Display KML network links

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C++

QML

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Sample viewer app

Display a file with a KML network link, including displaying any network link control messages at launch.

screenshot

Use case

KML files can reference other KML files on the network and support automatically refreshing content. For example, survey workers will benefit from KML data shown on their devices automatically refreshing to show the most up-to-date state. Additionally, discovering KML files linked to the data they are currently viewing provides additional information to make better decisions in the field.

How to use the sample

The sample will load the KML file automatically. The data shown should refresh automatically every few seconds. Pan and zoom to explore the map.

The message button will show the last message received from the KML network resource.

How it works

Create a KmlDataset from a KML source which has network links.
Construct a KmlLayer with the dataset and add the layer as an operational layer.
To listen for network messages by connecting to the signal, KmlDataset::kmlNetworkLinkMessageReceived.

Relevant API

KmlDataset(Url)
KmlLayer(KmlDataset)
KmlNetworkLink
kmlNetworkLinkMessageReceived

Offline data

This sample uses the radar.kmz file, which can be found on ArcGIS Online.

About the data

This map shows the current air traffic in parts of Europe with heading, altitude, and ground speed. Additionally, noise levels from ground monitoring stations are shown.

Sample Code

DisplayKmlNetworkLinks.cpp

DisplayKmlNetworkLinks.h

MessageButton.qml

DisplayKmlNetworkLinks.qml

Use dark colors for code blocksCopy
// [WriteFile Name=DisplayKmlNetworkLinks, 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 "DisplayKmlNetworkLinks.h"

#include "ArcGISTiledElevationSource.h"
#include "KmlDataset.h"
#include "KmlLayer.h"
#include "Scene.h"
#include "SceneQuickView.h"

using namespace Esri::ArcGISRuntime;

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

DisplayKmlNetworkLinks::~DisplayKmlNetworkLinks() = default;

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

QString DisplayKmlNetworkLinks::currentKmlNetworkMessage() const
{
  return m_currentKmlNetworkMessage;
}

void DisplayKmlNetworkLinks::setCurrentKmlNetworkMessage(const QString& message)
{
  m_currentKmlNetworkMessage = message;
  emit kmlMessageRecieved(message);
}

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

  // Create a scene and give it to the SceneView
  m_sceneView = findChild<SceneQuickView*>("sceneView");
  Scene* scene = new Scene(BasemapStyle::ArcGISImageryStandard, this);

  // Create a KML dataset from the given resource.
  // This is a KML resource that references other KML resources over a network.
  KmlDataset* dataset = new KmlDataset(QUrl("https://www.arcgis.com/sharing/rest/content/items/600748d4464442288f6db8a4ba27dc95/data"), this);
  connect(dataset, &KmlDataset::kmlNetworkLinkMessageReceived,
          this, [this](KmlNetworkLink* /*link*/, const QString& message)
  {
    setCurrentKmlNetworkMessage(message);
  });

  // Now that we have the data, we need a layer to interpret it.
  KmlLayer* fileLayer = new KmlLayer(dataset, this);
  scene->operationalLayers()->append(fileLayer);

  // Take a look at continental Europe, where we'll see most of the data.
  m_sceneView->setViewpoint(Viewpoint { Point { 8.150526, 50.472421, SpatialReference::wgs84() }, 20000000 } );
  m_sceneView->setArcGISScene(scene);
}