Create KML Multi Track

View on GitHub

Sample viewer app

Create, save and preview a KML multi-track, captured from a location data source.

screenshot

Use case

When capturing location data for outdoor activities such as hiking or skiing, it can be useful to record and share your path. This sample demonstrates how you can collect individual KML tracks during a navigation session, then combine and export them as a KML multi-track.

How to use the sample

Start the KML multi track sample application to begin moving along a simulated trail. Tap Record Track(s) to start recording your current path. Tap Stop Recording to end recording and capture a KML track. Repeat these steps to capture multiple KML tracks in a single session. Tap the Save button to save your recorded tracks as a .kmz file to local storage. Then load the created .kmz file containing your KML multi-track to view all created tracks on the map. Tap the Recenter icon to position the location at the center of the map view.

How it works

Create a Map with a basemap and a GraphicsOverlay to display the path geometry for your navigation route.
Create a SimulatedLocationDataSource to drive the LocationDisplay.
As you receive Location updates, add each point to a list of KmlTrackElement objects while recording.
Once recording stops, create a KmlTrack using one or more KmlTrackElement objects.
Combine one or more KmlTrack objects into a KmlMultiTrack.
Save the KmlMultiTrack inside a KmlDocument, then export the document to a .kmz file.
Load the saved .kmz file into a KmlDataset and locate the KmlDocument in the dataset's rootNodes. From the document's childNodes get the KmlPlacemark and retrieve the KmlMultiTrack geometry.
Retrieve the geometry of each track in the KmlMultiTrack by iterating through the list of tracks and obtaining the respective KmlTrack.geometry.

Relevant API

KmlDataset
KmlDocument
KmlMultiTrack
KmlPlacemark
KmlTrack
LocationDisplay
SimulatedLocationDataSource

Sample Code

CreateKmlMultiTrack.cpp

CreateKmlMultiTrack.h

CreateKmlMultiTrack.qml

Use dark colors for code blocksCopy
// [WriteFile Name=CreateKmlMultiTrack, Category=EditData]]
// [Legal]
// Copyright 2025 Esri.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// [Legal]

#ifdef PCH_BUILD
#include "pch.hpp"
#endif // PCH_BUILD

// sample headers
#include "CreateKmlMultiTrack.h"

// ArcGIS Maps SDK headers
#include "Basemap.h"
#include "Error.h"
#include "ErrorException.h"
#include "Geometry.h"
#include "GeometryEngine.h"
#include "Graphic.h"
#include "GraphicListModel.h"
#include "GraphicsOverlay.h"
#include "GraphicsOverlayListModel.h"
#include "KmlDataset.h"
#include "KmlDocument.h"
#include "KmlMultiTrack.h"
#include "KmlNodeListModel.h"
#include "KmlPlacemark.h"
#include "KmlTrack.h"
#include "KmlTrackElement.h"
#include "Location.h"
#include "LocationDisplay.h"
#include "Map.h"
#include "MapQuickView.h"
#include "MapTypes.h"
#include "MapViewTypes.h"
#include "Point.h"
#include "Polyline.h"
#include "PolylineBuilder.h"
#include "SimpleLineSymbol.h"
#include "SimpleMarkerSymbol.h"
#include "SimulatedLocationDataSource.h"
#include "SimulationParameters.h"
#include "SpatialReference.h"
#include "SymbolTypes.h"

// Qt headers
#include <QFile>
#include <QFileInfo>
#include <QFuture>
#include <QStandardPaths>
#include <QList>
#include <QUrl>

using namespace Esri::ArcGISRuntime;

// helper method to get cross platform data path
namespace
{
  QString defaultDataPath()
  {
    QString dataPath;

#ifdef Q_OS_IOS
    dataPath = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
#else
    dataPath = QStandardPaths::writableLocation(QStandardPaths::HomeLocation);
#endif

    return dataPath;
  }

  QString coastalTrailJson()
  {
    QFile jsonFile(":/Samples/EditData/CreateKmlMultiTrack/coastalTrail.json");
    if (!jsonFile.open(QIODevice::ReadOnly | QIODevice::Text))
    {
      qDebug() << "Failed to open JSON file";
      return {};
    }
    return jsonFile.readAll();
  }
} // namespace


CreateKmlMultiTrack::CreateKmlMultiTrack(QObject* parent /* = nullptr */):
  QObject(parent),
  m_map(new Map(BasemapStyle::ArcGISStreets, this)),
  m_graphicsOverlay(new GraphicsOverlay(this)),
  m_locationSymbol(new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Circle, Qt::red, 10, this)),
  m_lineSymbol(new SimpleLineSymbol(SimpleLineSymbolStyle::Solid, Qt::black, 3, this))
{
}

