fix for NullPointerException on overview map

[RinkeHeida]

I have a solution for this error when using an overviewMap:
java.lang.NullPointerException: null
at org.mapfish.print.map.MapChunkDrawer.renderImpl(MapChunkDrawer.java:86

I seem not be able to push my commit to this repo, can you add me as contributor?

Or use this fix in the next release:

src\main\java\org\mapfish\print\map\MapChunkDrawer.java

        mainTransformer = context.getLayout().getMainPage().getMap(name).createTransformer(context, params);

->

        mainTransformer = context.getLayout().getMainPage().getMap(null).createTransformer(context, params);

[jodygarnett]

Can you add that as a PR? You can do so right from GitHub by clicking edit on the file...

This project is not actively maintained so you really have to do stuff yourself there is nobody listening to do work for ya

[RinkeHeida]

Direct edit is not possible as I am not an owner.
When I edit through github.dev it is not possible to commit before I can do a PR

[jodygarnett]

I had a look at https://github.com/mapfish/mapfish-print-v2/main/src/main/java/org/mapfish/print/map/MapChunkDrawer.java and do not see how your change is used. Name should be non-null based on computeName being based on name and overviewMap value.

Can you provide some more information about what is going on please? I am not that familiar with the codebase.

[RinkeHeida]

Name is indeed set to a non-null name based on computeName, but using that name does somehow not work for an overviewMap getMap(). I believe the non-null is introduced in some version of mapfish print. We used an old version long time and moving to this version (or even 2.2) it broke our overviewMap. In all other cases it is possibly good to have non-null map name.

If name is passed in getMap(name), we do get an overviewMap, but it is on the same scale as the main map, so useless as an overviewMAp.
It should be a zoomed out versioin of the main map, with a rectancle showing what the boundary of the main map is.
With the change to getMap(null) we get the correct overviewMap.

[jodygarnett]

Interesting thanks for the explanation; so it must be looking up the name and finding the scale used by the main map. I wonder if providing the name + " Overview" would be more appropriate?

[RinkeHeida]

It should really be without a name by this change:
mainTransformer = context.getLayout().getMainPage().getMap(null).createTransformer(context, params);
I tried many different solutions last year (in code and in the config.yaml), but the only way the overviewMap is working as it should is by this change.
This change made it work and everything else is working as well (like scalebar etc). Here it is operational now for more than a year and used quite a lot.
Would be nice if the change can be merged, as otherwise I have to keep a separate repo locally.