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 a Portal 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 with OfflineMapTask.generateOfflineMap(params, downloadDirectoryPath) and start it with OfflineMapJob.start().
When the job is done, get the offline map with OfflineMapJob.result.offlineMap.
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.
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/* 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.
*
*/package com.esri.arcgismaps.sample.generateofflinemap
import android.app.AlertDialog
import android.os.Bundle
import android.util.Log
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import androidx.lifecycle.lifecycleScope
import com.arcgismaps.ApiKey
import com.arcgismaps.LoadStatus
import com.arcgismaps.geometry.Envelope
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.symbology.SimpleLineSymbol
import com.arcgismaps.mapping.symbology.SimpleLineSymbolStyle
import com.arcgismaps.mapping.view.Graphic
import com.arcgismaps.mapping.view.GraphicsOverlay
import com.arcgismaps.mapping.view.ScreenCoordinate
import com.arcgismaps.portal.Portal
import com.arcgismaps.portal.PortalItem
import com.arcgismaps.tasks.offlinemaptask.GenerateOfflineMapJob
import com.arcgismaps.tasks.offlinemaptask.GenerateOfflineMapParameters
import com.arcgismaps.tasks.offlinemaptask.OfflineMapTask
import com.arcgismaps.ArcGISEnvironment
import com.arcgismaps.Color
import com.esri.arcgismaps.sample.generateofflinemap.databinding.ActivityMainBinding
import com.esri.arcgismaps.sample.generateofflinemap.databinding.GenerateOfflineMapDialogLayoutBinding
import com.google.android.material.snackbar.Snackbar
import kotlinx.coroutines.launch
import java.io.File
classMainActivity : AppCompatActivity() {
privateval TAG = MainActivity::class.java.simpleName
// set up data binding for the activityprivateval activityMainBinding: ActivityMainBinding by lazy {
DataBindingUtil.setContentView(this, R.layout.activity_main)
}
privateval mapView by lazy {
activityMainBinding.mapView
}
privateval takeMapOfflineButton by lazy {
activityMainBinding.takeMapOfflineButton
}
privateval graphicsOverlay: GraphicsOverlay by lazy { GraphicsOverlay() }
privateval downloadArea: Graphic = Graphic()
overridefunonCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// authentication with an API key or named user is// required to access basemaps and other location services ArcGISEnvironment.apiKey = ApiKey.create(BuildConfig.API_KEY)
// add mapView to the lifecycle lifecycle.addObserver(mapView)
// disable the button until the map is loaded takeMapOfflineButton.isEnabled = false// create a portal item with the itemId of the web mapval portal = Portal(getString(R.string.portal_url))
val portalItem = PortalItem(portal, getString(R.string.item_id))
// create a symbol to show a box around the extent we want to download downloadArea.symbol = SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Color.red, 2F)
// add the graphic to the graphics overlay when it is created graphicsOverlay.graphics.add(downloadArea)
val map = ArcGISMap(portalItem)
lifecycleScope.launch {
map.load()
.onFailure {
showMessage(it.message.toString())
}
.onSuccess {
// limit the map scale to the largest layer scale map.maxScale = map.operationalLayers[6].maxScale ?: 0.0 map.minScale = map.operationalLayers[6].minScale ?: 0.0// set the map to the map view mapView.map = map
// add the graphics overlay to the map view when it is created mapView.graphicsOverlays.add(graphicsOverlay)
}
}
lifecycleScope.launch {
mapView.viewpointChanged.collect {
// upper left corner of the area to take offlineval minScreenPoint = ScreenCoordinate(200.0, 200.0)
// lower right corner of the downloaded areaval maxScreenPoint = ScreenCoordinate(
mapView.width - 200.0,
mapView.height - 200.0 )
// convert screen points to map pointsval minPoint = mapView.screenToLocation(minScreenPoint)
val maxPoint = mapView.screenToLocation(maxScreenPoint)
// use the points to define and return an envelopeif (minPoint != null && maxPoint != null) {
val envelope = Envelope(minPoint, maxPoint)
downloadArea.geometry = envelope
// enable the take map offline button only after the map is loadedif (!takeMapOfflineButton.isEnabled && map.loadStatus.value is LoadStatus.Loaded)
takeMapOfflineButton.isEnabled = true }
}
}
}
/**
* Use the generate offline map job to generate an offline map.
