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
The tapped position is passed to mapView.identifyLayersWithMaxResults
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.qml
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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
import QtQuick.Controls
import Esri.ArcGISRuntime
Rectangle {
id: rootRectangleclip: truewidth: 800height: 600property string msgText: ""MapView {
id: mapViewanchors.fill: parentComponent.onCompleted: {
// Set the focus on MapView to initially enable keyboard navigation forceActiveFocus();
}
Map {
Basemap {
initStyle: Enums.BasemapStyleArcGISTopographic
}
// add a map image layer and hide 2 of the sublayersArcGISMapImageLayer {
url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/SampleWorldCities/MapServer"onLoadStatusChanged: {
if (error) {
console.log("error:", error.message, error.additionalMessage)
return;
}
if (loadStatus !== Enums.LoadStatusLoaded)
return;
mapImageSublayers.get(1).visible = false;
mapImageSublayers.get(2).visible = false;
}
}
// add a feature layerFeatureLayer {
ServiceFeatureTable {
url: "https://sampleserver6.arcgisonline.com/arcgis/rest/services/DamageAssessment/FeatureServer/0" }
}
// set an initial viewpointViewpointCenter {
targetScale: 68015210Point {
x: -10977012.785807y: 4514257.550369spatialReference: SpatialReference { wkid: 3857 }
}
}
}
// identify layers on mouse clickonMouseClicked: mouse => {
const screenX = mouse.x;
const screenY = mouse.y;
const tolerance = 12;
const returnPopups = false;
const maxResults = 10;
mapView.identifyLayersWithMaxResults(screenX, screenY, tolerance, returnPopups, maxResults);
}
// handle the identify resultsonIdentifyLayersStatusChanged: {
if (identifyLayersStatus !== Enums.TaskStatusCompleted)
return;
// reset the message string msgText = "";
// loop through the resultsconst results = mapView.identifyLayersResults;
for (let i = 0; i < results.length; i++) {
const result = results[i];
const count = geoElementsCountFromResult(result);
const layerName = result.layerContent.name;
msgText += "%1 : %2".arg(layerName).arg(count);
// add new line character if not the final element in arrayif (i !== results.length)
msgText += "\n";
}
// show the message boxif (msgText.length > 0)
msgDialog.open();
}
// handle any errors on the map viewonErrorChanged: {
if (error)
console.log("error:", error.message, error.additionalMessage)
}
}
functiongeoElementsCountFromResult(identifyLayerResult) {
// create temp arrayconst tempResults = [identifyLayerResult];
// use Depth First Search approach to handle recursionlet count = 0;
let index = 0;
while (index < tempResults.length) {
//get the result object from the arrayconst identifyResult = tempResults[index];
// update count with geoElements from the result count += identifyResult.geoElements.length;
// check if the result has any sublayer results// if yes then add those result objects in the tempResults// array after the current resultif (identifyResult.sublayerResults.length > 0) {
tempResults.push(identifyResult.sublayerResults[index]);
}
// update the count and repeat index += 1;
}
return count;
}
Dialog {
id: msgDialogmodal: truex: Math.round(parent.width - width) / 2y: Math.round(parent.height - height) / 2standardButtons: Dialog.Ok
property alias text : textLabel.text
Text {
id: textLabeltext: msgText
}
}
}