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GeometryFromJson Method (String)

Creates a Geometry from an ArcGIS JSON representation.

Namespace:  Esri.ArcGISRuntime.Geometry
Assembly:  Esri.ArcGISRuntime (in Esri.ArcGISRuntime.dll) Version: 100.9.0
Syntax
public static Geometry FromJson(
	string json
)

Parameters

json
Type: SystemString
JSON representation of geometry.

Return Value

Type: Geometry
Geometry converted from a JSON String.
Remarks

Geometry can be serialized and de-serialized to and from JSON. The ArcGIS REST API documentation describes the JSON representation of geometry objects. You can use this encoding and decoding mechanism to exchange geometries with REST Web services or to store them in text files.

Examples

WPF

Example Name: ShowLocationHistory

Display your location history on the map.

Code example screen shot.

C#
// 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.

using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Location;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using System;
using System.Windows;

namespace ArcGISRuntime.WPF.Samples.ShowLocationHistory
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Show location history",
        category: "Location",
        description: "Display your location history on the map.",
        instructions: "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 `SystemLocationDataSource` instead.",
        tags: new[] { "GPS", "bread crumb", "breadcrumb", "history", "movement", "navigation", "real-time", "trace", "track", "trail", "Featured" })]
    public partial class ShowLocationHistory
    {
        // Track whether location tracking is enabled.
        private bool _isTrackingEnabled;

        // Location data source provides location data updates.
        private LocationDataSource _locationDataSource;

        // Graphics overlay to display the location history (points).
        private GraphicsOverlay _locationHistoryOverlay;

        // Graphics overlay to display the line created by the location points.
        private GraphicsOverlay _locationHistoryLineOverlay;

        // Polyline builder to more efficiently manage large location history graphic.
        private PolylineBuilder _polylineBuilder;

        // Track previous location to ensure the route line appears behind the animating location symbol.
        private MapPoint _lastPosition;

        public ShowLocationHistory()
        {
            InitializeComponent();
            Initialize();
        }

        private void Initialize()
        {
            // Add event handler for when this sample is unloaded.
            Unloaded += SampleUnloaded;

            // Create new Map with basemap.
            Map myMap = new Map(Basemap.CreateDarkGrayCanvasVector());

            // Display the map.
            MyMapView.Map = myMap;

            // Create and add graphics overlay for displaying the trail.
            _locationHistoryLineOverlay = new GraphicsOverlay();
            SimpleLineSymbol locationLineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.Lime, 2);
            _locationHistoryLineOverlay.Renderer = new SimpleRenderer(locationLineSymbol);
            MyMapView.GraphicsOverlays.Add(_locationHistoryLineOverlay);

            // Create and add graphics overlay for showing points.
            _locationHistoryOverlay = new GraphicsOverlay();
            SimpleMarkerSymbol locationPointSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Circle, System.Drawing.Color.Red, 3);
            _locationHistoryOverlay.Renderer = new SimpleRenderer(locationPointSymbol);
            MyMapView.GraphicsOverlays.Add(_locationHistoryOverlay);

            // Create the polyline builder.
            _polylineBuilder = new PolylineBuilder(SpatialReferences.WebMercator);

            // Start location services.
            HandleLocationReady();
        }

        private async void HandleLocationReady()
        {
            // Create a polyline of mock data.
            var simulatedLocations = (Polyline)Geometry.FromJson("{\"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}}");

            // Create a simulated location data source using the mock data.
            var parameters = new SimulationParameters(DateTimeOffset.Now, 150);
            var simulatedSource = new SimulatedLocationDataSource();
            simulatedSource.SetLocationsWithPolyline(simulatedLocations, parameters);

            // Set the location data source to the simulated source.
            _locationDataSource = simulatedSource;
            // Use this instead if you want real location: _locationDataSource = new SystemLocationDataSource();

            try
            {
                // Start the data source.
                await _locationDataSource.StartAsync();

                if (_locationDataSource.IsStarted)
                {
                    // Set the location display data source and enable location display.
                    MyMapView.LocationDisplay.DataSource = _locationDataSource;
                    MyMapView.LocationDisplay.IsEnabled = true;
                    MyMapView.LocationDisplay.AutoPanMode = LocationDisplayAutoPanMode.Recenter;
                    MyMapView.LocationDisplay.InitialZoomScale = 10000;

                    // Enable the button to start location tracking.
                    LocationTrackingButton.IsEnabled = true;
                }
                else
                {
                    ShowMessage("There was a problem enabling location", "Error");
                }
            }
            catch (Exception e)
            {
                System.Diagnostics.Debug.WriteLine(e);
                ShowMessage("There was a problem enabling location", "Error");
            }
        }

        private void ToggleLocationTracking()
        {
            // Toggle location tracking.
            _isTrackingEnabled = !_isTrackingEnabled;

            // Apply new configuration.
            if (_isTrackingEnabled)
            {
                // Configure new symbology first.
                _locationDataSource.LocationChanged += LocationDataSourceOnLocationChanged;

                // Update the UI.
                LocationTrackingButton.Content = "Stop tracking";
            }
            else
            {
                // Stop updating.
                _locationDataSource.LocationChanged -= LocationDataSourceOnLocationChanged;

                // Update the UI.
                LocationTrackingButton.Content = "Start tracking";
            }
        }

        private void LocationDataSourceOnLocationChanged(object sender, Location e)
        {
            // Remove the old line.
            _locationHistoryLineOverlay.Graphics.Clear();

            // Add any previous position to the history.
            if (_lastPosition != null)
            {
                _polylineBuilder.AddPoint(_lastPosition);
                _locationHistoryOverlay.Graphics.Add(new Graphic(_lastPosition));
            }

            // Store the current position.
            _lastPosition = e.Position;

            // Add the updated line.
            _locationHistoryLineOverlay.Graphics.Add(new Graphic(_polylineBuilder.ToGeometry()));
        }

        private void LocationTrackingButton_OnClick(object sender, RoutedEventArgs e) => ToggleLocationTracking();

        private void ShowMessage(string title, string detail) => MessageBox.Show(detail, title);

        private void SampleUnloaded(object sender, RoutedEventArgs e)
        {
            // Stop the location data source.
            MyMapView.LocationDisplay?.DataSource?.StopAsync();
        }
    }
}
XAML
<UserControl x:Class="ArcGISRuntime.WPF.Samples.ShowLocationHistory.ShowLocationHistory"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:esri="http://schemas.esri.com/arcgis/runtime/2013">
    <Grid>
        <esri:MapView x:Name="MyMapView" />
        <Border Style="{StaticResource BorderStyle}">
            <Button x:Name="LocationTrackingButton"
                    Content="Start tracking"
                    IsEnabled="False"
                    Click="LocationTrackingButton_OnClick" />
        </Border>
    </Grid>
</UserControl>
See Also
Additional Examples
Hyperlink to ExampleDescription
ShowLocationHistoryDisplay your location history on the map.