From 87956988069cfaaebf2fbb2b23dd6bf71de51012 Mon Sep 17 00:00:00 2001
From: Uli Bubenheimer <bubenheimer@users.noreply.github.com>
Date: Mon, 1 Jan 2024 15:36:15 -0500
Subject: [PATCH] Replace most GoogleMap() rememberUpdatedState() usages with
 single State object and encapsulate Subcomposition functionality

Fixes #492
---
 .../google/maps/android/compose/GoogleMap.kt  | 79 ++++++++++++++-----
 .../google/maps/android/compose/MapUpdater.kt | 11 +--
 2 files changed, 59 insertions(+), 31 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
index 8e89cb2a5..f6fa20d2a 100644
--- 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
@@ -27,11 +27,13 @@ import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.MutableState
+import androidx.compose.runtime.Stable
 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
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalInspectionMode
@@ -114,39 +116,74 @@ public fun GoogleMap(
         it.onMyLocationClick = onMyLocationClick
         it.onPOIClick = onPOIClick
     }
-    val currentLocationSource by rememberUpdatedState(locationSource)
-    val currentCameraPositionState by rememberUpdatedState(cameraPositionState)
-    val currentContentPadding by rememberUpdatedState(contentPadding)
-    val currentUiSettings by rememberUpdatedState(uiSettings)
-    val currentMapProperties by rememberUpdatedState(properties)
+
+    val mapUpdaterState = remember {
+        MapUpdaterState(
+            mergeDescendants,
+            contentDescription,
+            cameraPositionState,
+            contentPadding,
+            locationSource,
+            properties,
+            uiSettings
+        )
+    }.also {
+        it.mergeDescendants = mergeDescendants
+        it.contentDescription = contentDescription
+        it.cameraPositionState = cameraPositionState
+        it.contentPadding = contentPadding
+        it.locationSource = locationSource
+        it.mapProperties = properties
+        it.mapUiSettings = uiSettings
+    }
 
     val parentComposition = rememberCompositionContext()
     val currentContent by rememberUpdatedState(content)
     LaunchedEffect(Unit) {
         disposingComposition {
             mapView.newComposition(parentComposition, mapClickListeners) {
-                MapUpdater(
-                    mergeDescendants = mergeDescendants,
-                    contentDescription = contentDescription,
-                    cameraPositionState = currentCameraPositionState,
-                    contentPadding = currentContentPadding,
-                    locationSource = currentLocationSource,
-                    mapProperties = currentMapProperties,
-                    mapUiSettings = currentUiSettings,
-                )
-
-                MapClickListenerUpdater()
-
-                CompositionLocalProvider(
-                    LocalCameraPositionState provides cameraPositionState,
-                ) {
-                    currentContent?.invoke()
+                Subcomposition(mapUpdaterState) {
+                    // todo change parameter default to {} from "null", which is less meaningful
+                    currentContent ?: {}
                 }
             }
         }
     }
 }
 
+@Composable
+private inline fun Subcomposition(
+    mapUpdaterState: MapUpdaterState,
+    crossinline content: @GoogleMapComposable () -> Unit
+) {
+    MapUpdater(mapUpdaterState)
+
+    MapClickListenerUpdater()
+
+    CompositionLocalProvider(
+        LocalCameraPositionState provides mapUpdaterState.cameraPositionState
+    ) { content() }
+}
+
+@Stable
+internal class MapUpdaterState(
+    mergeDescendants: Boolean,
+    contentDescription: String?,
+    cameraPositionState: CameraPositionState,
+    contentPadding: PaddingValues,
+    locationSource: LocationSource?,
+    mapProperties: MapProperties,
+    mapUiSettings: MapUiSettings
+) {
+    var mergeDescendants by mutableStateOf(mergeDescendants)
+    var contentDescription by mutableStateOf(contentDescription)
+    var cameraPositionState by mutableStateOf(cameraPositionState)
+    var contentPadding by mutableStateOf(contentPadding)
+    var locationSource by mutableStateOf(locationSource)
+    var mapProperties by mutableStateOf(mapProperties)
+    var mapUiSettings by mutableStateOf(mapUiSettings)
+}
+
 internal suspend inline fun disposingComposition(factory: () -> Composition) {
     val composition = factory()
     try {
diff --git a/maps-compose/src/main/java/com/google/maps/android/compose/MapUpdater.kt b/maps-compose/src/main/java/com/google/maps/android/compose/MapUpdater.kt
index f27a000d3..3a331efe3 100644
--- a/maps-compose/src/main/java/com/google/maps/android/compose/MapUpdater.kt
+++ b/maps-compose/src/main/java/com/google/maps/android/compose/MapUpdater.kt
@@ -25,7 +25,6 @@ import androidx.compose.ui.platform.LocalLayoutDirection
 import androidx.compose.ui.unit.Density
 import androidx.compose.ui.unit.LayoutDirection
 import com.google.android.gms.maps.GoogleMap
-import com.google.android.gms.maps.LocationSource
 
 internal class MapPropertiesNode(
     val map: GoogleMap,
@@ -93,15 +92,7 @@ internal val NoPadding = PaddingValues()
 @SuppressLint("MissingPermission")
 @Suppress("NOTHING_TO_INLINE")
 @Composable
-internal inline fun MapUpdater(
-    mergeDescendants: Boolean = false,
-    contentDescription: String?,
-    cameraPositionState: CameraPositionState,
-    contentPadding: PaddingValues = NoPadding,
-    locationSource: LocationSource?,
-    mapProperties: MapProperties,
-    mapUiSettings: MapUiSettings,
-) {
+internal inline fun MapUpdater(mapUpdaterState: MapUpdaterState) = with(mapUpdaterState) {
     val map = (currentComposer.applier as MapApplier).map
     val mapView = (currentComposer.applier as MapApplier).mapView
     if (mergeDescendants) {