48 lines
1.4 KiB
Dart
48 lines
1.4 KiB
Dart
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import 'dart:math';
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///
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/// Convert decimal coordinate to degrees minutes seconds (DMS).
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///
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String convertDecimalToDMS(double decimalValue, {required bool isLatitude}) {
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bool isNegative = decimalValue < 0;
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double absoluteValue = decimalValue.abs();
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int degrees = absoluteValue.toInt();
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double minutesDecimal = (absoluteValue - degrees) * 60;
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int minutes = minutesDecimal.toInt();
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double secondsDecimal = (minutesDecimal - minutes) * 60;
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double seconds = double.parse(secondsDecimal.toStringAsFixed(2));
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String direction;
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if (isLatitude) {
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direction = isNegative ? 'S' : 'N';
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} else {
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direction = isNegative ? 'W' : 'E';
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}
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// return formatted string
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return '${degrees.abs()}° ${minutes.abs()}\' ${seconds.abs().toStringAsFixed(2)}" $direction';
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}
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///
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/// Distance in kilometers between two location coordinates
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///
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double calculateDistance(double lat1, double lon1, double lat2, double lon2) {
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const R = 6371; // earth radius in kilometers
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// distance between latitudes and longitudes
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final dLat = _degreesToRadians(lat2 - lat1);
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final dLon = _degreesToRadians(lon2 - lon1);
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final a = sin(dLat / 2) * sin(dLat / 2) +
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cos(_degreesToRadians(lat1)) * cos(_degreesToRadians(lat2)) *
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sin(dLon / 2) * sin(dLon / 2);
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final c = 2 * atan2(sqrt(a), sqrt(1 - a));
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return R * c;
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}
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double _degreesToRadians(double degrees) {
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return degrees * pi / 180;
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}
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