[Mapcss] Mapcss clarifications

[Sebastian Spaeth]

Before I start fudging the wiki, I'd like to have some clarifications on
mapcss, which might or might not have been discussed.

I take my infos from here: http://wiki.openstreetmap.org/wiki/MapCSS, right?

1) How are comments defined?
   - /*  comment here (which can span multiple lines? */  
   - # at start of line as comment? or also as : 
     way {color:red;} #FOO boo here
   - // type of comments?

   So far I went for the first solution, but what do others prefer? And
   that should be documented in the wiki. Should all three work?

2) How are nodes supposed to be rendered?
   - All the wiki page says about nodes/points, is "icon-image"
    Would a "width" argument on a node render a circle, with a casing
    argument render a border on that circle? Or are we restricted to
    icon images here? We'll often want to use icons, but being able to
    easily provide simple circle types with additional labeling would be
    nice. I know, implementation details are left to the renderer, but
    it would  be good to propose how those values could be used.

3) How is "fill-image" supposed to work on an area?
    Scale image and fill it, clipping the borders? Repeat as pattern? We
    probably want to borrow more CSS terms here to specify that
    behavior, right?

4) How are color names defined? Is there a CSS set of color names/values
    that we can use, or do we have our own set? I snatched the color
    names from the python imaging library for now which provides 140
    names.

5) What selector operators should we support? All I do now is ! < = > plus
   existence tests: way [highway].
   Is "way .highway" supposed to be identical to way [highway]? Also I
   used the '!' to negate all filters, so both forms work:
   - way [!highway] (does not have a highway tag at all)
   - way [!name=route66]
   
   Looking at your code, I see operators such as 'ne' and 'regex', can
   we list some of the basic supported operators that are supposed to
   work?

   Also, how do you separate left hand, operator and right hand What
   happens with spaces in left hand or right hand? Take these:
   ["high way" ne "Route 66"]
   [name eq NE Ave] (invalid?)
   [name = "bob said 'Hello \"Mom\". regex are cool'"]
   
   I know these are corner cases that look a bit constructed, but
   e.g. the spaces in tags/values problem is real at least.

6) From the spec, I did not get what this means:
   @import url("osmtags.css") osmtags;

   What happens here? All styles in osmtags.css only apply to elements
   with a 'class' osmtags? So osm data with osmtags="foo" would get it
   applied? I'm a bit unsure here.

7) What with declarations. I parse my style sheets once and pass the
   result to a renderer, what if I render 2 things at different
   levels. Would a { set tag=value; } remain persistent between runs? I
   presume not.

8) Rules are supposed to be applied in file order? Or in other words, is
   this supposed to render my horsepaths blue?
      way [highway] {color:blue;}
      way .horsepath { set highway=unclassified;}

There are more questions where those came from :-).
spaetz
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