Download preplanned map area

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Take a map offline using a preplanned map area.

Image of download preplanned map area

Use case

Generating offline maps on demand for a specific area can be time consuming for users and a processing load on the server. If areas of interest are known ahead of time, a web map author can pre-create packages for these areas. This way, the generation only needs to happen once, making the workflow more efficient for users and servers.

An archaeology team could define preplanned map areas for dig sites which can be taken offline for field use.

How to use the sample

Select a map area from the Preplanned Map Areas list. Tap the button to download the selected area. The download progress will be shown in the Downloads list. When a download is complete, select it to display the offline map in the map view.

How it works

Open the online Map from a PortalItem and display it.
Create an OfflineMapTask using the portal item.
Get the PreplannedMapAreas from the task, and then load them.
To download a selected map area, create the default DownloadPreplannedOfflineMapParameters from the task using the selected preplanned map area.
Set the update mode of the preplanned map area.
Use the parameters and a download path to create a DownloadPreplannedOfflineMapJob from the task.
Start the job. Once it has completed, get the DownloadPreplannedOfflineMapResult.
Get the Map from the result and display it in the MapView.

Relevant API

DownloadPreplannedOfflineMapJob
DownloadPreplannedOfflineMapParameters
DownloadPreplannedOfflineMapResult
OfflineMapTask
PreplannedMapArea

About the data

The Naperville stormwater network map is based on ArcGIS Solutions for Stormwater and provides a realistic depiction of a theoretical stormwater network.

Additional information

PreplannedUpdateMode can be used to set the way the preplanned map area receives updates in several ways:

NoUpdates - No updates will be performed. This mode is intended for when a static snapshot of the data is required, and it does not create a replica on the service. This is the mode used for this sample.
SyncWithFeatureServices - Changes, including local edits, will be synced directly with the underlying feature services. This is the default update mode.
DownloadScheduledUpdates - Scheduled, read-only updates will be downloaded from the online map area and applied to the local mobile geodatabases.

For more information about offline workflows, see Offline maps, scenes, and data in the ArcGIS Developers guide.

Sample Code

DownloadPreplannedMap.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.Graphics;
using Android.Graphics.Drawables;
using Android.OS;
using Android.Widget;
using ArcGISRuntime.Samples.Managers;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Portal;
using Esri.ArcGISRuntime.Tasks.Offline;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Debug = System.Diagnostics.Debug;
using Path = System.IO.Path;

namespace ArcGISRuntimeXamarin.Samples.DownloadPreplannedMap
{
    [Activity(ConfigurationChanges = Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Download preplanned map area",
        category: "Map",
        description: "Take a map offline using a preplanned map area.",
        instructions: "Select a map area from the Preplanned Map Areas list. Tap the button to download the selected area. The download progress will be shown in the Downloads list. When a download is complete, select it to display the offline map in the map view.",
        tags: new[] { "map area", "offline", "pre-planned", "preplanned" })]
    public class DownloadPreplannedMap : Activity
    {
        // Hold references to the UI controls.
        private MapView _myMapView;
        private LinearLayout _mapListView;
        private AlertDialog _progressView;
        private ProgressBar _progressBar;
        private TextView _helpLabel;
        private Button _showOnlineButton;

        // ID of a web map with preplanned map areas.
        private const string PortalItemId = "acc027394bc84c2fb04d1ed317aac674";

        // Folder to store the downloaded mobile map packages.
        private string _offlineDataFolder;

        // Task for taking map areas offline.
        private OfflineMapTask _offlineMapTask;

        // Hold onto the original map.
        private Map _originalMap;

        // Hold a list of available map areas.
        private readonly List<PreplannedMapArea> _mapAreas = new List<PreplannedMapArea>();

        // Most recently opened map package.
        private MobileMapPackage _mobileMapPackage;

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

            Title = "Download a preplanned map area";

            CreateLayout();
            Initialize();
        }

        private async void Initialize()
        {
            try
            {
                // The data manager provides a method to get a suitable offline data folder.
                _offlineDataFolder = Path.Combine(DataManager.GetDataFolder(), "SampleData", "DownloadPreplannedMapAreas");

                // If temporary data folder doesn't exists, create it.
                if (!Directory.Exists(_offlineDataFolder))
                {
                    Directory.CreateDirectory(_offlineDataFolder);
                }

