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OfflineMapTask Class

A task used to take a map offline.
Inheritance Hierarchy
SystemObject
  Esri.ArcGISRuntime.Tasks.OfflineOfflineMapTask

Namespace:  Esri.ArcGISRuntime.Tasks.Offline
Assembly:  Esri.ArcGISRuntime (in Esri.ArcGISRuntime.dll) Version: 100.11.0
Syntax
public sealed class OfflineMapTask

The OfflineMapTask type exposes the following members.

Properties
  NameDescription
Public propertyOnlineMap
Gets the online Map to be taken offline.
Public propertyPortalItem
Gets the PortalItem specifying the map to be take offline.
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Methods
  NameDescription
Public methodStatic memberCode exampleCreateAsync(Map)
Initializes a new instance of the OfflineMapTask class for the provided online map.
Public methodStatic memberCode exampleCreateAsync(PortalItem)
Initializes a new instance of the OfflineMapTask class from the specified PortalItem. The portal item must represent a webmap.
Public methodCode exampleCreateDefaultDownloadPreplannedOfflineMapParametersAsync
Public methodCode exampleCreateDefaultGenerateOfflineMapParametersAsync(Geometry)
Returns a Task of GenerateOfflineMapParameters created from the specified area of interest.
Public methodCreateDefaultGenerateOfflineMapParametersAsync(Geometry, Double, Double)
Public methodCode exampleCreateGenerateOfflineMapParameterOverridesAsync
Public methodCode exampleDownloadPreplannedOfflineMap(DownloadPreplannedOfflineMapParameters, String)
Returns a job that is used to download the PreplannedMapArea specified by the given parameters object.
Public methodDownloadPreplannedOfflineMap(PreplannedMapArea, String) Obsolete.
Returns a job that is used to download the specified preplanned map area of an online map.
Public methodDownloadPreplannedOfflineMap(PreplannedMapArea, String, Boolean) Obsolete.
Returns a job that is used to download the specified preplanned map area of an online map but excludes the map's basemap.
Public methodCode exampleGenerateOfflineMap(GenerateOfflineMapParameters, String)
Returns a job that is used to generate an offline map using the specified parameters.
Public methodCode exampleGenerateOfflineMap(GenerateOfflineMapParameters, String, GenerateOfflineMapParameterOverrides)
Returns a job that is used to generate an offline map using the specified parameters and overrides.
Public methodGetOfflineMapCapabilitiesAsync
Public methodCode exampleGetPreplannedMapAreasAsync
Asynchronously retrieves a list of offline map areas, if there are any.
Top
Remarks

Taking a map offline involves downloading an online map and its data, including all the supported layers, tables, renderers, web map configuration etc. so that it can be used offline without a network connection. There are two workflows available for taking maps offline:

  • the preplanned offline workflow
  • the on-demand offline workflow

Preplanned offline workflow. In this workflow the author of an online map can define individual geographical areas called map areas. These map areas prepare map content that is stored online. An app can download that map content to a device using the DownloadPreplannedOfflineMapJob.

On-demand offline workflow. Here the app passes a specific area of interest to a GenerateOfflineMapJob to generate and download the map content to the device. Using this workflow, you can choose to keep online only services (e.g. those that require a network connection) in your offline map. Be aware that an offline map which uses online only services will require a network connection and may require authentication.

Examples

WPF

Example Name: OfflineBasemapByReference

Use the `OfflineMapTask` to take a web map offline, but instead of downloading an online basemap, use one which is already on the device.

