Show location history

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C++

QML

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Sample viewer app

Display your location history on the map.

screenshot

Use case

You can track device location history and display it as lines and points on the map. The history can be used to visualize how the user moved through the world, to retrace their steps, or to create new feature geometry. An unmapped trail, for example, could be added to the map using this technique.

How to use the sample

Click 'Start tracking' to start tracking your location, which will appear as points on the map. A line will connect the points for easier visualization. Click 'Stop tracking' to stop updating the location history. This sample uses a simulated data source to allow the sample to be useful on desktop/non-mobile devices. To track a user's real position, use the DefaultLocationDataSource instead.

How it works

If necessary, request location permission from the operating system.
Create a graphics overlay to show each point and another graphics overlay for displaying the route line.
Create a SimulatedLocationDataSource and initialize it with a polyline. Start the SimulatedLocationDataSource to begin receiving location updates.
- NOTE: To track a user's real position, use DefaultLocationDataSource instead.
Connect to the LocationDisplay's LocationChanged signal to handle location updates.
Every time the location updates, store that location, display a point on the map, and re-create the route line.

Relevant API

Location::position
LocationDisplay::autoPanMode
LocationDisplay::dataSource
LocationDisplay::locationChanged
MapView::locationDisplay
SimulatedLocationDataSource

About the data

A custom set of points is used to create a Polyline and initialize a SimulatedLocationDataSource. This simulated location data source enables easier testing and allows the sample to be used on devices without an actively updating GPS signal.

Sample Code

ShowLocationHistory.cpp

ShowLocationHistory.h

ShowLocationHistory.qml

Use dark colors for code blocksCopy
// [WriteFile Name=ShowLocationHistory, Category=Maps]
// [Legal]
// Copyright 2020 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 "ShowLocationHistory.h"

#include "GeometryEngine.h"
#include "Graphic.h"
#include "GraphicsOverlay.h"
#include "Location.h"
#include "Map.h"
#include "MapQuickView.h"
#include "Polyline.h"
#include "PolylineBuilder.h"
#include "SimpleLineSymbol.h"
#include "SimpleMarkerSymbol.h"
#include "SimpleRenderer.h"
#include "SimulatedLocationDataSource.h"
#include "SimulationParameters.h"

using namespace Esri::ArcGISRuntime;

namespace
{
constexpr int initialZoomScale = 8000;
const Point initialCenter(-13185535.98, 4037766.28);
const QString polylineJson("{\"paths\":[[[-13185646.046666779,4037971.5966668758],[-13185586.780000051,4037827.6633333955],"
                           "[-13185514.813333312,4037709.1299999417],[-13185569.846666701,4037522.8633330846],"
                           "[-13185591.01333339,4037378.9299996048],[-13185629.113333428,4037283.6799995075],"
                           "[-13185770.93000024,4037425.4966663187],[-13185821.730000293,4037546.146666442],"
                           "[-13185880.996667018,4037704.8966666036],[-13185948.730000421,4037874.2300001099],"
                           "[-13185974.130000448,4037946.1966668498],[-13186120.180000596,4037958.896666863],"
                           "[-13186264.113334076,4037984.296666889],[-13186336.080000836,4038001.2300002342],"
                           "[-13186314.91333415,4037757.8133333195],[-13186272.580000773,4037560.9633331187],"
                           "[-13186187.913334005,4037463.59666635],[-13186431.33000092,4037404.3299996229],"
                           "[-13186676.863334503,4037290.0299995062],[-13187625.130002158,4038589.6633341513],"
                           "[-13187333.030001862,4038756.8800009824],[-13187091.730001617,4038617.1800008402],"
                           "[-13186791.163334643,4038805.5633343654],[-13186721.313334571,4038801.3300010278],"
                           "[-13186833.49666802,4038195.9633337436],[-13186977.677439401,4037699.8176972247],"
                           "[-13186784.921301765,4037820.4541915278],[-13186749.517113185,4038150.8932846226],"
                           "[-13186649.860878762,4038288.5762400767],[-13186556.760975549,4038323.9804286221],"
                           "[-13186472.839936033,4038481.3323777127],[-13186373.183701571,4038489.1999751539],"
                           "[-13186344.335844241,4038242.6819215398],[-13186126.665647998,4038308.245233661],"
                           "[-13185814.584282301,4038358.0733508728],[-13185651.987268206,4038116.8003622484],"
                           "[-13185203.534213299,4038048.6145176427],[-13184576.748949422,4038150.8932845518],"
                           "[-13184251.55492135,4037833.5668537691],[-13184146.653621957,4037524.1080205571],"
                           "[-13183949.963685593,4037621.1417224966],[-13183687.71043711,4037781.1162040718],"
                           "[-13183480.530370807,4037875.5273735262],[-13182307.629999243,4037859.7460188437],"
                           "[-13181376.039484169,4037820.9297473822],[-13180716.162869323,4038364.3575478429],"
                           "[-13180182.439136729,4038810.7446696493],[-13178474.523192419,4040237.2426458625],"
                           "[-13178321.134040033,4039740.6894803117],[-13177958.020228144,4039140.1550991111],"
                           "[-13177073.512224896,4037459.5898928214],[-13177757.842101147,4037589.9384406791],"
                           "[-13178386.308314031,4037799.427178307],[-13180095.012208173,4037811.6550856642],"
                           "[-13180126.165447287,4036845.9046731163],[-13179806.844746364,4036324.0879179495],"
                           "[-13180928.361354485,4035887.9425703473],[-13181598.155995468,4035428.432293402],"
                           "[-13182984.47513606,4034447.105261297],[-13182229.264383668,4033222.8051626245],"
                           "[-13182058.735615831,4033339.8690072047],[-13181939.035180708,4033691.2477038498],"
                           "[-13182116.65518121,4033861.1450956347],[-13181792.305615077,4034085.1007484416],"
                           "[-13182027.845180977,4034467.3698799671],[-13181877.254310986,4034644.9898804692],"
                           "[-13181630.130832028,4034517.5668366305],[-13181386.868657427,4034424.8955320208],"
                           "[-13181228.555178719,4034652.7124891868],[-13181379.14604871,4034942.3103160923],"
                           "[-13181267.168222306,4035189.4337950516],[-13181074.103004368,4035015.6750989081],"
                           "[-13180807.673003616,4034934.5877073747],[-13180618.469090037,4034814.8872722536],"
                           "[-13180599.162568243,4035374.7764042714],[-13181047.073873857,4035494.476839392],"
                           "[-13181317.365178969,4035413.3894478586],[-13180765.198655669,4035143.0981427468],"
                           "[-13180328.871263131,4034892.1133594285],[-13180270.951697765,4035258.9372735149],"
                           "[-13180325.009958787,4035718.4324922049],[-13180707.279090302,4035695.2646660525],"
                           "[-13181413.897788007,4035536.9511873648],[-13181618.54691902,4035807.2424924765],"
                           "[-13181884.976919774,4036065.949884512],[-13182159.129529245,4035861.3007534989],"
                           "[-13182174.57474668,4035668.2355355616],[-13182417.83692128,4035664.374231203],"
                           "[-13182784.660835361,4035409.5281435261],[-13182997.032575091,4035255.0759691764],"
                           "[-13182618.624747934,4034679.7416197238]]],"
                           "\"spatialReference\":{\"wkid\":102100,\"latestWkid\":3857}}");
}

