Add dynamic entity layer

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Display data from an ArcGIS stream service using a dynamic entity layer.

screenshot

Use case

A stream service is a type of service provided by ArcGIS Velocity and GeoEvent Server that allows clients to receive a stream of data observations via a web socket. ArcGIS Maps SDK for Qt allows you to connect to a stream service and manage the information as dynamic entities and display them in a dynamic entity layer. Displaying information from feeds such as a stream service is important in applications like dashboards where users need to visualize and track updates of real-world objects in real-time.

Use ArcGISStreamService to manage the connection to the stream service and purge options to manage how much data is stored and maintained by the application. The dynamic entity layer will display the latest received observation, and you can set track display properties to determine how to display historical information for each dynamic entity. This includes the number of previous observations to show, whether to display track lines in-between previous observations, and setting renderers.

How to use the sample

Use the controls to connect to or disconnect from the stream service, modify display properties in the dynamic entity layer, and purge all observations from the application.

How it works

Create an ArcGISStreamService with a URL
Create and configure an ArcGISStreamServiceFilter then set it to the stream service to limit the amount of data coming from the server.
Configure the DynamicEntityDataSourcePurgeOptions to manage when entities are removed from the application's cache
Add a Renderer to the layer to customize the appearance of the latest dynamic entity observations
Update the values in the layer's TrackDisplayProperties to customize the appearance of previous observations

Relevant API

ArcGISStreamService
ArcGISStreamServiceFilter
ConnectionStatus
DynamicEntity
DynamicEntityLayer
DynamicEntityPurgeOptions
TrackDisplayProperties

About the data

This sample uses a stream service that simulates live data coming from snowplows near Sandy, Utah. There are multiple vehicle types and multiple agencies operating the snowplows.

Additional information

More information about dynamic entities can be found in the [guide documentation](link goes here).

Sample Code

AddDynamicEntityLayer.cppAddDynamicEntityLayer.cppAddDynamicEntityLayer.hAddDynamicEntityLayer.qml
Use dark colors for code blocksCopy
// [WriteFile Name=AddDynamicEntityLayer, Category=Layers]
// [Legal]
// Copyright 2023 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 "AddDynamicEntityLayer.h"

#include "ArcGISStreamService.h"
#include "ArcGISStreamServiceFilter.h"
#include "DynamicEntityDataSourcePurgeOptions.h"
#include "DynamicEntityLayer.h"
#include "Envelope.h"
#include "Graphic.h"
#include "GraphicListModel.h"
#include "GraphicsOverlay.h"
#include "GraphicsOverlayListModel.h"
#include "LayerListModel.h"
#include "Map.h"
#include "MapQuickView.h"
#include "MapTypes.h"
#include "Point.h"
#include "RealTimeTypes.h"
#include "SimpleLineSymbol.h"
#include "SimpleMarkerSymbol.h"
#include "SimpleRenderer.h"
#include "SpatialReference.h"
#include "SymbolTypes.h"
#include "TaskWatcher.h"
#include "TrackDisplayProperties.h"
#include "UniqueValue.h"
#include "UniqueValueRenderer.h"
#include "Viewpoint.h"

using namespace Esri::ArcGISRuntime;

namespace
{
// This envelope is a limited region around Sandy, Utah. It will be the extent used by the `DynamicEntityFilter`.
const Envelope utahSandyEnvelope(
    Point(-112.110052, 40.718083, SpatialReference::wgs84()),
    Point(-111.814782, 40.535247, SpatialReference::wgs84()));
}

AddDynamicEntityLayer::AddDynamicEntityLayer(QObject* parent /* = nullptr */):
  QObject(parent),
  m_map(new Map(BasemapStyle::ArcGISDarkGray, this))
{
  // Create a dynamic entity data source from a given URL
  const QUrl streamServiceUrl("https://realtimegis2016.esri.com:6443/arcgis/rest/services/SandyVehicles/StreamServer");
  m_dynamicEntityDataSource = new ArcGISStreamService(streamServiceUrl, this);

  // Create and set an ArcGISStreamServiceFilter to filter what data is received from the server
  ArcGISStreamServiceFilter* streamServiceFilter = new ArcGISStreamServiceFilter(this);
  streamServiceFilter->setGeometry(utahSandyEnvelope);
  streamServiceFilter->setWhereClause("speed > 0");
  m_dynamicEntityDataSource->setFilter(streamServiceFilter);

  // Set purge options to manage when entities are removed from the cache
  m_dynamicEntityDataSource->purgeOptions()->setMaximumDuration(300.0 /*seconds*/);

  // Handle signals emitted when connection status changes to update the UI
  connect(m_dynamicEntityDataSource, &ArcGISStreamService::connectionStatusChanged, this, &AddDynamicEntityLayer::connectionStatusChanged);

  // Create a dynamic entity layer to display on the map and set the properties
  m_dynamicEntityLayer = new DynamicEntityLayer(m_dynamicEntityDataSource, this);

  // Set the track display properties to change what is displayed to the user
  m_dynamicEntityLayer->trackDisplayProperties()->setShowTrackLine(true);
  m_dynamicEntityLayer->trackDisplayProperties()->setShowPreviousObservations(true);