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 Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Portal;
using Esri.ArcGISRuntime.Security;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.Tasks;
using Esri.ArcGISRuntime.Tasks.Offline;
using Esri.ArcGISRuntime.UI;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Navigation;
using System.Windows.Threading;
using ArcGISRuntime.Samples.Managers;

namespace ArcGISRuntime.WPF.Samples.OfflineBasemapByReference
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Generate offline map with local basemap",
        category: "Map",
        description: "Use the `OfflineMapTask` to take a web map offline, but instead of downloading an online basemap, use one which is already on the device.",
        instructions: "1. Use the button to start taking the map offline.",
        tags: new[] { "Offline" })]
    [ArcGISRuntime.Samples.Shared.Attributes.OfflineData("628e8e3521cf45e9a28a12fe10c02c4d")]
    public partial class OfflineBasemapByReference
    {
        // The job to generate an offline map.
        private GenerateOfflineMapJob _generateOfflineMapJob;

        // The extent of the data to take offline.
        private readonly Envelope _areaOfInterest = new Envelope(-88.1541, 41.7690, -88.1471, 41.7720, SpatialReferences.Wgs84);

        // The ID for a web map item hosted on the server (water network map of Naperville IL).
        private const string WebMapId = "acc027394bc84c2fb04d1ed317aac674";

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

        private void ConfigureOfflineJobForBasemap(GenerateOfflineMapParameters parameters)
        {
            // Don't give the user a choice if there is no basemap specified.
            if (String.IsNullOrWhiteSpace(parameters.ReferenceBasemapFilename))
            {
                return;
            }

            // Get the path to the basemap directory.
            string basemapBasePath = DataManager.GetDataFolder("628e8e3521cf45e9a28a12fe10c02c4d");

            // Get the full path to the basemap by combining the name specified in the web map (ReferenceBasemapFilename)
            //  with the offline basemap directory.
            string basemapFullPath = Path.Combine(basemapBasePath, parameters.ReferenceBasemapFilename);

            // If the offline basemap doesn't exist, proceed without it.
            if (!File.Exists(basemapFullPath))
            {
                return;
            }

            // Get the user's choice.
            MessageBoxResult userChoice = MessageBox.Show("Use the offline basemap?", "Basemap choice", MessageBoxButton.YesNo);

            // If the user approves, use the offline basemap.
            if (userChoice == MessageBoxResult.Yes)
            {
                parameters.ReferenceBasemapDirectory = basemapBasePath;
            }
        }

        // Note: all code below (except call to ConfigureOfflineJobForBasemap) is identical to code in the Generate offline map sample.

        #region Generate offline map

        private async void Initialize()
        {
            try
            {
                // Call a function to set up the AuthenticationManager for OAuth.
                SetOAuthInfo();

                // Create the ArcGIS Online portal.
                ArcGISPortal portal = await ArcGISPortal.CreateAsync();

                // Get the Naperville water web map item using its ID.
                PortalItem webmapItem = await PortalItem.CreateAsync(portal, WebMapId);

                // Create a map from the web map item.
                Map onlineMap = new Map(webmapItem);

                // Display the map in the MapView.
                MyMapView.Map = onlineMap;

                // Disable user interactions on the map (no panning or zooming from the initial extent).
                MyMapView.InteractionOptions = new MapViewInteractionOptions
                {
                    IsEnabled = false
                };

                // Create a graphics overlay for the extent graphic and apply a renderer.
                SimpleLineSymbol aoiOutlineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.Red, 3);
                GraphicsOverlay extentOverlay = new GraphicsOverlay
                {
                    Renderer = new SimpleRenderer(aoiOutlineSymbol)
                };
                MyMapView.GraphicsOverlays.Add(extentOverlay);

                // Add a graphic to show the area of interest (extent) that will be taken offline.
                Graphic aoiGraphic = new Graphic(_areaOfInterest);
                extentOverlay.Graphics.Add(aoiGraphic);

                // Hide the map loading progress indicator.
                LoadingIndicator.Visibility = Visibility.Collapsed;

                // When the map view unloads, try to clean up existing output data folders.
                MyMapView.Unloaded += (s, e) =>
                {
                    // Find output mobile map folders in the temp directory.
                    string[] outputFolders = Directory.GetDirectories(Environment.ExpandEnvironmentVariables("%TEMP%"), "NapervilleWaterNetwork*");

