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KmlDatasetLoadAsync Method

Load the metadata for the object asynchronously.

Namespace:  Esri.ArcGISRuntime.Ogc
Assembly:  Esri.ArcGISRuntime (in Esri.ArcGISRuntime.dll) Version: 100.6.0.0
Syntax
C#
public Task LoadAsync()

Return Value

Type: Task
A task that represents the asynchronous load operation.

Implements

ILoadableLoadAsync
Remarks
Will load the metadata if the object is not loaded. Will always call Loaded if this is called.
Examples

Android

Example Name: PlayKmlTours

Play tours in KML files.

Code example screen shot.

C#
// 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 ArcGISRuntime.Samples.Managers;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Ogc;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using Debug = System.Diagnostics.Debug;

namespace ArcGISRuntimeXamarin.Samples.PlayKmlTours
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Play a KML tour",
        "Layers",
        "Play tours in KML files.",
        "")]
    [ArcGISRuntime.Samples.Shared.Attributes.OfflineData("f10b1d37fdd645c9bc9b189fb546307c")]
    public class PlayKmlTours : Activity
    {
        // Hold references to the UI controls.
        private SceneView _mySceneView;
        private Button _playButton;
        private Button _pauseButton;
        private Button _resetButton;

        // The KML tour controller provides player controls for KML tours.
        private readonly KmlTourController _tourController = new KmlTourController();

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

            Title = "Play a KML tour";

            CreateLayout();
            Initialize();
        }

        private async void Initialize()
        {
            // Load the scene with a basemap and a terrain surface.
            _mySceneView.Scene = new Scene(Basemap.CreateImagery());
            _mySceneView.Scene.BaseSurface.ElevationSources.Add(new ArcGISTiledElevationSource(new Uri("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer")));

            // Get the URL to the data.
            string filePath = DataManager.GetDataFolder("f10b1d37fdd645c9bc9b189fb546307c", "Esri_tour.kmz");
            Uri kmlUrl = new Uri(filePath);

            // Create the KML dataset and layer.
            KmlDataset dataset = new KmlDataset(kmlUrl);
            KmlLayer layer = new KmlLayer(dataset);

            // Add the layer to the map.
            _mySceneView.Scene.OperationalLayers.Add(layer);

            try
            {
                // Load the dataset.
                await dataset.LoadAsync();

                // Find the first KML tour.
                FindKmlTour(dataset.RootNodes);

                // Handle absence of tour gracefully.
                if (_tourController.Tour == null)
                {
                    throw new InvalidOperationException("No tour found. Can't enable touring for a KML file with no tours.");
                }

                // Listen for changes to the tour status.
                _tourController.Tour.PropertyChanged += Tour_PropertyChanged;

                // Enable the play button.
                _playButton.Enabled = true;
            }
            catch (Exception e)
            {
                Debug.WriteLine(e.ToString());
                new AlertDialog.Builder(this).SetMessage(e.ToString()).SetTitle("Error").Show();
            }
        }

        private void FindKmlTour(IEnumerable<KmlNode> rootNodes)
        {
            // Hold a list of nodes to explore.
            Queue<KmlNode> nodesToExplore = new Queue<KmlNode>();

            // Add each root node to the list.
            foreach (KmlNode rootNode in rootNodes)
            {
                nodesToExplore.Enqueue(rootNode);
            }

            // Keep exploring until a tour is found or there are no more nodes.
            while (nodesToExplore.Any())
            {
                // Remove a node from the queue.
                KmlNode currentNode = nodesToExplore.Dequeue();

                // If the node is a tour, use it.
                if (currentNode is KmlTour tourNode)
                {
                    _tourController.Tour = tourNode;
                    return;
                }

                // If the node is a container, add all of its children to the list of nodes to explore.
                if (currentNode is KmlContainer container)
                {
                    foreach (KmlNode node in container.ChildNodes)
                    {
                        nodesToExplore.Enqueue(node);
                    }
                }

                // Otherwise, continue.
            }
        }

        private void Tour_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            // Skip for everything except tour status property changes.
            if (e.PropertyName != nameof(KmlTour.TourStatus))
            {
                return;
            }

            // Set the UI based on the current state of the tour.
            switch (_tourController.Tour.TourStatus)
            {
                case KmlTourStatus.Completed:
                case KmlTourStatus.Initialized:
                    _playButton.Enabled = true;
                    _pauseButton.Enabled = false;
                    break;
                case KmlTourStatus.Paused:
                    _playButton.Enabled = true;
                    _pauseButton.Enabled = false;
                    _resetButton.Enabled = true;
                    break;
                case KmlTourStatus.Playing:
                    _resetButton.Enabled = true;
                    _playButton.Enabled = false;
                    _pauseButton.Enabled = true;
                    break;
            }
        }

