Map image layer sublayer visibility

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Change the visibility of sublayers.

screenshot

Use case

A map image layer may contain many sublayers such as different types of roads in a road network or city, county, and state borders in a US map. The user may only be interested in a subset of these sublayers. Or, perhaps showing all of the sublayers would show too much detail. In these cases, you can hide certain sublayers by changing their visibility.

How to use the sample

Each sublayer has a check box which can be used to toggle the visibility of the sublayer.

How it works

  1. Create an ArcGISMapImageLayer object with the URL to a map image service.
  2. Get the list of sublayers with mapImageLayer.Sublayers.
  3. For each layer in the sublayer list, set its visible property to true or false.

Relevant API

  • ArcGISMapImageLayer

Tags

layers, sublayers, visibility

Sample Code

ChangeSublayerVisibility.cs
                                                                                                                                                                                                                                    
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// Copyright 2016 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 System;
using System.Collections.Generic;
using CoreGraphics;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using Foundation;
using UIKit;

namespace ArcGISRuntime.Samples.ChangeSublayerVisibility
{
    [Register("ChangeSublayerVisibility")]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Map image layer sublayer visibility",
        category: "Layers",
        description: "Change the visibility of sublayers.",
        instructions: "Each sublayer has a check box which can be used to toggle the visibility of the sublayer.",
        tags: new[] { "layers", "sublayers", "visibility" })]
    public class ChangeSublayerVisibility : UIViewController
    {
        // Hold references to UI controls.
        private MapView _myMapView;
        private SublayersTable _sublayersTableView;
        private UIBarButtonItem _chooseLayersButton;

        // Hold a reference to the layer.
        private ArcGISMapImageLayer _mapImageLayer;

        public ChangeSublayerVisibility()
        {
            Title = "Change sublayer visibility";
        }

        private async void Initialize()
        {
            // Create a new Map instance with the basemap.
            Map map = new Map(SpatialReferences.Wgs84)
            {
                Basemap = new Basemap(BasemapStyle.ArcGISTopographic)
            };

            // Create a new ArcGISMapImageLayer instance and pass a URL to the service.
            _mapImageLayer = new ArcGISMapImageLayer(new Uri("https://sampleserver6.arcgisonline.com/arcgis/rest/services/SampleWorldCities/MapServer"));

            // Assign the Map to the MapView.
            _myMapView.Map = map;

            // Create a new instance of the Sublayers Table View Controller. This View Controller
            // displays a table of sublayers with a switch for setting the layer visibility.
            _sublayersTableView = new SublayersTable();

            try
            {
                // Await the load call for the layer.
                await _mapImageLayer.LoadAsync();

                // Add the map image layer to the map's operational layers.
                map.OperationalLayers.Add(_mapImageLayer);
            }
            catch (Exception e)
            {
                new UIAlertView("Error", e.ToString(), (IUIAlertViewDelegate) null, "OK", null).Show();
            }
        }

        private void sublayerButton_Clicked(object sender, EventArgs e)
        {
            if (_mapImageLayer.Sublayers.Count > 0)
            {
                _sublayersTableView.MapImageLayer = _mapImageLayer;
                NavigationController.PushViewController(_sublayersTableView, true);
            }
        }

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

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

            _myMapView = new MapView();
            _myMapView.TranslatesAutoresizingMaskIntoConstraints = false;

            _chooseLayersButton = new UIBarButtonItem();
            _chooseLayersButton.Title = "Choose sublayers";

            UIToolbar toolbar = new UIToolbar();
            toolbar.TranslatesAutoresizingMaskIntoConstraints = false;
            toolbar.Items = new[]
            {
                new UIBarButtonItem(UIBarButtonSystemItem.FlexibleSpace),
                _chooseLayersButton,
                new UIBarButtonItem(UIBarButtonSystemItem.FlexibleSpace)
            };

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

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

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

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

            // Subscribe to events.
            _chooseLayersButton.Clicked += sublayerButton_Clicked;
        }

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

            // Unsubscribe from events, per best practice.
            _chooseLayersButton.Clicked -= sublayerButton_Clicked;
        }
    }

    [Register("SublayersTable")]
    public sealed class SublayersTable : UITableViewController
    {
        public ArcGISMapImageLayer MapImageLayer { private get; set; }

        public SublayersTable()
        {
            Title = "Sublayers";
        }

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

            List<ArcGISSublayer> sublayers = new List<ArcGISSublayer>();

            // Add all the map image layer sublayers to a list and then pass that list to the SublayerDataSource.
            if (MapImageLayer != null)
            {
                sublayers.AddRange(MapImageLayer.Sublayers);

                TableView.Source = new SublayerDataSource(sublayers);
                TableView.Frame = new CGRect(0, 0, 100, 100);
            }
        }
    }

    public class SublayerDataSource : UITableViewSource
    {
        private readonly List<ArcGISSublayer> _sublayers;
        private UISwitch _visibilitySwitch;

        private const string CellId = "cellid";

        public SublayerDataSource(List<ArcGISSublayer> sublayers)
        {
            _sublayers = sublayers;
        }

        public override UITableViewCell GetCell(UITableView tableView, NSIndexPath indexPath)
        {
            // Create the cells in the table.
            UITableViewCell cell = new UITableViewCell(UITableViewCellStyle.Default, CellId);

            ArcGISMapImageSublayer sublayer = (ArcGISMapImageSublayer) _sublayers[indexPath.Row];
            cell.TextLabel.Text = sublayer.Name;

            // Create a UISwitch for controlling the layer visibility.
            _visibilitySwitch = new UISwitch
            {
                Frame = new CGRect(cell.Bounds.Width - 60, 7, 50, cell.Bounds.Height),
                Tag = indexPath.Row,
                On = sublayer.IsVisible
            };
            _visibilitySwitch.ValueChanged += VisibilitySwitch_ValueChanged;

            // Add the UISwitch to the cell's content view.
            cell.ContentView.AddSubview(_visibilitySwitch);

            return cell;
        }

        private void VisibilitySwitch_ValueChanged(object sender, EventArgs e)
        {
            // Get the row containing the UISwitch that was changed.
            var index = ((UISwitch) sender).Tag;

            // Set the sublayer visibility according to the UISwitch setting.
            ArcGISMapImageSublayer sublayer = (ArcGISMapImageSublayer) _sublayers[(int) index];
            sublayer.IsVisible = ((UISwitch) sender).On;
        }

        public override nint RowsInSection(UITableView tableview, nint section)
        {
            return _sublayers.Count;
        }

        protected override void Dispose(bool disposing)
        {
            base.Dispose(disposing);
            // Unsubscribe from events, per best practice.
            BeginInvokeOnMainThread(() => _visibilitySwitch.ValueChanged -= VisibilitySwitch_ValueChanged);
        }
    }
}

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