Generate offline map (overrides)

View inMAUIUWPWPFWinUIView on GitHub

Take a web map offline with additional options for each layer.

Image of generate offline map overrides

Use case

When taking a web map offline, you may adjust the data (such as layers or tiles) that is downloaded by using custom parameter overrides. This can be used to reduce the extent of the map or the download size of the offline map. It can also be used to highlight specific data by removing irrelevant data. Additionally, this workflow allows you to take features offline that don't have a geometry - for example, features whose attributes have been populated in the office, but still need a site survey for their geometry.

How to use the sample

Modify the overrides parameters:

  • Use the min/max scale input fields to adjust the level IDs to be taken offline for the streets basemap.
  • Use the extent buffer distance input field to set the buffer radius for the streets basemap.
  • Check the checkboxes for the feature operational layers you want to include in the offline map.
  • Use the min hydrant flow rate input field to only download features with a flow rate higher than this value.
  • Select the "Water Pipes" checkbox if you want to crop the water pipe features to the extent of the map.

After you have set up the overrides to your liking, tap the "Generate offline map" button to start the download. A progress bar will display. Tap the "Cancel" button if you want to stop the download. When the download is complete, the view will display the offline map. Pan around to see that it is cropped to the download area's extent.

How it works

  1. Load a web map from a PortalItem. Authenticate with the portal if required.
  2. Create an OfflineMapTask with the map.
  3. Generate default task parameters using the extent area you want to download with offlineMapTask.CreateDefaultGenerateOfflineMapParametersAsync(extent).
  4. Generate additional "override" parameters using the default parameters with offlineMapTask.CreateGenerateOfflineMapParameterOverridesAsync(parameters).
  5. For the basemap:
    • Get the parameters OfflineMapParametersKey for the basemap layer.
    • Get the ExportTileCacheParameters for the basemap layer with overrides.ExportTileCacheParameters[basemapParamKey].
    • Set the level IDs you want to download with exportTileCacheParametersLevelIDs().Add(levelID).
    • To buffer the extent, set the exportTileCacheParameters.AreaOfInterest property. B uffered geometry can be calculated with the GeometryEngine.
  6. To remove operational layers from the download:
    • Create a OfflineParametersKey with the operational layer.
    • Get the generate geodatabase layer options using the key with List<GenerateLayerOption> layerOptions = overrides.GenerateGeodatabaseParameters[key].LayerOptions;
    • Loop through each GenerateLayerOption in the the list, and remove it if the layer option's ID matches the layer's ID.
  7. To filter the features downloaded in an operational layer:
    • Get the layer options for the operational layer using the directions in step 6.
    • Loop through the layer options. If the option LayerID matches the layer's ID, set the filter clause with layerOption.WhereClause property and set the query option with layerOption.QueryOption property.
  8. To not crop a layer's features to the extent of the offline map (default is true):
    • Set the layerOption.UseGeometry property to false.
  9. Create a GenerateOfflineMapJob with offlineMapTask.GenerateOfflineMap(parameters, downloadPath, overrides).
  10. Get a reference to the offline map with job.GetResultAsync()

Relevant API

  • ExportTileCacheParameters
  • GenerateGeodatabaseParameters
  • GenerateLayerOption
  • GenerateOfflineMapJob
  • GenerateOfflineMapParameterOverrides
  • GenerateOfflineMapParameters
  • GenerateOfflineMapResult
  • OfflineMapParametersKey
  • OfflineMapTask

Additional information

For applications where you just need to take all layers offline, use the standard workflow (using only GenerateOfflineMapParameters). For a simple example of how you take a map offline, please consult the "Generate offline map" sample.

Tags

adjust, download, extent, filter, LOD, offline, override, parameters, reduce, scale range, setting

Sample Code

GenerateOfflineMapWithOverrides.xaml.csGenerateOfflineMapWithOverrides.xaml.csGenerateOfflineMapWithOverrides.xamlConfigureOverridesPage.xaml.csConfigureOverridesPage.xaml
Use dark colors for code blocksCopy
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
// Copyright 2022 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.Symbology;
using Esri.ArcGISRuntime.Tasks;
using Esri.ArcGISRuntime.Tasks.Offline;
using Esri.ArcGISRuntime.UI;

#if ANDROID

using Application = Microsoft.Maui.Controls.Application;

