fix!: leverage @StateFactoryMarker to flag State object creation wi…

…thout remember or similar mechanisms.

The PR replaces public constructors on State objects with `invoke()` factory functions in public companion objects. `@StateFactoryMarker` can only be applied to functions, not constructors. The chosen constructor replacement approach minimizes the required refactoring impact on correct State object usages, requiring no refactoring in the vast majority of cases.

Fixes googlemaps#506

maps-compose/src/main/java/com/google/maps/android/compose/CameraPositionState.kt

@@ -22,6 +22,7 @@ import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.saveable.Saver
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.StateFactoryMarker
 import androidx.compose.runtime.staticCompositionLocalOf
 import com.google.android.gms.maps.CameraUpdate
 import com.google.android.gms.maps.CameraUpdateFactory
@@ -59,7 +60,7 @@ public inline fun rememberCameraPositionState(
  *
  * @param position the initial camera position
  */
-public class CameraPositionState(
+public class CameraPositionState private constructor(
     position: CameraPosition = CameraPosition(LatLng(0.0, 0.0), 0f, 0f, 0f)
 ) {
     /**
@@ -302,6 +303,16 @@ public class CameraPositionState(
     }
 
     public companion object {
+        /**
+         * Creates a new [CameraPositionState] object
+         *
+         * @param position the initial camera position
+         */
+        @StateFactoryMarker
+        public operator fun invoke(
+            position: CameraPosition = CameraPosition(LatLng(0.0, 0.0), 0f, 0f, 0f)
+        ): CameraPositionState = CameraPositionState(position)
+
         /**
          * The default saver implementation for [CameraPositionState]
          */

maps-compose/src/main/java/com/google/maps/android/compose/Marker.kt

@@ -27,6 +27,7 @@ import androidx.compose.runtime.rememberCompositionContext
 import androidx.compose.runtime.saveable.Saver
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.StateFactoryMarker
 import androidx.compose.ui.geometry.Offset
 import com.google.android.gms.maps.model.AdvancedMarkerOptions
 import com.google.android.gms.maps.model.BitmapDescriptor
@@ -72,9 +73,7 @@ public enum class DragState {
  *
  * @param position the initial marker position
  */
-public class MarkerState(
-    position: LatLng = LatLng(0.0, 0.0),
-) {
+public class MarkerState private constructor(position: LatLng) {
     /**
      * Current position of the marker.
      */
@@ -113,6 +112,16 @@ public class MarkerState(
     }
 
     public companion object {
+        /**
+         * Creates a new [MarkerState] object
+         *
+         * @param position the initial marker position
+         */
+        @StateFactoryMarker
+        public operator fun invoke(
+            position: LatLng = LatLng(0.0, 0.0)
+        ): MarkerState = MarkerState(position)
+
         /**
          * The default saver implementation for [MarkerState]
          */

maps-compose/src/main/java/com/google/maps/android/compose/TileOverlay.kt

@@ -21,6 +21,7 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.StateFactoryMarker
 import com.google.android.gms.maps.model.TileOverlay
 import com.google.android.gms.maps.model.TileProvider
 import com.google.maps.android.ktx.addTileOverlay
@@ -122,7 +123,7 @@ public fun TileOverlay(
  *
  * [clearTileCache] can be called to request that the map refresh these tiles.
  */
-public class TileOverlayState {
+public class TileOverlayState private constructor() {
 
     internal var tileOverlay: TileOverlay? by mutableStateOf(null)
 
@@ -139,6 +140,13 @@ public class TileOverlayState {
             .clearTileCache()
     }
 
+    public companion object {
+        /**
+         * Creates a new [TileOverlayState] object
+         */
+        @StateFactoryMarker
+        public operator fun invoke(): TileOverlayState = TileOverlayState()
+    }
 }
 
 @Composable

maps-compose/src/main/java/com/google/maps/android/compose/streetview/StreetViewCameraPositionState.kt

@@ -5,6 +5,7 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.StateFactoryMarker
 import com.google.android.gms.maps.StreetViewPanorama
 import com.google.android.gms.maps.model.LatLng
 import com.google.android.gms.maps.model.StreetViewPanoramaCamera
@@ -18,7 +19,7 @@ public inline fun rememberStreetViewCameraPositionState(
     StreetViewCameraPositionState().apply(init)
 }
 
-public class StreetViewCameraPositionState {
+public class StreetViewCameraPositionState private constructor() {
 
     /**
      * The location of the panorama.
@@ -86,4 +87,13 @@ public class StreetViewCameraPositionState {
     public fun setPosition(panoId: String) {
         panorama?.setPosition(panoId)
     }
+
+    public companion object {
+        /**
+         * Creates a new [StreetViewCameraPositionState] object
+         */
+        @StateFactoryMarker
+        public operator fun invoke(): StreetViewCameraPositionState =
+            StreetViewCameraPositionState()
+    }
 }