fix: improve MarkerState API

app/src/main/AndroidManifest.xml

@@ -43,13 +43,13 @@
         android:name=".BasicMapActivity"
         android:exported="false" />
     <activity
-        android:name=".AdvancedMarkersActivity"
+        android:name=".markerexamples.AdvancedMarkersActivity"
         android:exported="false"/>
     <activity
         android:name=".MapInColumnActivity"
         android:exported="false"/>
     <activity
-        android:name=".MarkerClusteringActivity"
+        android:name=".markerexamples.MarkerClusteringActivity"
         android:exported="false"/>
     <activity
         android:name=".LocationTrackingActivity"
@@ -69,6 +69,21 @@
     <activity
         android:name=".RecompositionActivity"
         android:exported="false"/>
+    <activity
+        android:name=".markerexamples.markerdragevents.MarkerDragEventsActivity"
+        android:exported="false"/>
+    <activity
+        android:name=".markerexamples.markerscollection.MarkersCollectionActivity"
+        android:exported="false"/>
+    <activity
+        android:name=".markerexamples.syncingdraggablemarkerwithdatamodel.SyncingDraggableMarkerWithDataModelActivity"
+        android:exported="false"/>
+    <activity
+        android:name=".markerexamples.updatingnodragmarkerwithdatamodel.UpdatingNoDragMarkerWithDataModelActivity"
+        android:exported="false"/>
+    <activity
+        android:name=".markerexamples.draggablemarkerscollectionwithpolygon.DraggableMarkersCollectionWithPolygonActivity"
+        android:exported="false"/>
 
     <!-- Used by createComponentActivity() for unit testing -->
     <activity android:name="androidx.activity.ComponentActivity" />

app/src/main/java/com/google/maps/android/compose/BasicMapActivity.kt

@@ -141,7 +141,7 @@ fun GoogleMapView(
     val singapore4State = rememberMarkerState(position = singapore4)
 
     var circleCenter by remember { mutableStateOf(singapore) }
-    if (singaporeState.dragState == DragState.END) {
+    if (!singaporeState.isDragging) {
         circleCenter = singaporeState.position
     }
 
@@ -380,7 +380,7 @@ private fun DebugView(
         Text(text = "Camera position is ${cameraPositionState.position}")
         Spacer(modifier = Modifier.height(4.dp))
         val dragging =
-            if (markerState.dragState == DragState.DRAG) "dragging" else "not dragging"
+            if (markerState.isDragging) "dragging" else "not dragging"
         Text(text = "Marker is $dragging")
         Text(text = "Marker position is ${markerState.position}")
     }

app/src/main/java/com/google/maps/android/compose/MainActivity.kt

@@ -32,6 +32,13 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.unit.dp
+import com.google.maps.android.compose.markerexamples.AdvancedMarkersActivity
+import com.google.maps.android.compose.markerexamples.MarkerClusteringActivity
+import com.google.maps.android.compose.markerexamples.draggablemarkerscollectionwithpolygon.DraggableMarkersCollectionWithPolygonActivity
+import com.google.maps.android.compose.markerexamples.markerdragevents.MarkerDragEventsActivity
+import com.google.maps.android.compose.markerexamples.markerscollection.MarkersCollectionActivity
+import com.google.maps.android.compose.markerexamples.syncingdraggablemarkerwithdatamodel.SyncingDraggableMarkerWithDataModelActivity
+import com.google.maps.android.compose.markerexamples.updatingnodragmarkerwithdatamodel.UpdatingNoDragMarkerWithDataModelActivity
 import com.google.maps.android.compose.theme.MapsComposeSampleTheme
 