                    // Loop through the folder names and delete them.
                    foreach (string dir in outputFolders)
                    {
                        try
                        {
                            // Delete the folder.
                            Directory.Delete(dir, true);
                        }
                        catch (Exception)
                        {
                            // Ignore exceptions (files might be locked, for example).
                        }
                    }
                };
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString(), "Error loading map");
            }
        }

        private async void TakeMapOfflineButton_Click(object sender, RoutedEventArgs e)
        {
            // Create a new folder for the output mobile map.
            string packagePath = Path.Combine(Environment.ExpandEnvironmentVariables("%TEMP%"), @"NapervilleWaterNetwork");
            int num = 1;
            while (Directory.Exists(packagePath))
            {
                packagePath = Path.Combine(Environment.ExpandEnvironmentVariables("%TEMP%"), @"NapervilleWaterNetwork" + num.ToString());
                num++;
            }

            // Create the output directory.
            Directory.CreateDirectory(packagePath);

            try
            {
                // Show the progress indicator while the job is running.
                BusyIndicator.Visibility = Visibility.Visible;

                // Create an offline map task with the current (online) map.
                OfflineMapTask takeMapOfflineTask = await OfflineMapTask.CreateAsync(MyMapView.Map);

                // Create the default parameters for the task, pass in the area of interest.
                GenerateOfflineMapParameters parameters = await takeMapOfflineTask.CreateDefaultGenerateOfflineMapParametersAsync(_areaOfInterest);

                // Configure basemap settings for the job.
                ConfigureOfflineJobForBasemap(parameters);

                // Create the job with the parameters and output location.
                _generateOfflineMapJob = takeMapOfflineTask.GenerateOfflineMap(parameters, packagePath);

                // Handle the progress changed event for the job.
                _generateOfflineMapJob.ProgressChanged += OfflineMapJob_ProgressChanged;

                // Await the job to generate geodatabases, export tile packages, and create the mobile map package.
                GenerateOfflineMapResult results = await _generateOfflineMapJob.GetResultAsync();

                // Check for job failure (writing the output was denied, e.g.).
                if (_generateOfflineMapJob.Status != JobStatus.Succeeded)
                {
                    MessageBox.Show("Generate offline map package failed.", "Job status");
                    BusyIndicator.Visibility = Visibility.Collapsed;
                }

                // Check for errors with individual layers.
                if (results.LayerErrors.Any())
                {
                    // Build a string to show all layer errors.
                    System.Text.StringBuilder errorBuilder = new System.Text.StringBuilder();
                    foreach (KeyValuePair<Layer, Exception> layerError in results.LayerErrors)
                    {
                        errorBuilder.AppendLine($"{layerError.Key.Id} : {layerError.Value.Message}");
                    }

                    // Show layer errors.
                    string errorText = errorBuilder.ToString();
                    MessageBox.Show(errorText, "Layer errors");
                }

                // Display the offline map.
                MyMapView.Map = results.OfflineMap;

                // Apply the original viewpoint for the offline map.
                MyMapView.SetViewpoint(new Viewpoint(_areaOfInterest));

                // Enable map interaction so the user can explore the offline data.
                MyMapView.InteractionOptions.IsEnabled = true;

                // Show a message that the map is offline.
                MessageArea.Visibility = Visibility.Visible;

                // Hide the controls.
                TakeOfflineArea.Visibility = Visibility.Collapsed;
            }
            catch (TaskCanceledException)
            {
                // Generate offline map task was canceled.
                MessageBox.Show("Taking map offline was canceled");
            }
            catch (Exception ex)
            {
                // Exception while taking the map offline.
                MessageBox.Show(ex.Message, "Offline map error");
            }
            finally
            {
                // Hide the activity indicator when the job is done.
                BusyIndicator.Visibility = Visibility.Collapsed;
            }
        }

