Create a custom dynamic entity data source and display it using a dynamic entity layer.
Use case
Developers can create a custom DynamicEntityDataSource
to be able to visualize data from a variety of different feeds as dynamic entities using a DynamicEntityLayer
. An example of this is in a mobile situational awareness app, where a custom DynamicEntityDataSource
can be used to connect to peer-to-peer feeds in order to visualize real-time location tracks from teammates in the field.
How to use the sample
Run the sample to view the map and the dynamic entity layer displaying the latest observation from the custom data source. Tap on a dynamic entity to view its attributes in a callout.
How it works
Configure the custom data source:
- Create a custom data source implementation of a
DynamicEntityDataSource
. - Override
OnLoadAsync()
to specify theDynamicEntityDataSourceInfo
for a given unique entity ID field and a list ofField
objects matching the fields in the data source. - Override
OnConnectAsync()
to begin processing observations from the custom data source. - Loop through the observations and deserialize each observation into a
Point
object and aQVariantMap
containing the attributes. - Use
DynamicEntityDataSource::addObservation(mapPoint, attributes)
to add each observation to the custom data source.
Configure the map view:
- Create a
DynamicEntityLayer
using the custom data source implementation. - Update values in the layer's
TrackDisplayProperties
to customize the layer's appearance. - Set up the layer's
LabelDefinitions
to display labels for each dynamic entity. - Use
MapView::identifyLayerAsync
to select a dynamic entity and display the entity's attributes in aCallout
.
Relevant API
- DynamicEntity
- DynamicEntityDataSource
- DynamicEntityLayer
- LabelDefinition
- TrackDisplayProperties
About the data
This sample uses a .json file containing observations of marine vessels in the Pacific North West hosted on ArcGIS Online .
Additional information
In this sample, we iterate through features in a GeoJSON file to mimic messages coming from a real-time feed. You can create a custom dyamic entity data source to process any data that contains observations which can be translated into Point
objects with associated QVariantMap attributes.
Tags
data, dynamic, entity, label, labeling, live, real-time, stream, track
Sample Code
// [WriteFile Name=AddCustomDynamicEntityDataSource, 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 "AddCustomDynamicEntityDataSource.h"
#include "CustomDataSource.h"
#include "ServiceTypes.h"
#include "DynamicEntityDataSource.h"
#include "DynamicEntityLayer.h"
#include "Map.h"
#include "MapQuickView.h"
#include "MapTypes.h"
#include "Viewpoint.h"
#include "LayerListModel.h"
#include "Basemap.h"
#include "ArcGISMapImageLayer.h"
#include "TrackDisplayProperties.h"
#include "SimpleLabelExpression.h"
#include "TextSymbol.h"
#include "LabelDefinition.h"
#include "ServiceTypes.h"
#include "LabelDefinitionListModel.h"
#include "CalloutData.h"
#include "IdentifyLayerResult.h"
#include "DynamicEntityObservation.h"
#include "DynamicEntity.h"
#include "AttributeListModel.h"
#include "DynamicEntityChangedInfo.h"
#include "DynamicEntityDataSourcePurgeOptions.h"
#include <QFuture>
#include <QtConcurrent/QtConcurrent>
using namespace Esri::ArcGISRuntime;
AddCustomDynamicEntityDataSource::AddCustomDynamicEntityDataSource(QObject* parent /* = nullptr */):
QObject(parent),
m_map(new Map(BasemapStyle::ArcGISOceans, this))
{
// This is a custom class that inherits from DynamicEntityDataSource. It was written specifically for this sample.
