Add drag event to platform interface

Author: JamesMcIntosh

packages/google_maps_flutter/google_maps_flutter_platform_interface/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.1.1
+
+* Add additional marker drag events
+
 ## 2.1.0
 
 * Add support for Hybrid Composition when building the Google Maps widget on Android. Set

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/events/map_event.dart

@@ -102,6 +102,26 @@ class InfoWindowTapEvent extends MapEvent<MarkerId> {
   InfoWindowTapEvent(int mapId, MarkerId markerId) : super(mapId, markerId);
 }
 
+/// An event fired when a [Marker] is starting to be dragged to a new [LatLng].
+class MarkerDragStartEvent extends _PositionedMapEvent<MarkerId> {
+  /// Build a MarkerDragStart Event triggered from the map represented by `mapId`.
+  ///
+  /// The `position` on this event is the [LatLng] on which the Marker was picked up from.
+  /// The `value` of this event is a [MarkerId] object that represents the Marker.
+  MarkerDragStartEvent(int mapId, LatLng position, MarkerId markerId)
+      : super(mapId, position, markerId);
+}
+
+/// An event fired when a [Marker] is being dragged to a new [LatLng].
+class MarkerDragEvent extends _PositionedMapEvent<MarkerId> {
+  /// Build a MarkerDrag Event triggered from the map represented by `mapId`.
+  ///
+  /// The `position` on this event is the [LatLng] on which the Marker was dragged to.
+  /// The `value` of this event is a [MarkerId] object that represents the Marker.
+  MarkerDragEvent(int mapId, LatLng position, MarkerId markerId)
+      : super(mapId, position, markerId);
+}
+
 /// An event fired when a [Marker] is dragged to a new [LatLng].
 class MarkerDragEndEvent extends _PositionedMapEvent<MarkerId> {
   /// Build a MarkerDragEnd Event triggered from the map represented by `mapId`.

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/method_channel/method_channel_google_maps_flutter.dart

@@ -124,6 +124,16 @@ class MethodChannelGoogleMapsFlutter extends GoogleMapsFlutterPlatform {
     return _events(mapId).whereType<InfoWindowTapEvent>();
   }
 
+  @override
+  Stream<MarkerDragStartEvent> onMarkerDragStart({required int mapId}) {
+    return _events(mapId).whereType<MarkerDragStartEvent>();
+  }
+
+  @override
+  Stream<MarkerDragEvent> onMarkerDrag({required int mapId}) {
+    return _events(mapId).whereType<MarkerDragEvent>();
+  }
+
   @override
   Stream<MarkerDragEndEvent> onMarkerDragEnd({required int mapId}) {
     return _events(mapId).whereType<MarkerDragEndEvent>();
@@ -174,6 +184,20 @@ class MethodChannelGoogleMapsFlutter extends GoogleMapsFlutterPlatform {
           MarkerId(call.arguments['markerId']),
         ));
         break;
+      case 'marker#onDragStart':
+        _mapEventStreamController.add(MarkerDragStartEvent(
+          mapId,
+          LatLng.fromJson(call.arguments['position'])!,
+          MarkerId(call.arguments['markerId']),
+        ));
+        break;
+      case 'marker#onDrag':
+        _mapEventStreamController.add(MarkerDragEvent(
+          mapId,
+          LatLng.fromJson(call.arguments['position'])!,
+          MarkerId(call.arguments['markerId']),
+        ));
+        break;
       case 'marker#onDragEnd':
         _mapEventStreamController.add(MarkerDragEndEvent(
           mapId,

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/platform_interface/google_maps_flutter_platform.dart

@@ -303,6 +303,16 @@ abstract class GoogleMapsFlutterPlatform extends PlatformInterface {
     throw UnimplementedError('onInfoWindowTap() has not been implemented.');
   }
 
+  /// A [Marker] has been dragged to a different [LatLng] position.
+  Stream<MarkerDragStartEvent> onMarkerDragStart({required int mapId}) {
+    throw UnimplementedError('onMarkerDragEnd() has not been implemented.');
+  }
+
+  /// A [Marker] has been dragged to a different [LatLng] position.
+  Stream<MarkerDragEvent> onMarkerDrag({required int mapId}) {
+    throw UnimplementedError('onMarkerDragEnd() has not been implemented.');
+  }
+
   /// A [Marker] has been dragged to a different [LatLng] position.
   Stream<MarkerDragEndEvent> onMarkerDragEnd({required int mapId}) {
     throw UnimplementedError('onMarkerDragEnd() has not been implemented.');

packages/google_maps_flutter/google_maps_flutter_platform_interface/lib/src/types/marker.dart

@@ -147,6 +147,8 @@ class Marker implements MapsObject {
     this.visible = true,
     this.zIndex = 0.0,
     this.onTap,
+    this.onDrag,
+    this.onDragStart,
     this.onDragEnd,
   }) : assert(alpha == null || (0.0 <= alpha && alpha <= 1.0));
 
@@ -207,9 +209,15 @@ class Marker implements MapsObject {
   /// Callbacks to receive tap events for markers placed on this map.
   final VoidCallback? onTap;
 
+  /// Signature reporting the new [LatLng] at the start of a drag event.
+  final ValueChanged<LatLng>? onDragStart;
+
   /// Signature reporting the new [LatLng] at the end of a drag event.
   final ValueChanged<LatLng>? onDragEnd;
 
+  /// Signature reporting the new [LatLng] during the drag event.
+  final ValueChanged<LatLng>? onDrag;
+
   /// Creates a new [Marker] object whose values are the same as this instance,
   /// unless overwritten by the specified parameters.
   Marker copyWith({
@@ -225,6 +233,8 @@ class Marker implements MapsObject {
     bool? visibleParam,
     double? zIndexParam,
     VoidCallback? onTapParam,
+    ValueChanged<LatLng>? onDragStartParam,
+    ValueChanged<LatLng>? onDragParam,
     ValueChanged<LatLng>? onDragEndParam,
   }) {
     return Marker(
@@ -241,6 +251,8 @@ class Marker implements MapsObject {
       visible: visibleParam ?? visible,
       zIndex: zIndexParam ?? zIndex,
       onTap: onTapParam ?? onTap,
+      onDragStart: onDragStartParam ?? onDragStart,
+      onDrag: onDragParam ?? onDrag,
       onDragEnd: onDragEndParam ?? onDragEnd,
     );
   }

packages/google_maps_flutter/google_maps_flutter_platform_interface/pubspec.yaml

@@ -4,7 +4,7 @@ repository: https://github.com/flutter/plugins/tree/master/packages/google_maps_
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+maps%22
 # NOTE: We strongly prefer non-breaking changes, even at the expense of a
 # less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
-version: 2.1.0
+version: 2.1.1
 
 environment:
   sdk: '>=2.12.0 <3.0.0'