Offline geocode

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Geocode addresses to locations and reverse geocode locations to addresses offline.

Image of offline geocode

Use case

You can use an address locator file to geocode addresses and locations. For example, you could provide offline geocoding capabilities to field workers repairing critical infrastructure in a disaster when network availability is limited.

How to use the sample

Type the address in the Search menu option or select from the list to Geocode the address and view the result on the map. Tap the location you want to reverse geocode. Tap the pin to see the full address.

How it works

  1. Use the path of a .loc file to create a LocatorTask object.
  2. Set up GeocodeParameters and call GeocodeAsync to get geocode results.

Relevant API

  • GeocodeParameters
  • GeocodeResult
  • LocatorTask
  • ReverseGeocodeParameters

Offline data

This sample downloads the following items from ArcGIS Online automatically:

Tags

geocode, geocoder, locator, offline, package, query, search

Sample Code

OfflineGeocode.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.Text;
using Android.Views;
using Android.Widget;
using ArcGISRuntime.Samples.Managers;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.Tasks.Geocoding;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Threading.Tasks;

namespace ArcGISRuntimeXamarin.Samples.OfflineGeocode
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Offline geocode",
        category: "Search",
        description: "Geocode addresses to locations and reverse geocode locations to addresses offline.",
        instructions: "Type the address in the Search menu option or select from the list to `Geocode` the address and view the result on the map. Tap the location you want to reverse geocode. Tap the pin to see the full address.",
        tags: new[] { "geocode", "geocoder", "locator", "offline", "package", "query", "search" })]
    [ArcGISRuntime.Samples.Shared.Attributes.OfflineData("22c3083d4fa74e3e9b25adfc9f8c0496", "344e3b12368543ef84045ef9aa3c32ba")]
    public class OfflineGeocode : Activity
    {
        // Hold references to the UI controls.
        private MapView _myMapView;
        private EditText _addressSearchBar;
        private Button _suggestButton;
        private Button _searchButton;

        // Addresses for suggestion.
        private readonly string[] _addresses =
        {
            "910 N Harbor Dr, San Diego, CA 92101",
            "2920 Zoo Dr, San Diego, CA 92101",
            "111 W Harbor Dr, San Diego, CA 92101",
            "868 4th Ave, San Diego, CA 92101",
            "750 A St, San Diego, CA 92101"
        };

        // The LocatorTask provides geocoding services.
        private LocatorTask _geocoder;

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

            Title = "Offline geocode";

            CreateLayout();
            Initialize();
        }

        private async void Initialize()
        {
            // Get the offline tile package and use it as a basemap.
            string basemapPath = DataManager.GetDataFolder("22c3083d4fa74e3e9b25adfc9f8c0496", "streetmap_SD.tpkx");
            ArcGISTiledLayer tiledBasemapLayer = new ArcGISTiledLayer(new TileCache(basemapPath));

            // Create new Map with basemap.
            Map myMap = new Map(new Basemap(tiledBasemapLayer));

            // Provide Map to the MapView.
            _myMapView.Map = myMap;

            // Add a graphics overlay for showing pins.
            _myMapView.GraphicsOverlays.Add(new GraphicsOverlay());

            // Enable tap-for-info pattern on results.
            _myMapView.GeoViewTapped += MyMapView_GeoViewTapped;

            try
            {
                // Get the path to the locator.
                string locatorPath = DataManager.GetDataFolder("344e3b12368543ef84045ef9aa3c32ba", "san-diego-locator.loc");

                // Load the geocoder.
                _geocoder = await LocatorTask.CreateAsync(new Uri(locatorPath));

                // Enable interaction now that the geocoder is ready.
                _suggestButton.Enabled = true;
                _addressSearchBar.Enabled = true;
                _searchButton.Enabled = true;
            }
            catch (Exception ex)
            {
                new AlertDialog.Builder(this).SetMessage(ex.ToString()).SetTitle("Error").Show();
            }
        }

        private void _searchHintButton_Click(object sender, EventArgs e)
        {
            // Create an AlertDialog.
            AlertDialog.Builder builder = new AlertDialog.Builder(this);

            // Provide the addresses; lambda updates the search with the selected item.
            builder.SetTitle("Suggestions").SetItems(_addresses, (_sender, _e) =>
            {
                string address = _addresses[_e.Which]; // get the selected address
                _addressSearchBar.Text = address;
                updateSearch();
            });

            // Show the dialog.
            AlertDialog alert = builder.Create();
            alert.Show();
        }

        private void SearchButton_Click(object sender, EventArgs e)
        {
            updateSearch();
        }

        private async void updateSearch()
        {
            // Get the text in the search bar.
            string enteredText = _addressSearchBar.Text;

            // Clear existing marker.
            _myMapView.GraphicsOverlays[0].Graphics.Clear();
            _myMapView.DismissCallout();

            // Return gracefully if the textbox is empty or the geocoder isn't ready.
            if (String.IsNullOrWhiteSpace(enteredText) || _geocoder == null)
            {
                return;
            }

            try
            {
                // Get suggestions based on the input text.
                IReadOnlyList<GeocodeResult> geocodeResults = await _geocoder.GeocodeAsync(enteredText);

