Style a feature layer

Learn how to apply renderers and label definitions to a feature layer based on attribute values.

style a feature layer

Applications can display feature layer data with different styles to enhance the visualization. The type of Renderer you choose depends on your application. A SimpleRenderer applies the same symbol to all features, a UniqueValueRenderer applies a different symbol to each unique attribute value, and a ClassBreaksRenderer applies a symbol to a range of numeric values. Renderers are responsible for accessing the data and applying the appropriate symbol to each feature when the layer draws. You can also use a LabelDefinition to show attribute information for features. Visit the Styles and data visualization documentation to learn more about styling layers.

You can also author, style and save web maps, web scenes, and layers as portal items and then add them to the map in your application. Visit the following tutorials to learn more about adding portal items.

In this tutorial, you will apply different renderers to enhance the visualization of three feature layers with data for the Santa Monica Mountains: Trailheads with a single symbol, Trails based on elevation change and bike use, and Parks and Open Spaces based on the type of park.

Prerequisites

Before starting this tutorial, you need the following:

  1. An ArcGIS Location Platform or ArcGIS Online account.

  2. A development and deployment environment that meets the system requirements.

  3. An IDE for Android development in Kotlin.

Steps

Open an Android Studio project

  1. To start this tutorial, complete the Display a map tutorial, or download and unzip the Display a map solution in a new folder.

  2. Modify the old project for use in this new tutorial.

  3. Get an access token and set the API key in MainActivity.kt.

Add import statements

In the Android view, open app > kotlin+java > com.example.app > MainScreen.kt. Replace the import statements with the imports needed for this tutorial.

MainScreen.kt
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@file:OptIn(ExperimentalMaterial3Api::class)

package com.example.app.screens

import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.padding
import androidx.compose.material3.ExperimentalMaterial3Api
import androidx.compose.material3.Scaffold
import androidx.compose.material3.Text
import androidx.compose.material3.TopAppBar
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Modifier
import androidx.compose.ui.res.stringResource
import com.arcgismaps.Color
import com.arcgismaps.data.ServiceFeatureTable
import com.arcgismaps.mapping.ArcGISMap
import com.arcgismaps.mapping.BasemapStyle
import com.arcgismaps.mapping.Viewpoint
import com.arcgismaps.mapping.labeling.ArcadeLabelExpression
import com.arcgismaps.mapping.labeling.LabelDefinition
import com.arcgismaps.mapping.layers.FeatureLayer
import com.arcgismaps.mapping.symbology.ClassBreak
import com.arcgismaps.mapping.symbology.ClassBreaksRenderer
import com.arcgismaps.mapping.symbology.FontStyle
import com.arcgismaps.mapping.symbology.FontWeight
import com.arcgismaps.mapping.symbology.PictureMarkerSymbol
import com.arcgismaps.mapping.symbology.SimpleFillSymbol
import com.arcgismaps.mapping.symbology.SimpleFillSymbolStyle
import com.arcgismaps.mapping.symbology.SimpleLineSymbol
import com.arcgismaps.mapping.symbology.SimpleLineSymbolStyle
import com.arcgismaps.mapping.symbology.SimpleRenderer
import com.arcgismaps.mapping.symbology.TextSymbol
import com.arcgismaps.mapping.symbology.UniqueValue
import com.arcgismaps.mapping.symbology.UniqueValueRenderer
import com.arcgismaps.toolkit.geoviewcompose.MapView
import com.example.app.R

Create a function to add a feature layer

You can add a feature layer from a feature service hosted in ArcGIS. Each feature layer contains features with a single geometry type (point, line, or polygon), and a set of attributes. Once added to the map, feature layers can be symbolized, styled, and labeled in a variety of ways.

Define variables that store feature service URLs used by the app's layers, and then create a helper function to add a layer to the map's list of operational layers. You will use this code throughout the tutorial as you add and symbolize various layers.

  1. In createMap() add four read-only String variables: three for accessing feature layers, and a fourth for accessing a static image for use in a picture marker symbol. You will use these resources in future steps.

    MainScreen.kt
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    fun createMap(): ArcGISMap {
    
        val parksAndOpenSpaces =
            "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Parks_and_Open_Space/FeatureServer/0"
        val trails =
            "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trails/FeatureServer/0"
        val trailheads =
            "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0"
        val trailheadImage =
            "https://static.arcgis.com/images/Symbols/NPS/npsPictograph_0231b.png"
    
        return ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
            initialViewpoint = Viewpoint(
                latitude = 34.0270,
                longitude = -118.8050,
                scale = 72000.0
            )
    
        }
    }
    
    Expand
  2. In the apply block for ArcGISMap, insert code that adds FeatureLayers to the map's operationalLayers. For now, the listOf() function has no parameters. In this tutorial, you will be adding each new feature layer to the list of parameters.

