[mkgmap-dev] question regarding MapRoad

Fri Oct 18 08:11:53 BST 2013

Hi Steve,

> Yes MapRoad should probably not be limited to 250 points since it is in
> .mkgmap.general and the limitations should be applied on the conversion
> to Polyline.
yes, absolutely, and I already have it working.

> OK - not sure where to start and I think the first task is to understand
> how the data flows through the different classes. I will think about it 
> over the weekend.

I did a lot of research during the last days and created some patches based
on it. My general approach for now:
1) StyledConverter (and RoadMerger) should try to create as few MapRoads
as possible, so that indexes do not contain multiple entries.

2) With the end of StyledConverter.end() we know the number of
a) MapRoad instances and b)  CoordNode instances.
With the current implementation that means:
For a routable map we must make sure that this number is not changed in
the following chain for level 0, means, no filter should remove
a MapRoad instance (or replace it by a MapLine) or replace 
a CoordNode by a normal Coord instance.  The current implementation 
contain errors like this, e.g.  in LineSplitterFilter (fixed with r2765).
I try to add sanity checks for this.

3) For all levels > 0 there is no need to bother about CoordNodes,
and it is also okay to drop MapRoad instances in the filters.
Current implementation of the filters doesn't 
completely ignore CoordNodes, so it is possible that 
overlaying lines are "moved". This should not happen.

Conclusion:
To remove obsolete checks in StyledConverter we have to make sure
that all these errors are fixed and that all img write methods are
working correct with the changed input. The latter is quite difficult.

I'll create a branch to experiment with this.

Gerd

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