Group layers

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Sample viewer app

Group a collection of layers together and toggle their visibility as a group.

screenshot

Use case

Group layers communicate to the user that layers are related and can be managed together.

In a land development project, you might group layers according to the phase of development.

How to use the sample

The layers in the map will be displayed in a table of contents. Toggle the checkbox next to a layer's name to change its visibility. Turning a group layer's visibility off will override the visibility of its child layers.

How it works

  1. Create an empty GroupLayer.
  2. Create a new layer and add it to the group layer's layers collection.
  3. Set the group layer's GroupVisibilityMode to change its behavior:
  • GroupVisibilityMode::Independent allows each sublayer to change its visibility independently.
  • GroupVisibilityMode::Exclusive allows only one sublayer to be visible at a time.
  • GroupVisibilityMode::Inherited treats the group layer as if it is one merged layer.
  1. Create a ListView and bind the model the the scene's operational layer list model.
  2. Create a delegate for the group layer and and another delegate for all other layers. The group layer delegate will have nested checkboxes.
  3. Check that the layer is a group layer. If true, load the group layer delegate. If false, load the other delegate.
  4. Each delegate will use the name and layerVisible roles exposed on the LayerListModel.
  5. To toggle the visibility of the group, simply change the group layer's visibility property.

Relevant API

  • GroupLayer

Additional information

The full extent of a group layer may change when child layers are added/removed. Group layers do not have a spatial reference, but the full extent will have the spatial reference of the first child layer.

Tags

group layer

Sample Code

GroupLayers.cppGroupLayers.cppGroupLayers.hGroupLayers.qml
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// [WriteFile Name=GroupLayers, 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 "GroupLayers.h"

#include "ArcGISTiledElevationSource.h"
#include "Scene.h"
#include "SceneQuickView.h"
#include "GroupLayer.h"
#include "ArcGISSceneLayer.h"
#include "FeatureLayer.h"
#include "ServiceFeatureTable.h"
#include "Viewpoint.h"
#include "Envelope.h"

using namespace Esri::ArcGISRuntime;

GroupLayers::GroupLayers(QObject* parent /* = nullptr */):
  QObject(parent),
  m_scene(new Scene(BasemapStyle::ArcGISImageryStandard, this))
{
  // create a new elevation source from Terrain3D REST service
  ArcGISTiledElevationSource* elevationSource = new ArcGISTiledElevationSource(
        QUrl("https://elevation3d.arcgis.com/arcgis/rest/services/WorldElevation3D/Terrain3D/ImageServer"), this);

  // add the elevation source to the scene to display elevation
  m_scene->baseSurface()->elevationSources()->append(elevationSource);

  // Create layers and append to a group layer
  ArcGISSceneLayer* layer1 = new ArcGISSceneLayer(QUrl("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/DevA_BuildingShells/SceneServer"), this);
  ArcGISSceneLayer* layer2 = new ArcGISSceneLayer(QUrl("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/DevB_BuildingShells/SceneServer"), this);
  GroupLayer* groupLayer = new GroupLayer(QList<Layer*>{layer1, layer2}, this);
  groupLayer->setName("Buildings group");
  groupLayer->setVisibilityMode(GroupVisibilityMode::Exclusive);

  // Create additional layers
  ArcGISSceneLayer* layer3 = new ArcGISSceneLayer(QUrl("https://tiles.arcgis.com/tiles/P3ePLMYs2RVChkJx/arcgis/rest/services/DevA_Trees/SceneServer"), this);
  ServiceFeatureTable* ft1 = new ServiceFeatureTable(QUrl("https://services.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/DevelopmentProjectArea/FeatureServer/0"), this);
  FeatureLayer* layer4 = new FeatureLayer(ft1, this);
  ServiceFeatureTable* ft2 = new ServiceFeatureTable(QUrl("https://services.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/DevA_Pathways/FeatureServer/1"), this);
  FeatureLayer* layer5 = new FeatureLayer(ft2, this);

  // Add layers to the scene
  m_scene->operationalLayers()->append(groupLayer);
  m_scene->operationalLayers()->append(layer3);
  m_scene->operationalLayers()->append(layer4);
  m_scene->operationalLayers()->append(layer5);

  connect(m_scene, &Scene::doneLoading, this, [this](Error e)
  {
    if (!e.isEmpty())
      return;

    m_layerListModel = m_scene->operationalLayers();
    emit layerListModelChanged();
  });
}

GroupLayers::~GroupLayers() = default;

void GroupLayers::init()
{
  // Register classes for QML
  qmlRegisterType<SceneQuickView>("Esri.Samples", 1, 0, "SceneView");
  qmlRegisterType<GroupLayers>("Esri.Samples", 1, 0, "GroupLayersSample");
  qmlRegisterUncreatableType<LayerListModel>("Esri.Samples", 1, 0, "AbstractListModel", "AbstractListModel is uncreateable");
}

SceneQuickView* GroupLayers::sceneView() const
{
  return m_sceneView;
}

// Set the view (created in QML)
void GroupLayers::setSceneView(SceneQuickView* sceneView)
{
  if (!sceneView || sceneView == m_sceneView)
  {
    return;
  }

  m_sceneView = sceneView;
  m_sceneView->setArcGISScene(m_scene);

  // create initial viewpoint
  Geometry env = Geometry::fromJson(R"({"spatialReference":{
                                    "wkid":4326
                                    },
                                    "xmax":-122.67960721754773,
                                    "xmin":-122.68647066116789,
                                    "ymax":45.53584958588318,
                                    "ymin":45.531539857343745
                                    })");
  // zoom to viewpoint
  m_sceneView->setViewpoint(Viewpoint(env.extent()));

  emit sceneViewChanged();
}

LayerListModel* GroupLayers::getGroupLayerListModel(int layerId)
{
  if (!m_scene)
    return nullptr;

  GroupLayer* groupLayer = static_cast<GroupLayer*>(m_scene->operationalLayers()->at(layerId));

  if (groupLayer)
    return groupLayer->layers();

  return nullptr;
}

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