44 lines
1.5 KiB
Dart
44 lines
1.5 KiB
Dart
import 'dart:math' as math;
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import 'package:intl/intl.dart';
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import 'package:tuple/tuple.dart';
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// adapted from Mike Mitterer's dart-latlong library
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String _decimal2sexagesimal(final double dec) {
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double _round(final double value, {final int decimals = 6}) => (value * math.pow(10, decimals)).round() / math.pow(10, decimals);
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List<int> _split(final double value) {
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// NumberFormat is necessary to create digit after comma if the value
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// has no decimal point (only necessary for browser)
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final List<String> tmp = NumberFormat('0.0#####').format(_round(value, decimals: 10)).split('.');
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return <int>[
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int.parse(tmp[0]).abs(),
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int.parse(tmp[1])
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];
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}
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final List<int> parts = _split(dec);
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final int integerPart = parts[0];
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final int fractionalPart = parts[1];
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final int deg = integerPart;
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final double min = double.parse('0.$fractionalPart') * 60;
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final List<int> minParts = _split(min);
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final int minFractionalPart = minParts[1];
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final double sec = (double.parse('0.$minFractionalPart') * 60);
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return '$deg° ${min.floor()}′ ${_round(sec, decimals: 2).toStringAsFixed(2)}″';
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}
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// return coordinates formatted as DMS, e.g. ['41°24′12.2″ N', '2°10′26.5″E']
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List<String> toDMS(Tuple2<double, double> latLng) {
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if (latLng == null) return [];
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final lat = latLng.item1;
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final lng = latLng.item2;
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return [
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'${_decimal2sexagesimal(lat)} ${lat < 0 ? 'S' : 'N'}',
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'${_decimal2sexagesimal(lng)} ${lng < 0 ? 'W' : 'E'}'
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];
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}
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