ShowLocationHistory::ShowLocationHistory(QObject* parent /* = nullptr */):
  QObject(parent),
  m_map(new Map(BasemapStyle::ArcGISDarkGray, this)),
  m_locationHistoryOverlay(new GraphicsOverlay(this)),
  m_locationHistoryLineOverlay(new GraphicsOverlay(this))
{
  // graphics overlay for displaying the trail
  SimpleLineSymbol* locationLineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle::Solid, Qt::green, 2, this);
  m_locationHistoryLineOverlay->setRenderer(new SimpleRenderer(locationLineSymbol, this));
  m_locationHistoryLineGraphic = new Graphic(this);
  m_locationHistoryLineOverlay->graphics()->append(m_locationHistoryLineGraphic);

  // graphics overlay for showing points
  SimpleMarkerSymbol* locationPointSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Circle, Qt::red, 3, this);
  m_locationHistoryOverlay->setRenderer(new SimpleRenderer(locationPointSymbol, this));

  m_polylineBuilder = new PolylineBuilder(SpatialReference::webMercator(), this);
  m_simulatedLocationDataSource = new SimulatedLocationDataSource(this);
}

void ShowLocationHistory::handleLocationChanges()
{
  SimulationParameters* simulationParameters = new SimulationParameters(QDateTime::currentDateTime(), 30.0, 0.0, 0.0, this); // set speed

  m_simulatedLocationDataSource->setLocationsWithPolyline(Polyline::fromJson(polylineJson), simulationParameters);

  m_mapView->locationDisplay()->setDataSource(m_simulatedLocationDataSource);
  m_mapView->locationDisplay()->setAutoPanMode(LocationDisplayAutoPanMode::Recenter);
  m_mapView->locationDisplay()->setInitialZoomScale(initialZoomScale);
  m_mapView->locationDisplay()->start();

  m_simulatedLocationDataSource->start();

  // if tracking is enabled then show location history
  connect(m_mapView->locationDisplay(), &LocationDisplay::locationChanged, this, [this](const Location& location)
  {
    if (!m_trackingEnabled)
    {
      return;
    }

    // clear old route
    m_locationHistoryLineGraphic->setGeometry(Geometry());

    if (m_lastPosition.isValid())
    {
      m_polylineBuilder->addPoint(m_lastPosition);
      m_locationHistoryOverlay->graphics()->append(new Graphic(m_lastPosition, this));
    }

    // store the current position
    m_lastPosition = location.position();

    // update the polyline
    m_locationHistoryLineGraphic->setGeometry(m_polylineBuilder->toGeometry());
  });
}

ShowLocationHistory::~ShowLocationHistory() = default;

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

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

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

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

  // set initial viewpoint near UCLA, Los Angeles
  m_mapView->setViewpointCenter(initialCenter, initialZoomScale);

  m_mapView->graphicsOverlays()->append(m_locationHistoryLineOverlay);
  m_mapView->graphicsOverlays()->append(m_locationHistoryOverlay);

  handleLocationChanges();

  emit mapViewChanged();
}