CreateKmlMultiTrack::~CreateKmlMultiTrack() = default;

void CreateKmlMultiTrack::init()
{
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<CreateKmlMultiTrack>("Esri.Samples", 1, 0, "CreateKmlMultiTrackSample");
}

MapQuickView* CreateKmlMultiTrack::mapView() const
{
  return m_mapView;
}

// Set the view (created in QML)
void CreateKmlMultiTrack::setMapView(MapQuickView* mapView)
{
  if (m_mapView)
  {
    m_mapView->setMap(nullptr); // Remove map from old mapView.
    m_mapView->graphicsOverlays()->clear(); // Remove Graphics overlays from old mapView.
  }

  m_mapView = mapView;

  if (!m_mapView)
  {
    return;
  }

  m_mapView->graphicsOverlays()->append(m_graphicsOverlay);
  m_mapView->setMap(m_map);
  emit mapViewChanged();

  // Automatically enable recenter button when navigation pan is disabled
  connect(m_mapView->locationDisplay(), &LocationDisplay::autoPanModeChanged, this, [this](LocationDisplayAutoPanMode autoPanMode)
  {
    m_isRecenterButtonEnabled = (autoPanMode == LocationDisplayAutoPanMode::Off);
    emit isRecenterButtonEnabledChanged();
  });

  // Listen for changes in location
  connect(m_mapView->locationDisplay(), &LocationDisplay::locationChanged, this, [this](const Location& location)
  {
    if (m_isRecordingTrack)
    {
      addTrackElement(location.position());
      m_polylineBuilder->addPoint(location.position());
    }
  });

  // turn on map view's navigation mode
  m_mapView->locationDisplay()->setAutoPanMode(LocationDisplayAutoPanMode::Navigation);
}

void CreateKmlMultiTrack::startNavigation()
{
  // Get the hiking path geometry
  auto routeGeometry = geometry_cast<Polyline>(Geometry::fromJson(coastalTrailJson()));
  constexpr double velocity = 25.0;
  constexpr double horizontalAccuracy = 0.0;
  constexpr double verticalAccuracy = 0.0;
  constexpr double paddingInDips = 25.0;

  // Create a simulated location data source from json data with simulation parameters to set a consistent velocity
  auto* simulationParameters = new SimulationParameters(QDateTime::currentDateTime(), velocity, horizontalAccuracy, verticalAccuracy, this);
  m_simulatedLocationDataSource = new SimulatedLocationDataSource(this);
  m_simulatedLocationDataSource->setLocationsWithPolyline(routeGeometry, simulationParameters);

  // Set the map's initial viewpoint
  m_mapView->setViewpointGeometryAsync(routeGeometry, paddingInDips);

  // Set the simulated location data source as the location data source for this app
  m_mapView->locationDisplay()->setDataSource(m_simulatedLocationDataSource);

  // Start the location data source
  m_simulatedLocationDataSource->start();
}

void CreateKmlMultiTrack::addTrackElement(const Point& locationPoint)
{
  // Add a new element to the list of KML track elements
  auto* trackElement = new KmlTrackElement(QDateTime::currentDateTime(), locationPoint, nullptr, this);
  m_kmlTrackElements.append(trackElement);
  emit elementsCountChanged();

  // Add a graphic at the location's position
  auto* graphic = new Graphic(locationPoint, m_locationSymbol, this);
  m_graphicsOverlay->graphics()->append(graphic);
}

void CreateKmlMultiTrack::startRecordingKmlTrack()
{
  m_isRecordingTrack = true;
  emit isRecordingTrackChanged();

  m_kmlTrackElements.clear();
  emit elementsCountChanged();

  m_polylineBuilder = new PolylineBuilder(SpatialReference::wgs84(), this);
}

void CreateKmlMultiTrack::stopRecordingKmlTrack()
{
  if (m_kmlTrackElements.isEmpty())
  {
    return;
  }

  m_polylineBuilderList.append(m_polylineBuilder);

  const KmlTrack kmlTrack(m_kmlTrackElements, KmlAltitudeMode::RelativeToGround);
  m_kmlTracks.append(kmlTrack);
  emit multiTrackCountChanged();

  displayKmlTracks();
  m_isRecordingTrack = false;
  emit isRecordingTrackChanged();
}

void CreateKmlMultiTrack::displayKmlTracks()
{
  m_graphicsOverlay->graphics()->clear();
  for (const auto* polyLineBuilder : m_polylineBuilderList)
  {
    // Add the polyline graphic to the map
    auto* graphic = new Graphic(polyLineBuilder->toPolyline(), m_lineSymbol, this);
    m_graphicsOverlay->graphics()->append(graphic);
  }
}

