Distance measurement analysis

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// Copyright 2021 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;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using Esri.ArcGISRuntime.UI.GeoAnalysis;
using Foundation;
using System;
using System.Diagnostics;
using UIKit;

namespace ArcGISRuntime.Samples.DistanceMeasurement
{
    [Register("DistanceMeasurement")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Distance measurement analysis",
        category: "Analysis",
        description: "Measure distances between two points in 3D.",
        instructions: "Choose a unit system for the measurement. Tap any location in the scene to start measuring. Move the mouse to an end location, and tap to complete the measurement. Tap a new location to clear and start a new measurement.",
        tags: new[] { "3D", "analysis", "distance", "measure" })]
    public class DistanceMeasurement : UIViewController
    {
        // Hold references to UI controls.
        private SceneView _mySceneView;
        private UILabel _resultLabel;
        private UIBarButtonItem _helpButton;
        private UIBarButtonItem _changeUnitsButton;

        // URLs to various services used to provide an interesting scene for the sample.
        private readonly Uri _buildingService = new Uri("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/Buildings_Brest/SceneServer/layers/0");
        private readonly Uri _worldElevationService = new Uri("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer");

        // Reference to the measurement.
        private LocationDistanceMeasurement _distanceMeasurement;

        public DistanceMeasurement()
        {
            Title = "Distance measurement analysis";
        }

        private void Initialize()
        {
            // Create a scene with elevation.
            Surface sceneSurface = new Surface();
            sceneSurface.ElevationSources.Add(new ArcGISTiledElevationSource(_worldElevationService));
            Scene myScene = new Scene(BasemapStyle.ArcGISTopographic)
            {
                BaseSurface = sceneSurface
            };

            // Create and add a building layer.
            ArcGISSceneLayer buildingsLayer = new ArcGISSceneLayer(_buildingService);
            myScene.OperationalLayers.Add(buildingsLayer);

            // Create and add an analysis overlay.
            AnalysisOverlay measureAnalysisOverlay = new AnalysisOverlay();
            _mySceneView.AnalysisOverlays.Add(measureAnalysisOverlay);

            // Create an initial distance measurement and show it.
            MapPoint start = new MapPoint(-4.494677, 48.384472, 24.772694, SpatialReferences.Wgs84);
            MapPoint end = new MapPoint(-4.495646, 48.384377, 58.501115, SpatialReferences.Wgs84);
            _distanceMeasurement = new LocationDistanceMeasurement(start, end);
            measureAnalysisOverlay.Analyses.Add(_distanceMeasurement);

            // Keep the UI updated.
            _distanceMeasurement.MeasurementChanged += MeasurementChanged;

            // Show the scene in the view.
            _mySceneView.Scene = myScene;
            _mySceneView.SetViewpointCamera(new Camera(start, 200, 45, 45, 0));
        }

        private void MeasurementChanged(object sender, EventArgs e)
        {
            // This is needed because measurement change events occur on a non-UI thread and this code accesses UI object.
            BeginInvokeOnMainThread(() =>
            {
                // Update the labels with new values in the format {value} {unit system}.
                string direct = $"{_distanceMeasurement.DirectDistance.Value:F} {_distanceMeasurement.DirectDistance.Unit.Abbreviation}";
                string vertical = $"{_distanceMeasurement.VerticalDistance.Value:F} {_distanceMeasurement.VerticalDistance.Unit.Abbreviation}";
                string horizontal = $"{_distanceMeasurement.HorizontalDistance.Value:F} {_distanceMeasurement.HorizontalDistance.Unit.Abbreviation}";
                _resultLabel.Text = $"Direct: {direct}, V: {vertical}, H: {horizontal}";
            });
        }

        private async void MySceneView_GeoViewTapped(object sender, GeoViewInputEventArgs e)
        {
            try
            {
                // Get the geographic location for the current mouse position.
                MapPoint geoPoint = await _mySceneView.ScreenToLocationAsync(e.Position);

                if (geoPoint == null) return;

                // Update the location distance measurement.
                _distanceMeasurement.EndLocation = geoPoint;
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex.ToString());
            }
        }

        private void UnitChangeButton_TouchUpInside(object sender, EventArgs e)
        {
            // Create the view controller that will present the list of unit systems.
            UIAlertController unitSystemSelectionAlert =
                UIAlertController.Create(null, "Change unit system", UIAlertControllerStyle.ActionSheet);