                // Stop if there are no suggestions.
                if (!geocodeResults.Any())
                {
                    new AlertDialog.Builder(this).SetMessage("No results found.").SetTitle("No results").Show();
                    return;
                }

                // Get the full address for the first suggestion.
                GeocodeResult firstSuggestion = geocodeResults.First();
                IReadOnlyList<GeocodeResult> addresses = await _geocoder.GeocodeAsync(firstSuggestion.Label);

                // Stop if the geocoder does not return a result.
                if (addresses.Count < 1)
                {
                    return;
                }

                // Show a graphic for the address.
                Graphic point = await GraphicForPoint(addresses.First().DisplayLocation);
                _myMapView.GraphicsOverlays[0].Graphics.Add(point);

                // Update the map extent to show the marker.
                _myMapView.SetViewpoint(new Viewpoint(addresses.First().Extent));
            }
            catch (Exception ex)
            {
                new AlertDialog.Builder(this).SetMessage(ex.ToString()).SetTitle("Error").Show();
            }
        }

        private async Task<Graphic> GraphicForPoint(MapPoint point)
        {
            // Get current assembly that contains the image
            Assembly currentAssembly = Assembly.GetExecutingAssembly();

            // Get image as a stream from the resources
            // Picture is defined as EmbeddedResource and DoNotCopy
            Stream resourceStream = currentAssembly.GetManifestResourceStream(
                "ArcGISRuntime.Resources.PictureMarkerSymbols.pin_star_blue.png");

            // Create new symbol using asynchronous factory method from stream
            PictureMarkerSymbol pinSymbol = await PictureMarkerSymbol.CreateAsync(resourceStream);
            pinSymbol.Width = 60;
            pinSymbol.Height = 60;
            // The image is a pin; offset the image so that the pinpoint
            //     is on the point rather than the image's true center
            pinSymbol.LeaderOffsetX = 30;
            pinSymbol.OffsetY = 14;
            return new Graphic(point, pinSymbol);
        }

        private async void MyMapView_GeoViewTapped(object sender, GeoViewInputEventArgs e)
        {
            try
            {
                // Clear existing callout and graphics.
                _myMapView.DismissCallout();
                _myMapView.GraphicsOverlays[0].Graphics.Clear();

                // Add a graphic for the tapped point.
                Graphic pinGraphic = await GraphicForPoint(e.Location);
                _myMapView.GraphicsOverlays[0].Graphics.Add(pinGraphic);

                // Reverse geocode to get addresses.
                ReverseGeocodeParameters parameters = new ReverseGeocodeParameters();
                parameters.ResultAttributeNames.Add("*");
                parameters.MaxResults = 1;
                IReadOnlyList<GeocodeResult> addresses = await _geocoder.ReverseGeocodeAsync(e.Location, parameters);

                // Skip if there are no results.
                if (!addresses.Any())
                {
                    new AlertDialog.Builder(this).SetMessage("No results found.").SetTitle("No results").Show();
                    return;
                }

                // Get the first result.
                GeocodeResult address = addresses.First();

                // Use the address as the callout title.
                string calloutTitle = address.Attributes["Street"].ToString();
                string calloutDetail = address.Attributes["City"] + ", " + address.Attributes["State"] + " " + address.Attributes["ZIP"];

                // Define the callout.
                CalloutDefinition calloutBody = new CalloutDefinition(calloutTitle, calloutDetail);

                // Show the callout on the map at the tapped location.
                _myMapView.ShowCalloutForGeoElement(pinGraphic, e.Position, calloutBody);
            }
            catch (Exception ex)
            {
                new AlertDialog.Builder(this).SetMessage(ex.ToString()).SetTitle("Error").Show();
            }
        }

        private void CreateLayout()
        {
            // Initialize the layout.
            LinearLayout layout = new LinearLayout(this) {Orientation = Orientation.Vertical};
            LinearLayout searchBarLayout = new LinearLayout(this);

            // Add the search bar.
            _addressSearchBar = new EditText(this)
            {
                LayoutParameters = new LinearLayout.LayoutParams(
                    ViewGroup.LayoutParams.MatchParent,
                    ViewGroup.LayoutParams.MatchParent,
                    1.0f
                ),
                InputType = InputTypes.ClassText | InputTypes.TextVariationNormal
            };
            _addressSearchBar.SetMaxLines(1);
            layout.AddView(searchBarLayout);
            searchBarLayout.AddView(_addressSearchBar);

            // Add a search button.
            _searchButton = new Button(this) {Text = "Search"};
            searchBarLayout.AddView(_searchButton);

            // Add a suggestion button.
            _suggestButton = new Button(this) {Text = "Suggest"};
            layout.AddView(_suggestButton);

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

            // Keep the search bar from overflowing into multiple lines.
            _addressSearchBar.SetMaxLines(1);

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

            // Disable the buttons and search bar until the geocoder is ready.
            _suggestButton.Enabled = false;
            _addressSearchBar.Enabled = false;
            _searchButton.Enabled = false;

            // Hook up the UI event handlers for suggestion & search.
            _suggestButton.Click += _searchHintButton_Click;
            _searchButton.Click += SearchButton_Click;
        }
    }
}

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