OpenLayers Map View extension for Exhibit

[Ryan Lee]

I'd like to announce the availability of an OpenLayers [1] Map View
extension for Exhibit. Based in large part on the existing Google Maps
View extension, it currently replicates most of the GM functionality.
The settings are nearly the same, differences detailed below. To make
use of it in your Exhibit, add "?service=openlayers" to the
map-extension.js URL in the appropriate script tag and set the
ex:viewClass to "OLMap".

There are plans for expansion in the near future, but for now please let
me know if you have any questions, observations, or bug reports on this
basic implementation. You can see it in action here:

http://trunk.simile-widgets.org/exhibit/examples/presidents/presidents-openlayers.html

= Settings =

All of the settings listed for the Map View [2] can be used with the
OpenLayers extension except:

- ex:size (there are no different sizes for map controls available)
- ex:type (there are no predefined tilesets for maps; currently
included are an unlabelled geopolitical boundary map and a satellite
imagery map)

Not all of the settings have been tested. Please let me know if you run
into any problems.

1. http://openlayers.org/
2. http://simile.mit.edu/wiki/Exhibit/2.0/Map_View

[John Callahan]

Very cool. I love it! Thanks for going completely open source! Maybe
you can even use OpenStreetMap as the default map.


Two quick questions:

1) Can this also replicate the polygon, polyline, and kml features David
added recently?

2) When filtering, are all of the markers wiped clean before the subset
is re-added? I'm just curious if there's any way around that for
performance issues (say with 500 markers).


- John

**************************************************
John Callahan, Geospatial Application Developer
Delaware Geological Survey, University of Delaware
URL: http://www.dgs.udel.edu
**************************************************

[Ryan Lee]

Hi John,

John Callahan wrote:
> Very cool. I love it! Thanks for going completely open source! Maybe
> you can even use OpenStreetMap as the default map.

Thanks, that's a great suggestion.

> Two quick questions:
>
> 1) Can this also replicate the polygon, polyline, and kml features David
> added recently?

I'll be looking into the polygon and polyline features in the near
future, but no; it will probably trigger errors if you try to use them
right now.

> 2) When filtering, are all of the markers wiped clean before the subset
> is re-added? I'm just curious if there's any way around that for
> performance issues (say with 500 markers).

Yes, that's what's happening behind the scenes. I can try to see if the
OL API provides a better mechanism for hiding and showing.

Thanks for the feedback!

[Ryan Lee]

A quick update on the OL Map view.

Ryan Lee wrote:
> Hi John,
>
> John Callahan wrote:
>> Very cool. I love it! Thanks for going completely open source! Maybe
>> you can even use OpenStreetMap as the default map.
>
> Thanks, that's a great suggestion.

And it's now the default map.

>> Two quick questions:
>>
>> 1) Can this also replicate the polygon, polyline, and kml features David
>> added recently?
>
> I'll be looking into the polygon and polyline features in the near
> future, but no; it will probably trigger errors if you try to use them
> right now.

I've added polygon and polyline support.

>> 2) When filtering, are all of the markers wiped clean before the subset
>> is re-added? I'm just curious if there's any way around that for
>> performance issues (say with 500 markers).
>
> Yes, that's what's happening behind the scenes. I can try to see if the
> OL API provides a better mechanism for hiding and showing.

It does not, unfortunately.

--
Ryan Lee rya...@csail.mit.edu
http://simile.mit.edu/