Take a web map offline.
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. 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
- Create an
ArcGISMap
with aPortal
item pointing to the web map. - Create
GenerateOfflineMapParameters
specifying the download area geometry, minimum scale, and maximum scale. - Create an
OfflineMapTask
with the map. - Create the
OfflineMapJob
withOfflineMapTask.generateOfflineMap(params, downloadDirectoryPath)
and start it withOfflineMapJob.start()
. - 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
/* 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.ArcGISRuntimeEnvironment;
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);
// authentication with an API key or named user is required
// to access basemaps and other location services
ArcGISRuntimeEnvironment.setApiKey(BuildConfig.API_KEY);
// 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());
}
}
}