Implement layer filtering (flutter-mapbox-gl#997)

android/src/main/java/com/mapbox/mapboxgl/MapboxMapController.java

@@ -27,6 +27,7 @@
 import com.google.gson.Gson;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
+import com.google.gson.JsonParser;
 import com.mapbox.android.core.location.LocationEngine;
 import com.mapbox.android.core.location.LocationEngineCallback;
 import com.mapbox.android.core.location.LocationEngineProvider;
@@ -59,7 +60,9 @@
 import com.mapbox.mapboxsdk.plugins.localization.LocalizationPlugin;
 import com.mapbox.mapboxsdk.style.expressions.Expression;
 import com.mapbox.mapboxsdk.style.layers.CircleLayer;
+import com.mapbox.mapboxsdk.style.layers.FillExtrusionLayer;
 import com.mapbox.mapboxsdk.style.layers.FillLayer;
+import com.mapbox.mapboxsdk.style.layers.HeatmapLayer;
 import com.mapbox.mapboxsdk.style.layers.HillshadeLayer;
 import com.mapbox.mapboxsdk.style.layers.Layer;
 import com.mapbox.mapboxsdk.style.layers.LineLayer;
@@ -1107,6 +1110,46 @@ public void onFailure(@NonNull Exception exception) {
           style.removeLayer(layerId);
           interactiveFeatureLayerIds.remove(layerId);
 
+          result.success(null);
+          break;
+        }
+      case "style#setFilter":
+        {
+          if (style == null) {
+            result.error(
+                "STYLE IS NULL",
+                "The style is null. Has onStyleLoaded() already been invoked?",
+                null);
+          }
+          String layerId = call.argument("layerId");
+          String filter = call.argument("filter");
+
+          Layer layer = style.getLayer(layerId);
+
+          JsonParser parser = new JsonParser();
+          JsonElement jsonElement = parser.parse(filter);
+          Expression expression = Expression.Converter.convert(jsonElement);
+
+          if (layer instanceof CircleLayer) {
+            ((CircleLayer) layer).setFilter(expression);
+          } else if (layer instanceof FillExtrusionLayer) {
+            ((FillExtrusionLayer) layer).setFilter(expression);
+          } else if (layer instanceof FillLayer) {
+            ((FillLayer) layer).setFilter(expression);
+          } else if (layer instanceof HeatmapLayer) {
+            ((HeatmapLayer) layer).setFilter(expression);
+          } else if (layer instanceof LineLayer) {
+            ((LineLayer) layer).setFilter(expression);
+          } else if (layer instanceof SymbolLayer) {
+            ((SymbolLayer) layer).setFilter(expression);
+          } else {
+            result.error(
+                "INVALID LAYER TYPE",
+                String.format("Layer '%s' does not support filtering.", layerId),
+                null);
+            break;
+          }
+
           result.success(null);
           break;
         }

example/lib/layer.dart

@@ -22,7 +22,9 @@ class LayerState extends State {
   static final LatLng center = const LatLng(-33.86711, 151.1947171);
 
   late MapboxMapController controller;
-  Timer? timer;
+  Timer? bikeTimer;
+  Timer? filterTimer;
+  int filteredId = 0;
 
   @override
   Widget build(BuildContext context) {
@@ -136,15 +138,22 @@ class LayerState extends State {
       ),
       minzoom: 11,
     );
-    timer = Timer.periodic(
-        Duration(milliseconds: 10),
-        (t) => controller.setGeoJsonSource(
-            "moving", _movingFeature(t.tick / 2000)));
+
+    bikeTimer = Timer.periodic(Duration(milliseconds: 10), (t) {
+      controller.setGeoJsonSource("moving", _movingFeature(t.tick / 2000));
+    });
+
+    controller.setFilter('fills', ['==', 'id', filteredId]);
+    filterTimer = Timer.periodic(Duration(seconds: 3), (t) {
+      filteredId = filteredId == 0 ? 1 : 0;
+      controller.setFilter('fills', ['==', 'id', filteredId]);
+    });
   }
 