                // Create a portal to enable access to the portal item.
                ArcGISPortal portal = await ArcGISPortal.CreateAsync();

                // Create the portal item from the portal item ID.
                PortalItem webMapItem = await PortalItem.CreateAsync(portal, PortalItemId);

                // Show the map.
                _originalMap = new Map(webMapItem);
                _myMapView.Map = _originalMap;

                // Create an offline map task for the web map item.
                _offlineMapTask = await OfflineMapTask.CreateAsync(webMapItem);

                // Find the available preplanned map areas.
                IReadOnlyList<PreplannedMapArea> preplannedAreas = await _offlineMapTask.GetPreplannedMapAreasAsync();

                // Load each item, then add it to the list of areas.
                foreach (PreplannedMapArea area in preplannedAreas)
                {
                    await area.LoadAsync();
                    _mapAreas.Add(area);
                }

                // Show the map areas in the UI.
                ConfigureMapsButtons();

                // Hide the loading indicator.
                _progressView.Dismiss();
            }
            catch (Exception ex)
            {
                // Something unexpected happened, show the error message.
                Debug.WriteLine(ex);
                new AlertDialog.Builder(this).SetMessage(ex.ToString()).SetTitle("There was an error.").Show();
            }
        }

        private void ShowOnlineClick(object sender, EventArgs e)
        {
            // Show the map.
            _myMapView.Map = _originalMap;

            // Disable the button.
            _showOnlineButton.Enabled = false;
        }

        private async Task DownloadMapAreaAsync(PreplannedMapArea mapArea)
        {
            // Close the current mobile package.
            _mobileMapPackage?.Close();

            // Set up UI for downloading.
            _progressBar.SetProgress(0, false);
            _progressView.SetMessage("Downloading map area...");
            _progressView.Show();

            // Create folder path where the map package will be downloaded.
            string path = Path.Combine(_offlineDataFolder, mapArea.PortalItem.Title);

            // If the area is already downloaded, open it.
            if (Directory.Exists(path))
            {
                try
                {
                    // Open the offline map package.
                    _mobileMapPackage = await MobileMapPackage.OpenAsync(path);

                    // Open the first map in the package.
                    _myMapView.Map = _mobileMapPackage.Maps.First();

                    // Update the UI.
                    _progressView.SetMessage("");
                    _progressView.Dismiss();
                    _helpLabel.Text = "Opened offline area.";
                    return;
                }
                catch (Exception e)
                {
                    Debug.WriteLine(e);
                    new AlertDialog.Builder(this).SetMessage(e.Message).SetTitle("Couldn't open offline area. Proceeding to take area offline.").Show();
                }
            }

            // Create download parameters.
            DownloadPreplannedOfflineMapParameters parameters = await _offlineMapTask.CreateDefaultDownloadPreplannedOfflineMapParametersAsync(mapArea);

            // Set the update mode to not receive updates.
            parameters.UpdateMode = PreplannedUpdateMode.NoUpdates;

            // Create the job.
            DownloadPreplannedOfflineMapJob job = _offlineMapTask.DownloadPreplannedOfflineMap(parameters, path);

            // Set up event to update the progress bar while the job is in progress.
            job.ProgressChanged += OnJobProgressChanged;

            try
            {
                // Download the area.
                DownloadPreplannedOfflineMapResult results = await job.GetResultAsync();

                // Set the update mode to not receive updates.
                parameters.UpdateMode = PreplannedUpdateMode.NoUpdates;

                // Handle possible errors and show them to the user.
                if (results.HasErrors)
                {
                    // Accumulate all layer and table errors into a single message.
                    string errors = "";

                    foreach (KeyValuePair<Layer, Exception> layerError in results.LayerErrors)
                    {
                        errors = $"{errors}\n{layerError.Key.Name} {layerError.Value.Message}";
                    }

                    foreach (KeyValuePair<FeatureTable, Exception> tableError in results.TableErrors)
                    {
                        errors = $"{errors}\n{tableError.Key.TableName} {tableError.Value.Message}";
                    }

                    // Show the message.
                    new AlertDialog.Builder(this).SetMessage(errors).SetTitle("Warning!").Show();
                }

                // Show the downloaded map.
                _myMapView.Map = results.OfflineMap;

