google_polyline_algorithm

Package Overview

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A Dart implementation of Google's Polyline Encoding algorithm, used to compress latitude and longitude coordinates into a compact string format. This lossy compression reduces data size for map paths, making it ideal for efficient transmission and storage in geolocation applications. The package supports all major platforms including Android, iOS, Web, macOS, Windows, and Linux. It enables developers to encode and decode polylines with minimal overhead, maintaining sufficient accuracy for most mapping use cases.

Use cases

Map route visualization
Efficient GPS data transmission
Compact storage of geographic paths
Real-time location tracking
Geospatial data sharing
Offline map data

Key features

Lossy coordinate compression
Cross-platform support
Simple encoding/decoding API
High performance
Accurate for typical map distances
Lightweight dependency

Suitable for

Mobile and web mapping apps
Location-based services
Route planning tools
Data-efficient geospatial APIs
Applications handling large GPS datasets

Considerations

Loss of precision due to compression
Not suitable for high-accuracy scientific measurements
Requires careful handling of edge cases in extreme latitudes
Limited to polyline-only geometry
May need validation for critical navigation systems

Original README

Original README snapshot from the linked source repository. Visit the repository for the latest content.

Build GitHub

Dart implementation of Googles Polyline Encoding lossy compression Algorithm.

Getting Started

This package adds following methods to work with Googles Polyline Encoding Algorithm:

encodePoint(num current, {num previous = 0, int accuracyExponent = 5}) encodes a single coordinate
encodePolyline(List<List<num>> coordinates, {int accuracyExponent = 5}) encodes a list of coordinates into an encoded polyline stirng
decodePolyline(String polyline, {int accuracyExponent = 5}) decodes an encoded polyline string into a list of coordinates

Examples

import 'package:google_polyline_algorithm/google_polyline_algorithm.dart';

final coord = encodePoint(-179.9832104);
print(coord);
// output is `~oia@'

final coords = encodePolyline([
  [38.5, -120.2],
  [40.7, -120.95],
  [43.252, -126.453],
]);
print(coords);
// output is `_p~iF~ps|U_ulLnnqC_mqNvxq`@'

final polyline = decodePolyline('_p~iF~ps|U_ulLnnqC_mqNvxq`@');
print(polyline);
// output is [[38.5, -120.2],[40.7, -120.95],[43.252, -126.453],]

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