Group layers

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Group a collection of layers together and toggle their visibility as a group.

Image of group layers

Use case

Group layers communicate to the user that layers are related and can be managed together.

In a land development project, you might group layers according to the phase of development.

How to use the sample

The layers in the map will be displayed in a table of contents. Toggle the checkbox next to a layer's name to change its visibility. Turning a group layer's visibility off will override the visibility of its child layers.

How it works

NOTE See WPF for an example of using a TreeView with a hierarchical data template.

  1. Create an empty GroupLayer.
  2. Add a child layer to the group layer's layers collection.
  3. To build the table of contents, use a TreeView with a HierarchicalDataTemplate.
  4. To toggle the visibility of the group, change the group layer's visibility property.

Relevant API

  • GroupLayer
  • ILayerContent

Additional information

The full extent of a group layer may change when child layers are added/removed. Group layers do not have a spatial reference, but the full extent will have the spatial reference of the first child layer.

Group layers can be saved to web scenes. In web maps, group layers will be ignored.

Tags

group layer, layers

Sample Code

GroupLayers.cs
                                                                                                                                                     
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// Copyright 2019 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 Android.App;
using Android.OS;
using Android.Views;
using Android.Widget;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Linq;
using System.Threading.Tasks;

namespace ArcGISRuntimeXamarin.Samples.GroupLayers
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Group layers",
        category: "Layers",
        description: "Group a collection of layers together and toggle their visibility as a group.",
        instructions: "The layers in the map will be displayed in a table of contents. Toggle the checkbox next to a layer's name to change its visibility. Turning a group layer's visibility off will override the visibility of its child layers.",
        tags: new[] { "group layer", "layers" })]
    public class GroupLayers : Activity
    {
        // Hold references to the UI controls.
        private SceneView _mySceneView;
        private LinearLayout _layerListView;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            Title = "Group layers";

            CreateLayout();
            Initialize();
        }

        private async void Initialize()
        {
            // Create the layers.
            ArcGISSceneLayer devOne = new ArcGISSceneLayer(new Uri("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/DevA_Trees/SceneServer"));
            FeatureLayer devTwo = new FeatureLayer(new Uri("https://services.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/DevA_Pathways/FeatureServer/1"));
            ArcGISSceneLayer devThree = new ArcGISSceneLayer(new Uri("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/DevB_BuildingShells/SceneServer"));
            ArcGISSceneLayer nonDevOne = new ArcGISSceneLayer(new Uri("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/DevA_BuildingShells/SceneServer"));
            FeatureLayer nonDevTwo = new FeatureLayer(new Uri("https://services.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/DevelopmentProjectArea/FeatureServer/0"));

            // Create the group layer and add sublayers.
            GroupLayer gLayer = new GroupLayer();
            gLayer.Name = "Group: Dev A";
            gLayer.Layers.Add(devOne);
            gLayer.Layers.Add(devTwo);
            gLayer.Layers.Add(devThree);

            // Create the scene with a basemap.
            _mySceneView.Scene = new Scene(BasemapStyle.ArcGISImageryStandard);

            // Add the top-level layers to the scene.
            _mySceneView.Scene.OperationalLayers.Add(gLayer);
            _mySceneView.Scene.OperationalLayers.Add(nonDevOne);
            _mySceneView.Scene.OperationalLayers.Add(nonDevTwo);

            // Wait for all of the layers in the group layer to load.
            await Task.WhenAll(gLayer.Layers.ToList().Select(m => m.LoadAsync()).ToList());

            // Zoom to the extent of the group layer.
            _mySceneView.SetViewpoint(new Viewpoint(gLayer.FullExtent));

            // Add the layer list to the UI.
            foreach (Layer layer in _mySceneView.Scene.OperationalLayers)
            {
                AddLayersToUI(layer);
            }
        }

        private async void AddLayersToUI(Layer layer, int nestLevel = 0)
        {
            // Wait for the layer to load - ensures that the UI will be up-to-date.
            await layer.LoadAsync();

            // Add a row for the current layer.
            _layerListView.AddView(ViewForLayer(layer, nestLevel));

            // Add rows for any children of this layer if it is a group layer.
            if (layer is GroupLayer layerGroup)
            {
                foreach (Layer child in layerGroup.Layers)
                {
                    AddLayersToUI(child, nestLevel + 1);
                }
            }
        }

        private View ViewForLayer(Layer layer, int nestLevel = 0)
        {
            // Create the view that holds the row.
            LinearLayout rowContainer = new LinearLayout(this);
            rowContainer.Orientation = Orientation.Horizontal;

            // Padding implements the nesting/hieararchy display.
            rowContainer.SetPadding(32 * nestLevel, 0, 0, 0);

            // Create and configure the visibility toggle.
            CheckBox toggle = new CheckBox(this);
            toggle.Checked = true;
            toggle.CheckedChange += (sender, args) => layer.IsVisible = toggle.Checked;
            rowContainer.AddView(toggle);

            // Add a label for the layer.
            rowContainer.AddView(new TextView(this) {Text = layer.Name});

            return rowContainer;
        }

        private void CreateLayout()
        {
            // Create a new vertical layout for the app.
            var layout = new LinearLayout(this) {Orientation = Orientation.Vertical};

            _layerListView = new LinearLayout(this);
            _layerListView.Orientation = Orientation.Vertical;

            layout.AddView(_layerListView);

            // Add the map view to the layout.
            _mySceneView = new SceneView(this);
            layout.AddView(_mySceneView);

            // Show the layout in the app.
            SetContentView(layout);
        }

        protected override void OnDestroy()
        {
            base.OnDestroy();

            // Remove the sceneview
            (_mySceneView.Parent as ViewGroup).RemoveView(_mySceneView);
            _mySceneView.Dispose();
            _mySceneView = null;
        }
    }
}

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