    MainScreen.kt
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    fun createMap(): ArcGISMap {
    
        val parksAndOpenSpaces =
            "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Parks_and_Open_Space/FeatureServer/0"
        val trails =
            "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trails/FeatureServer/0"
        val trailheads =
            "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0"
        val trailheadImage =
            "https://static.arcgis.com/images/Symbols/NPS/npsPictograph_0231b.png"
    
        return ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
            initialViewpoint = Viewpoint(
                latitude = 34.0270,
                longitude = -118.8050,
                scale = 72000.0
            )
    
            operationalLayers.addAll(
    
                listOf(
    
                )
    
            )
    
        }
    }
    
    Expand
  3. Add a top-level helper function named createFeatureLayer() that takes a feature service URI as an argument and returns a FeatureLayer created from the URI.

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    fun createFeatureLayer(featureServiceUri: String): FeatureLayer {
        // Create a service feature table from a Uri
        val serviceFeatureTable = ServiceFeatureTable(featureServiceUri)
        // Return a feature layer created from the service feature table
        return FeatureLayer.createWithFeatureTable(serviceFeatureTable)
    }
    
    Expand

Add a layer with a unique value renderer

Create a method to apply a different symbol for each type of park area to the Parks and Open Spaces feature layer.

  1. Add a top-level function named createOpenSpaceLayer().

    MainScreen.kt
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    fun createOpenSpaceLayer(featureServiceUri: String): FeatureLayer {
        // Create fill symbol objects to represent the parks and open spaces layer
        val magentaFillSymbol = SimpleFillSymbol(SimpleFillSymbolStyle.Solid, Color.fromRgba(255, 0, 255), null)
        val greenFillSymbol = SimpleFillSymbol(SimpleFillSymbolStyle.Solid, Color.green, null)
        val blueFillSymbol = SimpleFillSymbol(SimpleFillSymbolStyle.Solid, Color.fromRgba(0, 0, 255), null)
        val redFillSymbol = SimpleFillSymbol(SimpleFillSymbolStyle.Solid, Color.red, null)
    
        // Create a unique value for natural areas, regional open spaces, local parks, and regional recreation parks
        val naturalAreas = UniqueValue(
            description = "Natural Areas",
            label = "Natural Areas",
            symbol = magentaFillSymbol,
            values = listOf("Natural Areas")
        )
        val regionalOpenSpace = UniqueValue(
            description = "Regional Open Space",
            label = "Regional Open Space",
            symbol = greenFillSymbol,
            values = listOf("Regional Open Space")
        )
        val localPark = UniqueValue(
            description = "Local Park",
            label = "Local Park",
            symbol = blueFillSymbol,
            values = listOf("Local Park")
        )
        val regionalRecreationPark = UniqueValue(
            description = "Regional Recreation Park",
            label = "Regional Recreation Park",
            symbol = redFillSymbol,
            values = listOf("Regional Recreation Park")
        )
        // Create a unique value list with the fill symbols
        val uniqueValuesList = listOf(
            naturalAreas,
            regionalOpenSpace,
            localPark,
            regionalRecreationPark
        )
    
        // Create and assign a unique value renderer to the feature layer
        val openSpacesUniqueValueRenderer =
            UniqueValueRenderer(
                fieldNames = listOf("TYPE"),
                uniqueValues = uniqueValuesList,
                defaultLabel = "Open Spaces",
                defaultSymbol = null
            )
    
        // Create a parks and open spaces feature layer
        val featureLayer = createFeatureLayer(featureServiceUri).apply {
            // Style the feature layer using the unique value renderer
            renderer = openSpacesUniqueValueRenderer
            // Set the layer opacity to semi-transparent
            opacity = 0.2f
        }
    
        return featureLayer
    }
    
    Expand
  2. In createMap(), add the Parks and Open Space feature layer to the map's operational layers by calling createOpenSpaceLayer().

    MainScreen.kt
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    fun createMap(): ArcGISMap {
    
        val parksAndOpenSpaces =
            "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Parks_and_Open_Space/FeatureServer/0"
        val trails =
            "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trails/FeatureServer/0"
        val trailheads =
            "https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0"
        val trailheadImage =
            "https://static.arcgis.com/images/Symbols/NPS/npsPictograph_0231b.png"
    
        return ArcGISMap(BasemapStyle.ArcGISTopographic).apply {
            initialViewpoint = Viewpoint(
                latitude = 34.0270,
                longitude = -118.8050,
                scale = 72000.0
            )
    
            operationalLayers.addAll(
    
                listOf(
    
                    createOpenSpaceLayer(parksAndOpenSpaces),
    
                )
    
            )
    
        }
    }
    
    Expand
  3. Click Run > Run > app to run the app.

When the app opens, Parks and Open Spaces feature layer is added to the map. The map displays the different types of parks and open spaces with four unique symbols.

Add a layer with a class breaks renderer

Create a method to apply a different symbol for each of the five ranges of elevation gain to the Trails feature layer.

  1. Add a top-level function named createTrailsLayer().

    MainScreen.kt
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    Use dark colors for code blocks