fix: Prevent MapView from being recreated when still in composition (g…

…ooglemaps#137) Addresses a bug wherein the underlying MapView gets recreated due to lifecycle events, however, the GoogleMap composable never leaves the composition. In this state, map properties (markers, camera position, etc.) don't get restored. Change-Id: Iba141aa2f325fa505ef8cc2f015117bcaea856c4
webfrea-k · Jun 7, 2022 · 83b1cd7 · 83b1cd7
1 parent 0d01aeb
commit 83b1cd7
Showing 1 changed file with 15 additions and 8 deletions.
diff --git a/maps-compose/src/main/java/com/google/maps/android/compose/GoogleMap.kt b/maps-compose/src/main/java/com/google/maps/android/compose/GoogleMap.kt
@@ -15,20 +15,18 @@
 package com.google.maps.android.compose
 
 import android.content.ComponentCallbacks
-import android.content.Context
 import android.content.res.Configuration
 import android.location.Location
 import android.os.Bundle
-import android.view.ViewGroup
-import android.widget.FrameLayout
-import android.widget.LinearLayout
 import androidx.compose.foundation.layout.PaddingValues
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.Composition
 import androidx.compose.runtime.CompositionContext
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.MutableState
 import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCompositionContext
 import androidx.compose.runtime.rememberUpdatedState
@@ -38,7 +36,6 @@ import androidx.compose.ui.platform.LocalLifecycleOwner
 import androidx.compose.ui.viewinterop.AndroidView
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.LifecycleEventObserver
-import com.google.android.gms.maps.GoogleMap
 import com.google.android.gms.maps.GoogleMapOptions
 import com.google.android.gms.maps.LocationSource
 import com.google.android.gms.maps.MapView
@@ -162,8 +159,9 @@ private suspend inline fun MapView.newComposition(
 private fun MapLifecycle(mapView: MapView) {
     val context = LocalContext.current
     val lifecycle = LocalLifecycleOwner.current.lifecycle
+    val previousState = remember { mutableStateOf(Lifecycle.Event.ON_CREATE) }
     DisposableEffect(context, lifecycle, mapView) {
-        val mapLifecycleObserver = mapView.lifecycleObserver()
+        val mapLifecycleObserver = mapView.lifecycleObserver(previousState)
         val callbacks = mapView.componentCallbacks()
 
         lifecycle.addObserver(mapLifecycleObserver)
@@ -176,17 +174,26 @@ private fun MapLifecycle(mapView: MapView) {
     }
 }
 
-private fun MapView.lifecycleObserver(): LifecycleEventObserver =
+private fun MapView.lifecycleObserver(previousState: MutableState<Lifecycle.Event>): LifecycleEventObserver =
     LifecycleEventObserver { _, event ->
+        event.targetState
         when (event) {
-            Lifecycle.Event.ON_CREATE -> this.onCreate(Bundle())
+            Lifecycle.Event.ON_CREATE -> {
+                // Skip calling mapView.onCreate if the lifecycle did not go through onDestroy - in
+                // this case the GoogleMap composable also doesn't leave the composition. So,
+                // recreating the map does not restore state properly which must be avoided.
+                if (previousState.value != Lifecycle.Event.ON_STOP) {
+                    this.onCreate(Bundle())
+                }
+            }
             Lifecycle.Event.ON_START -> this.onStart()
             Lifecycle.Event.ON_RESUME -> this.onResume()
             Lifecycle.Event.ON_PAUSE -> this.onPause()
             Lifecycle.Event.ON_STOP -> this.onStop()
             Lifecycle.Event.ON_DESTROY -> this.onDestroy()
             else -> throw IllegalStateException()
         }
+        previousState.value = event
     }
 
 private fun MapView.componentCallbacks(): ComponentCallbacks =