Kotlin owns the download so tiles land in the exact dir the engine reads
(files/brouter/segments4) — no Rust path guessing. processBrouterCommand now
dispatches: dltile:<tile> streams brouter.de/brouter/segments4/<tile>.rd5 to a
.tmp then renames, writing progress/final state to brouter_dl_<tile>.json;
listtiles writes brouter_tiles.json. Tile names are sanitized ([A-Za-z0-9_]).
Rust relays: brouter_download_tile / brouter_download_status / brouter_list_tiles.
JS: BRouter.downloadTile/downloadStatus/listTiles/downloadTileAndWait.
Compiles into the apk. Not yet exercised on device (phone offline) — the tile
selection UI and the end-to-end download->offline-route test are the remaining
Stage 2 work. IMPLEMENTATION_PLAN updated.
End-to-end offline routing confirmed on the phone: shortest ~5.4 km in Rostov
(3.2s cold), trekking cross-tile Rostov->region 44.8 km / 316 m ascend
(1.2s), 617 ms on the apk-shipped data. JS -> Rust brouter_route -> Kotlin
engine -> GPX works through the whole chain.
The 1.6.3 distribution ships lookups.dat v10, but the live brouter.de/segments4
tiles are v11 ("lookup version mismatch"). Replaced the vendored lookups.dat +
trekking/shortest profiles with the v11 set from abrensch/brouter master
(misc/profiles2); the 1.6.3 engine accepts them. Profiles and lookups MUST match
the segments' version.
Analysis in docs/brouter-findings.md: how BRouter knows roads (.rd5
segments), routes and reaches low elevation gain (profile uphill/downhill
cost + kinematics), the three call surfaces, and an evaluation of two ideas
— fill GPS gaps along roads, and offline waypoint route planning. License is
MIT; the engine has no desktop-only deps, so it embeds on Android ART.
Stage 1 (embed + bridge, compiles into the apk; on-device route not yet run):
- vendored brouter-1.6.3-all.jar into the Android module (dexes cleanly) and
bundled the trekking/shortest profiles + lookups.dat as assets, copied to
files/brouter/profiles2 on launch
- MainActivity: a brouter_command.txt handler on the existing FileObserver
runs btools.router.RoutingEngine off the UI thread (recipe taken via javap
from ServerHandler) and returns the track as GPX
- Rust brouter_route command: same file bridge as GPS (request + command,
poll for the result), registered in the invoke handler
- frontend/js/router.js: BRouter.route(points, profile) -> GPX (parseRouteGPX)
- LICENSE-brouter (MIT notice) kept alongside the vendored engine
Segments (.rd5, ~13-23 MB per 5x5 tile) are delivered later (Stage 2, wired
download inside BalDav). IMPLEMENTATION_PLAN.md tracks the 5 stages.
