[OpenLayers-Dev] Re: [OpenLayers 3] code sprint summary, and request for comments

[Peter Robins]

On 21 September 2010 12:34, Eric Lemoine <eric.lemoine at camptocamp.com> wrote:
> Right. Do you think the proposed design doesn't address this scenario?

not sure :-) Google's overlay layers are commercial layers but should
not be part of the Google master group, as then you wouldn't be able
to overlay them. As long as the proposal can handle that, no problem.

>> The layerswitcher was just an example. Vectors would be another
>> example of the advantage of separating OL layer from source. A vector
>> layer might take data from several different sources, which might be
>> in different projections - the projection is a property of the source
>> not the layer. The vector layer doesn't need a projection property, as
>> it will always be that of the map, as determined by the baselayer (or
>> whatever you want to call it). The read() function should use the
>> projection defined in the source file (or the default for formats like
>> kml that are always in one (non-)projection), and do the appropriate
>> transforms. The current requirement to specify internal/external
>> projections shouldn't be necessary.
>
> Our BBOX, Fixed, and Save strategies already have support for this. If
> the vector layer has a projection defined then the strategy will do
> the transformation. Are you thinking of something else?

yes. Setting projection on the layer doesn't help in the case where
you have more than one source in different projections (though I agree
that's probably not very common). IMO it also confuses things, as it's
not the projection that the feature coordinates of the layer are in,
which will always be the same as the map projection. IMO it would be
better if this were renamed sourceProjection or some such. If you add
the ability to reproject maps, then the projection of the vectors
currently in the layer will have to be transformed from the old map
projection to the new. The current layer projection property won't be
of use for this.