > without removing layer and controls.
> >
> > For second solution I have found the piece of code below, (which also
> works)
> > but returns me to the initial question how do I specify in this context
> > projection an style parameters?:
> >
> > *OpenLayers.loadURL("geojson.php", {}, null, styleMap: new
> > OpenLayers.StyleMap(style)}, onLoadgml, onLoadFailedgml);
> >
> > function onLoadgml(r) {
> >      if (r.status == 200) {
> >         var p = new OpenLayers.Format.GeoJSON();
> >          var f = p.read(r.responseText);
> >          specimens.addFeatures(f);
> >      }
> > }*
> > *
> > ....
> >
> > *I would somehow prefer the second strategy. Could somebody give me a
> hint
> > on how to include *{format: OpenLayers.Format.GeoJSON, projection: new
> > OpenLayers.Projection("EPSG:4326")* in script so that OL renders vector
> > features at the right place*?
> >
> > *All the best,
> > Adorian
> >
> > On Sat, Jun 28, 2008 at 5:32 PM, Christopher Schmidt <
> > crschmidt at metacarta.com> wrote:
> >
> >> On Sat, Jun 28, 2008 at 04:39:19PM +0200, Adorian Ardelean wrote:
> >> > Hi,
> >> >
> >> > I am trying to load a GeoJSON file in a layer on top of a google map
> >> > (OpenLayers 2.6).
> >> >
> >> > I used for now:
> >> > var colfeatures = new OpenLayers.Layer.GML("specimens", "geojson.php",
> >> > {format: OpenLayers.Format.GeoJSON});
> >> > map.addLayer(colfeatures);
> >> >
> >> > Entities show up on the map somewhere close to 0,0. For other vector
> >> > entities (coordinates) I push through code this is solved with
> >> >
> >> > var g = new OpenLayers.Projection("EPSG:4326");
> >> > var p = new OpenLayers.Projection("EPSG:900913");
> >> >
> >> > and .tranform(g,p)
> >> >
> >> > but I do not know how to apply this directly on features read from
> >> GeoJSON.
> >> > Is there a way to loop through all entities in colfeatures and apply
> >> > transform(g.p) or can somebody suggest me a better approach?
> >> {format: OpenLayers.Format.GeoJSON} ->
> >>  { format: OpenLayers.Format.GeoJSON,
> >>   projection: new OpenLayers.Projection("EPSG:4326")
> >>  }
> >>
> >> Regards,
> >> --
> >> Christopher Schmidt
> >> MetaCarta
> >>
> >
> >
> > http://mybiosis.info
> >
>
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