KMLHelper.cc

/****************************************************************************
 *
 * (c) 2009-2020 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
 *
 * QGroundControl is licensed according to the terms in the file
 * COPYING.md in the root of the source code directory.
 *
 ****************************************************************************/

#include "KMLHelper.h"

#include <QFile>
#include <QVariant>

const char* KMLHelper::_errorPrefix = QT_TR_NOOP("KML file load failed. %1");

QDomDocument KMLHelper::_loadFile(const QString& kmlFile, QString& errorString)
{
    QFile file(kmlFile);

    errorString.clear();

    if (!file.exists()) {
        errorString = QString(_errorPrefix).arg(tr("File not found: %1").arg(kmlFile));
        return QDomDocument();
    }

    if (!file.open(QIODevice::ReadOnly)) {
        errorString = QString(_errorPrefix).arg(tr("Unable to open file: %1 error: $%2").arg(kmlFile).arg(file.errorString()));
        return QDomDocument();
    }

    QDomDocument doc;
    QString errorMessage;
    int errorLine;
    if (!doc.setContent(&file, &errorMessage, &errorLine)) {
        errorString = QString(_errorPrefix).arg(tr("Unable to parse KML file: %1 error: %2 line: %3").arg(kmlFile).arg(errorMessage).arg(errorLine));
        return QDomDocument();
    }

    return doc;
}

ShapeFileHelper::ShapeType KMLHelper::determineShapeType(const QString& kmlFile, QString& errorString)
{
    QDomDocument domDocument = KMLHelper::_loadFile(kmlFile, errorString);
    if (!errorString.isEmpty()) {
        return ShapeFileHelper::Error;
    }

    QDomNodeList rgNodes = domDocument.elementsByTagName("Polygon");
    if (rgNodes.count()) {
        return ShapeFileHelper::Polygon;
    }

    rgNodes = domDocument.elementsByTagName("LineString");
    if (rgNodes.count()) {
        return ShapeFileHelper::Polyline;
    }

    errorString = QString(_errorPrefix).arg(tr("No supported type found in KML file."));
    return ShapeFileHelper::Error;
}

bool KMLHelper::loadPolygonFromFile(const QString& kmlFile, QList<QGeoCoordinate>& vertices, QString& errorString)
{
    errorString.clear();
    vertices.clear();

    QDomDocument domDocument = KMLHelper::_loadFile(kmlFile, errorString);
    if (!errorString.isEmpty()) {
        return false;
    }

    QDomNodeList rgNodes = domDocument.elementsByTagName("Polygon");
    if (rgNodes.count() == 0) {
        errorString = QString(_errorPrefix).arg(tr("Unable to find Polygon node in KML"));
        return false;
    }

    QDomNode coordinatesNode = rgNodes.item(0).namedItem("outerBoundaryIs").namedItem("LinearRing").namedItem("coordinates");
    if (coordinatesNode.isNull()) {
        errorString = QString(_errorPrefix).arg(tr("Internal error: Unable to find coordinates node in KML"));
        return false;
    }

    QString coordinatesString = coordinatesNode.toElement().text().simplified();
    QStringList rgCoordinateStrings = coordinatesString.split(" ");

    QList<QGeoCoordinate> rgCoords;
    for (int i=0; i<rgCoordinateStrings.count()-1; i++) {
        QString coordinateString = rgCoordinateStrings[i];

        QStringList rgValueStrings = coordinateString.split(",");

        QGeoCoordinate coord;
        coord.setLongitude(rgValueStrings[0].toDouble());
        coord.setLatitude(rgValueStrings[1].toDouble());

        rgCoords.append(coord);
    }

    // Determine winding, reverse if needed. QGC wants clockwise winding
    double sum = 0;
    for (int i=0; i<rgCoords.count(); i++) {
        QGeoCoordinate coord1 = rgCoords[i];
        QGeoCoordinate coord2 = (i == rgCoords.count() - 1) ? rgCoords[0] : rgCoords[i+1];

        sum += (coord2.longitude() - coord1.longitude()) * (coord2.latitude() + coord1.latitude());
    }
    bool reverse = sum < 0.0;
    if (reverse) {
        QList<QGeoCoordinate> rgReversed;

        for (int i=0; i<rgCoords.count(); i++) {
            rgReversed.prepend(rgCoords[i]);
        }
        rgCoords = rgReversed;
    }

    vertices = rgCoords;

    return true;
}

bool KMLHelper::loadPolylineFromFile(const QString& kmlFile, QList<QGeoCoordinate>& coords, QString& errorString)
{
    errorString.clear();
    coords.clear();

    QDomDocument domDocument = KMLHelper::_loadFile(kmlFile, errorString);
    if (!errorString.isEmpty()) {
        return false;
    }

    QDomNodeList rgNodes = domDocument.elementsByTagName("LineString");
    if (rgNodes.count() == 0) {
        errorString = QString(_errorPrefix).arg(tr("Unable to find LineString node in KML"));
        return false;
    }

    QDomNode coordinatesNode = rgNodes.item(0).namedItem("coordinates");
    if (coordinatesNode.isNull()) {
        errorString = QString(_errorPrefix).arg(tr("Internal error: Unable to find coordinates node in KML"));
        return false;
    }

    QString coordinatesString = coordinatesNode.toElement().text().simplified();
    QStringList rgCoordinateStrings = coordinatesString.split(" ");

    QList<QGeoCoordinate> rgCoords;
    for (int i=0; i<rgCoordinateStrings.count()-1; i++) {
        QString coordinateString = rgCoordinateStrings[i];

        QStringList rgValueStrings = coordinateString.split(",");

        QGeoCoordinate coord;
        coord.setLongitude(rgValueStrings[0].toDouble());
        coord.setLatitude(rgValueStrings[1].toDouble());

        rgCoords.append(coord);
    }

    coords = rgCoords;

    return true;
}