Manage operational layers

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Sample viewer app

Add, remove, and reorder operational layers in a map.

screenshot

Use case

Operational layers display the primary content of the map and usually provide dynamic content for the user to interact with (as opposed to basemap layers that provide context).

The order of operational layers in a map determines the visual hierarchy of layers in the view. You can bring attention to a specific layer by rendering above other layers.

How to use the sample

When the app starts, a list displays the operational layers that are currently displayed in the map. Select the menu option on the list item to remove or reorder the layer. The map will be updated automatically.

The second list shows layers that have been removed from the map. Select the menu option on the list item to add it to the map.

How it works

  1. Get the operational layers LayerListModel from the map using Map::operationalLayers.
  2. Add or remove layers using operationalLayers()->append(layer) and operationalLayers()->remove(layer) respectively. The last layer in the list will be rendered on top.

Relevant API

  • Map
  • ArcGISMapImageLayer
  • LayerListModel
  • LayerListModel::append
  • LayerListModel::move
  • LayerListModel::removeAt

Tags

add, delete, layer, map, remove

Sample Code

ManageOperationalLayers.cppManageOperationalLayers.cppManageOperationalLayers.hDrawOrderLayerListModel.cppDrawOrderLayerListModel.hManageOperationalLayers.qml
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// [WriteFile Name=ManageOperationalLayers, Category=Layers]
// [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 "ManageOperationalLayers.h"

#include "Map.h"
#include "MapQuickView.h"
#include "ArcGISMapImageLayer.h"
#include "DrawOrderLayerListModel.h"

using namespace Esri::ArcGISRuntime;

ManageOperationalLayers::ManageOperationalLayers(QObject* parent /* = nullptr */):
  QObject(parent),
  m_map(new Map(BasemapStyle::ArcGISTopographic, this)),
  m_elevationLayer(new ArcGISMapImageLayer(QUrl("https://sampleserver5.arcgisonline.com/arcgis/rest/services/Elevation/WorldElevations/MapServer"), this)),
  m_censusLayer(new ArcGISMapImageLayer(QUrl("https://sampleserver5.arcgisonline.com/arcgis/rest/services/Census/MapServer"), this)),
  m_damageLayer(new ArcGISMapImageLayer(QUrl("https://sampleserver5.arcgisonline.com/arcgis/rest/services/DamageAssessment/MapServer"), this)),
  m_drawOrderListModel(new DrawOrderLayerListModel(this))
{
  // add layers to the map
  m_map->operationalLayers()->append(m_elevationLayer);
  m_map->operationalLayers()->append(m_censusLayer);
  m_map->operationalLayers()->append(m_damageLayer);

  // Create a custom DrawOrderListModel. This is a QSortFilterProxyModel used to
  // "reverse" the order appearance so the top level layer displays at the top
  // of the list view instead of the bottom, which is the default behavior. This
  // will closer match the widely accepted standard table of contents UX where
  // the top level layer displays at the top of the view.
  m_drawOrderListModel->setLayerListModel(m_map->operationalLayers());
}

ManageOperationalLayers::~ManageOperationalLayers() = default;

void ManageOperationalLayers::init()
{
  // Register the map view for QML
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<ManageOperationalLayers>("Esri.Samples", 1, 0, "ManageOperationalLayersSample");
  qmlRegisterUncreatableType<QAbstractItemModel>("Esri.Samples", 1, 0, "AbstractItemModel", "AbstractItemModel is uncreateable");
}

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

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

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

  emit mapViewChanged();
}

QAbstractItemModel* ManageOperationalLayers::layerListModel() const
{
  return m_drawOrderListModel;
}

void ManageOperationalLayers::moveLayerUp(int index)
{
  if (!m_drawOrderListModel || !m_map)
    return;

  // get the index and move the layer up
  int modelIndex = m_drawOrderListModel->mappedIndex(index);
  m_map->operationalLayers()->move(modelIndex, modelIndex + 1);
}

void ManageOperationalLayers::moveLayerDown(int index)
{
  if (!m_drawOrderListModel || !m_map)
    return;

  // get the index and move the layer down
  int modelIndex = m_drawOrderListModel->mappedIndex(index);
  m_map->operationalLayers()->move(modelIndex, modelIndex - 1);
}

void ManageOperationalLayers::removeLayer(int index)
{
  if (!m_drawOrderListModel || !m_map)
    return;

  // get the index
  int modelIndex = m_drawOrderListModel->mappedIndex(index);
  Layer* lyr = m_map->operationalLayers()->at(modelIndex);

  // add the layer to the other list
  m_deletedLayers.append(lyr);
  m_deletedLayersListNames.append(lyr->name());
  emit deletedLayersListChanged();

  // remove from the map
  m_map->operationalLayers()->removeAt(modelIndex);
}

void ManageOperationalLayers::addLayer(int index)
{
  if (!m_drawOrderListModel || !m_map)
    return;

  // get the layer from the deleted list
  Layer* lyr = m_deletedLayers.at(index);
  if (!lyr)
    return;

  // remove the layer from the deleted list
  m_deletedLayers.removeAt(index);
  m_deletedLayersListNames.removeAt(index);
  emit deletedLayersListChanged();

  // add the layer to the map's operational layers
  m_map->operationalLayers()->append(lyr);
}

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