Implements booleanOverlap and line_overlap function

lib/src/bbox.dart

@@ -9,10 +9,12 @@ BBox bbox(GeoJSONObject geoJson, {bool recompute = false}) {
   }
 
   var result = BBox.named(
-    lat1: double.infinity,
+    // min x & y
     lng1: double.infinity,
-    lat2: double.negativeInfinity,
+    lat1: double.infinity,
+    // max x & y
     lng2: double.negativeInfinity,
+    lat2: double.negativeInfinity,
   );
 
   coordEach(

lib/src/booleans/boolean_overlap.dart

@@ -0,0 +1,147 @@
+import 'package:turf/helpers.dart';
+import 'package:turf/line_segment.dart';
+import 'package:turf/src/invariant.dart';
+import 'package:turf/src/line_intersect.dart';
+import 'package:turf/src/line_overlap.dart';
+import 'package:turf_equality/turf_equality.dart';
+
+/// Compares two geometries of the same dimension and returns [true] if their
+/// intersection Set results in a geometry different from both but of the same
+/// dimension. It applies to [Polygon]/[Polygon], [LineString]/[LineString], [MultiPoint]/
+/// [MultiPoint], [MultiLineString]/[MultiLineString] and [MultiPolygon]/[MultiPolygon].
+/// In other words, it returns [true] if the two geometries overlap, provided that
+/// neither completely contains the other.
+/// Takes [feature1] and [feature2] which could be [Feature]<[LineString]|
+/// [MultiLineString]|[Polygon]|[MultiPolygon]>
+/// example
+/// ```dart
+/// var poly1 = Polygon(
+///   coordinates: [
+///     [
+///       Position.of([0, 0]),
+///       Position.of([0, 5]),
+///       Position.of([5, 5]),
+///       Position.of([5, 0]),
+///       Position.of([0, 0])
+///     ]
+///   ],
+/// );
+/// var poly2 = Polygon(
+///   coordinates: [
+///     [
+///       Position.of([1, 1]),
+///       Position.of([1, 6]),
+///       Position.of([6, 6]),
+///       Position.of([6, 1]),
+///       Position.of([1, 1])
+///     ]
+///   ],
+/// );
+/// var poly3 = Polygon(
+///   coordinates: [
+///     [
+///       Position.of([10, 10]),
+///       Position.of([10, 15]),
+///       Position.of([15, 15]),
+///       Position.of([15, 10]),
+///       Position.of([10, 10])
+///     ]
+///   ],
+/// );
+/// booleanOverlap(poly1, poly2);
+/// //=true
+/// booleanOverlap(poly2, poly3);
+/// //=false
+/// ```
+bool booleanOverlap(GeoJSONObject feature1, GeoJSONObject feature2) {
+  var geom1 = getGeom(feature1);
+  var geom2 = getGeom(feature2);
+
+  if ((feature1 is MultiPoint && feature2 is! MultiPoint) ||
+      ((feature1 is LineString || feature1 is MultiLineString) &&
+          feature2 is! LineString &&
+          feature2 is! MultiLineString) ||
+      ((feature1 is Polygon || feature1 is MultiPolygon) &&
+          feature2 is! Polygon &&
+          feature2 is! MultiPolygon)) {
+    throw Exception("features must be of the same type");
+  }
+  if (feature1 is Point) throw Exception("Point geometry not supported");
+
+  // features must be not equal
+  var equality = Equality(precision: 6);
+  if (equality.compare(feature1, feature2)) {
+    return false;
+  }
+
+  var overlap = 0;
+
+  if (geom1 is MultiPoint) {
+    for (var i = 0; i < geom1.coordinates.length; i++) {
+      for (var j = 0; j < (geom2 as MultiPoint).coordinates.length; j++) {
+        if (geom1.coordinates[i] == geom2.coordinates[j]) {
+          return true;
+        }
+      }
+    }
+    return false;
+  } else if (feature1 is MultiLineString) {
+    segmentEach(
+      feature1,
+      (
+        Feature<LineString> currentSegment,
+        int featureIndex,
+        int? multiFeatureIndex,
+        int? geometryIndex,
+        int segmentIndex,
+      ) {
+        segmentEach(
+          feature2,
+          (
+            Feature<LineString> currentSegment1,
+            int featureIndex,
+            int? multiFeatureIndex,
+            int? geometryIndex,
+            int segmentIndex,
+          ) {
+            if (lineOverlap(currentSegment, currentSegment1)
+                .features
+                .isNotEmpty) {
+              overlap++;
+            }
+          },
+        );
+      },
+    );
+  } else if (feature1 is Polygon || feature1 is MultiPolygon) {
+    segmentEach(
+      feature1,
+      (
+        Feature<LineString> currentSegment,
+        int featureIndex,
+        int? multiFeatureIndex,
+        int? geometryIndex,
+        int segmentIndex,
+      ) {
+        segmentEach(
+          feature2,
+          (
+            Feature<LineString> currentSegment1,
+            int featureIndex,
+            int? multiFeatureIndex,
+            int? geometryIndex,
+            int segmentIndex,
+          ) {
+            if (lineIntersect(currentSegment, currentSegment1)
+                .features
+                .isNotEmpty) {
+              overlap++;
+            }
+          },
+        );
+      },
+    );
+  }
+
+  return overlap > 0;
+}

