[Mapcss] relative width for overlays

[Peter Wendorff]

  Hi.
I'm not developing mapcss-related stuff yet, but perhaps I can propose a 
solution for the question discussed here.

Perhaps you could include a kind of standard value, cascaded as every 
other value.
The default value could be set for the overall map object. I'll call it 
#map for now.
With this it could be possible to set all line widths (or other 
measurements perhaps as well) to a base value:

#map {
   base-stroke-width: 5;
}

If no other value for stroke-width is specified, this base value is used 
for the real stroke width of this object.

To use relative values for another css rule, we now can use

.residential
{
   relative-stroke-width: 2;
}

.footway
{
   relative-stroke-width: -2;
}

Of course implementations have to deal with styles interfering with each 
other, e.g.

.cycleway
{
   relative-stroke-width: -2;
   stroke-width:5;
}

but I think, that's a part of CSS and should be handled in other cases 
as well, taking the last defined value or anything like that.

regards
Peter Wendorff

On 03.10.2010 16:49, Komяpa wrote:
>>> Thanks for you answers! Because it is so common, I was tempted to use a
>>> shortcut:
>>>
>>>     width: +4;
>> I was going to suggest the same thing. I think the notion of "define
>> this width relative to another width" is so common, it's worth having
>> notation for it.
> This syntax should be thought more to be pushed into more-or-less
> standard mapcss.
>
> 1) it becomes a lot harder to parse. +1 and 1 are considered the same
> in most programming languages, so you can't just linearly transform
> mapcss into (for example) JSON form, also can't even hold in a single
> variable.
>
> 2) what should be used for a base for adding and substracting widths?
>
> 3) Most of those use-cases are well-covered (IMHO) with casing thing.
>
>
>