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@burritojustice
Last active January 12, 2017 21:54
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polyline decoder
license: mit
<!DOCTYPE html>
<head>
<meta charset="utf-8">
<script src="https://d3js.org/d3.v4.min.js"></script>
<style>
body { margin:0;position:fixed;top:0;right:0;bottom:0;left:0; }
</style>
</head>
<body>
<script>
// This is adapted from the implementation in Project-OSRM
// https://github.com/DennisOSRM/Project-OSRM-Web/blob/master/WebContent/routing/OSRM.RoutingGeometry.js
function polyline_decode(str, precision) {
var index = 0,
lat = 0,
lng = 0,
coordinates = [],
shift = 0,
result = 0,
byte = null,
latitude_change,
longitude_change,
factor = Math.pow(10, precision || 6);
// Coordinates have variable length when encoded, so just keep
// track of whether we've hit the end of the string. In each
// loop iteration, a single coordinate is decoded.
while (index < str.length) {
// Reset shift, result, and byte
byte = null;
shift = 0;
result = 0;
do {
byte = str.charCodeAt(index++) - 63;
result |= (byte & 0x1f) << shift;
shift += 5;
} while (byte >= 0x20);
latitude_change = ((result & 1) ? ~(result >> 1) : (result >> 1));
shift = result = 0;
do {
byte = str.charCodeAt(index++) - 63;
result |= (byte & 0x1f) << shift;
shift += 5;
} while (byte >= 0x20);
longitude_change = ((result & 1) ? ~(result >> 1) : (result >> 1));
lat += latitude_change;
lng += longitude_change;
coordinates.push([lat / factor, lng / factor]);
}
var points = JSON.stringify(coordinates);
console.log(points);
return coordinates;
};
var input = 'g~iagArdumhFbF`HrVq\\tYm_@jBhClO~RvX~^`\\tc@dEbGlAzAhVp\\jBfCj`@~h@jAxAnDdF`GnIfJhM~HzK`CdDre@so@tJiMtIiLvNqRtZya@bKgN~IkLl@{@vW_^jG]dELvDl@zE|@tExA|ExBzEfDzFfErFbFpGpG`H`HzG~HhWb\\|DbFvHlJze@nh@|JvN|JtOdJtOnIvNfItOdcAzqBrFlKbGlJpGlJhH~HvH~HxHrGfIpGdJrFlJtElJvDdKdDzJzBlKhBzJz@tK^bKLdKMjK_@jKk@dKmAvIkAtI{AhSsF`MuD|IwDtYwMhHwChHyCrFiB~HiCxHyBlIiBtKyBlJ{AtJkAfIm@zK}@baDuNbe@mA~qAaGtJO~HOrKNbK\\dK|@tJz@|JjBzJxBfJfClJfD|IvD~ItEtIdE`]`RhHfDfIvDnHfC`IxBfIzA~HjA~H|@fI\\nI?nI]nIm@dJkA|IkBnJwCfIwCtIuE~HuEhIqGfIqH`HoH~GoJrG}IhGmJvN}TdF_I`GoIjFqGzFsGzFcFbGeFxGsE`HwDvIwDfIwCfIyB|I{AlJkAdK{@bKm@tJ]rbC{K~N_@tO]tNOxb@pHxGjApGzAzKvCzV~HflA~^~Bj@`ClAxBxAtEfDfDvDhCtExBbF`BdFrApGjAbGtEvX~I`{@bA~HrApHzApGjFfX|Jhb@jAbGbBfN\\`GLnIFxW\\ry@^vXF~]TxWNj`@?jAT|_@Vj`@d@`f@D|T?rFFtEt@h`A?fDFxC\\hu@bAlgB^pg@zEfCfqAlt@ld@hWnc@jVrAz@||Ap{@xBz_AFxBkB}@'
polyline_decode(input);
</script>
</body>
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