        // Show changes in job progress.
        private void OfflineMapJob_ProgressChanged(object sender, EventArgs e)
        {
            // Get the job.
            GenerateOfflineMapJob job = sender as GenerateOfflineMapJob;

            // Dispatch to the UI thread.
            Dispatcher.Invoke(() =>
            {
                // Show the percent complete and update the progress bar.
                Percentage.Text = job.Progress > 0 ? job.Progress.ToString() + " %" : string.Empty;
                ProgressBar.Value = job.Progress;
            });
        }

        private void CancelJobButton_Click(object sender, RoutedEventArgs e)
        {
            // The user canceled the job.
            _generateOfflineMapJob.Cancel();
        }

        #endregion Generate offline map

        #region Authentication

        // Constants for OAuth-related values.
        // - The URL of the portal to authenticate with (ArcGIS Online).
        private const string ServerUrl = "https://www.arcgis.com/sharing/rest";

        // - The Client ID for an app registered with the server (the ID below is for a public app created by the ArcGIS Runtime team).
        private const string AppClientId = @"lgAdHkYZYlwwfAhC";

        // - A URL for redirecting after a successful authorization (this must be a URL configured with the app).
        private const string OAuthRedirectUrl = @"my-ags-app://auth";

        private void SetOAuthInfo()
        {
            // Register the server information with the AuthenticationManager, including the OAuth settings.
            ServerInfo serverInfo = new ServerInfo
            {
                ServerUri = new Uri(ServerUrl),
                TokenAuthenticationType = TokenAuthenticationType.OAuthImplicit,
                OAuthClientInfo = new OAuthClientInfo
                {
                    ClientId = AppClientId,
                    RedirectUri = new Uri(OAuthRedirectUrl)
                }
            };

            // Register this server with AuthenticationManager.
            AuthenticationManager.Current.RegisterServer(serverInfo);

            // Use the custom OAuthAuthorize class (defined in this module) to handle OAuth communication.
            AuthenticationManager.Current.OAuthAuthorizeHandler = new OAuthAuthorize();

            // Use a function in this class to challenge for credentials.
            AuthenticationManager.Current.ChallengeHandler = new ChallengeHandler(CreateCredentialAsync);
        }

        private async Task<Credential> CreateCredentialAsync(CredentialRequestInfo info)
        {
            // ChallengeHandler function for AuthenticationManager that will be called whenever a secured resource is accessed.
            Credential credential;

            try
            {
                // AuthenticationManager will handle challenging the user for credentials.
                credential = await AuthenticationManager.Current.GenerateCredentialAsync(info.ServiceUri);
            }
            catch (Exception)
            {
                // Exception will be reported in calling function.
                throw;
            }

            return credential;
        }

        private class OAuthAuthorize : IOAuthAuthorizeHandler
        {
            // A window to contain the OAuth UI.
            private Window _authWindow;

            // A TaskCompletionSource to track the completion of the authorization.
            private TaskCompletionSource<IDictionary<string, string>> _taskCompletionSource;

            // URL for the authorization callback result (the redirect URI configured for the application).
            private string _callbackUrl;

            // URL that handles the OAuth request.
            private string _authorizeUrl;

            // A function to handle authorization requests. It takes the URIs for the secured service, the authorization endpoint, and the redirect URI.
            public Task<IDictionary<string, string>> AuthorizeAsync(Uri serviceUri, Uri authorizeUri, Uri callbackUri)
            {
                // If the TaskCompletionSource.Task has not completed, authorization is in progress.
                if (_taskCompletionSource != null || _authWindow != null)
                {
                    // Allow only one authorization process at a time.
                    throw new Exception("Authorization is in progress");
                }

                // Store the authorization and redirect URLs.
                _authorizeUrl = authorizeUri.AbsoluteUri;
                _callbackUrl = callbackUri.AbsoluteUri;

                // Create a task completion source to track completion.
                _taskCompletionSource = new TaskCompletionSource<IDictionary<string, string>>();

