Selecting features, whether by query or identify, can be an important step both in editing data and visualizing results. One possible use case would be to query a feature layer containing street furniture. A query might look for type "bench" and return a list of bench features contained in the features with an attribute of type bench. These might be selected for further editing (see FeatureQueryResult) or may just be highlighted visually.
How to use the sample
Tap on a feature in the map. All features within a given tolerance (in pixels) of the tap will be selected.
How it works
Create a ServiceFeatureTable from a feature service URL.
Create a FeatureLayer from the service feature table.
Identify nearby features at the clicked location using mapView.identifyLayer(featureLayer, screenCoordinate, tolerance, returnPopupsOnly, maxResults) on the map view.
Select all identified features in the feature layer with identifyLayerResult.geoElements.filterIsInstance<Feature>().
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/* Copyright 2022 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.
*
*/package com.esri.arcgismaps.sample.selectfeaturesinfeaturelayer
import android.os.Bundle
import android.util.Log
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import androidx.lifecycle.lifecycleScope
import com.arcgismaps.ApiKey
import com.arcgismaps.ArcGISEnvironment
import com.arcgismaps.Color
import com.arcgismaps.data.Feature
import com.arcgismaps.data.ServiceFeatureTable
import com.arcgismaps.geometry.Envelope
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.Viewpoint
import com.arcgismaps.mapping.layers.FeatureLayer
import com.arcgismaps.mapping.view.ScreenCoordinate
import com.esri.arcgismaps.sample.selectfeaturesinfeaturelayer.databinding.ActivityMainBinding
import com.google.android.material.snackbar.Snackbar
import kotlinx.coroutines.launch
classMainActivity : AppCompatActivity() {
privateval TAG = MainActivity::class.java.simpleName
// set up data binding for the activityprivateval activityMainBinding: ActivityMainBinding by lazy {
DataBindingUtil.setContentView(this, R.layout.activity_main)
}
privateval mapView by lazy {
activityMainBinding.mapView
}
privateval gdbPerCapitalURL =
"https://services1.arcgis.com/4yjifSiIG17X0gW4/arcgis/rest/services/GDP_per_capita_1960_2016/FeatureServer/0"// create service feature table and a feature layer from itprivateval serviceFeatureTable = ServiceFeatureTable(gdbPerCapitalURL)
privateval featureLayer = FeatureLayer(serviceFeatureTable)
overridefunonCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
// authentication with an API key or named user is// required to access basemaps and other location services ArcGISEnvironment.apiKey = ApiKey.create(BuildConfig.API_KEY)
lifecycle.addObserver(mapView)
// create a map with the streets base map typeval streetsMap = ArcGISMap(BasemapStyle.ArcGISStreets).apply {
// add the feature layer to the map's operational layers operationalLayers.add(featureLayer)
}
mapView.apply {
// set the map to be displayed in the layout's map view map = streetsMap
// set an initial view point setViewpoint(
Viewpoint(
Envelope(
-1131596.019761,
3893114.069099,
3926705.982140,
7977912.461790 )
)
)
// give any item selected on the map view a red selection halo selectionProperties.color = Color.red
// set an on touch listener on the map view lifecycleScope.launch {
onSingleTapConfirmed.collect { tapEvent ->
// get the tapped coordinateval screenCoordinate = tapEvent.screenCoordinate
getSelectedFeatureLayer(screenCoordinate)
}
}
}
}
/**
* Displays the number of features selected on the given [screenCoordinate]
*/privatesuspendfungetSelectedFeatureLayer(screenCoordinate: ScreenCoordinate) {
// clear the previous selection featureLayer.clearSelection()
// set a tolerance for accuracy of returned selections from point tappedval tolerance = 25.0// create a IdentifyLayerResult using the screen coordinateval identifyLayerResult =
mapView.identifyLayer(featureLayer, screenCoordinate, tolerance, false, -1)
// handle the result's onSuccess and onFailure identifyLayerResult.apply {
onSuccess { identifyLayerResult ->
// get the elements in the selection that are featuresval features = identifyLayerResult.geoElements.filterIsInstance<Feature>()
// add the features to the current feature layer selection featureLayer.selectFeatures(features)
Snackbar.make(mapView, "${features.size} features selected", Snackbar.LENGTH_SHORT).show()
}
onFailure {
val errorMessage = "Select feature failed: " + it.message
Log.e(TAG, errorMessage)
Snackbar.make(mapView, errorMessage, Snackbar.LENGTH_SHORT).show()
}
}
}
}