Generate offline map

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Take a web map offline.

Image of generate offline map

Use case

Taking a web map offline allows users continued productivity when their network connectivity is poor or nonexistent. For example, by taking a map offline, a field worker inspecting utility lines in remote areas could still access a feature's location and attribute information.

How to use the sample

Once the map loads, zoom to the extent you want to take offline. The red border shows the extent that will be downloaded. Tap the "Take Map Offline" button to start the offline map job. You will be prompted to sign in using an ARCGIS Online organizational account. The progress bar will show the job's progress. When complete, the offline map will replace the online map in the map view.

How it works

  1. Create an ArcGISMap with a Portal item pointing to the web map.
  2. Create GenerateOfflineMapParameters specifying the download area geometry, minimum scale, and maximum scale.
  3. Create an OfflineMapTask with the map.
  4. Create the OfflineMapJob with OfflineMapTask.generateOfflineMap(params, downloadDirectoryPath) and start it with OfflineMapJob.start().
  5. When the job is done, get the offline map with OfflineMapJob.getResult().getOfflineMap().

Relevant API

  • GenerateOfflineMapJob
  • GenerateOfflineMapParameters
  • GenerateOfflineMapResult
  • OfflineMapTask
  • Portal

About the data

The map used in this sample shows the stormwater network within Naperville, IL, USA, with cartography designed for web and mobile devices with offline support.

Additional information

The creation of the offline map can be fine-tuned using parameter overrides for feature layers, or by using local basemaps to achieve more customised results.

Tags

download, offline, save, web map

Sample Code

MainActivity.java
                                                                                                                                                                                                                      
/* Copyright 2018 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.
 *
 */

package com.esri.arcgisruntime.sample.generateofflinemap;

import java.io.File;

import android.app.ProgressDialog;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.widget.Button;
import android.widget.Toast;

import androidx.appcompat.app.AppCompatActivity;
import com.esri.arcgisruntime.concurrent.Job;
import com.esri.arcgisruntime.geometry.Envelope;
import com.esri.arcgisruntime.geometry.Point;
import com.esri.arcgisruntime.loadable.LoadStatus;
import com.esri.arcgisruntime.mapping.ArcGISMap;
import com.esri.arcgisruntime.mapping.view.Graphic;
import com.esri.arcgisruntime.mapping.view.GraphicsOverlay;
import com.esri.arcgisruntime.mapping.view.MapView;
import com.esri.arcgisruntime.portal.Portal;
import com.esri.arcgisruntime.portal.PortalItem;
import com.esri.arcgisruntime.security.AuthenticationManager;
import com.esri.arcgisruntime.security.DefaultAuthenticationChallengeHandler;
import com.esri.arcgisruntime.symbology.SimpleLineSymbol;
import com.esri.arcgisruntime.tasks.offlinemap.GenerateOfflineMapJob;
import com.esri.arcgisruntime.tasks.offlinemap.GenerateOfflineMapParameters;
import com.esri.arcgisruntime.tasks.offlinemap.GenerateOfflineMapResult;
import com.esri.arcgisruntime.tasks.offlinemap.OfflineMapTask;

public class MainActivity extends AppCompatActivity {

  private static final String TAG = MainActivity.class.getSimpleName();

  private MapView mMapView;
  private Button mTakeMapOfflineButton;
  private GraphicsOverlay mGraphicsOverlay;
  private Graphic mDownloadArea;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    // get a reference to the map view
    mMapView = findViewById(R.id.mapView);

    // access button to take the map offline and disable it until map is loaded
    mTakeMapOfflineButton = findViewById(R.id.takeMapOfflineButton);
    mTakeMapOfflineButton.setEnabled(false);

    // handle authentication with the portal
    AuthenticationManager.setAuthenticationChallengeHandler(new DefaultAuthenticationChallengeHandler(this));

    // create a portal item with the itemId of the web map
    Portal portal = new Portal(getString(R.string.portal_url), false);
    PortalItem portalItem = new PortalItem(portal, getString(R.string.item_id));

    // create a map with the portal item
    ArcGISMap map = new ArcGISMap(portalItem);
    map.addDoneLoadingListener(() -> {
      if (map.getLoadStatus() == LoadStatus.LOADED) {
        // limit the map scale to the largest layer scale
        map.setMaxScale(map.getOperationalLayers().get(6).getMaxScale());
        map.setMinScale(map.getOperationalLayers().get(6).getMinScale());
      } else {
        String error = "Map failed to load: " + map.getLoadError().getMessage();
        Toast.makeText(this, error, Toast.LENGTH_LONG).show();
        Log.e(TAG, error);
      }
    });

    // set the map to the map view
    mMapView.setMap(map);

