feat: add clusterMinPoints option Android and iOS (#3601)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: MarkusWendorf

include/mbgl/style/sources/geojson_source.hpp

@@ -29,6 +29,7 @@ struct GeoJSONOptions {
     bool cluster = false;
     uint16_t clusterRadius = 50;
     uint8_t clusterMaxZoom = 17;
+    size_t clusterMinPoints = 2;
     using ClusterExpression = std::pair<std::shared_ptr<mbgl::style::expression::Expression>,
                                         std::shared_ptr<mbgl::style::expression::Expression>>;
     using ClusterProperties = std::map<std::string, ClusterExpression>;

platform/android/MapLibreAndroid/src/main/java/org/maplibre/android/style/sources/GeoJsonOptions.kt

@@ -100,6 +100,17 @@ class GeoJsonOptions : HashMap<String?, Any?>() {
         return this
     }
 
+     /**
+     * Minimum number of points to form a cluster
+     *
+     * @param clusterMinPoints minimum number of points to form a cluster - Defaults to 2
+     * @return the current instance for chaining
+     */
+    fun withClusterMinPoints(clusterMinPoints: Int): GeoJsonOptions {
+        this["clusterMinPoints"] = clusterMinPoints
+        return this
+    }
+
     /**
      * An object defining custom properties on the generated clusters if clustering is enabled,
      * aggregating values from clustered points. Has the form {"property_name": [operator, [map_expression]]} or

platform/android/MapLibreAndroidTestApp/src/main/java/org/maplibre/android/testapp/activity/style/GeoJsonClusteringActivity.kt

@@ -139,6 +139,7 @@ class GeoJsonClusteringActivity : AppCompatActivity() {
                 .withCluster(true)
                 .withClusterMaxZoom(14)
                 .withClusterRadius(50)
+                .withClusterMinPoints(3)
                 .withClusterProperty(
                     "max",
                     Expression.max(Expression.accumulated(), Expression.get("max")),

platform/darwin/src/MLNShapeSource.h

@@ -44,6 +44,15 @@ FOUNDATION_EXTERN MLN_EXPORT const MLNShapeSourceOption MLNShapeSourceOptionClus
  */
 FOUNDATION_EXTERN MLN_EXPORT const MLNShapeSourceOption MLNShapeSourceOptionClusterRadius;
 
+/**
+ An `NSNumber` object containing an integer; specifies the minimum number of points to form a
+ cluster if clustering is enabled. The default value is 2.
+
+ This option only affects point features within an ``MLNShapeSource`` object; it
+ is ignored when creating an ``MLNComputedShapeSource`` object.
+ */
+FOUNDATION_EXTERN MLN_EXPORT const MLNShapeSourceOption MLNShapeSourceOptionClusterMinPoints;
+
 /**
  An `NSDictionary` object where the key is an `NSString`. The dictionary key will
  be the feature attribute key. The resulting attribute value is
@@ -233,7 +242,7 @@ MLN_EXPORT
  for the source.
 
  This class supports the following options: ``MLNShapeSourceOptionClustered``,
- ``MLNShapeSourceOptionClusterRadius``,
+ ``MLNShapeSourceOptionClusterRadius``, ``MLNShapeSourceOptionClusterMinPoints``,
  ``MLNShapeSourceOptionMaximumZoomLevelForClustering``,
  ``MLNShapeSourceOptionMinimumZoomLevel``, ``MLNShapeSourceOptionMinimumZoomLevel``,
  ``MLNShapeSourceOptionBuffer``, and

platform/darwin/src/MLNShapeSource.mm

@@ -19,6 +19,7 @@
 
 const MLNShapeSourceOption MLNShapeSourceOptionBuffer = @"MLNShapeSourceOptionBuffer";
 const MLNShapeSourceOption MLNShapeSourceOptionClusterRadius = @"MLNShapeSourceOptionClusterRadius";
+const MLNShapeSourceOption MLNShapeSourceOptionClusterMinPoints = @"MLNShapeSourceOptionClusterMinPoints";
 const MLNShapeSourceOption MLNShapeSourceOptionClustered = @"MLNShapeSourceOptionClustered";
 const MLNShapeSourceOption MLNShapeSourceOptionClusterProperties = @"MLNShapeSourceOptionClusterProperties";
 const MLNShapeSourceOption MLNShapeSourceOptionMaximumZoomLevel = @"MLNShapeSourceOptionMaximumZoomLevel";
@@ -70,6 +71,14 @@
         geoJSONOptions->clusterRadius = value.integerValue;
     }
 