                // Call a function to show the login controls, make sure it runs on the UI thread.
                Dispatcher dispatcher = Application.Current.Dispatcher;
                if (dispatcher == null || dispatcher.CheckAccess())
                    AuthorizeOnUIThread(_authorizeUrl);
                else
                {
                    Action authorizeOnUIAction = () => AuthorizeOnUIThread(_authorizeUrl);
                    dispatcher.BeginInvoke(authorizeOnUIAction);
                }

                // Return the task associated with the TaskCompletionSource.
                return _taskCompletionSource.Task;
            }

            // A function to challenge for OAuth credentials on the UI thread.
            private void AuthorizeOnUIThread(string authorizeUri)
            {
                // Create a WebBrowser control to display the authorize page.
                WebBrowser authBrowser = new WebBrowser();

                // Handle the navigating event for the browser to check for a response sent to the redirect URL.
                authBrowser.Navigating += WebBrowserOnNavigating;

                // Display the web browser in a new window.
                _authWindow = new Window
                {
                    Content = authBrowser,
                    Height = 420,
                    Width = 350,
                    WindowStartupLocation = WindowStartupLocation.CenterOwner
                };

                // Set the app's window as the owner of the browser window (if main window closes, so will the browser).
                if (Application.Current != null && Application.Current.MainWindow != null)
                {
                    _authWindow.Owner = Application.Current.MainWindow;
                }

                // Handle the window closed event then navigate to the authorize url.
                _authWindow.Closed += OnWindowClosed;
                authBrowser.Navigate(authorizeUri);

                // Display the Window.
                _authWindow?.ShowDialog();
            }

            private void OnWindowClosed(object sender, EventArgs e)
            {
                // If the browser window closes, return the focus to the main window.
                _authWindow?.Owner?.Focus();

                // If the task wasn't completed, the user must have closed the window without logging in.
                if (_taskCompletionSource != null && !_taskCompletionSource.Task.IsCompleted)
                {
                    // Set the task completion to indicate a canceled operation.
                    _taskCompletionSource.TrySetCanceled();
                }

                _taskCompletionSource = null;
                _authWindow = null;
            }

            // Handle browser navigation (page content changing).
            private void WebBrowserOnNavigating(object sender, NavigatingCancelEventArgs e)
            {
                // Check for a response to the callback url.
                WebBrowser webBrowser = sender as WebBrowser;
                Uri uri = e.Uri;

                // If no browser, uri, or an empty url return.
                if (webBrowser == null || uri == null || _taskCompletionSource == null || String.IsNullOrEmpty(uri.AbsoluteUri))
                {
                    return;
                }

                // Check if the new content is from the callback url.
                bool isRedirected = uri.AbsoluteUri.StartsWith(_callbackUrl);

                if (isRedirected)
                {
                    // Cancel the event to prevent it from being handled elsewhere.
                    e.Cancel = true;

                    // Get a local copy of the task completion source.
                    TaskCompletionSource<IDictionary<string, string>> tcs = _taskCompletionSource;
                    _taskCompletionSource = null;

                    // Close the window.
                    _authWindow?.Close();

                    // Call a helper function to decode the response parameters (which includes the authorization key).
                    IDictionary<string, string> authResponse = DecodeParameters(uri);

                    // Set the result for the task completion source.
                    tcs.SetResult(authResponse);
                }
            }

            // A helper function that decodes values from a querystring into a dictionary of keys and values.
            private static IDictionary<string, string> DecodeParameters(Uri uri)
            {
                // Create a dictionary of key value pairs returned in an OAuth authorization response URI query string.
                string answer = "";

                // Get the values from the URI fragment or query string.
                if (!string.IsNullOrEmpty(uri.Fragment))
                {
                    answer = uri.Fragment.Substring(1);
                }
                else
                {
                    if (!string.IsNullOrEmpty(uri.Query))
                    {
                        answer = uri.Query.Substring(1);
                    }
                }