lib/src/line_overlap.dart

@@ -0,0 +1,195 @@
+import 'package:rbush/rbush.dart';
+import 'package:turf/bbox.dart';
+import 'package:turf/helpers.dart';
+import 'package:turf/line_segment.dart';
+import 'package:turf/nearest_point_on_line.dart';
+import 'package:turf/src/booleans/boolean_point_on_line.dart';
+import 'package:turf/src/invariant.dart';
+import 'package:turf/src/meta/feature.dart';
+import 'package:turf_equality/turf_equality.dart';
+
+/// Takes any [LineString] or [Polygon] and returns the overlapping [LineString]s
+/// between both [Feature]s. [line1] is a [Feature]<[LineString]|[MultiLineString]
+/// |[Polygon]|[MultiPolygon]> or any [LineString] or [Polygon], [line2] is a
+/// [Feature]<[LineString]|[MultiLineString]|[Polygon]|[MultiPolygon]> or any
+/// [LineString] or [Polygon]. [tolerance=0] Tolerance distance to match
+/// overlapping line segments (in kilometers) returns a [FeatureCollection]<[LineString]>
+/// lines(s) that are overlapping between both [Feature]s.
+/// example
+/// ```dart
+/// var line1 = LineString(
+///   coordinates: [
+///     Position.of([115, -35]),
+///     Position.of([125, -30]),
+///     Position.of([135, -30]),
+///     Position.of([145, -35])
+///   ],
+/// );
+/// var line2 = LineString(
+///   coordinates: [
+///     Position.of([115, -25]),
+///     Position.of([125, -30]),
+///     Position.of([135, -30]),
+///     Position.of([145, -25])
+///   ],
+/// );
+/// var overlapping = lineOverlap(line1, line2);
+/// //addToMap
+/// var addToMap = [line1, line2, overlapping]
+///```
+FeatureCollection<LineString> lineOverlap(
+    GeoJSONObject line1, GeoJSONObject line2,
+    {num tolerance = 0}) {
+  RBushBox _toRBBox(Feature<LineString> feature) {
+    return RBushBox.fromList(bbox(feature).toList());
+  }
+
+  // Containers
+  var features = <Feature<LineString>>[];
+
+  // Create Spatial Index
+  var tree = RBushBase<Feature<LineString>>(
+    maxEntries: 4,
+    getMinX: (Feature<LineString> feature) => bbox(feature).lng1.toDouble(),
+    getMinY: (Feature<LineString> feature) => bbox(feature).lat1.toDouble(),
+    toBBox: _toRBBox,
+  );
+
+  FeatureCollection<LineString> line = lineSegment(line1);
+  tree.load(line.features);
+  Feature<LineString>? overlapSegment;
+  List<Feature<LineString>> additionalSegments = [];
+
+  // Line Intersection
+
+  // Iterate over line segments
+  segmentEach(line2, (Feature<LineString> currentSegment, int featureIndex,
+      int? multiFeatureIndex, int? geometryIndex, int segmentIndex) {
+    bool doesOverlap = false;
+    var list = tree.search(_toRBBox(currentSegment));
+    // Iterate over each segments which falls within the same bounds
+    featureEach(FeatureCollection<LineString>(features: list),
+        (Feature currentFeature, int featureIndex) {
+      if (!doesOverlap) {
+        var coords = getCoords(currentSegment) as List<Position>;
+        var coordsMatch = getCoords(currentFeature) as List<Position>;
+
+        coords.sort(((a, b) {
+          return a.lng < b.lng
+              ? -1
+              : a.lng > b.lng
+                  ? 1
+                  : 0;
+        }));
+
+        coordsMatch.sort(((a, b) {
+          return a.lng < b.lng
+              ? -1
+              : a.lng > b.lng
+                  ? 1
+                  : 0;
+        }));
+
+        Equality eq = Equality();
+        // Segment overlaps feature - with dummy LineStrings just to use eq.
+        if (eq.compare(LineString(coordinates: coords),
+            LineString(coordinates: coordsMatch))) {
+          doesOverlap = true;
+          // Overlaps already exists - only append last coordinate of segment
+          if (overlapSegment != null) {
+            overlapSegment = concatSegment(overlapSegment!, currentSegment) ??
+                overlapSegment;
