Download a preplanned map area

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C++

QML

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Sample viewer app

Take a map offline using a preplanned map area.

screenshot

Use case

Generating offline maps on demand for a specific area can be time consuming for users and a processing load on the server. If areas of interest are known ahead of time, a web map author can pre-create packages for these areas. This way, the generation only needs to happen once, making the workflow more efficient for users and servers.

An archaeology team could define preplanned map areas for dig sites which can be taken offline for field use.

How to use the sample

Select a map area from the Preplanned Map Areas list. Click the Download button to download the selected area. The download progress will be displayed through a progress bar. When a download is complete, select it to display the offline map in the map view.

How it works

Open the online Map from a PortalItem and display it.
Create an OfflineMapTask using the portal item.
Get the PreplannedMapAreas from the task, and then load them.
To download a selected map area, create the default DownloadPreplannedOfflineMapParameters from the task using the selected preplanned map area.
Set the update mode of the preplanned map area.
Use the parameters and a download path to create a DownloadPreplannedOfflineMapJob from the task.
Start the job. Once it has completed, get the DownloadPreplannedOfflineMapResult.
Get the map from the result and display it in the MapView.

Relevant API

DownloadPreplannedOfflineMapJob
DownloadPreplannedOfflineMapParameters
DownloadPreplannedOfflineMapResult
OfflineMapTask
PreplannedMapArea

About the data

The Naperville stormwater network map is based on ArcGIS Solutions for Stormwater and provides a realistic depiction of a theoretical stormwater network.

Additional information

PreplannedUpdateMode can be used to set the way the preplanned map area receives updates in several ways:

NoUpdates - No updates will be performed. This mode is intended for when a static snapshot of the data is required, and it does not create a replica. This is the mode used for this sample.
SyncWithFeatureServices - Changes, including local edits, will be synced directly with the underlying feature services. This is the default update mode.
DownloadScheduledUpdates - Scheduled, read-only updates will be downloaded from the online map area and applied to the local mobile geodatabases.

For more information about offline workflows, see Offline maps, scenes, and data in the ArcGIS Developers guide.

Sample Code

DownloadPreplannedMap.cpp

DownloadPreplannedMap.h

DownloadPreplannedMap.qml

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// [WriteFile Name=DownloadPreplannedMap, Category=Maps]
// [Legal]
// 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.
// [Legal]

#ifdef PCH_BUILD
#include "pch.hpp"
#endif // PCH_BUILD

#include "DownloadPreplannedMap.h"

#include "DownloadPreplannedOfflineMapJob.h"
#include "DownloadPreplannedOfflineMapResult.h"
#include "Graphic.h"
#include "Map.h"
#include "MapQuickView.h"
#include "OfflineMapTask.h"
#include "PreplannedMapArea.h"
#include "PreplannedMapAreaListModel.h"
#include "SimpleLineSymbol.h"
#include "SimpleRenderer.h"

using namespace Esri::ArcGISRuntime;

DownloadPreplannedMap::DownloadPreplannedMap(QObject* parent /* = nullptr */):
  QObject(parent),
  m_graphicsOverlay(new GraphicsOverlay(this)),
  m_portalItem(new PortalItem("acc027394bc84c2fb04d1ed317aac674", this)),
  m_lineSymbol(new SimpleLineSymbol(SimpleLineSymbolStyle::Solid, QColor(Qt::red), 5, this)),
  m_busy(true)
{
  m_graphicsOverlay->setRenderer(new SimpleRenderer(m_lineSymbol, this));

  connect(m_portalItem, &PortalItem::doneLoading, this, [this] ()
  {
    m_offlineMapTask = new OfflineMapTask(m_map, this);
    m_mapView->graphicsOverlays()->append(m_graphicsOverlay);

    connect(m_offlineMapTask, &OfflineMapTask::doneLoading, this, [this] ()
    {
      connect(m_offlineMapTask, &OfflineMapTask::preplannedMapAreasCompleted, this, &DownloadPreplannedMap::loadPreplannedMapAreas);

      // fetch preplanned map areas from the portal item
      m_offlineMapTask->preplannedMapAreas();
    });

    connect(m_offlineMapTask, &OfflineMapTask::createDefaultDownloadPreplannedOfflineMapParametersCompleted, this, [this] (QUuid ,const DownloadPreplannedOfflineMapParameters& parameters)
    {

      m_params = parameters;

      /* Set the update mode to not receive updates.
       * Other options:
       * SyncWithFeatureServices - changes will be synced directly with the
       * underlying feature services.
       * DownloadScheduledUpdates - schedulded, read-only updates will be
       * downloaded and applied to the local geodatabase. */
      m_params.setUpdateMode(PreplannedUpdateMode::NoUpdates);

      m_preplannedMapJob = m_offlineMapTask->downloadPreplannedOfflineMap(m_params, m_path);
      connect(m_preplannedMapJob, &DownloadPreplannedOfflineMapJob::progressChanged, this, [this] ()
      {
        m_percentDownloaded = .01 * m_preplannedMapJob->progress();
        emit percentDownloadedChanged();
      });
      connect(m_preplannedMapJob, &DownloadPreplannedOfflineMapJob::jobDone, this, &DownloadPreplannedMap::onDownloadPreplannedMapJobCompleted);

