[mkgmap-dev] overlays file for POIs

Sat Jan 16 21:45:48 GMT 2010

On Sat, Jan 16, 2010 at 07:37:01PM +0100, Felix Hartmann wrote:
> Hi, would it be possible to integrate an overlays file for POIs? The  
> current overlays file (inside the style-file) only works for polylines.  
> I would like to do the same for POIs. (I don't think it is needed for  
> polygons, but maybe someone has creative ideas in his head and would  
> like to have it for polygons too).
>
> I don't manage to program this, but I hope that it proves easy as we  
> already have that functionality for lines. Would be great if it could be  
> integrated. I tried to do it by using "continue" but this does not work.  
> (continue will only work if the key or value is different).

Could the "continue" action be made to work?  Such rules might be easier
to follow than overlay definitions, but I guess it is a matter of taste.

As far as I can tell from the source code, the following pieces of code
implement the line overlays:

StyleImpl.getOverlays(LineAdder)
 * called by StyledConverter constructor
 * wraps calls to the passed LineAdder.addLine() by OverlayReader.addLine()
 * the passed LineAdder would be this one defined in StyledConverter:
	private LineAdder lineAdder = new LineAdder() {
		public void add(MapLine element) {
			if (element instanceof MapRoad)
				collector.addRoad((MapRoad) element);
			else
				collector.addLine(element);
		}
	};

You would have to implement something similar around StyledConverter.addPoint()
or StyledConverter.collector.addPoint().

I find your example use case of symbols for public transportation stops
extremely useful.  I hope that someone will make this happen.  Sorry,
there are only so many hours in my days, and the top priority on my "roadmap"
is to create multi-layered maps.

By the way, house numbers and bike route numbers could be useful to put on
user-selectable map layers.  Couldn't you actually create the numbers as
text labels?  Could the addresslayer_style of
http://wiki.openstreetmap.org/wiki/DE:All_in_one_Garmin_Map
be doing exactly that?

Best regards,

	Marko