            // Needed to prevent a crash on iPad.
            UIPopoverPresentationController
                presentationPopover = unitSystemSelectionAlert.PopoverPresentationController;
            if (presentationPopover != null)
            {
                presentationPopover.BarButtonItem = (UIBarButtonItem)sender;
                presentationPopover.PermittedArrowDirections = UIPopoverArrowDirection.Down;
            }

            // Show an option for each unit system.
            foreach (UnitSystem system in Enum.GetValues(typeof(UnitSystem)))
            {
                // Upon selecting a unit system, update the distance measure.
                unitSystemSelectionAlert.AddAction(UIAlertAction.Create(system.ToString(), UIAlertActionStyle.Default,
                    action => _distanceMeasurement.UnitSystem = system));
            }

            // Show the alert.
            PresentViewController(unitSystemSelectionAlert, true, null);
        }

        private void ShowHelp_Click(object sender, EventArgs e)
        {
            // Prompt for the type of convex hull to create.
            UIAlertController unionAlert = UIAlertController.Create("Tap to update", "Tap in the scene to set a new end point for the distance measurement.", UIAlertControllerStyle.Alert);
            unionAlert.AddAction(UIAlertAction.Create("Ok", UIAlertActionStyle.Default, null));

            // Show the alert.
            PresentViewController(unionAlert, true, null);
        }

        public override void ViewDidLoad()
        {
            base.ViewDidLoad();
            Initialize();
        }

        public override void LoadView()
        {
            // Create and configure the views.
            View = new UIView { BackgroundColor = ApplicationTheme.BackgroundColor };

            _mySceneView = new SceneView();
            _mySceneView.TranslatesAutoresizingMaskIntoConstraints = false;

            UIToolbar toolbar = new UIToolbar();
            toolbar.TranslatesAutoresizingMaskIntoConstraints = false;

            _resultLabel = new UILabel
            {
                Text = "Tap to measure distance.",
                BackgroundColor = UIColor.FromWhiteAlpha(0f, .6f),
                TextColor = UIColor.White,
                TextAlignment = UITextAlignment.Center,
                TranslatesAutoresizingMaskIntoConstraints = false
            };

            _helpButton = new UIBarButtonItem();
            _helpButton.Title = "Help";

            _changeUnitsButton = new UIBarButtonItem();
            _changeUnitsButton.Title = "Change units";

            toolbar.Items = new[]
            {
                _changeUnitsButton,
                new UIBarButtonItem(UIBarButtonSystemItem.FlexibleSpace),
                _helpButton
            };

            // Add the views.
            View.AddSubviews(_mySceneView, toolbar, _resultLabel);

            // Lay out the views.
            NSLayoutConstraint.ActivateConstraints(new[]
            {
                _mySceneView.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
                _mySceneView.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                _mySceneView.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                _mySceneView.BottomAnchor.ConstraintEqualTo(toolbar.TopAnchor),

                toolbar.BottomAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.BottomAnchor),
                toolbar.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                toolbar.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),

                _resultLabel.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
                _resultLabel.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
                _resultLabel.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
                _resultLabel.HeightAnchor.ConstraintEqualTo(40)
            });
        }

        public override void ViewWillAppear(bool animated)
        {
            base.ViewWillAppear(animated);

            // Subscribe to events.
            _mySceneView.GeoViewTapped += MySceneView_GeoViewTapped;
            _helpButton.Clicked += ShowHelp_Click;
            _changeUnitsButton.Clicked += UnitChangeButton_TouchUpInside;
            if (_distanceMeasurement != null) _distanceMeasurement.MeasurementChanged += MeasurementChanged;
        }

        public override void ViewDidDisappear(bool animated)
        {
            base.ViewDidDisappear(animated);

            // Unsubscribe from events, per best practice.
            _mySceneView.GeoViewTapped -= MySceneView_GeoViewTapped;
            _helpButton.Clicked -= ShowHelp_Click;
            _changeUnitsButton.Clicked -= UnitChangeButton_TouchUpInside;
            if (_distanceMeasurement != null) _distanceMeasurement.MeasurementChanged -= MeasurementChanged;
        }
    }
}