How to make offline maps and navigation in Android?

Question

Android

I have the following task: when the application starts, it will determine the user's location and download a map and data for offline route planning within a certain radius. I've looked at a lot of examples, but in all examples, maps and data for offline navigation are prepared in advance, and I need everything to happen dynamically when the application is running. I chose Graphhopper for offline navigation and OSM for offline maps. The app is being developed on Android.

Answer 1

map display tiles can be loaded dynamically, even vector ones. it is in a bunch of programs.
dynamically loaded routing system does not currently exist. although there are theoretical attempts.
but in both cases, going offline outside the downloaded zone will break off the whole buzz (from practice) therefore, even on caching raster map viewers, they pre-download the region with a margin for offline use.
so you're trying to mix green with cold.
Osm vector maps are not that big, but they provide all the possibilities for displaying, routing and searching for searches within the loaded area. IMHO it's not such a big problem to download a maximum of a hundred megs for convenient full-fledged functionality.
You can try to cut into smaller areas.