CustomDataSource* dataSource = new CustomDataSource(":/Samples/Layers/AddCustomDynamicEntityDataSource/AIS_MarineCadastre_SelectedVessels_CustomDataSource.json", "MMSI", 10, this);
m_dynamicEntityLayer = new DynamicEntityLayer(dataSource, this);
m_map->operationalLayers()->append(m_dynamicEntityLayer);
// Set previous observation properties
m_dynamicEntityLayer->trackDisplayProperties()->setShowPreviousObservations(true);
m_dynamicEntityLayer->trackDisplayProperties()->setShowTrackLine(true);
m_dynamicEntityLayer->trackDisplayProperties()->setMaximumObservations(20);
// Even when not displayed, previous observations are stored until purged
m_dynamicEntityLayer->dataSource()->purgeOptions()->setMaximumObservationsPerTrack(20);
// Show the vessel names as labels above the observation points
SimpleLabelExpression* simpleLabelExpression = new SimpleLabelExpression("[VesselName]", this);
TextSymbol* labelSymbol = new TextSymbol(this);
labelSymbol->setColor(Qt::red);
labelSymbol->setSize(12);
LabelDefinition* labelDef = new LabelDefinition(simpleLabelExpression, labelSymbol, this);
labelDef->setPlacement(LabelingPlacement::PointAboveCenter);
m_dynamicEntityLayer->labelDefinitions()->append(labelDef);
m_dynamicEntityLayer->setLabelsEnabled(true);
}
AddCustomDynamicEntityDataSource::~AddCustomDynamicEntityDataSource() = default;
void AddCustomDynamicEntityDataSource::init()
{
// Register the map view for QML
qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
qmlRegisterType<AddCustomDynamicEntityDataSource>("Esri.Samples", 1, 0, "AddCustomDynamicEntityDataSourceSample");
}
MapQuickView* AddCustomDynamicEntityDataSource::mapView() const
{
return m_mapView;
}
// Set the view (created in QML)
void AddCustomDynamicEntityDataSource::setMapView(MapQuickView* mapView)
{
if (!mapView || mapView == m_mapView)
return;
m_mapView = mapView;
m_mapView->setMap(m_map);
m_mapView->setViewpointAsync(Viewpoint(47.984, -123.657, 3e6));
// Create a slot to listen for mouse clicks
connect(m_mapView, &MapQuickView::mouseClicked, this, &AddCustomDynamicEntityDataSource::identifyLayerAtMouseClick);
emit mapViewChanged();
}
void AddCustomDynamicEntityDataSource::identifyLayerAtMouseClick(const QMouseEvent &e)
{
// Hide the callout (if it is already hidden this will do nothing)
m_mapView->calloutData()->setVisible(false);
// Reseting m_tempParent gives it a new parent and cleans up any previously owned children like IdentifyLayerResult and DynamicEntity objects
m_tempParent.reset(new QObject(this));
m_mapView->identifyLayerAsync(m_map->operationalLayers()->first(), e.position(), 10, false, m_tempParent.get())
.then(this, [this](IdentifyLayerResult* result)
{
if (!result || result->geoElements().empty())
return;
if (DynamicEntityObservation* observation = dynamic_cast<DynamicEntityObservation*>(result->geoElements().constFirst()))
{
DynamicEntity* dynamicEntity = observation->dynamicEntity();
if (!dynamicEntity)
return;
// Get updated info about the dynamic entity every time it updates
connect(dynamicEntity, &DynamicEntity::dynamicEntityChanged, this, [this](DynamicEntityChangedInfo* changedInfo)
{
// changedInfo will be cleaned up when m_tempParent is reset, but they will persist until then
// a new DynamicEntityChangedInfo object will be created every time the dynamic entity updates
// we can call deleteLater() to delete the object sooner when we leave this event loop
changedInfo->deleteLater();
// Get the current/most recent observation and populate a popup with its information
DynamicEntityObservation* currentObservation = changedInfo->receivedObservation();
QString calloutText =
{
"Vessel Name: " + currentObservation->attributes()->attributeValue("VesselName").toString() + "\n" +
"Call Sign: " + currentObservation->attributes()->attributeValue("CallSign").toString() + "\n" +
"Course over Ground: " + currentObservation->attributes()->attributeValue("COG").toString() + "º\n" +
"Speed over Ground: " + currentObservation->attributes()->attributeValue("SOG").toString() + " knots"
};
m_mapView->calloutData()->setDetail(calloutText);
m_mapView->calloutData()->setGeoElement(currentObservation);
m_mapView->calloutData()->setVisible(true);
});
}
});
}