Add support for background location tracking

[martijn00]

Also see: flutter/plugins#656

[eliashdezr]

This is one of the main reasons I haven't switch one of my apps to Flutter, background location tracking is a must. Thanks for keeping this on track!

[aidandavis]

I'm also looking into this. Wanting to build an app in a corporate setting with a background GPS tracking requirement. flutter/plugins#656 (mentioned above) isn't on Pub yet and only supports iOS.
I'll subscribe to this thread for any updates.

[aidandavis]

I ended up writing my own implementation (on Android, at least), based off this Google sample that runs when the app closes.

I'm pushing the location data to firebase, so I didn't need to send anything back up the method channel. I just upload straight to Firebase using native code when a location result arrives. This means I can't generalise it to help this plugin out, but that sample repo might be useful.

[velegip]

I found a solution to generalize your @aidandavis method.
In this packege all locations stored in sqlite.
If your foreground service can accept store provider sqlite/firebase/... .
With MethodChannel we can get the db file location, and the flutter app can read it.

Update: The Google sample not prevent Doze Mode. If the device uses doze the network and the gps can be killed with your service too.

Update 2: This stackoverflow thread help against chinese roms battery saving things, and adds app to protected list.
This against Doze

[aidandavis]

That's definitely a way to do it. The problem still remaining is doing something with the data while the app is in background or the sytem chooses to close it.

With regards to Doze, it should only apply when the phone is stationary (like on a table). There's no point tracking location updates at that point anyway - the last location sent prior to Doze would still be accurate.

[sestegra]

On top of this, Dart code could be embedded as the same way implemented in alarm_manager_android. The Android callback calls Dart code without the app running.