 class MainActivity : ComponentActivity() {
@@ -141,6 +148,41 @@ class MainActivity : ComponentActivity() {
                             }) {
                             Text(getString(R.string.recomposition_activity))
                         }
+                        Spacer(modifier = Modifier.padding(5.dp))
+                        Button(
+                            onClick = {
+                                context.startActivity(Intent(context, MarkerDragEventsActivity::class.java))
+                            }) {
+                            Text(getString(R.string.marker_drag_events_activity))
+                        }
+                        Spacer(modifier = Modifier.padding(5.dp))
+                        Button(
+                            onClick = {
+                                context.startActivity(Intent(context, MarkersCollectionActivity::class.java))
+                            }) {
+                            Text(getString(R.string.markers_collection_activity))
+                        }
+                        Spacer(modifier = Modifier.padding(5.dp))
+                        Button(
+                            onClick = {
+                                context.startActivity(Intent(context, SyncingDraggableMarkerWithDataModelActivity::class.java))
+                            }) {
+                            Text(getString(R.string.syncing_draggable_marker_with_data_model))
+                        }
+                        Spacer(modifier = Modifier.padding(5.dp))
+                        Button(
+                            onClick = {
+                                context.startActivity(Intent(context, UpdatingNoDragMarkerWithDataModelActivity::class.java))
+                            }) {
+                            Text(getString(R.string.updating_non_draggable_marker_with_data_model))
+                        }
+                        Spacer(modifier = Modifier.padding(5.dp))
+                        Button(
+                            onClick = {
+                                context.startActivity(Intent(context, DraggableMarkersCollectionWithPolygonActivity::class.java))
+                            }) {
+                            Text(getString(R.string.draggable_markers_collection_with_polygon))
+                        }
                     }
                 }
             }

app/src/main/java/com/google/maps/android/compose/AdvancedMarkersActivity.kt → app/src/main/java/com/google/maps/android/compose/markerexamples/AdvancedMarkersActivity.kt

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package com.google.maps.android.compose
+package com.google.maps.android.compose.markerexamples
 
 
 import android.R.drawable.ic_menu_myplaces
@@ -36,6 +36,12 @@ import com.google.android.gms.maps.model.CameraPosition
 import com.google.android.gms.maps.model.LatLng
 import com.google.android.gms.maps.model.Marker
 import com.google.android.gms.maps.model.PinConfig
+import com.google.maps.android.compose.AdvancedMarker
+import com.google.maps.android.compose.GoogleMap
+import com.google.maps.android.compose.MapProperties
+import com.google.maps.android.compose.MapType
+import com.google.maps.android.compose.rememberCameraPositionState
+import com.google.maps.android.compose.rememberMarkerState
 
 
 private const val TAG = "AdvancedMarkersActivity"

app/src/main/java/com/google/maps/android/compose/MarkerClusteringActivity.kt → app/src/main/java/com/google/maps/android/compose/markerexamples/MarkerClusteringActivity.kt

@@ -1,4 +1,4 @@
-package com.google.maps.android.compose
+package com.google.maps.android.compose.markerexamples
 
 import android.os.Bundle
 import android.util.Log
@@ -40,9 +40,16 @@ import com.google.android.gms.maps.model.CameraPosition
 import com.google.android.gms.maps.model.LatLng
 import com.google.maps.android.clustering.ClusterItem
 import com.google.maps.android.clustering.algo.NonHierarchicalViewBasedAlgorithm
+import com.google.maps.android.compose.GoogleMap
+import com.google.maps.android.compose.MapsComposeExperimentalApi
+import com.google.maps.android.compose.MarkerInfoWindow
 import com.google.maps.android.compose.clustering.Clustering
 import com.google.maps.android.compose.clustering.rememberClusterManager
 import com.google.maps.android.compose.clustering.rememberClusterRenderer
+import com.google.maps.android.compose.rememberCameraPositionState
+import com.google.maps.android.compose.rememberMarkerState
+import com.google.maps.android.compose.singapore
+import com.google.maps.android.compose.singapore2
 import kotlin.random.Random
 
 private val TAG = MarkerClusteringActivity::class.simpleName

app/src/main/java/com/google/maps/android/compose/markerexamples/draggablemarkerscollectionwithpolygon/DraggableMarkersCollectionWithPolygonActivity.kt

