Create a delegate for MapboxNavigation called requireMapboxNavigation

[kmadsen]

Description

There is some consistent boilerplate required to setup the MapboxNavigationApp. I've just spent a bit of time migrating :libnavui-androidauto: to use the MapboxNavigationApp #6141 and I've explored a few approaches with the examples repository mapbox/mapbox-navigation-android-examples#129. We also discussed some ambiguous scenarios where we want to access MapboxNavigation directly and it requires an unsafe call MapboxNavigationApp.current()!!. #6226 (comment). This delegate removes the need for !! with specific guidelines.

This is my favorite approach so far. Create a delegate that hooks up MapboxNavigation to your LifecycleOwner. I migrated a random example from the qa-test-app to show what it looks like, take a look at the FeedbackActivity. EDIT migrated another example InactiveRouteStylingActivity.

Screenshots or Gifs

Inside any LifecycleOwner you can use the requireMapboxNavigation delegate like this. And then you have access to mapboxNavigation as if you constructed it inside.

Default can be used when [MapboxNavigationApp] is setup elsewhere.

val mapboxNavigation by requireMapboxNavigation()

Initialize the [MapboxNavigationApp] when you are ready to use it

val mapboxNavigation by requireMapboxNavigation {
  MapboxNavigationApp.setup(..)
}

Initialize and setup subscriptions

val mapboxNavigation by requireMapboxNavigation(
  onInitialize = {
    MapboxNavigationApp.setup(
      NavigationOptions.Builder(this)
          .accessToken(accessToken)
          .build()
    )
  },
  onResumedObserver = object : MapboxNavigationObserver {
    override fun onAttached(mapboxNavigation: MapboxNavigation) {
      mapboxNavigation.registerLocationObserver(locationObserver)
      mapboxNavigation.registerRoutesObserver(routesObserver)
    }
    override fun onDetached(mapboxNavigation: MapboxNavigation) {
      mapboxNavigation.unregisterLocationObserver(locationObserver)
      mapboxNavigation.unregisterRoutesObserver(routesObserver)
    }
  }
)

Another example

private val mapboxNavigation by requireMapboxNavigation(
  onCreatedObserver = object : MapboxNavigationObserver {
    override fun onAttached(mapboxNavigation: MapboxNavigation) {
      binding.mapView.location.apply {
        setLocationProvider(navigationLocationProvider)
        enabled = true
      }
      mapboxNavigation.registerLocationObserver(locationObserver)
      mapboxNavigation.registerRoutesObserver(routesObserver)
    }

    override fun onDetached(mapboxNavigation: MapboxNavigation) {
      mapboxNavigation.unregisterLocationObserver(locationObserver)
      mapboxNavigation.unregisterRoutesObserver(routesObserver)
    }
   }
) {
  MapboxNavigationApp.setup(
    NavigationOptions.Builder(this)
        .accessToken(Utils.getMapboxAccessToken(this))
        .build()
  )
}

[codecov]

Codecov Report

Merging #6233 (8dbc73a) into main (847f8a9) will increase coverage by 0.02%.
The diff coverage is 75.00%.

@@             Coverage Diff              @@
##               main    #6233      +/-   ##
============================================
+ Coverage     68.81%   68.84%   +0.02%     
- Complexity     4346     4348       +2     
============================================
  Files           649      650       +1     
  Lines         26183    26223      +40     
  Branches       3067     3075       +8     
============================================
+ Hits          18019    18052      +33     
- Misses         6998     7001       +3     
- Partials       1166     1170       +4     

Impacted Files	Coverage Δ
...vigation/core/lifecycle/RequireMapboxNavigation.kt	75.00% <75.00%> (ø)
...x/navigation/core/lifecycle/MapboxNavigationApp.kt	20.00% <0.00%> (+10.00%)	⬆️

[kmadsen]

This is a bug. If you background the app it will unsubscribe. The subscribe happens in onCreate so the subscription is lost.

[kmadsen]

This never loads unless you reference it. The lazy load can be confusing.

Also, the onCreate callback from activity happens before the Lifecycle onCreate. That causes a crash if you try to reference this delegate without using Lifecycle callbacks.

[kmadsen]

Fixed it but was finding another race condition along the way.

mapboxNavigation.setRoutes(listOf(route))
binding.startNavigation.visibility = View.GONE
startSimulation(mapboxNavigation.getRoutes()[0]) <=== crashes because routes are not set yet