Parse Google Earth Route KML

parse-google-earth-route.php

<?php

class XMLElement extends \SimpleXMLElement
{
  public function get($attr, $default = null)
  {
    if (empty($this->{$attr})) {
      return $default;
    }
    return $this->{$attr};
  }
}

class InvalidRouteException extends \Exception
{
  public function __construct($message, $code = 0, Exception $previous = null) {
    parent::__construct($message, $code, $previous);
  }
}

function getCoordinates(XMLElement $route): string
{
  // $route->Document->Placemark->LineString->coordinates
  
  if(!$document = $route->get('Document')) {
    throw new InvalidRouteException("Missing route->Document.");
  }

  if(!$placemark = $document->get('Placemark')) {
    throw new InvalidRouteException("Missing route->Document->Placemark.");
  }

  if(!$lineString = $placemark->get('LineString')) {
    throw new InvalidRouteException("Missing route->Document->Placemark->LineString.");
  }

  if(!$coordinates = $lineString->get('coordinates')) {
    throw new InvalidRouteException("Missing route->Document->Placemark->LineString->coordinates.");
  }

  return $coordinates;
}

$route_kml = <<<XML
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" 
  xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">
<Document>
  <name>Mombasa-Mbale.kml</name>
  <StyleMap id="dir_route">
    <Pair>
      <key>normal</key>
      <styleUrl>#dir_route1</styleUrl>
    </Pair>
    <Pair>
      <key>highlight</key>
      <styleUrl>#dir_route0</styleUrl>
    </Pair>
  </StyleMap>
  <Style id="dir_route0">
    <LineStyle>
      <color>7fa00000</color>
      <width>6</width>
    </LineStyle>
  </Style>
  <Style id="dir_route1">
    <LineStyle>
      <color>7fa00000</color>
      <width>6</width>
    </LineStyle>
  </Style>
  <Placemark id="1.3.2">
    <name>Mombasa-Mbale</name>
    <styleUrl>#dir_route</styleUrl>
    <LineString>
      <coordinates>
        39.6326861,-4.0406225,0 39.6326861,-4.0406225,0 39.6325268,-4.0402901,0 39.6324947,-4.0402233,0 
        39.6324592,-4.040204,0 39.6324346,-4.0401842,0 39.6324228,-4.0401734,0 39.6324031,-4.040149,0
      </coordinates>
    </LineString>
  </Placemark>
</Document>
</kml>
XML;

$route = simplexml_load_string($route_kml, XMLElement::class);

$coordinates = getCoordinates($route);

// Clean up
$coordinates = preg_replace('/\s+/S', '|', trim($coordinates));

// toArray
$coordinates = explode('|', $coordinates);

print json_encode($coordinates);