    // create a graphics overlay for the map view
    mGraphicsOverlay = new GraphicsOverlay();
    mMapView.getGraphicsOverlays().add(mGraphicsOverlay);

    // create a graphic to show a box around the extent we want to download
    mDownloadArea = new Graphic();
    mGraphicsOverlay.getGraphics().add(mDownloadArea);
    SimpleLineSymbol simpleLineSymbol = new SimpleLineSymbol(SimpleLineSymbol.Style.SOLID, Color.RED, 2);
    mDownloadArea.setSymbol(simpleLineSymbol);

    // update the download area box whenever the viewpoint changes
    mMapView.addViewpointChangedListener(viewpointChangedEvent -> {
      if (map.getLoadStatus() == LoadStatus.LOADED) {
        // upper left corner of the area to take offline
        android.graphics.Point minScreenPoint = new android.graphics.Point(200, 200);
        // lower right corner of the downloaded area
        android.graphics.Point maxScreenPoint = new android.graphics.Point(mMapView.getWidth() - 200,
            mMapView.getHeight() - 200);
        // convert screen points to map points
        Point minPoint = mMapView.screenToLocation(minScreenPoint);
        Point maxPoint = mMapView.screenToLocation(maxScreenPoint);
        // use the points to define and return an envelope
        if (minPoint != null && maxPoint != null) {
          Envelope envelope = new Envelope(minPoint, maxPoint);
          mDownloadArea.setGeometry(envelope);
          // enable the take map offline button only after the map is loaded
          mTakeMapOfflineButton.setEnabled(true);
        }
      }
    });

    // create a progress dialog to show download progress
    ProgressDialog progressDialog = new ProgressDialog(this);
    progressDialog.setTitle("Generate offline map job");
    progressDialog.setMessage("Taking map offline...");
    progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
    progressDialog.setIndeterminate(false);
    progressDialog.setProgress(0);

    // when the button is clicked, start the offline map task job
    mTakeMapOfflineButton.setOnClickListener(v -> {
      progressDialog.show();

      // delete any offline map already in the cache
      String tempDirectoryPath = getExternalCacheDir() + File.separator + "offlineMap";
      deleteDirectory(new File(tempDirectoryPath));

      // specify the extent, min scale, and max scale as parameters
      double minScale = mMapView.getMapScale();
      double maxScale = mMapView.getMap().getMaxScale();
      // minScale must always be larger than maxScale
      if (minScale <= maxScale) {
        minScale = maxScale + 1;
      }
      GenerateOfflineMapParameters generateOfflineMapParameters = new GenerateOfflineMapParameters(
          mDownloadArea.getGeometry(), minScale, maxScale);
      // set job to cancel on any errors
      generateOfflineMapParameters.setContinueOnErrors(false);

      // create an offline map offlineMapTask with the map
      OfflineMapTask offlineMapTask = new OfflineMapTask(mMapView.getMap());

      // create an offline map job with the download directory path and parameters and start the job
      GenerateOfflineMapJob job = offlineMapTask.generateOfflineMap(generateOfflineMapParameters, tempDirectoryPath);

      // replace the current map with the result offline map when the job finishes
      job.addJobDoneListener(() -> {
        if (job.getStatus() == Job.Status.SUCCEEDED) {
          GenerateOfflineMapResult result = job.getResult();
          mMapView.setMap(result.getOfflineMap());
          mGraphicsOverlay.getGraphics().clear();
          mTakeMapOfflineButton.setEnabled(false);
          Toast.makeText(this, "Now displaying offline map.", Toast.LENGTH_LONG).show();
        } else {
          String error = "Error in generate offline map job: " + job.getError().getAdditionalMessage();
          Toast.makeText(this, error, Toast.LENGTH_LONG).show();
          Log.e(TAG, error);
        }
        progressDialog.dismiss();
      });

      // show the job's progress with the progress dialog
      job.addProgressChangedListener(() -> progressDialog.setProgress(job.getProgress()));

      // start the job
      job.start();
    });

  }

  @Override
  protected void onPause() {
    mMapView.pause();
    super.onPause();
  }

  @Override
  protected void onResume() {
    super.onResume();
    mMapView.resume();
  }

  @Override
  protected void onDestroy() {
    mMapView.dispose();
    super.onDestroy();
  }

  /**
   * Recursively deletes all files in the given directory.
   *
   * @param file to delete
   */
  private static void deleteDirectory(File file) {
    if (file.isDirectory())
      for (File subFile : file.listFiles()) {
        deleteDirectory(subFile);
      }
    if (!file.delete()) {
      Log.e(TAG, "Failed to delete file: " + file.getPath());
    }
  }
}