Get Bounds From Center and Distance

main.dart

import 'dart:math';

const earthRadius = 3958.8; // in miles
const earthCircumference = 2 * pi * earthRadius;

class Point {
  final double lng;
  final double lat;

  Point({
    required this.lng,
    required this.lat,
  });

  @override
  String toString() {
    return '$lat,$lng';
  }
}

class Bounds {
  final Point north;
  final Point south;
  final Point east;
  final Point west;

  Bounds({
    required this.north,
    required this.south,
    required this.east,
    required this.west,
  });

  factory Bounds.fromCenter(Point center, double radius) {
    final deltaLatitude = 360 * radius / earthCircumference;
    final deltaLongitude = deltaLatitude / cos(center.lat * pi / 180);
    
    return Bounds(
      north: Point(lat: center.lat + deltaLatitude, lng: center.lng),
      south: Point(lat: center.lat - deltaLatitude, lng: center.lng),
      west: Point(lat: center.lat, lng: center.lng - deltaLongitude),
      east: Point(lat: center.lat, lng: center.lng + deltaLongitude),
    );
  }

  @override
  String toString() {
    return 'Bounds(north: $north, south: $south, east: $east, west: $west)';
  }
}

void main() {
  final center = Point(lat: 51.503231, lng: -0.119189);

  final distance = 10.0;

  final bounds = Bounds.fromCenter(center, distance);

  print(center);
  print(bounds.north);
  print(bounds.south);
  print(bounds.east);
  print(bounds.west);
}