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:
  4. GroupVisibilityMode::Independent allows each sublayer to change its visibility independently.
  5. GroupVisibilityMode::Exclusive allows only one sublayer to be visible at a time.
  6. GroupVisibilityMode::Inherited treats the group layer as if it is one merged layer.
  7. Create a ListView and bind the model the the scene's operational layer list model.
  8. Create a delegate for the group layer and and another delegate for all other layers. The group layer delegate will have nested checkboxes.
  9. Check that the layer is a group layer. If true, load the group layer delegate. If false, load the other delegate.
  10. Each delegate will use the name and layerVisible roles exposed on the LayerListModel.
  11. 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.qmlGroupLayers.cppGroupLayers.h
                                                                                                             
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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]

import QtQuick 2.6
import QtQuick.Controls 2.2
import Esri.Samples 1.0

Item {

    SceneView {
        id: view
        anchors.fill: parent
    }

    // Declare the C++ instance which creates the scene etc. and supply the view
    GroupLayersSample {
        id: sampleModel
        sceneView: view
    }

    // Create a window to display the layers
    Rectangle {
        id: layerVisibilityRect
        anchors {
            fill: layerVisibilityListView
            margins: -5
        }
        color: "lightgrey"
        border.color: "#4D4D4D"
        opacity: 0.9
        radius: 5
    }

    // Create a list view to display the items
    ListView {
        id: layerVisibilityListView
        anchors {
            left: parent.left
            top: parent.top
            margins: 10
        }
        width: 250
        height: childrenRect.height
        clip: true

        // Assign the model to the list model of layers
        model: sampleModel.layerListModel

        // Assign the delegate to the delegate created above
        delegate: Item {
            height: childrenRect.height

            // select the component based on the layer type
            // GroupLayer is LayerType int value of 22. See API doc for more details:
            // https://developers.arcgis.com/qt/layers/
            Loader {
                sourceComponent: layerType === 22 ?
                                     groupLayerDelegate : layerDelegate
            }

            // Delegate for GroupLayers - Contains secondary repeater for sublayers
            Component {
                id: groupLayerDelegate
                Column {
                    CheckBox {
                        id: parentBox
                        text: name
                        checked: layerVisible
                        onCheckedChanged: layerVisible = checked
                    }

                    Repeater {
                        model: sampleModel.getGroupLayerListModel(layerVisibilityListView.currentIndex)
                        delegate: RadioDelegate {
                            checked: index === 0
                            text: name
                            leftPadding: indicator.width
                            width: layerVisibilityRect.width - leftPadding
                            onCheckedChanged: layerVisible = checked
                        }
                    }
                }
            }

            // Delegate for all other layers - standard Checkbox
            Component {
                id: layerDelegate
                CheckBox {
                    text: name
                    checked: layerVisible
                    onCheckedChanged: layerVisible = checked;
                }
            }
        }
    }
}

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