NAVAND-1001: use immediate dispatcher to guarantee that language will change before voice instructions

Author: dzinad

CHANGELOG.md

@@ -28,6 +28,7 @@ Mapbox welcomes participation and contributions from everyone.
 - Fixed standalone `MapboxManeuverView` appearance when the app also integrates Drop-In UI. [#6774](https://github.com/mapbox/mapbox-navigation-android/pull/6774)
 - Introduced `NavigationViewListener.onSpeedInfoClicked` that would be triggered when `MapboxSpeedInfoView` is clicked upon. [#6770](https://github.com/mapbox/mapbox-navigation-android/pull/6770)
 - Each newly instantiated MapboxRouteArrowView class will initialize the layers with the provided options on the first render call. Previously this would only be done if the layers hadn't already been initialized.  [#6466](https://github.com/mapbox/mapbox-navigation-android/pull/6466)
+- Fixed an issue where the first voice instruction might have been played twice. [#6766](https://github.com/mapbox/mapbox-navigation-android/pull/6766)
 
 ## Mapbox Navigation SDK 2.10.0-rc.1 - 16 December, 2022
 ### Changelog

libnavui-voice/src/main/java/com/mapbox/navigation/ui/voice/api/MapboxAudioGuidance.kt

@@ -14,7 +14,6 @@ import kotlinx.coroutines.CoroutineDispatcher
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import kotlinx.coroutines.FlowPreview
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.SupervisorJob
 import kotlinx.coroutines.flow.Flow
@@ -25,9 +24,7 @@ import kotlinx.coroutines.flow.combine
 import kotlinx.coroutines.flow.distinctUntilChanged
 import kotlinx.coroutines.flow.filter
 import kotlinx.coroutines.flow.first
-import kotlinx.coroutines.flow.flatMapConcat
 import kotlinx.coroutines.flow.flatMapLatest
-import kotlinx.coroutines.flow.flowOf
 import kotlinx.coroutines.flow.map
 import kotlinx.coroutines.flow.updateAndGet
 import kotlinx.coroutines.launch
@@ -123,7 +120,7 @@ internal constructor(
     /**
      * Top level flow that will switch based on the language and muted state.
      */
-    @OptIn(ExperimentalCoroutinesApi::class, FlowPreview::class)
+    @OptIn(ExperimentalCoroutinesApi::class)
     private fun audioGuidanceFlow(
         mapboxNavigation: MapboxNavigation
     ): Flow<MapboxAudioGuidanceState> {
@@ -146,18 +143,15 @@ internal constructor(
                 } else {
                     voiceInstructions
                         .filter { it.voiceInstructions != lastPlayedInstructions }
-                        .flatMapConcat {
+                        .map {
                             lastPlayedInstructions = it.voiceInstructions
                             val announcement = audioGuidance.speak(it.voiceInstructions)
-                            flowOf(announcement)
-                        }
-                        .map { speechAnnouncement ->
-                            internalStateFlow.updateAndGet {
+                            internalStateFlow.updateAndGet { state ->
                                 MapboxAudioGuidanceState(
-                                    isPlayable = it.isPlayable,
-                                    isMuted = it.isMuted,
-                                    voiceInstructions = it.voiceInstructions,
-                                    speechAnnouncement = speechAnnouncement
+                                    isPlayable = state.isPlayable,
+                                    isMuted = state.isMuted,
+                                    voiceInstructions = state.voiceInstructions,
+                                    speechAnnouncement = announcement
                                 )
                             }
                         }
@@ -195,7 +189,10 @@ internal constructor(
          * Construct an instance without registering to [MapboxNavigationApp].
          */
         @JvmStatic
-        fun create() = MapboxAudioGuidance(MapboxAudioGuidanceServices(), Dispatchers.Main)
+        fun create() = MapboxAudioGuidance(
+            MapboxAudioGuidanceServices(),
+            Dispatchers.Main.immediate
+        )
 
         /**
          * Get the registered instance or create one and register it to [MapboxNavigationApp].