A C++ header-only Polyline Encoder/Decoder

C++ implementation of Google Encoded Polyline Algorithm Format.
The implementation guarantees to conform with the results of the Google Interactive Polyline Encoder Utility.

Installation

As Polylineencoder is a single header library no installation required. Just include polylineencoder.h in your project and instantiate gepaf::PolylineEncoder class template.

Prerequisites

No special requirements except C++11 compliant compiler. The class is tested with gcc 4.8.4 and MSVC 12.0 (Visual Studio 2013). In order to build and run unit tests for this project you are required to have Google Test library installed on the system. For more details see the CI badges (Travis CI & AppVeyor CI).

Usage Example:

All code is in gepaf namespace. gepaf stands for Google Encoded Polyline Algorithm Format.

#include <polylineencoder.h>

// Create an encoder with precision of 5 decimal places (default)
// In order to create objects with other precision use template parameter
// like: gepaf::PolylineEncoder<6>
gepaf::PolylineEncoder<> encoder;

// Poles and equator.
encoder.addPoint(-90.0, -180.0);
encoder.addPoint(.0, .0);
encoder.addPoint(90.0, 180.0);

auto res = encoder.encode(); // "~bidP~fsia@_cidP_gsia@_cidP_gsia@"
encoder.clear(); // Clear the list of points.

// Decode a string using static function.
auto polyline = gepaf::PolylineEncoder<>::decode("~bidP~fsia@_cidP_gsia@_cidP_gsia@");

// Iterate over all points and print coordinates of each.
for (const auto &point : polyline) {
    printf("(%f, %f)\n", point.latitude(), point.longitude());
}

Building and Testing

There are unit tests provided for PolylineEncoder class template. You can find them in the test/ directory. To run them you have to build and run the test application (linking with Google Test library is required). For doing that you can invoke the following commands from the terminal, assuming that compiler and environment are already configured:

Linux (gcc)

cd test
g++ -std=c++11 -I..\src main.cpp -o test
./test

or with CMake

cd test
cmake ..
make
./poly_test

Windows

cd test
cl /W4 /EHsc /I..\src main.cpp /link /out:test.exe
test

or with CMake

cd test
cmake .. -G "NMake Makefiles"
nmake
poly_test

See Also

• Encoded Polyline Algorithm