feat: Add marker drag event callback to Marker composable

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

@@ -28,8 +28,10 @@ import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.wrapContentSize
 import androidx.compose.material.Button
@@ -49,7 +51,6 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.platform.testTag
 import androidx.compose.ui.unit.dp
 import com.google.android.gms.maps.CameraUpdateFactory
-import com.google.android.gms.maps.GoogleMapOptions
 import com.google.android.gms.maps.model.BitmapDescriptorFactory
 import com.google.android.gms.maps.model.CameraPosition
 import com.google.android.gms.maps.model.LatLng
@@ -60,6 +61,7 @@ private const val TAG = "MapSampleActivity"
 
 val singapore = LatLng(1.35, 103.87)
 val singapore2 = LatLng(1.40, 103.77)
+val defaultCameraPosition = CameraPosition.fromLatLngZoom(singapore, 11f)
 
 class MapSampleActivity : ComponentActivity() {
 
@@ -69,7 +71,7 @@ class MapSampleActivity : ComponentActivity() {
             var isMapLoaded by remember { mutableStateOf(false) }
             // Observing and controlling the camera's state can be done with a CameraPositionState
             val cameraPositionState = rememberCameraPositionState {
-                position = CameraPosition.fromLatLngZoom(singapore, 11f)
+                position = defaultCameraPosition
             }
 
             Box(Modifier.fillMaxSize()) {
@@ -106,6 +108,13 @@ fun GoogleMapView(
     cameraPositionState: CameraPositionState,
     onMapLoaded: () -> Unit,
 ) {
+    val singaporePositionState = rememberMarkerPositionState(position = singapore)
+    val singapore2PositionState = rememberMarkerPositionState(position = singapore2)
+    var circlePositionState by remember { mutableStateOf(singapore) }
+    if (singaporePositionState.dragState == DragState.END) {
+        circlePositionState = singaporePositionState.position
+    }
+
     var uiSettings by remember { mutableStateOf(MapUiSettings(compassEnabled = false)) }
     var shouldAnimateZoom by remember { mutableStateOf(true) }
     var ticker by remember { mutableStateOf(0) }
@@ -129,22 +138,23 @@ fun GoogleMapView(
             false
         }
         MarkerInfoWindowContent(
-            position = singapore,
+            positionState = singaporePositionState,
             title = "Zoom in has been tapped $ticker times.",
             onClick = markerClick,
+            draggable = true,
         ) {
             Text(it.title ?: "Title", color = Color.Red)
         }
         MarkerInfoWindowContent(
-            position = singapore2,
+            positionState = singapore2PositionState,
             title = "Marker with custom info window.\nZoom in has been tapped $ticker times.",
             icon = BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_BLUE),
             onClick = markerClick,
         ) {
             Text(it.title ?: "Title", color = Color.Blue)
         }
         Circle(
-            center = singapore,
+            center = circlePositionState,
             fillColor = MaterialTheme.colors.secondary,
             strokeColor = MaterialTheme.colors.secondaryVariant,
             radius = 1000.0,
@@ -156,6 +166,20 @@ fun GoogleMapView(
             Log.d("GoogleMap", "Selected map type $it")
             mapProperties = mapProperties.copy(mapType = it)
         })
+        Button(
+            modifier = Modifier.padding(4.dp),
+            colors = ButtonDefaults.buttonColors(
+                backgroundColor = MaterialTheme.colors.onPrimary,
+                contentColor = MaterialTheme.colors.primary
+            ),
+            onClick = {
+                mapProperties = mapProperties.copy(mapType = MapType.NORMAL)
+                cameraPositionState.position = defaultCameraPosition
+                singaporePositionState.position = singapore
+            }
+        ) {
+            Text(text = "RESET MAP", style = MaterialTheme.typography.body1)
+        }
         val coroutineScope = rememberCoroutineScope()
         ZoomControls(
             shouldAnimateZoom,
@@ -186,7 +210,7 @@ fun GoogleMapView(
                 uiSettings = uiSettings.copy(zoomControlsEnabled = it)
             }
         )
-        DebugView(cameraPositionState)
+        DebugView(cameraPositionState, singaporePositionState)
     }
 }
 
@@ -263,7 +287,10 @@ private fun MapButton(text: String, onClick: () -> Unit) {
 }
 
 @Composable
-private fun DebugView(cameraPositionState: CameraPositionState) {
+private fun DebugView(
+    cameraPositionState: CameraPositionState,
+    markerPositionState: MarkerPositionState
+) {
     Column(
         Modifier
             .fillMaxWidth(),
@@ -273,5 +300,10 @@ private fun DebugView(cameraPositionState: CameraPositionState) {
             if (cameraPositionState.isMoving) "moving" else "not moving"
         Text(text = "Camera is $moving")
         Text(text = "Camera position is ${cameraPositionState.position}")
+        Spacer(modifier = Modifier.height(4.dp))
+        val dragging =
+            if (markerPositionState.dragState == DragState.DRAG) "dragging" else "not dragging"
+        Text(text = "Marker is $dragging")
+        Text(text = "Marker position is ${markerPositionState.position}")
     }
-}
+}

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

@@ -15,7 +15,6 @@
 package com.google.maps.android.compose
 
 import androidx.compose.runtime.AbstractApplier
-import androidx.compose.ui.platform.ComposeView
 import com.google.android.gms.maps.GoogleMap
 import com.google.android.gms.maps.MapView
 import com.google.android.gms.maps.model.Circle
@@ -112,21 +111,24 @@ internal class MapApplier(
         }
         map.setOnMarkerDragListener(object : GoogleMap.OnMarkerDragListener {
             override fun onMarkerDrag(marker: Marker) {
-                val markerDragState =
-                    decorations.nodeForMarker(marker)?.markerDragState
-                markerDragState?.dragState = DragState.DRAG
+                with(decorations.nodeForMarker(marker)) {
+                    this?.markerPositionState?.position = marker.position
+                    this?.markerPositionState?.dragState = DragState.DRAG
+                }
             }
 
             override fun onMarkerDragEnd(marker: Marker) {
-                val markerDragState =
-                    decorations.nodeForMarker(marker)?.markerDragState
-                markerDragState?.dragState = DragState.END
+                with(decorations.nodeForMarker(marker)) {
+                    this?.markerPositionState?.position = marker.position
+                    this?.markerPositionState?.dragState = DragState.END
+                }
             }
 
             override fun onMarkerDragStart(marker: Marker) {
-                val markerDragState =
-                    decorations.nodeForMarker(marker)?.markerDragState
-                markerDragState?.dragState = DragState.START
+                with(decorations.nodeForMarker(marker)) {
+                    this?.markerPositionState?.position = marker.position
+                    this?.markerPositionState?.dragState = DragState.START
+                }
             }
         })
         map.setInfoWindowAdapter(