*
* @param view: the button which calls this function
*/funcreateOfflineMapJob(view: View) {
// offline map pathval offlineMapPath = getExternalFilesDir(null)?.path + "/offlineMap"// delete any offline map already in the cache File(offlineMapPath).deleteRecursively()
// specify the extent, min scale, and max scale as parametersvar minScale: Double = mapView.mapScale.value
val maxScale: Double = mapView.map?.maxScale ?: 0.0// minScale must always be larger than maxScaleif (minScale <= maxScale) {
minScale = maxScale + 1 }
// get the geometry of the downloadAreaval geometry = downloadArea.geometry
if (geometry == null) {
showMessage("Could not get geometry of the downloadArea")
return }
// set the offline map parametersval generateOfflineMapParameters = GenerateOfflineMapParameters(
geometry, minScale, maxScale
).apply {
// set job to cancel on any errors continueOnErrors = false }
// get the map from the MapViewval map = mapView.map
if (map == null) {
showMessage("Could not get map from MapView")
return }
// create an offline map task with the mapval offlineMapTask = OfflineMapTask(map)
// create an offline map job with the download directory path and parameters and start the jobval offlineMapJob = offlineMapTask.generateOfflineMap(
generateOfflineMapParameters,
offlineMapPath
)
// create an alert dialog to show the download progressval progressDialogLayoutBinding =
GenerateOfflineMapDialogLayoutBinding.inflate(layoutInflater)
val progressDialog = createProgressDialog(offlineMapJob).apply {
setCancelable(false)
setView(progressDialogLayoutBinding.root)
show()
}
// handle offline job loading, error and succeed status lifecycleScope.launch {
displayOfflineMapFromJob(offlineMapJob, progressDialogLayoutBinding, progressDialog)
}
}
/**
* Initiates, and tracks the result of the [offlineMapJob] while displaying
* the progress to the [progressDialog]
*/privatesuspendfundisplayOfflineMapFromJob(
offlineMapJob: GenerateOfflineMapJob,
progressDialogLayout: GenerateOfflineMapDialogLayoutBinding,
progressDialog: AlertDialog ) {
// create a flow-collector for the job's progress lifecycleScope.launch {
offlineMapJob.progress.collect {
// display the current job's progress valueval progressPercentage = offlineMapJob.progress.value
progressDialogLayout.progressBar.progress = progressPercentage
progressDialogLayout.progressTextView.text = "$progressPercentage%" }
}
// start the job offlineMapJob.start()
offlineMapJob.result().onSuccess {
mapView.map = it.offlineMap
graphicsOverlay.graphics.clear()
// disable and remove the button to take the map offline once the offline map is showing takeMapOfflineButton.isEnabled = false takeMapOfflineButton.visibility = View.GONE
showMessage("Map saved at: " + offlineMapJob.downloadDirectoryPath)
// close the progress dialog progressDialog.dismiss()
}.onFailure {
progressDialog.dismiss()
showMessage(it.message.toString())
}
}
/**
* Create a progress dialog box for tracking the generate offline map job.
*
* @param job the generate offline map job progress to be tracked
* @return an AlertDialog set with the dialog layout view
*/privatefuncreateProgressDialog(job: GenerateOfflineMapJob): AlertDialog {
val builder = AlertDialog.Builder(this).apply {
setTitle("Generating offline map...")
// provide a cancel button on the dialog setNegativeButton("Cancel") { _, _ ->
lifecycleScope.launch { job.cancel() }
}
setCancelable(true)
val dialogLayoutBinding = GenerateOfflineMapDialogLayoutBinding.inflate(layoutInflater)
setView(dialogLayoutBinding.root)
}
return builder.create()
}
privatefunshowMessage(message: String) {
Log.e(TAG, message)
Snackbar.make(activityMainBinding.root, message, Snackbar.LENGTH_SHORT).show()
}
}