Offline maps at state/country borders

[ShammyLevva]

Following discussion on the Facebook Cachly User Group from a user that lives on the border of Germany and wanted to know if there was a way of selecting two or more offline lists. I was thinking about this. I can see that technically the selector selects just a single map and it would require a fair bit of re-writing to change that. Reading another article on lists it hit me that a possible solution may be as follows:

Since the users download the offline maps to their device, might it be possible to have the option (similar to merge lists) to merge maps locally. For this to work the user would need to have downloaded the maps to merge to their local device. A merge option could then allow them to select two maps and combine the data into one newer offline map. This sort of user driven solution that was entirely local to their device would allow anyone on a state/country border to choose the maps either side of that border and to merge them locally according to their own needs. If they needed more than 2 maps merged they could do it in stages merge two then merge a third into the merged map. This keeps the interface simple.

[Nic Hubbard]

Our offline maps are databases with many various files pertaining to different things on the OSM maps. Merging these files on the client side wouldn't be possible.

Opening two map databases at the same time is technically possible, but it would take a lot of rewriting of core offline map code and I also worry about the memory implications of opening two DB's at the same time.

I do have this on our feature list but it would be a major change and not an easy one.

[ShammyLevva]

Ah ok shame. I'd sort of thought it might just be records in a map database that could be merged. Oh well. I can see that showing two at once is going to be far harder to achieve, without risking breaking something. I had hoped that some form of client side solution might be a way forward. I'm guessing from what you've done before server side the maps are generated according to parameters you specify so tweaks will affect everyone thus isn't an option either.