[mapserver-dev] ms rfc 48: adding a type keyword to the styleblock

Tamas Szekeres szekerest at gmail.com
Mon Nov 10 10:15:24 EST 2008

2008/11/10 Daniel Morissette <dmorissette at mapgears.com>:
> Guys, let's keep in mind that the simplicity of MapServer used to be its
> main advantage? Did we forget that "MapServer is not a full-featured GIS
> system, nor does it aspire to be"?


While I understand the concept behind the idea  above, in this
particular case I don't really know what you are proposing. Did you
mean that this RFC should drop the idea of representing the functions
(along with the parameters) by using a geometry expression and should
return to the original version by introducing as many new keywords as
the number of the functions are planned to be implemented in this
phase. In this case the author might have to provide a possible
alternative to specify those parameters possibly by introducing
further keywords to the parser.
>From the user's perspective I don't think these expressions are more
complicated to understand than the syntax in the TEXT labels for
example with the current implementation.

> While it may sound cool to perform a
> centroid(convexhull(buffer([geom],0.5))) in a style at rendering time, that
> remains a purely theoretical example with no application in real life as far
> as I can tell... BTW, do we also expect that a feature rendered after such a
> complex operation should be clickable (queryable) as well and how do we plan
> on managing that if all those operations are done only at rendering time in
> the style object and not in the data source where the query happens?

I'd note that those examples have been introduced only to demonstrate
the necessity to the argument to be represented in the expressions,
but no one have stressed that this level of detail in the expressions
should be required to implement at all. But ommitting those arguments
in the syntax may lead to backward incompatible changes if someone
will like to extend this functionality in the future.
With regards to the clickable comment I'm not sure if mapserver
currently provides this way for example when using the pixmap symbols
by taking care of the pixel extent or the transparent areas of those
symbols, it may be the subject of a further RFC, however.

Best regards,


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