+    if (NSNumber *value = options[MLNShapeSourceOptionClusterMinPoints]) {
+        if (![value isKindOfClass:[NSNumber class]]) {
+            [NSException raise:NSInvalidArgumentException
+                        format:@"MLNShapeSourceOptionClusterMinPoints must be an NSNumber."];
+        }
+        geoJSONOptions->clusterMinPoints = value.integerValue;
+    }
+
     if (NSNumber *value = options[MLNShapeSourceOptionMaximumZoomLevelForClustering]) {
         if (![value isKindOfClass:[NSNumber class]]) {
             [NSException raise:NSInvalidArgumentException

platform/darwin/test/MLNShapeSourceTests.mm

@@ -18,6 +18,7 @@ - (void)testGeoJSONOptionsFromDictionary {
     NSArray *clusterPropertyArray = @[reduceExpression, mapExpression];
     NSDictionary *options = @{MLNShapeSourceOptionClustered: @YES,
                               MLNShapeSourceOptionClusterRadius: @42,
+                              MLNShapeSourceOptionClusterMinPoints: @3,
                               MLNShapeSourceOptionClusterProperties: @{@"sumValue": clusterPropertyArray},
                               MLNShapeSourceOptionMaximumZoomLevelForClustering: @98,
                               MLNShapeSourceOptionMaximumZoomLevel: @99,
@@ -29,6 +30,7 @@ - (void)testGeoJSONOptionsFromDictionary {
     XCTAssertTrue(mbglOptions->cluster);
     XCTAssertEqual(mbglOptions->clusterRadius, 42);
     XCTAssertEqual(mbglOptions->clusterMaxZoom, 98);
+    XCTAssertEqual(mbglOptions->clusterMinPoints, 3UL);
     XCTAssertEqual(mbglOptions->maxzoom, 99);
     XCTAssertEqual(mbglOptions->buffer, 1976);
     XCTAssertEqual(mbglOptions->tolerance, 0.42);

platform/ios/MapLibre.docc/For_Style_Authors.md

@@ -150,6 +150,7 @@ In style JSON    | In the SDK
 `tolerance`      | `MLNShapeSourceOptionSimplificationTolerance`
 `cluster`        | `MLNShapeSourceOptionClustered`
 `clusterRadius`  | `MLNShapeSourceOptionClusterRadius`
+`clusterMinPoints`  | `MLNShapeSourceOptionClusterMinPoints`
 `clusterMaxZoom` | `MLNShapeSourceOptionMaximumZoomLevelForClustering`
 `lineMetrics`    | `MLNShapeSourceOptionLineDistanceMetrics`
 

src/mbgl/style/conversion/geojson_options.cpp

@@ -81,6 +81,16 @@ std::optional<GeoJSONOptions> Converter<GeoJSONOptions>::operator()(const Conver
         }
     }
 
+    const auto clusterMinPointsValue = objectMember(value, "clusterMinPoints");
+    if (clusterMinPointsValue) {
+        if (toNumber(*clusterMinPointsValue)) {
+            options.clusterMinPoints = static_cast<size_t>(*toNumber(*clusterMinPointsValue));
+        } else {
+            error.message = "GeoJSON source clusterMinPoints value must be a number";
+            return std::nullopt;
+        }
+    }
+
     const auto lineMetricsValue = objectMember(value, "lineMetrics");
     if (lineMetricsValue) {
         if (toBool(*lineMetricsValue)) {

src/mbgl/style/sources/geojson_source_impl.cpp

@@ -99,6 +99,8 @@ std::shared_ptr<GeoJSONData> GeoJSONData::create(const GeoJSON& geoJSON,
         clusterOptions.maxZoom = options->clusterMaxZoom;
         clusterOptions.extent = util::EXTENT;
         clusterOptions.radius = static_cast<uint16_t>(::round(scale * options->clusterRadius));
+        clusterOptions.minPoints = options->clusterMinPoints;
+
         auto feature = std::make_shared<Feature>();
         clusterOptions.map = [feature, options](const PropertyMap& properties) -> PropertyMap {
             PropertyMap ret{};

test/style/conversion/geojson_options.test.cpp

@@ -40,6 +40,7 @@ TEST(GeoJSONOptions, RetainsDefaults) {
     ASSERT_EQ(converted.cluster, defaults.cluster);
     ASSERT_EQ(converted.clusterRadius, defaults.clusterRadius);
     ASSERT_EQ(converted.clusterMaxZoom, defaults.clusterMaxZoom);
+    ASSERT_EQ(converted.clusterMinPoints, defaults.clusterMinPoints);
     ASSERT_TRUE(converted.clusterProperties.empty());
 }
 
@@ -53,6 +54,7 @@ TEST(GeoJSONOptions, FullConversion) {
         "cluster": true,
         "clusterRadius": 4,
         "clusterMaxZoom": 5,
+        "clusterMinPoints": 6,
         "lineMetrics": true,
         "clusterProperties": {
             "max": ["max", ["get", "scalerank"]],
@@ -73,6 +75,7 @@ TEST(GeoJSONOptions, FullConversion) {
     ASSERT_EQ(converted.cluster, true);
     ASSERT_EQ(converted.clusterRadius, 4);
     ASSERT_EQ(converted.clusterMaxZoom, 5);
+    ASSERT_EQ(converted.clusterMinPoints, 6);
     ASSERT_EQ(converted.clusterProperties.size(), 3);
     ASSERT_EQ(converted.clusterProperties.count("max"), 1);
     ASSERT_EQ(converted.clusterProperties.count("sum"), 1);