#endif

namespace ArcGIS.Samples.GenerateOfflineMapWithOverrides
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Generate offline map (overrides)",
        category: "Map",
        description: "Take a web map offline with additional options for each layer.",
        instructions: "Modify the overrides parameters:",
        tags: new[] { "LOD", "adjust", "download", "extent", "filter", "offline", "override", "parameters", "reduce", "scale range", "setting" })]
    [ArcGIS.Samples.Shared.Attributes.ClassFile("ConfigureOverridesPage.xaml.cs", "ConfigureOverridesPage.xaml")]
    public partial class GenerateOfflineMapWithOverrides : ContentPage
    {
        // The job to generate an offline map.
        private GenerateOfflineMapJob _generateOfflineMapJob;

        // The extent of the data to take offline.
        private 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 GenerateOfflineMapWithOverrides()
        {
            InitializeComponent();

            // Load the web map, show area of interest, restrict map interaction, and set up authorization.
            _ = Initialize();
        }

        private async Task Initialize()
        {
            try
            {
                // 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.
                var 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.
                var aoiOutlineSymbol = new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, System.Drawing.Color.Red, 3);
                var 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.
                var aoiGraphic = new Graphic(_areaOfInterest);
                extentOverlay.Graphics.Add(aoiGraphic);

                // Hide the map loading progress indicator.
                LoadingIndicator.IsVisible = false;
            }
            catch (Exception ex)
            {
                await Application.Current.MainPage.DisplayAlert("Alert", ex.ToString(), "OK");
            }
        }

        private async void TakeMapOfflineButton_Click(object sender, EventArgs e)
        {
            try
            {
                // Clean up any previous outputs in the temp directory.
                string tempPath = $"{Path.GetTempPath()}";
                string[] outputFolders = Directory.GetDirectories(tempPath, "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).
                    }
                }

                // Create a new folder for the output mobile map.
                string packagePath = Path.Combine(tempPath, @"NapervilleWaterNetwork");
                int num = 1;
                while (Directory.Exists(packagePath))
                {
                    packagePath = Path.Combine(tempPath, @"NapervilleWaterNetwork" + num.ToString());
                    num++;
                }

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

                // 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);

                // Generate parameter overrides for more in-depth control of the job.
                GenerateOfflineMapParameterOverrides overrides = await takeMapOfflineTask.CreateGenerateOfflineMapParameterOverridesAsync(parameters);

                // Create the UI for configuring the overrides.
                var configurationPage = new ConfigureOverridesPage(overrides, MyMapView.Map);

                // Wait for the user to finish with the configuration, then continue.
                configurationPage.Disappearing += async (o, args) =>
                {
                    try
                    {
                        // Re-show the busy indicator.
                        BusyIndicator.IsVisible = true;

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

                        // 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)
                        {
                            await Application.Current.MainPage.DisplayAlert("Alert", "Generate offline map package failed.", "OK");
                            BusyIndicator.IsVisible = false;
                        }

                        // 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();
                            await Application.Current.MainPage.DisplayAlert("Alert", errorText, "OK");
                        }

                        // 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.
                        await Application.Current.MainPage.DisplayAlert("Alert", "Map is offline.", "OK");

                        TakeMapOfflineButton.IsEnabled = false;
                    }
                    catch (TaskCanceledException)
                    {
                        // Generate offline map task was canceled.
                        await Application.Current.MainPage.DisplayAlert("Alert", "Taking map offline was canceled.", "OK");
                    }
                    catch (Exception ex)
                    {
                        // Exception while taking the map offline.
                        await Application.Current.MainPage.DisplayAlert("Alert", ex.ToString(), "OK");
                    }
                    finally
                    {
                        // Hide the busy indicator.
                        BusyIndicator.IsVisible = false;
                    }
                };

                // Show the configuration UI.
                await Shell.Current.Navigation.PushModalAsync(configurationPage, true);
            }
            catch (Exception ex)
            {
                await Application.Current.MainPage.DisplayAlert("Alert", ex.ToString(), "OK");
            }
        }

        // 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.
            Microsoft.Maui.ApplicationModel.MainThread.BeginInvokeOnMainThread(() =>
            {
                // Show the percent complete and update the progress bar.
                Percentage.Text = job.Progress > 0 ? job.Progress.ToString() + " %" : string.Empty;
                ProgressBar.Progress = job.Progress / 100.0;
            });
        }

        private void CancelJobButton_Click(object sender, EventArgs e)
        {
            // The user canceled the job.
            _generateOfflineMapJob.CancelAsync();

            // Hide the busy indicator.
            BusyIndicator.IsVisible = false;
        }
    }
}

Your browser is no longer supported. Please upgrade your browser for the best experience. See our browser deprecation post for more details.