[OpenLayers-Dev] Developement of an external vector symbol library

Erik Uzureau erik.uzureau at metacarta.com
Thu Oct 18 13:38:23 EDT 2007


Dear Barbara,

This project sounds *excellent*. This is just the sort of thing that
OpenLayers needs in order to step it up to the next level.

In a previous thread, I have proposed the creation of an Addins
directory, which all things going right, should probably be together
within the next week or so.

I think your proposal for an OpenLayers Icons Repository would be a
*great* candidate for the Addins directory. I'm sure many people
developing OL apps would love to have access to these symbols.

Erik

On 10/18/07, Barbara Philippot <barbara.philippot at camptocamp.com> wrote:
> Hi,
>
>
> We are trying to improve vector rendering for points geometry, allowing
> users to display symbols such as a square, a triangle, a plane, a church
> and so on instead of just a circle.
>
> At present, we have a library in SVG (using the <symbol> element) and a
> library in VML (using the <shapetype> element). Symbols are loaded when
> the root element <svg> (or <div> in VML) is created, and when the
> drawPoint function is called with a specific style for the point, it
> references the specified symbol with <use href=#symbol> in SVG and
> <shape type=#symbol> in VML.
>
> http://dev.openlayers.org/sandbox/camptocamp/vectorSymbols/examples/vector-symbols.html
>
> We are thinking about creating a single library, in order to be generic
> and so that people can add their own symbols in one file and not both
> SVG and VML.
>
> Problems we meet are :
>
> - We  would need to draw complex symbols. SVG <symbol> element allows it
> since several <path> or predefined <shape> can be included inside but in
> VML, the <shapetype> element isn't so permissive since we can't include
> several shapes or groups of elements inside. So only simple symbols (one
> shape, color, stroke-width, etc) would be allowed...
>
> - which language is better to write the single library : SVG since SVG
> symbols are quite spread on the web (with problem above in mind) or
> javascript to have a generic way to encode symbols, or another language?
>
> - A single library involves to develop a way to transform SVG into VML
> or a certain language into SVG and VML, and there are significant
> differences between the two (shapetype vs symbol, path element accepting
> decimal numbers in SVG and not in VML, etc)
>
> Any ideas about these problems?
>
> So do you think it's worth it or offering predefined symbols and letting
> people adding their code into SVG library and VML library would be
> satisfactory?
>
>
> Regards,
>
> Barbara
>
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