[mkgmap-dev] How can we use prefix/suffix feature in road names?

Wed Apr 12 11:13:28 BST 2017

Hi all,

recently I learned about this feature which is already partly implemented in mkgmap, but not easy to use with OSM data.
See 
http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2017q2/026602.html
There is at least one visible effect of these 0x1e and 0x1f characters: When you zoom out MapSource removes the prefix / suffix part(s) from
the name. So "Rue de la Concorde" is displayed as "Concorde" which requires less space and probably allows to display more names.
If I got that right the prefixes and suffixes are also excluded from the index by mkgmap, but that might not yet work.

My understanding is that we need a way to change the a road label "Rue de la Concorde" 
to "Rue de la" + 0x1e +"Concorde" or "Fernrodder Strasse" to "Fernrodder" + 0x1f + "Strasse".

Does anybody already use that feature in style rules? 

I can think of several ways to implement that. 
1) A collection of style rules for well known prefixes and suffixes.
I fear those would be quite complex.

2) A new option file listing prefixes and suffixes and some Java code to modify all road labels. Format of the file might be
prefix=Rue de la 
prefix=Rue du 
prefix=Rue de
prefix=Rue
prefix=Rua
prefix=Chemin de la
prefix=Chemin du
prefix=Chemin de
prefix=Chemin
...
suffix=Road
suffix=Steet
suffix=Strasse
suffix=Weg
...

I assume it is possible to compile a single regular expression from this, so performance should not be a problem.

Gerd