Identify layers

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Sample viewer app

Identify features in all layers in a map.

screenshot

Use case

IdentifyLayers allows users to tap on a map, returning features at that location across multiple layers. Because some layer types have sublayers, the sample recursively counts results for sublayers within each layer.

How to use the sample

Tap to identify features. An alert will show all layers with features under the cursor, as well as a layer count.

How it works

  1. The tapped position is passed to MapView::identifyLayers
  2. For each IdentifyLayerResult in the results, features are counted.

    • Note: there is one identify result per layer with matching features; if the feature count is 0, that means a sublayer contains the matching features.

Relevant API

  • IdentifyLayerResult
  • IdentifyLayerResult::layerContent::name
  • IdentifyLayerResult::sublayerResults
  • MapView::identifyLayers

Additional information

The GeoView supports two methods of identify: identifyLayer(), which identifies features within a specific layer and identifyLayers(), which identifies features for all layers in the current view.

Tags

identify, recursion, recursive, sublayers

Sample Code

IdentifyLayers.qmlIdentifyLayers.cppIdentifyLayers.h
                                                  
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// [WriteFile Name=IdentifyLayers, Category=Maps]
// [Legal]
// Copyright 2017 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

IdentifyLayersSample {
    id: rootRectangle
    clip: true
    width: 800
    height: 600

    // add a mapView component
    MapView {
        anchors.fill: parent
        objectName: "mapView"
    }

    Dialog {
        id: msgDialog
        modal: true
        x: Math.round(parent.width - width) / 2
        y: Math.round(parent.height - height) / 2
        standardButtons: Dialog.Ok
        property alias text : textLabel.text
        Text {
            id: textLabel
            text: message
        }
    }

    onShowMessage: {
        if (message.length > 0)
            msgDialog.open();
    }
}

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