new change to use intaleq_map sdk v2 04-17-1

packages/flutter-sdk/lib/src/utils/polyline_utils.dart

@@ -1,10 +1,18 @@
-import 'package:maplibre_gl/maplibre_gl.dart';
+import 'dart:math' show sin, cos, sqrt, atan2, pi;
+import 'package:maplibre_gl/maplibre_gl.dart' show LatLng;
 
+/// Utility functions for working with encoded polylines and coordinates.
 class PolylineUtils {
-  /// Decode a Google-encoded polyline string into a list of LatLng coordinates.
+  PolylineUtils._();
+
+  // ── Encoding / Decoding ────────────────────────────────────
+
+  /// Decodes a [Google-encoded polyline](https://developers.google.com/maps/documentation/utilities/polylinealgorithm)
+  /// string into a list of [LatLng] coordinates.
   static List<LatLng> decode(String encoded) {
-    List<LatLng> points = [];
-    int index = 0, len = encoded.length;
+    final points = <LatLng>[];
+    int index = 0;
+    final len = encoded.length;
     int lat = 0, lng = 0;
 
     while (index < len) {
@@ -14,7 +22,7 @@ class PolylineUtils {
         result |= (b & 0x1f) << shift;
         shift += 5;
       } while (b >= 0x20);
-      int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
+      final dlat = (result & 1) != 0 ? ~(result >> 1) : (result >> 1);
       lat += dlat;
 
       shift = 0;
@@ -24,11 +32,61 @@ class PolylineUtils {
         result |= (b & 0x1f) << shift;
         shift += 5;
       } while (b >= 0x20);
-      int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
+      final dlng = (result & 1) != 0 ? ~(result >> 1) : (result >> 1);
       lng += dlng;
 
       points.add(LatLng(lat / 1E5, lng / 1E5));
     }
     return points;
   }
+
+  /// Encodes a list of [LatLng] points to a Google-encoded polyline string.
+  static String encode(List<LatLng> points) {
+    final result = StringBuffer();
+    int prevLat = 0, prevLng = 0;
+
+    for (final point in points) {
+      final lat = (point.latitude * 1E5).round();
+      final lng = (point.longitude * 1E5).round();
+      _encodeValue(result, lat - prevLat);
+      _encodeValue(result, lng - prevLng);
+      prevLat = lat;
+      prevLng = lng;
+    }
+    return result.toString();
+  }
+
+  static void _encodeValue(StringBuffer buf, int value) {
+    var v = value < 0 ? ~(value << 1) : (value << 1);
+    while (v >= 0x20) {
+      buf.writeCharCode(((0x20 | (v & 0x1f)) + 63));
+      v >>= 5;
+    }
+    buf.writeCharCode((v + 63));
+  }
+
+  // ── Distance ───────────────────────────────────────────────
+
+  /// Returns the Haversine distance in **metres** between two [LatLng] points.
+  static double distanceBetween(LatLng a, LatLng b) {
+    const earthRadius = 6371000.0; // metres
+    final dLat = _toRad(b.latitude - a.latitude);
+    final dLng = _toRad(b.longitude - a.longitude);
+    final sinDLat = sin(dLat / 2);
+    final sinDLng = sin(dLng / 2);
+    final h = sinDLat * sinDLat +
+        cos(_toRad(a.latitude)) * cos(_toRad(b.latitude)) * sinDLng * sinDLng;
+    return 2 * earthRadius * atan2(sqrt(h), sqrt(1 - h));
+  }
+
+  /// Returns the total length of a polyline in metres.
+  static double totalLength(List<LatLng> points) {
+    double total = 0;
+    for (int i = 0; i < points.length - 1; i++) {
+      total += distanceBetween(points[i], points[i + 1]);
+    }
+    return total;
+  }
+
+  static double _toRad(double deg) => deg * pi / 180.0;
 }