/**
* Read a single section (route or track) of a GPX file and add it to the total route
* The sections are merged into one, with a straight line between the end of one and the start of the next.
*
* @param DOMElement $route Route or track root element
*/
private function readGPXSection(DOMElement $route)
{
if ($route->tagName == "trk") {
$routePoints = $route->getElementsByTagName("trkpt");
} else {
$routePoints = $route->getElementsByTagName("rtept");
}
/* Now we start to iterate through all the waypoints.
* For each point, we want the distance from the last point (added to cumulative
* distance) and the height *increase* since the last point.
* We assume that the points are close enough together that we can treat the surface
* of the Earth as a plane and use Pythagoras' theorem to calculate distances.
* To start with, we make the start point the previous point.
*/
$numPoints = $routePoints->length;
$lastKnownHeight = null;
// Last known height - used if some nodes are missing height data
$prevPoint = null;
$iWrite = count($this->wayPoints);
for ($iRead = 0; $iRead < $numPoints; $iRead++) {
// Get the position of this waypoint
$next = $routePoints->item($iRead);
$nextPoint = new Waypoint();
$nextPoint->latLng = new LatLng($next->attributes->getNamedItem("lat")->nodeValue, $next->attributes->getNamedItem("lon")->nodeValue);
// Now see if we can get the time, speed & altitude
if ($next->hasChildNodes()) {
foreach ($next->childNodes as $childNode) {
if ($childNode->nodeType == XML_ELEMENT_NODE) {
switch ($childNode->tagName) {
case "ele":
$nextPoint->alt = (int) $childNode->nodeValue;
break;
case "time":
$nextPoint->time = $childNode->nodeValue;
break;
}
}
}
}
$this->wayPoints[$iWrite] = $nextPoint;
// If we're on anything but the first waypoint, get the previous one for some calculations
if ($iWrite >= 1) {
$prevPoint = $this->wayPoints[$iWrite - 1];
// Calculate distance & total ascent
$this->distance += $nextPoint->distanceTo($prevPoint);
if (isset($nextPoint->alt) && isset($lastKnownHeight)) {
$this->ascent += max($nextPoint->alt - $lastKnownHeight, 0);
}
}
// Store the height for future rounds - if another waypoint is missing height info
// we look back to the last time we had it
if (isset($nextPoint->alt)) {
$lastKnownHeight = $nextPoint->alt;
}
$iWrite++;
}
}
