@turf/boolean-contains: allow boundary points in MultiPoint containment checks

packages/turf-boolean-contains/index.ts

@@ -157,12 +157,21 @@ function isMultiPointOnLine(lineString: LineString, multiPoint: MultiPoint) {
 }
 
 function isMultiPointInPoly(polygon: Polygon, multiPoint: MultiPoint) {
+  let oneInside = false;
   for (const coord of multiPoint.coordinates) {
-    if (!booleanPointInPolygon(coord, polygon, { ignoreBoundary: true })) {
+    // All points must be inside polygon (boundary OK)
+    if (!booleanPointInPolygon(coord, polygon)) {
       return false;
     }
+    // Track if at least one point is strictly in the interior
+    if (!oneInside) {
+      oneInside = booleanPointInPolygon(coord, polygon, {
+        ignoreBoundary: true,
+      });
+    }
   }
-  return true;
+  // At least one point must be in the interior (not just on boundary)
+  return oneInside;
 }
 
 function isLineOnLine(lineString1: LineString, lineString2: LineString) {

packages/turf-boolean-contains/package.json

@@ -6,7 +6,8 @@
   "contributors": [
     "Rowan Winsemius <@rowanwins>",
     "Denis Carriere <@DenisCarriere>",
-    "Samuel Arbibe <@samuelarbibe>"
+    "Samuel Arbibe <@samuelarbibe>",
+    "Espen Hovlandsdal <@rexxars>"
   ],
   "license": "MIT",
   "bugs": {

packages/turf-boolean-contains/test/true/MultiPoint/Polygon/MultiPointOneOnBoundaryOneInterior.geojson

@@ -0,0 +1,32 @@
+{
+  "type": "FeatureCollection",
+  "features": [
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "Polygon",
+        "coordinates": [
+          [
+            [0, 0],
+            [1, 0],
+            [1, 1],
+            [0, 1],
+            [0, 0]
+          ]
+        ]
+      }
+    },
+    {
+      "type": "Feature",
+      "properties": {},
+      "geometry": {
+        "type": "MultiPoint",
+        "coordinates": [
+          [0.5, 0.5],
+          [1, 1]
+        ]
+      }
+    }
+  ]
+}