  // Create renderers for observations and their tracklines to change how they are styled

  // Create a unique value renderer for the latest observations
  QList<UniqueValue*> entityValues;
  entityValues.append(new UniqueValue("","", {3}, new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Circle, Qt::magenta, 8, this), this));
  entityValues.append(new UniqueValue("","", {4}, new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Circle, Qt::green, 8, this), this));

  UniqueValueRenderer* entityRenderer = new UniqueValueRenderer("", new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Circle, Qt::blue, 8, this), {"agency"}, entityValues, this);
  m_dynamicEntityLayer->setRenderer(entityRenderer);

  // Create a unique value renderer for the previous observations
  QList<UniqueValue*> previousObservationValues;

  previousObservationValues.append(new UniqueValue("","", {3}, new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Circle, Qt::magenta, 3, this), this));
  previousObservationValues.append(new UniqueValue("","", {4}, new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Circle, Qt::green, 3, this), this));

  UniqueValueRenderer* trackRenderer = new UniqueValueRenderer("", new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Circle, Qt::blue, 3, this), {"agency"}, previousObservationValues);
  m_dynamicEntityLayer->trackDisplayProperties()->setPreviousObservationRenderer(trackRenderer);

  // Use a simple renderer to change the style of the trackline
  m_dynamicEntityLayer->trackDisplayProperties()->setTrackLineRenderer(new SimpleRenderer(new SimpleLineSymbol(SimpleLineSymbolStyle::Solid, Qt::lightGray, 2, this)));

  m_map->operationalLayers()->append(m_dynamicEntityLayer);
}

AddDynamicEntityLayer::~AddDynamicEntityLayer() = default;

void AddDynamicEntityLayer::init()
{
  // Register the map view for QML
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<AddDynamicEntityLayer>("Esri.Samples", 1, 0, "AddDynamicEntityLayerSample");
}

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

// Set the view (created in QML)
void AddDynamicEntityLayer::setMapView(MapQuickView* mapView)
{
  if (!mapView || mapView == m_mapView)
    return;

  m_mapView = mapView;
  m_mapView->setMap(m_map);

  // Create and show a dashed line around the filter area
  GraphicsOverlay* borderOverlay = new GraphicsOverlay(this);
  borderOverlay->graphics()->append(new Graphic(utahSandyEnvelope, new SimpleLineSymbol(SimpleLineSymbolStyle::Dash, Qt::red, 2, this), this));
  m_mapView->graphicsOverlays()->append(borderOverlay);

  // Set the initial viewpoint to this area
  m_mapView->setViewpointAndWait(Viewpoint(utahSandyEnvelope));

  emit mapViewChanged();
}

void AddDynamicEntityLayer::setObservationsPerTrack(int observationsPerTrack)
{
  // Update the number of entity observations displayed using the value from the UI slider
  m_dynamicEntityLayer->trackDisplayProperties()->setMaximumObservations(observationsPerTrack);
}

void AddDynamicEntityLayer::showTrackLines(bool showTrackLines)
{
  // Show or hide the lines that connect previous observations
  m_dynamicEntityLayer->trackDisplayProperties()->setShowTrackLine(showTrackLines);
}

void AddDynamicEntityLayer::showPreviousObservations(bool showPreviousObservations)
{
  // Show or hide previous observations (if maximum observations is greater than 1)
  m_dynamicEntityLayer->trackDisplayProperties()->setShowPreviousObservations(showPreviousObservations);
}

QString AddDynamicEntityLayer::connectionStatus() const
{
  // Return the current dynamic entity data source connection status as a string to display in the UI
  switch (m_dynamicEntityDataSource->connectionStatus())
  {
    case ConnectionStatus::Disconnected:
      return "Disconnected";
    case ConnectionStatus::Connecting:
      return "Connecting";
    case ConnectionStatus::Connected:
      return "Connected";
    case ConnectionStatus::Failed:
      return "Failed";
    default:
      return "Unknown";
  }
}

void AddDynamicEntityLayer::enableDisableConnection()
{
  // Handle the UI connection switch and disable or enable connection
  switch (m_dynamicEntityDataSource->connectionStatus())
  {
    case ConnectionStatus::Disconnected:
      m_dynamicEntityDataSource->connectDataSource();
      break;
    case ConnectionStatus::Connecting:
      // Do nothing and allow data source to finish connecting
      break;
    case ConnectionStatus::Connected:
      m_dynamicEntityDataSource->disconnectDataSource();
      break;
    case ConnectionStatus::Failed:
      qWarning() << "Unable to connect to dynamic entity data source";
      break;
    default:
      break;
  }
}

void AddDynamicEntityLayer::purgeAllObservations()
{
  // Remove all current observations from the cache
  m_dynamicEntityDataSource->purgeAll();
}

ArcGIS Maps SDK for QtC++ samples

Add dynamic entity layer

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ArcGIS Maps SDK for QtC++ samples

Add dynamic entity layer

Use case

How to use the sample

How it works

Relevant API

About the data

Additional information

Tags

Sample Code

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