// Exports the [KmlMultiTrack] as a kmz file to local storage.
void CreateKmlMultiTrack::exportKmlMultiTrack()
{
  // Create a KML document
  auto* kmlDocument = new KmlDocument(this);

  // Create a KML multi-track
  const KmlMultiTrack multiTrack(m_kmlTracks, false);

  // Add the multi-track as a placemark
  auto* placemark = new KmlPlacemark(multiTrack, this);
  kmlDocument->childNodesListModel()->insert(0, placemark);

  // Define the save file path
  const auto localKmlFilePath = defaultDataPath() + "/ArcGIS/Runtime/Data/kml/HikingTracks.kmz";
  QFile localKmlFile(localKmlFilePath);
  if (localKmlFile.exists())
  {
    localKmlFile.remove();
  }
  // Save KML file to local storage
  // Write the KML document to the chosen path.
  kmlDocument->saveAsAsync(localKmlFilePath).then(this, [localKmlFilePath, this]()
  {
    qDebug() << "Saved KmlMultiTrack: " + QFileInfo(localKmlFilePath).filePath();
    stopNavigation();
  }).onFailed([](const ErrorException&)
  {
    qDebug() << "Error saving KML file";
  });
}

void CreateKmlMultiTrack::stopNavigation()
{
  if (m_simulatedLocationDataSource)
  {
    m_simulatedLocationDataSource->stop();
  }
  m_isShowTracksFromFileEnabled = true;
  emit isShowTracksFromFileEnabledChanged();
}

void CreateKmlMultiTrack::loadLocalKmlFile()
{
  const auto localKmlFilePath = defaultDataPath() + "/ArcGIS/Runtime/Data/kml/HikingTracks.kmz";
  const QFile localKmlFile(localKmlFilePath);
  if (!localKmlFile.exists())
  {
    qDebug() << "Error locating KML file";
    return;
  }

  auto* localKmlDataset = new KmlDataset(QUrl::fromLocalFile(localKmlFilePath), this);
  connect(localKmlDataset, &KmlDataset::doneLoading, this, [this, localKmlDataset]()
  {
    if (localKmlDataset->loadStatus() != LoadStatus::Loaded)
    {
      qDebug() << "Error parsing KML file " +  localKmlDataset->loadError().message();
      return;
    }

    const auto* kmlDocument = dynamic_cast<KmlDocument*>(localKmlDataset->rootNodes().at(0));
    if (!kmlDocument)
    {
      qDebug() << "Error: Root node is not a KmlDocument.";
      return;
    }

    const auto* kmlPlacemark = dynamic_cast<KmlPlacemark*>(kmlDocument->childNodesListModel()->at(0));
    if (!kmlPlacemark)
    {
      qDebug() << "Error: First child node is not a KmlPlacemark.";
      return;
    }

    const auto kmlMultiTrack = static_cast<KmlMultiTrack>(kmlPlacemark->kmlGeometry());

    QList<Geometry> geometries;
    for (const auto& track : kmlMultiTrack.tracks())
    {
      geometries.append(track.geometry());
    }
    const auto allTracksGeometry = GeometryEngine::unionOf(geometries);
    if (allTracksGeometry.isEmpty())
    {
      qDebug() << "KmlMultiTrack has no geometry";
      return;
    }

    m_mapView->setViewpointGeometryAsync(allTracksGeometry, 25.0);

    m_trackGeometries.append(allTracksGeometry);
    for (const auto& track : kmlMultiTrack.tracks())
    {
      m_trackGeometries.append(track.geometry());
    }
    emit trackGeometriesCountChanged();
  });

  localKmlDataset->load();
}

void CreateKmlMultiTrack::previewKmlTrack(int index)
{
  m_mapView->setViewpointGeometryAsync(m_trackGeometries[index], 25.0);
}

void CreateKmlMultiTrack::recenter()
{
  m_mapView->locationDisplay()->setAutoPanMode(LocationDisplayAutoPanMode::Navigation);
  m_isRecenterButtonEnabled = false;
  emit isRecenterButtonEnabledChanged();
}

void CreateKmlMultiTrack::reset()
{
  qDeleteAll(m_kmlTrackElements);
  m_kmlTrackElements.clear();
  m_kmlTracks.clear();
  qDeleteAll(m_polylineBuilderList);
  m_polylineBuilderList.clear();
  m_trackGeometries.clear();
  m_graphicsOverlay->graphics()->clear();
  m_isShowTracksFromFileEnabled = false;
  emit isShowTracksFromFileEnabledChanged();
}

int CreateKmlMultiTrack::elementsCount() const
{
  return m_kmlTrackElements.count();
}

int CreateKmlMultiTrack::multiTrackCount() const
{
  return m_kmlTracks.count();
}

int CreateKmlMultiTrack::trackGeometriesCount() const
{
  return m_trackGeometries.count();
}