        // Play the tour when the button is pressed.
        private void Play_Clicked(object sender, EventArgs e) => _tourController?.Play();

        // Pause the tour when the button is pressed.
        private void Pause_Clicked(object sender, EventArgs e) => _tourController?.Pause();

        // Reset the tour when the button is pressed.
        private void Reset_Clicked(object sender, EventArgs e) => _tourController?.Reset();

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

            // Reset the tour controller when the sample closes - avoids a crash.
            _tourController?.Reset();
        }

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

            // Add a help label.
            TextView helpLabel = new TextView(this);
            helpLabel.Text = "Use the buttons to play the tour. Contains audio. 🎧";
            layout.AddView(helpLabel);

            // Add a row with buttons.
            _playButton = new Button(this) {Text = "Play", Enabled = false};
            _playButton.Click += Play_Clicked;
            _pauseButton = new Button(this) {Text = "Pause", Enabled = false};
            _pauseButton.Click += Pause_Clicked;
            _resetButton = new Button(this) {Text = "Reset", Enabled = false};
            _resetButton.Click += Reset_Clicked;

            LinearLayout rowLayout = new LinearLayout(this) {Orientation = Orientation.Horizontal};

            LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.MatchParent,
                ViewGroup.LayoutParams.MatchParent,
                1.0f
            );
            _playButton.LayoutParameters = param;
            _pauseButton.LayoutParameters = param;
            _resetButton.LayoutParameters = param;

            rowLayout.AddView(_playButton);
            rowLayout.AddView(_pauseButton);
            rowLayout.AddView(_resetButton);

            layout.AddView(rowLayout);

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

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

Xamarin Forms Android

Example Name: PlayKmlTours

Play tours in KML files.

Code example screen shot.

C#
// 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 ArcGISRuntime.Samples.Managers;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Ogc;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Linq;
using Xamarin.Forms;

namespace ArcGISRuntimeXamarin.Samples.PlayKmlTours
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Play a KML tour",
        "Layers",
        "Play tours in KML files.",
        "")]
    [ArcGISRuntime.Samples.Shared.Attributes.OfflineData("f10b1d37fdd645c9bc9b189fb546307c")]
    public partial class PlayKmlTours : ContentPage
    {
        // The KML tour controller provides player controls for KML tours.
        private readonly KmlTourController _tourController = new KmlTourController();

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

        private async void Initialize()
        {
            // Load the scene with a basemap and a terrain surface.
            MySceneView.Scene = new Scene(Basemap.CreateImagery());
            MySceneView.Scene.BaseSurface.ElevationSources.Add(new ArcGISTiledElevationSource(new Uri("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer")));

            // Get the URL to the data.
            string filePath = DataManager.GetDataFolder("f10b1d37fdd645c9bc9b189fb546307c", "Esri_tour.kmz");
            Uri kmlUrl = new Uri(filePath);

            // Create the KML dataset and layer.
            KmlDataset dataset = new KmlDataset(kmlUrl);
            KmlLayer layer = new KmlLayer(dataset);

            // Add the layer to the map.
            MySceneView.Scene.OperationalLayers.Add(layer);

            try
            {
                // Load the dataset.
                await dataset.LoadAsync();

                // Find the first KML tour.
                FindKmlTour(dataset.RootNodes);

                // Handle absence of tour gracefully.
                if (_tourController.Tour == null)
                {
                    throw new InvalidOperationException("No tour found. Can't enable touring for a KML file with no tours.");
                }

                // Listen for changes to the tour status.
                _tourController.Tour.PropertyChanged += Tour_PropertyChanged;

                // Subscribe to notifications about leaving so that the tour can be reset.
                // This looks different because of sample viewer plumbing.
                // Replace `((ArcGISRuntime.SamplePage)this.Parent)` with `this` in your app.
                ((Page)this.Parent).Disappearing += Sample_Unloaded;

                // Enable the play button.
                PlayButton.IsEnabled = true;

                // Hide the status bar.
                LoadingStatusBar.IsVisible = false;
            }
            catch (Exception e)
            {
                Debug.WriteLine(e.ToString());
                await Application.Current.MainPage.DisplayAlert("Error", e.ToString(), "OK");
            }
        }

        private void FindKmlTour(IEnumerable<KmlNode> rootNodes)
        {
            // Hold a list of nodes to explore.
            Queue<KmlNode> nodesToExplore = new Queue<KmlNode>();