   @override
   void dispose() {
-    timer?.cancel();
+    bikeTimer?.cancel();
+    filterTimer?.cancel();
     super.dispose();
   }
 }
@@ -186,7 +195,7 @@ final _fills = {
     {
       "type": "Feature",
       "id": 0, // web currently only supports number ids
-      "properties": <String, dynamic>{},
+      "properties": <String, dynamic>{'id': 0},
       "geometry": {
         "type": "Polygon",
         "coordinates": [
@@ -211,7 +220,7 @@ final _fills = {
     {
       "type": "Feature",
       "id": 1,
-      "properties": <String, dynamic>{},
+      "properties": <String, dynamic>{'id': 1},
       "geometry": {
         "type": "Polygon",
         "coordinates": [

ios/Classes/MapboxMapController.swift

@@ -720,6 +720,40 @@ class MapboxMapController: NSObject, FlutterPlatformView, MGLMapViewDelegate, Ma
             mapView.style?.removeLayer(layer)
             result(nil)
 
+        case "style#setFilter":
+            guard let arguments = methodCall.arguments as? [String: Any] else { return }
+            guard let layerId = arguments["layerId"] as? String else { return }
+            guard let filter = arguments["filter"] as? String else { return }
+            guard let layer = mapView.style?.layer(withIdentifier: layerId) else {
+                result(nil)
+                return
+            }
+
+            do {
+                let filter = try JSONSerialization.jsonObject(
+                    with: filter.data(using: .utf8)!,
+                    options: .fragmentsAllowed
+                )
+                let predicate = NSPredicate(mglJSONObject: filter)
+                if let layer = layer as? MGLVectorStyleLayer {
+                    layer.predicate = predicate
+                } else {
+                    result(FlutterError(
+                        code: "invalidLayerType",
+                        message: "Invalid layer type",
+                        details: "Layer '\(layerId)' does not support filtering."
+                    ))
+                    return
+                }
+                result(nil)
+            } catch {
+                result(FlutterError(
+                    code: "invalidExpression",
+                    message: "Invalid filter expression",
+                    details: "Could not parse filter expression."
+                ))
+            }
+
         case "source#addGeoJson":
             guard let arguments = methodCall.arguments as? [String: Any] else { return }
             guard let sourceId = arguments["sourceId"] as? String else { return }

lib/src/controller.dart

@@ -1056,6 +1056,10 @@ class MapboxMapController extends ChangeNotifier {
     return _mapboxGlPlatform.removeLayer(layerId);
   }
 
+  Future<void> setFilter(String layerId, dynamic filter) {
+    return _mapboxGlPlatform.setFilter(layerId, filter);
+  }
+
   /// Returns the point on the screen that corresponds to a geographical coordinate ([latLng]). The screen location is in screen pixels (not display pixels) relative to the top left of the map (not of the whole screen)
   ///
   /// Note: The resulting x and y coordinates are rounded to [int] on web, on other platforms they may differ very slightly (in the range of about 10^-10) from the actual nearest screen coordinate.

mapbox_gl_platform_interface/lib/src/mapbox_gl_platform_interface.dart

@@ -86,6 +86,8 @@ abstract class MapboxGlPlatform {
 
   Future<void> removeLayer(String imageLayerId);
 
+  Future<void> setFilter(String layerId, dynamic filter);
+
   Future<Point> toScreenLocation(LatLng latLng);
 
   Future<List<Point>> toScreenLocationBatch(Iterable<LatLng> latLngs);

mapbox_gl_platform_interface/lib/src/method_channel_mapbox_gl.dart

@@ -472,6 +472,16 @@ class MethodChannelMapboxGl extends MapboxGlPlatform {
     }
   }
 
+  @override
+  Future<void> setFilter(String layerId, dynamic filter) async {
+    try {
+      return await _channel.invokeMethod('style#setFilter',
+          <String, Object>{'layerId': layerId, 'filter': jsonEncode(filter)});
+    } on PlatformException catch (e) {
+      return new Future.error(e);
+    }
+  }
+
   @override
   Future<LatLng> toLatLng(Point screenLocation) async {
     try {

mapbox_gl_web/lib/src/mapbox_web_gl_platform.dart

@@ -629,6 +629,11 @@ class MapboxWebGlPlatform extends MapboxGlPlatform
     _map.removeLayer(layerId);
   }
 
+  @override
+  Future<void> setFilter(String layerId, dynamic filter) async {
+    _map.setFilter(layerId, filter);
+  }
+
   @override
   Future<void> addGeoJsonSource(String sourceId, Map<String, dynamic> geojson,
       {String? promoteId}) async {