Geodesic operations

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage x:Class="ArcGIS.Samples.GeodesicOperations.GeodesicOperations"
             xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:esriUI="clr-namespace:Esri.ArcGISRuntime.Maui;assembly=Esri.ArcGISRuntime.Maui">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>
        <Label x:Name="ResultsLabel"
               Grid.Row="0"
               FontSize="25"
               HorizontalTextAlignment="Center">
            Tap to set an end point.
        </Label>
        <esriUI:MapView x:Name="MyMapView" Grid.Row="1" />
    </Grid>
</ContentPage>

// Copyright 2022 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.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;

using Colors = System.Drawing.Color;
using PointCollection = Esri.ArcGISRuntime.Geometry.PointCollection;

namespace ArcGIS.Samples.GeodesicOperations
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Geodesic operations",
        category: "Geometry",
        description: "Calculate a geodesic path between two points and measure its distance.",
        instructions: "Tap anywhere on the map. A line graphic will display the geodesic line between the two points. In addition, text that indicates the geodesic distance between the two points will be updated. Tap elsewhere and a new line will be created.",
        tags: new[] { "densify", "distance", "geodesic", "geodetic" })]
    public partial class GeodesicOperations : ContentPage
    {
        // Hold references to the graphics and start point.
        private Graphic _startLocationGraphic;
        private Graphic _endLocationGraphic;
        private Graphic _pathGraphic;
        private MapPoint _startPoint;

        public GeodesicOperations()
        {
            InitializeComponent();

            // Setup the control references and execute initialization.
            Initialize();
        }

        private void Initialize()
        {
            MyMapView.Map = new Map(BasemapStyle.ArcGISImageryStandard);

            // Create the graphics overlay and add it to the map view.
            GraphicsOverlay graphicsOverlay = new GraphicsOverlay();
            MyMapView.GraphicsOverlays.Add(graphicsOverlay);

            // Add a graphic at JFK to serve as the origin.
            _startPoint = new MapPoint(-73.7781, 40.6413, SpatialReferences.Wgs84);
            SimpleMarkerSymbol startMarker = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Circle, Colors.Blue, 10);
            _startLocationGraphic = new Graphic(_startPoint, startMarker);

            // Create the graphic for the destination.
            _endLocationGraphic = new Graphic
            {
                Symbol = startMarker
            };

            // Create the graphic for the path.
            _pathGraphic = new Graphic
            {
                Symbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Dash, Colors.Blue, 5)
            };

            // Add the graphics to the overlay.
            graphicsOverlay.Graphics.Add(_startLocationGraphic);
            graphicsOverlay.Graphics.Add(_endLocationGraphic);
            graphicsOverlay.Graphics.Add(_pathGraphic);

            // Update end location when the user taps.
            MyMapView.GeoViewTapped += MyMapViewOnGeoViewTapped;
        }

        private void MyMapViewOnGeoViewTapped(object sender, Esri.ArcGISRuntime.Maui.GeoViewInputEventArgs geoViewInputEventArgs)
        {
            // Get the tapped point, projected to WGS84.
            MapPoint destination = (MapPoint)geoViewInputEventArgs.Location.Project(SpatialReferences.Wgs84);

            // Update the destination graphic.
            _endLocationGraphic.Geometry = destination;

            // Get the points that define the route polyline.
            PointCollection polylinePoints = new PointCollection(SpatialReferences.Wgs84)
            {
                (MapPoint) _startLocationGraphic.Geometry,
                destination
            };

            // Create the polyline for the two points.
            Polyline routeLine = new Polyline(polylinePoints);

            // Densify the polyline to show the geodesic curve.
            Geometry pathGeometry = routeLine.DensifyGeodetic(1, LinearUnits.Kilometers, GeodeticCurveType.Geodesic);

            // Apply the curved line to the path graphic.
            _pathGraphic.Geometry = pathGeometry;

            // Calculate and show the distance.
            GeodeticDistanceResult geodeticDistance = _startPoint.DistanceGeodetic(destination, LinearUnits.Kilometers, AngularUnits.Grads, GeodeticCurveType.Geodesic);
            ResultsLabel.Text = $"{(int)geodeticDistance.Distance} kilometers";
        }
    }
}