            // Add each root node to the list.
            foreach (KmlNode rootNode in rootNodes)
            {
                nodesToExplore.Enqueue(rootNode);
            }

            // Keep exploring until a tour is found or there are no more nodes.
            while (nodesToExplore.Any())
            {
                // Remove a node from the queue.
                KmlNode currentNode = nodesToExplore.Dequeue();

                // If the node is a tour, use it.
                if (currentNode is KmlTour tour)
                {
                    _tourController.Tour = tour;
                    return;
                }

                // If the node is a container, add all of its children to the list of nodes to explore.
                if (currentNode is KmlContainer container)
                {
                    foreach (KmlNode node in container.ChildNodes)
                    {
                        nodesToExplore.Enqueue(node);
                    }
                }

                // Otherwise, continue.
            }
        }

        private void Tour_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            // Skip for everything except tour status property changes.
            if (e.PropertyName != nameof(KmlTour.TourStatus))
            {
                return;
            }

            // Set the UI based on the current state of the tour.
            switch (_tourController.Tour.TourStatus)
            {
                case KmlTourStatus.Completed:
                case KmlTourStatus.Initialized:
                    PlayButton.IsEnabled = true;
                    PauseButton.IsEnabled = false;
                    break;
                case KmlTourStatus.Paused:
                    PlayButton.IsEnabled = true;
                    PauseButton.IsEnabled = false;
                    ResetButton.IsEnabled = true;
                    break;
                case KmlTourStatus.Playing:
                    ResetButton.IsEnabled = true;
                    PlayButton.IsEnabled = false;
                    PauseButton.IsEnabled = true;
                    break;
            }
        }

        // Play the tour when the button is pressed.
        private void Play_Clicked(object sender, EventArgs e) => _tourController?.Play();

        // Pause the tour when the button is pressed.
        private void Pause_Clicked(object sender, EventArgs e) => _tourController?.Pause();

        // Reset the tour when the button is pressed.
        private void Reset_Clicked(object sender, EventArgs e) => _tourController?.Reset();

        // Reset the tour when the user leaves the sample - avoids a crash.
        private void Sample_Unloaded(object sender, EventArgs e) => _tourController?.Reset();
    }
}
XAML
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"             
             xmlns:esriUI="clr-namespace:Esri.ArcGISRuntime.Xamarin.Forms;assembly=Esri.ArcGISRuntime.Xamarin.Forms"
             xmlns:resources="clr-namespace:Forms.Resources;assembly=ArcGISRuntime"
             x:Class="ArcGISRuntimeXamarin.Samples.PlayKmlTours.PlayKmlTours">
    <RelativeLayout>
        <esriUI:SceneView x:Name="MySceneView" Style="{StaticResource SceneWithFormStyle}"
                        BindingContext="{x:Reference Name=ResponsiveFormContainer}" />
        <resources:ResponsiveFormContainer x:Name="ResponsiveFormContainer">
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*" />
                    <ColumnDefinition Width="*" />
                    <ColumnDefinition Width="*" />
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto" />
                    <RowDefinition Height="Auto" />
                    <RowDefinition Height="Auto" />
                </Grid.RowDefinitions>
                <Label Text="Use the buttons to control the tour. Contains audio. 🎧"
                           Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="3"
                           Margin="0,0,0,5"
                           />
                <Button x:Name="PlayButton"
                        Grid.Row="1" Grid.Column="0"
                        Text="Play"
                        IsEnabled="False"
                        Clicked="Play_Clicked" />
                <Button x:Name="PauseButton"
                        Grid.Row="1" Grid.Column="1"
                        Margin="5,0,5,0"
                        Text="Pause"
                        IsEnabled="False"
                        Clicked="Pause_Clicked" />
                <Button x:Name="ResetButton"
                        Grid.Row="1" Grid.Column="2"
                        Text="Reset"
                        IsEnabled="False"
                        Clicked="Reset_Clicked" />
                <ActivityIndicator x:Name="LoadingStatusBar"
                                   Grid.Row="2" Grid.Column="0" Grid.ColumnSpan="3"
                                   Margin="0,5,0,0"
                                   IsEnabled="True" IsRunning="True"  />
            </Grid>
        </resources:ResponsiveFormContainer>
    </RelativeLayout>
</ContentPage>
See Also
Additional Examples
Hyperlink to ExampleDescription
ListKmlContentsList the contents of a KML file. KML files can contain a hierarchy of features, including network links to other KML content.
PlayKmlToursPlay tours in KML files.