From tartami...@gmail.com on December 26, 2013 18:09:20

Building a Mapsforge theme involves a lot of compromise about what to show and when, which leads to building unnecessary forks that are difficult to maintain an use and/or to cluttered maps. This would be much more simple to handle if we could have a mean to give the end-user some choice on display decisions hiding stuff that's not needed in that moment to unclutter the map.

Adding an optional class attribute would allow the end user to filter elements shown on the map in a very simple way.
Syntax is simple, class="name1,name2,nameN".
The xml is parsed and the list of classes is shown to the user in form of a check-boxed list, for example in an easy to access lateral drawer. When drawing the map, only instructions with at least one class checked are executed. Of course instructions without a class are always executed.

To maximize flexibility the class attribute should be usable on every instruction, not only . However if a is turned off everything inside it is ignored, regardless of its own classes.

A mechanism to determine what classes are checked by default, and maybe to define groups of mutually exclusive classes, would add further usefulness (a lot, actually). But I think it can come independently at a later stage.

Original issue: http://code.google.com/p/mapsforge/issues/detail?id=474