Using view-less Fragment to request location permissions.

Author: tomaszrybakiewicz

libnavui-dropin/src/main/java/com/mapbox/navigation/dropin/permission/LocationPermissionComponent.kt

@@ -5,6 +5,7 @@ import android.content.Context
 import androidx.activity.ComponentActivity
 import androidx.activity.result.ActivityResultCallback
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.fragment.app.FragmentActivity
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.repeatOnLifecycle
 import com.mapbox.android.core.permissions.PermissionsManager
@@ -63,8 +64,12 @@ internal class LocationPermissionComponent(
                 store.dispatch(TripSessionStarterAction.OnLocationPermission(true))
             }
         } else {
-            launcher?.launch(LOCATION_PERMISSIONS)
-
+            val fragActivity = componentActivityRef.get() as? FragmentActivity
+            if (fragActivity != null) {
+                PermissionsLauncherFragment.create(fragActivity, LOCATION_PERMISSIONS, callback)
+            } else {
+                launcher?.launch(LOCATION_PERMISSIONS)
+            }
             notifyGrantedOnForegrounded(mapboxNavigation.navigationOptions.applicationContext)
         }
     }
@@ -93,6 +98,9 @@ internal class LocationPermissionComponent(
     override fun onDetached(mapboxNavigation: MapboxNavigation) {
         super.onDetached(mapboxNavigation)
 
+        (componentActivityRef.get() as? FragmentActivity)?.also {
+            PermissionsLauncherFragment.destroy(it)
+        }
         launcher?.unregister()
     }
 

libnavui-dropin/src/main/java/com/mapbox/navigation/dropin/permission/PermissionsLauncherFragment.kt

@@ -0,0 +1,65 @@
+package com.mapbox.navigation.dropin.permission
+
+import android.content.Context
+import android.content.pm.PackageManager.PERMISSION_GRANTED
+import androidx.activity.result.ActivityResultCallback
+import androidx.activity.result.ActivityResultCaller
+import androidx.activity.result.ActivityResultLauncher
+import androidx.activity.result.contract.ActivityResultContracts.RequestMultiplePermissions
+import androidx.core.content.ContextCompat.checkSelfPermission
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.FragmentActivity
+
+/**
+ * A view-less fragment that requests permissions using [ActivityResultCaller] interface.
+ */
+internal class PermissionsLauncherFragment(
+    private val permissions: Array<String>,
+    private val onResult: ActivityResultCallback<Map<String, Boolean>>
+) : Fragment() {
+
+    private var launcher: ActivityResultLauncher<Array<String>>? = null
+
+    override fun onAttach(context: Context) {
+        super.onAttach(context)
+        val areGranted = permissions.fold(false) { acc, permission ->
+            acc && checkSelfPermission(context, permission) == PERMISSION_GRANTED
+        }
+        if (!areGranted) {
+            launcher = registerForActivityResult(RequestMultiplePermissions(), onResult)
+            launcher?.launch(permissions)
+        }
+    }
+
+    override fun onDetach() {
+        super.onDetach()
+        launcher?.unregister()
+    }
+
+    companion object {
+        const val TAG = "MapboxPermissionsLauncherFragment"
+
+        fun create(
+            fragActivity: FragmentActivity,
+            permissions: Array<String>,
+            onResult: ActivityResultCallback<Map<String, Boolean>>
+        ) {
+            fragActivity.supportFragmentManager.apply {
+                val t = beginTransaction()
+                findFragmentByTag(TAG)?.also { t.remove(it) }
+                t.add(PermissionsLauncherFragment(permissions, onResult), TAG)
+                t.commit()
+            }
+        }
+
+        fun destroy(fragActivity: FragmentActivity) {
+            if (!fragActivity.isFinishing) {
+                fragActivity.supportFragmentManager.apply {
+                    findFragmentByTag(TAG)?.also {
+                        beginTransaction().remove(it).commit()
+                    }
+                }
+            }
+        }
+    }
+}