      // Start job to take preplanned map area offline.
      m_preplannedMapJob->start();
      m_busy = false;
      emit busyChanged();
    });

    // Load offline map task.
    m_offlineMapTask->load();
  });

  m_map = new Map(m_portalItem, this);
}

DownloadPreplannedMap::~DownloadPreplannedMap() = default;

void DownloadPreplannedMap::init()
{
  // Register the map view for QML
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<DownloadPreplannedMap>("Esri.Samples", 1, 0, "DownloadPreplannedMapSample");
  qmlRegisterUncreatableType<PreplannedMapAreaListModel>("Esri.Samples", 1, 0, "AbstractListModel", "DownloadPreplannedMapSample");
}

MapQuickView* DownloadPreplannedMap::mapView() const
{
  return m_mapView;
}

// Set the view (created in QML)
void DownloadPreplannedMap::setMapView(MapQuickView* mapView)
{
  if (!mapView || mapView == m_mapView)
    return;

  m_mapView = mapView;
  m_mapView->setMap(m_map);

  emit mapViewChanged();
}

void DownloadPreplannedMap::checkIfMapAreaIsLoaded(int index)
{
  if (!m_offlineMapTask)
    return;

  if (m_offlineMapTask->preplannedMapAreaList()->isEmpty())
    return;

  PreplannedMapArea* mapArea = m_offlineMapTask->preplannedMapAreaList()->at(index);

  if (!mapArea || mapArea->loadStatus() != LoadStatus::Loaded)
    return;

  m_busy = true;
  m_viewingOnlineMaps = false;
  emit busyChanged();
  emit viewingOnlineMapsChanged();

  if(m_graphicsOverlay->isVisible())
    m_graphicsOverlay->setVisible(false);

  loadSelectedMap(index);
}

void DownloadPreplannedMap::loadSelectedMap(int index)
{
  checkIfMapExists(index);

  if (m_preplannedMapExists)
    loadExistingPreplannedMap();
  else
    m_offlineMapTask->createDefaultDownloadPreplannedOfflineMapParameters(m_offlineMapTask->preplannedMapAreaList()->at(index));
}

void DownloadPreplannedMap::checkIfMapExists(int index)
{
  if (!m_offlineMapTask)
    return;

  if (m_offlineMapTask->preplannedMapAreaList()->isEmpty())
    return;

  PreplannedMapArea* mapArea = m_offlineMapTask->preplannedMapAreaList()->at(index);

  if (!mapArea || mapArea->loadStatus() != LoadStatus::Loaded)
    return;

  m_path = QString(m_tempPath.path() + "/" + mapArea->portalItem()->title());
  QDir tempDir(m_path);

  m_preplannedMapExists = tempDir.exists();
  emit preplannedMapExistsChanged();

  if (m_viewingOnlineMaps)
    m_mapView->setViewpointGeometry(mapArea->areaOfInterest());
}

void DownloadPreplannedMap::showOnlineMap(int index)
{
  m_viewingOnlineMaps = true;
  emit viewingOnlineMapsChanged();
  m_mapView->setMap(m_map);
  const Geometry areaOfInterest = m_offlineMapTask->preplannedMapAreaList()->at(index)->areaOfInterest();
  m_mapView->setViewpointGeometry(areaOfInterest);
  m_graphicsOverlay->setVisible(true);
}

void DownloadPreplannedMap::onDownloadPreplannedMapJobCompleted()
{
  if (m_preplannedMapJob->jobStatus() != JobStatus::Succeeded)
    return;

  m_mapView->setMap(m_preplannedMapJob->result()->offlineMap());
  m_preplannedMapExists = true;
  emit preplannedMapExistsChanged();
  m_viewingOnlineMaps = false;
  emit viewingOnlineMapsChanged();
}

void DownloadPreplannedMap::loadPreplannedMapAreas()
{
  m_preplannedList = m_offlineMapTask->preplannedMapAreaList();
  m_busy = false;
  emit preplannedListChanged();
  emit busyChanged();

  for (PreplannedMapArea* mapArea : *m_preplannedList)
  {
    connect(mapArea, &PreplannedMapArea::doneLoading, this, [this, mapArea] (Error e)
    {
      if (!e.isEmpty())
      {
        qDebug() << e.message() << " - " << e.additionalMessage();
        return;
      }

      Graphic* areaOfInterest = new Graphic(mapArea->areaOfInterest(), this);
      m_graphicsOverlay->graphics()->append(areaOfInterest);
    });

    mapArea->load();
  }
}

void DownloadPreplannedMap::loadExistingPreplannedMap()
{
  if (m_mmpk)
  {
    delete m_mmpk;
    m_mmpk = nullptr;
  }

  m_mmpk = new MobileMapPackage(m_path, this);

  connect(m_mmpk, &MobileMapPackage::doneLoading, this, [this] (Error e)
  {
    if (!e.isEmpty())
      qDebug() << e.message() << " - " << e.additionalMessage();

    m_mapView->setMap(m_mmpk->maps().at(0));
    m_busy = false;
    emit busyChanged();
    m_graphicsOverlay->setVisible(false);
    m_viewingOnlineMaps = false;
    emit viewingOnlineMapsChanged();
  });

  m_mmpk->load();
}