Identify layer features

View on GitHubSample viewer app

Identify features in all layers in a map.

Image of identify layers

Use case

"Identify layers" operation 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. A bottom text banner will show all layers with features under the tapped location, as well as the number of features.

How it works

  1. The tapped position is passed to MapView.identifyLayers(...) method.
  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.sublayerResults
  • LayerContent

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

MainActivity.ktMainActivity.ktComposeMapView.ktMapViewModel.ktMainScreen.kt
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/* Copyright 2023 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.identifylayerfeatures

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
import androidx.compose.runtime.Composable
import com.arcgismaps.ApiKey
import com.arcgismaps.ArcGISEnvironment
import com.esri.arcgismaps.sample.sampleslib.theme.SampleAppTheme
import com.esri.arcgismaps.sample.identifylayerfeatures.screens.MainScreen

class MainActivity : ComponentActivity() {

    override fun onCreate(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)

        setContent {
            SampleAppTheme {
                IdentifyLayerFeaturesApp()
            }
        }
    }

    @Composable
    private fun IdentifyLayerFeaturesApp() {
        Surface(
            color = MaterialTheme.colorScheme.background
        ) {
            MainScreen(
                sampleName = getString(R.string.app_name),
                application = application
            )
        }
    }
}

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