Hi,

I think that this kind of discussion belongs to mapserver-users (cc:ed). I hope 
that developers read also the users mailing list, and users may have more to 
say about what they consider hard with styles. Also, Mapserver users learn from 
reading mails like this, and that there are mails on the list at all proves 
that the project is not dead. Developers can discuss on the dev list or in 
GitHub about how to implement the “size by expression” with C++ and so on.

One thing that always feels odd to me is that why we do not have any default 
style for points but we must especially define some symbol in the mapfile. I 
have been thinking that perhaps we could have internal, hard coded symbols at 
least for these 6 which are defined in the SLD standard:

“The WellKnownName element gives the well-known name of the shape of the mark. 
Allowed values include at least “square”, “circle”, “triangle”, “star”, 
“cross”, and “x”, though map servers may draw a different symbol instead if 
they don't have a shape for all of these. The default WellKnownName is 
“square”. Renderings of these marks may be made solid or hollow depending on 
Fill and Stroke elements. These elements are discussed in Subclauses 11.2.2 and 
11.1.3, respectively.”

If user gives no symbol in the mapfile for points it would mean “square”. If 
symbol with the same name than WellKnownName is defined in mapfile or in 
symbolset it would override the standard symbol. If there is a special need for 
non-visible points  we could have one more: SYMBOL “NONE”.

-Jukka Rahkonen-

Lähettäjä: mapserver-dev [mailto:[email protected]] 
Puolesta Seth G
Lähetetty: 25. lokakuuta 2016 13:20
Vastaanottaja: [email protected]
Aihe: [mapserver-dev] MapServer tutorial - symbology


Hi all,

I have updated the second quick start tutorial on SYMBOLS and symbolizing data. 
A draft page is available at: 
https://geographika.github.io/tutorial/quickstart/symbolizing.html

I ran through this with around 6 people, and a few questions came up. If anyone 
can provide details that would be very helpful. Also comments/improvements on 
the tutorials are very welcome.

1. Are there any performance or other benefits of VECTOR symbols over 
IMAGE/SVG? (Although I think SVG is currently not available in ms4w - 
http://www.ms4w.com/trac/ticket/3 ). The manual entering of coordinate details 
seems pretty difficult compared to using/making SVGs.

2. At the top of the http://mapserver.org/mapfile/style.html#style page there 
is the sentence "The final intent is to have named styles (Not yet supported) 
that will be re-usable through the mapfile." I presume this means there was a 
plan to use STYLES similar to a SYMBOLSET? Are there still any plans to do this?

3. I was looking to create circle symbols of different sizes based on an 
attribute, using one of the datasets from Natural Earth. The cities with large 
populations has a smaller "RANK_MAX" - so the size needs to be inverse to an 
attribute. There does not appear to be any easy way to do this without 
modifying the data.  You can set the size using an attribute e.g. "SIZE 
[MYHEIGHT]" but is there a good reason why a MapServer expression couldn't be 
used here? I can add as a feature request to GitHub if it could be a nice 
addition.

A final question - should I post these emails to the dev or users MapServers 
lists?

Regards,

Seth
--
web: http://geographika.co.uk
twitter: @geographika
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