                // Update the UI.
                _helpLabel.Text = "Downloaded offline area.";
                _showOnlineButton.Enabled = true;
            }
            catch (Exception ex)
            {
                // Report any errors.
                Debug.WriteLine(ex);
                new AlertDialog.Builder(this).SetMessage(ex.Message).SetTitle("Downloading map area failed.").Show();
            }
            finally
            {
                _progressBar.SetProgress(0, false);
                _progressView.SetMessage("");
                _progressView.Dismiss();
            }
        }

        private void OnJobProgressChanged(object sender, EventArgs e)
        {
            // Because the event is raised on a background thread, the dispatcher must be used to
            // ensure that UI updates happen on the UI thread.
            RunOnUiThread(() =>
            {
                // Update the UI with the progress.
                DownloadPreplannedOfflineMapJob downloadJob = sender as DownloadPreplannedOfflineMapJob;
                _progressBar.SetProgress(downloadJob.Progress, true);
                _progressView.SetMessage($"{downloadJob.Progress}%");
            });
        }

        private void DeleteButtonOnClick(object sender, EventArgs e)
        {
            try
            {
                // Set up UI for downloading.
                _progressView.SetMessage("Deleting map areas...");
                _progressView.Show();

                // Reset the map.
                _myMapView.Map = _originalMap;

                // Close the current mobile package.
                _mobileMapPackage?.Close();

                // Delete all data from the temporary data folder.
                Directory.Delete(_offlineDataFolder, true);
                Directory.CreateDirectory(_offlineDataFolder);

                // Update the UI.
                _helpLabel.Text = "Deleted offline areas.";
                _showOnlineButton.Enabled = false;
            }
            catch (Exception ex)
            {
                // Report the error.
                Debug.WriteLine(ex);
                new AlertDialog.Builder(this).SetMessage(ex.ToString()).SetTitle("Deleting map areas failed.").Show();
            }
            finally
            {
                _progressView.Dismiss();
            }
        }

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

            // Add a help label.
            _helpLabel = new TextView(this);
            _helpLabel.Text = "Select a map area to take offline.";
            layout.AddView(_helpLabel);

            // Add space for adding options for each map.
            _mapListView = new LinearLayout(this) { Orientation = Orientation.Horizontal };
            layout.AddView(_mapListView);

            // Create a new layout for the buttons.
            LinearLayout buttonLayout = new LinearLayout(this) { Orientation = Orientation.Horizontal };

            // Add button for deleting map areas.
            Button deleteButton = new Button(this) { Text = "Delete offline areas" };
            deleteButton.Click += DeleteButtonOnClick;
            buttonLayout.AddView(deleteButton);

            // Add button for showing the original map.
            _showOnlineButton = new Button(this) { Text = "Show online map", Enabled = false };
            _showOnlineButton.Click += ShowOnlineClick;
            buttonLayout.AddView(_showOnlineButton);

            // Add the buttons to the layout.
            layout.AddView(buttonLayout);

            // Add the map view to the layout.
            _myMapView = new MapView(this);
            layout.AddView(_myMapView);

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

            // Create the progress dialog display.
            _progressBar = new ProgressBar(this);
            _progressBar.SetProgress(0, true);
            AlertDialog.Builder builder = new AlertDialog.Builder(this).SetView(_progressBar);
            builder.SetCancelable(true);
            _progressView = builder.Create();
        }

        private async void ConfigureMapsButtons()
        {
            foreach (PreplannedMapArea mapArea in _mapAreas)
            {
                Button mapButton = new Button(this);

                mapButton.SetTextColor(Color.Black);
                mapButton.Background = Drawable.CreateFromStream(await mapArea.PortalItem.Thumbnail.GetEncodedBufferAsync(), "");
                mapButton.Text = mapArea.PortalItem.Title.Substring(0, 6);
                mapButton.Click += async (o, e) => { await DownloadMapAreaAsync(mapArea); };
                _mapListView.AddView(mapButton);

                LinearLayout.LayoutParams lparams = (LinearLayout.LayoutParams)mapButton.LayoutParameters;
                lparams.SetMargins(5, 5, 0, 5);
                mapButton.LayoutParameters = lparams;
            }
        }

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

            // Close the current mobile package.
            _mobileMapPackage?.Close();
        }
    }
}