Display KML

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Display KML from a URL, portal item, or local KML file.

screenshot

Use case

Keyhole Markup Language (KML) is a data format used by Google Earth. KML is popular as a transmission format for consumer use and for sharing geographic data between apps. You can use Runtime to display KML files, with full support for a variety of features, including network links, 3D models, screen overlays, and tours.

How to use the sample

Use the drop-down menu to select a source. A KML file from that source will be loaded and displayed in the map.

How it works

  1. To create a KML layer from a URL, create a KmlDataset using the URL to the KML file. Then pass the dataset to the KmlLayer constructor.
  2. To create a KML layer from a portal item, construct a PortalItem with a Portal and the KML portal item ID. Pass the portal item to the KmlLayer constructor.
  3. To create a KML layer from a local file, create a KmlDataset using the absolute file path to the local KML file. Then pass the dataset to the KmlLayer constructor.
  4. Add the layer as an operational layer to the map with map::operationalLayers()::append(kmlLayer).

Relevant API

  • KmlDataset
  • KmlLayer

Offline data

To set up the sample's offline data, see the Use offline data in the samples section of the Qt Samples repository overview.

Link Local Location
US State Capitals <userhome>/ArcGIS/Runtime/Data/kml/US_State_Capitals.kml

About the data

This sample displays three different KML files:

  • From URL - this is a map of the significant weather outlook produced by NOAA/NWS. It uses KML network links to always show the latest data.
  • From local file - this is a map of U.S. state capitals. It doesn't define an icon, so the default pushpin is used for the points.
  • From portal item - this is a map of U.S. states.

Tags

keyhole, KML, KMZ, OGC

Sample Code

DisplayKml.cppDisplayKml.cppDisplayKml.hDisplayKml.qml
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// [WriteFile Name=DisplayKml, Category=Layers]
// [Legal]
// Copyright 2018 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

#include "DisplayKml.h"

#include "ArcGISTiledElevationSource.h"
#include "Scene.h"
#include "SceneQuickView.h"
#include "Viewpoint.h"
#include "Camera.h"
#include "SpatialReference.h"
#include "KmlLayer.h"
#include "KmlDataset.h"
#include "PortalItem.h"

#include <QDir>
#include <QtCore/qglobal.h>

#ifdef Q_OS_IOS
#include <QStandardPaths>
#endif // Q_OS_IOS

using namespace Esri::ArcGISRuntime;

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

  #ifdef Q_OS_ANDROID
    dataPath = "/sdcard";
  #elif defined Q_OS_IOS
    dataPath = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
  #else
    dataPath = QDir::homePath();
  #endif

    return dataPath;
  }
} // namespace

DisplayKml::DisplayKml(QQuickItem* parent /* = nullptr */):
  QQuickItem(parent)
{
}

DisplayKml::~DisplayKml() = default;

void DisplayKml::init()
{
  // Register classes for QML
  qmlRegisterType<SceneQuickView>("Esri.Samples", 1, 0, "SceneView");
  qmlRegisterType<DisplayKml>("Esri.Samples", 1, 0, "DisplayKmlSample");
}

void DisplayKml::componentComplete()
{
  QQuickItem::componentComplete();

  // Create a scene and give it to the SceneView
  m_sceneView = findChild<SceneQuickView*>("sceneView");
  m_scene = new Scene(BasemapStyle::ArcGISImagery, this);
  Surface* surface = new Surface(this);
  surface->elevationSources()->append(
        new ArcGISTiledElevationSource(
          QUrl("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"),
          this));
  m_scene->setBaseSurface(surface);
  m_sceneView->setArcGISScene(m_scene);

  // Create a viewpoint
  const Point pt(-98, 39, SpatialReference::wgs84());
  constexpr int scale = 10000000;
  const Camera camera(pt, scale, 0, 0, 0);
  m_viewpoint = Viewpoint(pt, scale, camera);
}

void DisplayKml::createFromUrl()
{
  clearLayers();

  // Create the Dataset from an Online URL
  m_kmlDataset = new KmlDataset(QUrl("https://www.wpc.ncep.noaa.gov/kml/noaa_chart/WPC_Day1_SigWx.kml"), this);

  // Create the Layer
  m_kmlLayer = new KmlLayer(m_kmlDataset, this);

  // Add the layer to the scene
  addLayerToScene(m_kmlLayer);
}

void DisplayKml::createFromFile()
{
  clearLayers();

  // Create the Dataset from a local file
  const QString dataPath = defaultDataPath() + "/ArcGIS/Runtime/Data/kml/";
  m_kmlDataset = new KmlDataset(QUrl(dataPath + "US_State_Capitals.kml"), this);

  // Create the Layer
  m_kmlLayer = new KmlLayer(m_kmlDataset, this);

  // Add the layer to the scene
  addLayerToScene(m_kmlLayer);
}

void DisplayKml::createFromPortalItem()
{
  clearLayers();

  // Create the PortalItem
  m_portalItem = new PortalItem(QStringLiteral("9fe0b1bfdcd64c83bd77ea0452c76253"), this);

  // Create the Layer
  m_kmlLayer = new KmlLayer(m_portalItem, this);

  // Add the layer to the scene
  addLayerToScene(m_kmlLayer);
}

void DisplayKml::addLayerToScene(KmlLayer* layer)
{
  if (!m_scene)
    return;

  m_scene->operationalLayers()->append(layer);

  if (m_viewpoint.isEmpty())
    return;

  m_sceneView->setViewpoint(m_viewpoint);
}

void DisplayKml::clearLayers()
{
  if (!m_scene)
    return;

  // remove the layers
  m_scene->operationalLayers()->clear();

  // clean up the kml datasets
  if (m_kmlDataset)
  {
    delete m_kmlDataset;
    m_kmlDataset = nullptr;
  }

  // clean up the portal items
  if (m_portalItem)
  {
    delete m_portalItem;
    m_portalItem = nullptr;
  }

  // clean up the kml layers
  if (m_kmlLayer)
  {
    delete m_kmlLayer;
    m_kmlLayer = nullptr;
  }
}

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