+          } else {
+            overlapSegment = currentSegment;
+          }
+          // Match segments which don't share nodes (Issue #901)
+        } else if (tolerance == 0
+            ? booleanPointOnLine(Point(coordinates: coords[0]), currentFeature.geometry as LineString) &&
+                booleanPointOnLine(Point(coordinates: coords[1]),
+                    currentFeature.geometry as LineString)
+            : nearestPointOnLine(currentFeature.geometry as LineString, Point(coordinates: coords[0]))
+                        .properties!['dist'] <=
+                    tolerance &&
+                nearestPointOnLine(currentFeature.geometry as LineString, Point(coordinates: coords[1]))
+                        .properties!['dist'] <=
+                    tolerance) {
+          doesOverlap = true;
+          if (overlapSegment != null) {
+            overlapSegment = concatSegment(overlapSegment!, currentSegment) ??
+                overlapSegment;
+          } else {
+            overlapSegment = currentSegment;
+          }
+        } else if (tolerance == 0
+            ? booleanPointOnLine(Point(coordinates: coordsMatch[0]),
+                    currentSegment.geometry as LineString) &&
+                booleanPointOnLine(Point(coordinates: coordsMatch[1]),
+                    currentSegment.geometry as LineString)
+            : nearestPointOnLine(currentSegment.geometry as LineString,
+                            Point(coordinates: coordsMatch[0]))
+                        .properties!['dist'] <=
+                    tolerance &&
+                nearestPointOnLine(
+                            currentSegment.geometry as LineString, Point(coordinates: coordsMatch[1]))
+                        .properties!['dist'] <=
+                    tolerance) {
+          // Do not define doesOverlap = true since more matches can occur
+          // within the same segment
+          // doesOverlaps = true;
+          if (overlapSegment != null) {
+            Feature<LineString>? combinedSegment = concatSegment(
+                overlapSegment!, currentFeature as Feature<LineString>);
+            if (combinedSegment != null) {
+              overlapSegment = combinedSegment;
+            } else {
+              additionalSegments.add(currentFeature);
+            }
+          } else {
+            overlapSegment = currentFeature as Feature<LineString>;
+          }
+        }
+      }
+    });
+
+    // Segment doesn't overlap - add overlaps to results & reset
+    if (doesOverlap == false && overlapSegment != null) {
+      features.add(overlapSegment!);
+      if (additionalSegments.isNotEmpty) {
+        features.addAll(additionalSegments);
+        additionalSegments = [];
+      }
+      overlapSegment = null;
+    }
+  });
+  // Add last segment if exists
+  if (overlapSegment != null) features.add(overlapSegment!);
+
+  return FeatureCollection(features: features);
+}
+
+Feature<LineString>? concatSegment(
+  Feature<LineString> line,
+  Feature<LineString> segment,
+) {
+  var coords = getCoords(segment) as List<Position>;
+  var lineCoords = getCoords(line) as List<Position>;
+  Position start = lineCoords[0];
+  Position end = lineCoords[lineCoords.length - 1];
+  List<Position> positions = (line.geometry as LineString).clone().coordinates;
+
+  if (coords[0] == start) {
+    positions.insert(0, coords[1]);
+  } else if (coords[0] == end) {
+    positions.add(coords[1]);
+  } else if (coords[1] == start) {
+    positions.insert(0, coords[0]);
+  } else if (coords[1] == end) {
+    positions.add(coords[0]);
+  } else {
+    return null;
+  } // If the overlap leaves the segment unchanged, return null so that this can be
+  // identified.
+
+  // Otherwise return the mutated line.
+  return Feature(geometry: LineString(coordinates: positions));
+}