@@ -0,0 +1,192 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.maps.android.compose.markerexamples.draggablemarkerscollectionwithpolygon
+
+import android.os.Bundle
+import androidx.activity.ComponentActivity
+import androidx.activity.compose.setContent
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.Immutable
+import androidx.compose.runtime.Stable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.key
+import androidx.compose.runtime.mutableStateMapOf
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshots.SnapshotStateMap
+import androidx.compose.ui.Modifier
+import com.google.android.gms.maps.model.LatLng
+import com.google.maps.android.compose.GoogleMap
+import com.google.maps.android.compose.Marker
+import com.google.maps.android.compose.MarkerState
+import com.google.maps.android.compose.Polygon
+import com.google.maps.android.compose.defaultCameraPosition
+import com.google.maps.android.compose.rememberCameraPositionState
+import com.google.maps.android.compose.theme.MapsComposeSampleTheme
+
+/**
+ * Data type representing a location.
+ *
+ * This only stores location position, for illustration,
+ * but could hold other data related to the location.
+ */
+@Immutable
+private data class LocationData(val position: LatLng)
+
+/**
+ * Unique, stable key for location
+ */
+private class LocationKey
+
+/**
+ * Encapsulates mapping from data model to MarkerStates. Part of view model.
+ * MarkerStates are relegated to an implementation detail.
+ * Use new [DraggableMarkersModel] instance if data model is updated externally:
+ * MarkerStates are source of truth after initialization from data model.
+ */
+@Stable
+private class DraggableMarkersModel(dataModel: Map<LocationKey, LocationData>) {
+    // This initializes MarkerState from our model once (model is initial source of truth)
+    // and never updates it from the model afterwards.
+    // See SyncingDraggableMarkerWithDataModelActivity for rationale.
+    private val markerDataMap: SnapshotStateMap<LocationKey, MarkerState> = mutableStateMapOf(
+        *dataModel.entries.map { (locationKey, locationData) ->
+            locationKey to MarkerState(locationData.position)
+        }.toTypedArray()
+    )
+
+    /** Add new marker location to model */
+    fun addLocation(locationData: LocationData) {
+        markerDataMap += LocationKey() to MarkerState(locationData.position)
+    }
+
+    /** Delete marker location from model */
+    private fun deleteLocation(locationKey: LocationKey) {
+        markerDataMap -= locationKey
+    }
+
+    /**
+     * Render Markers from model
+     */
+    @Composable
+    fun Markers() = markerDataMap.forEach { (locationKey, markerState) ->
+        key(locationKey) {
+            LocationMarker(
+                markerState,
+                onClick = { deleteLocation(locationKey) }
+            )
+        }
+    }
+
+    /**
+     * List of functions providing current positions of Markers.
+     *
+     * Calling from composition will trigger recomposition when Markers and their positions
+     * change.
+     */
+    val markerPositionsModel: List<() -> LatLng>
+        get() = markerDataMap.values.map { { it.position } }
+}
+
+/**
+ * Demonstrates how to sync a data model with a changing collection of
+ * draggable markers using keys, while keeping a Polygon of the marker positions in sync with
+ * the current marker position.
+ *
+ * The user can add a location marker to the model by clicking the map and delete a location from
+ * the model by clicking a marker.
+ *
+ * This example builds on top of ideas from MarkersCollectionActivity and
+ * SyncingDraggableMarkerWithDataModelActivity.
+ */
+class DraggableMarkersCollectionWithPolygonActivity : ComponentActivity() {
+    // Simplistic data model from repository being set from outside (should be part of view model);
+    // Only stores [LocationData], for illustration, but could hold additional data.
+    private var dataModel: Map<LocationKey, LocationData> = mapOf()
+        set(value) {
+            field = value
+            markersModel = DraggableMarkersModel(value)
+        }
+
+    private var markersModel by mutableStateOf(DraggableMarkersModel(dataModel))
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+
+        setContent {
+            MapsComposeSampleTheme {
+                GoogleMapWithLocations(
+                    markersModel,
+                    modifier = Modifier.fillMaxSize()
+                )
+            }
+        }
+    }
+}
+
+/**
+ * A GoogleMap with locations represented by markers
+ */
+@Composable
+private fun GoogleMapWithLocations(
+    markersModel: DraggableMarkersModel,
+    modifier: Modifier = Modifier
+) {
+    val cameraPositionState = rememberCameraPositionState { position = defaultCameraPosition }
+
+    GoogleMap(
+        modifier = modifier,
+        cameraPositionState = cameraPositionState,
+        onMapClick = { position -> markersModel.addLocation(LocationData(position)) }
+    ) {
+        markersModel.Markers()
+
+        Polygon(markersModel::markerPositionsModel)
+    }
+}
+
+/**
+ * A draggable GoogleMap Marker representing a location on the map
+ */
+@Composable
+private fun LocationMarker(
+    markerState: MarkerState,
+    onClick: () -> Unit
+) {
+    Marker(
+        state = markerState,
+        draggable = true,
+        onClick = {
+            onClick()
+
+            true
+        }
+    )
+}
+
+/**
+ * A Polygon. Helps isolate recompositions while a Marker is being dragged.
+ */
+@Composable
+private fun Polygon(markerPositionsModel: () -> List<() -> LatLng>) {
+    val movingMarkerPositions = markerPositionsModel()
+
+    if (movingMarkerPositions.isNotEmpty()) {
+        val markerPositions = movingMarkerPositions.map { it() }
+
+        Polygon(markerPositions)
+    }
+}