[OpenLayers-Dev] Developement of an external vector symbol

Cameron Shorter cameron.shorter at gmail.com
Sun Oct 21 06:44:22 EDT 2007

This sounds like a great initiative and I'd be surprised if there isn't 
already a number of projects which transform between SVG and VML.
I know that there has been work converting GML to SVG, and hence there 
shouldn't be much work transforming GeoRSS to SVG.

So I suggest:
1. Before you do any development, research available tools that you can use.
2. Create one vector library (either SVG or VML) and use a translation 
tool to automatically convert from one to the other.
3. Precompile the alternative library. Ie, don't convert SVG to VML on 
the fly in Javascript. It will slow the browser down.
3. I suspect that SVG would be a better format to support than VML. I 
believe SVG is used by a number of other projects, eg the Linux Icon 
4. Search for existing icon libraries and consider extending the 
existing icon libraries rather than creating a new project. Maybe make a 
geographic version of the library.
5. Think bigger than just OpenLayers. You start the free icon library 
used by all Open Source GIS projects. It might be a candidate project 
for: http://wiki.osgeo.org/index.php/OSGeo_Labs
(Although you may want to seed your project within Openlayers)

Barbara Philippot wrote:
> Ian Mayo a écrit :
>> Barbara,
>> I'm afraid I can't offer an opinion on your languages challenge.  It
>> would be great if there was a pre-existing file-format for vector
>> symbols, then we just specify filenames rather than hard-code the
>> vectored shapes.
> Yes, this is why we are trying to do. But people would have to specify
> two filenames (one in SVG, the other in VML) to replace the pre-existing
> symbol catalogue files and it's not still the ideal solution but perhaps
> it's the only one.
>> I'm currenlty working on provision of per-entry icons (images) for
>> georss feeds. [1].  I've made good progress, but may have to pause my
>> efforts for the next 7 days, see my demo at: [2].   Had you considered
>> using the symbols on a per-entry fashion in a georss feed?  I suspect
>> it's fortunate I've got a self-induced development pause: it would
>> seem to be worth offering per-entry symbols as well as icons.
>> Appreciate your thoughts/opinions.
> Well, I hadn't considered using symbols in a georss feed and I don't
> know well Georss format. For the moment, symbols are associated with
> points geometry with a style.use="symbol" in the same way as images were
> associated with style.externalGraphic. So, I haven't looked in detail to
> the way you attach icons to GeoRss nodes but it seems that you would be
> able to use SVG and VML symbols as well as images.
> I hope to make progress before your development pause ends :-)
>> Ian.
>> 1. http://trac.openlayers.org/ticket/1073
>> 2. http://dev.openlayers.org/sandbox/ianmayo/branches/rss/openlayers/examples/georss.html
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Cameron Shorter
Systems Architect, http://lisasoft.com.au
Tel: +61 (0)2 8570 5050
Mob: +61 (0)419 142 254

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