                // Parse parameters into key / value pairs.
                Dictionary<string, string> keyValueDictionary = new Dictionary<string, string>();
                string[] keysAndValues = answer.Split(new[] {'&'}, StringSplitOptions.RemoveEmptyEntries);
                foreach (string kvString in keysAndValues)
                {
                    string[] pair = kvString.Split('=');
                    string key = pair[0];
                    string value = string.Empty;
                    if (key.Length > 1)
                    {
                        value = Uri.UnescapeDataString(pair[1]);
                    }

                    keyValueDictionary.Add(key, value);
                }

                // Return the dictionary of string keys/values.
                return keyValueDictionary;
            }
        }

        #endregion
    }
}
XAML
<UserControl x:Class="ArcGISRuntime.WPF.Samples.OfflineBasemapByReference.OfflineBasemapByReference"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:esri="http://schemas.esri.com/arcgis/runtime/2013">
    <Grid>
        <esri:MapView x:Name="MyMapView" />
        <Border x:Name="TakeOfflineArea" Style="{StaticResource BorderStyle}">
            <StackPanel>
                <Button Content="Take map offline"
                        Click="TakeMapOfflineButton_Click"
                        IsEnabled="True" />
            </StackPanel>
        </Border>
        <Border x:Name="MessageArea" Style="{StaticResource BorderStyle}" Visibility="Collapsed">
            <StackPanel>
                <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Margin="10"
                           FontWeight="Bold"
                           Text="Map is offline!" />
            </StackPanel>
        </Border>
        <Grid x:Name="BusyIndicator" Background="#807f7f7f" Visibility="Collapsed">
            <Grid HorizontalAlignment="Center" VerticalAlignment="Center">
                <Grid.RowDefinitions>
                    <RowDefinition Height="auto" />
                    <RowDefinition Height="auto" />
                    <RowDefinition Height="auto" />
                </Grid.RowDefinitions>
                <TextBlock HorizontalAlignment="Center" VerticalAlignment="Center" Margin="10"
                           Foreground="White" FontSize="18">
                    <Run Text="Generating offline map... " />
                    <Run x:Name="Percentage" Text="" />
                </TextBlock>
                <ProgressBar x:Name="ProgressBar"
                             Grid.Row="1"
                             Minimum="0" Maximum="100"
                             IsEnabled="True"
                             HorizontalAlignment="Center" VerticalAlignment="Center"
                             Width="100" Height="10" Margin="0,0,0,10" />
                <Button Content="Cancel"
                        Grid.Row="2"
                        Click="CancelJobButton_Click"
                        HorizontalAlignment="Center"
                        Width="100" />
            </Grid>
        </Grid>
        <Grid x:Name="LoadingIndicator"
              Background="#807f7f7f"
              Visibility="Visible">
            <Grid HorizontalAlignment="Center" VerticalAlignment="Center">
                <Grid.RowDefinitions>
                    <RowDefinition Height="auto" />
                    <RowDefinition Height="auto" />
                </Grid.RowDefinitions>
                <TextBlock Text="Loading online map..."
                           Foreground="White" FontSize="18"
                           Margin="10" />
                <ProgressBar Grid.Row="1"
                             IsEnabled="True" IsIndeterminate="True"
                             Width="100" Height="10"
                             HorizontalAlignment="Center" VerticalAlignment="Center" />
            </Grid>
        </Grid>
    </Grid>
</UserControl>
See Also
Additional Examples
Hyperlink to ExampleDescription
DownloadPreplannedMapTake a map offline using a preplanned map area.
GenerateOfflineMapTake a web map offline.
GenerateOfflineMapWithOverridesTake a web map offline with additional options for each layer.
OfflineBasemapByReferenceUse the `OfflineMapTask` to take a web map offline, but instead of downloading an online basemap, use one which is already on the device.