Apply unique value renderer

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//
// Copyright 2024 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
//
//   https://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.
//

import 'package:arcgis_maps/arcgis_maps.dart';
import 'package:flutter/material.dart';

import '../../utils/sample_state_support.dart';

class ApplyUniqueValueRenderer extends StatefulWidget {
  const ApplyUniqueValueRenderer({super.key});

  @override
  State<ApplyUniqueValueRenderer> createState() =>
      _ApplyUniqueValueRendererState();
}

class _ApplyUniqueValueRendererState extends State<ApplyUniqueValueRenderer>
    with SampleStateSupport {
  // Create a controller for the map view.
  final _mapViewController = ArcGISMapView.createController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      // Add a map view to the widget tree and set a controller.
      body: ArcGISMapView(
        controllerProvider: () => _mapViewController,
        onMapViewReady: onMapViewReady,
      ),
    );
  }

  void onMapViewReady() {
    // Create a map with a Basemap style and an initial viewpoint.
    final map = ArcGISMap.withBasemapStyle(BasemapStyle.arcGISTopographic);
    map.initialViewpoint = Viewpoint.fromCenter(
      ArcGISPoint(x: -12356253.6, y: 3842795.4),
      scale: 52681563.2,
    );

    // Create a feature layer from a service feature table and set a unique value renderer.
    final uri = Uri.parse(
      'https://sampleserver6.arcgisonline.com/arcgis/rest/services/Census/MapServer/3',
    );
    final serviceFeatureTable = ServiceFeatureTable.withUri(uri);
    final featureLayer = FeatureLayer.withFeatureTable(serviceFeatureTable);
    featureLayer.renderer = _configureUniqueValueRenderer();

    // Add the feature layer to the map.
    map.operationalLayers.add(featureLayer);
    // Set the map to the MapViewController.
    _mapViewController.arcGISMap = map;
  }

  /// Configure a unique value renderer.
  Renderer? _configureUniqueValueRenderer() {
    final stateOutlineSymbol = SimpleLineSymbol(
      style: SimpleLineSymbolStyle.solid,
      color: Colors.white,
      width: 0.7,
    );

    // Create fill symbols for each region.
    final pacificFillSymbol = SimpleFillSymbol(
      style: SimpleFillSymbolStyle.solid,
      color: const Color.fromARGB(255, 0, 0, 255),
      outline: stateOutlineSymbol,
    );
    final mountainFillSymbol = SimpleFillSymbol(
      style: SimpleFillSymbolStyle.solid,
      color: const Color.fromARGB(255, 0, 255, 0),
      outline: stateOutlineSymbol,
    );
    final westSouthCentralFillSymbol = SimpleFillSymbol(
      style: SimpleFillSymbolStyle.solid,
      color: const Color.fromARGB(255, 250, 125, 0),
      outline: stateOutlineSymbol,
    );

    // Create unique values for each region.
    final pacificValue = UniqueValue(
      description: 'Pacific Region',
      label: 'Pacific',
      symbol: pacificFillSymbol,
      values: ['Pacific'],
    );
    final mountainValue = UniqueValue(
      description: 'Rocky Mountain Region',
      label: 'Mountain',
      symbol: mountainFillSymbol,
      values: ['Mountain'],
    );
    final westSouthCentralValue = UniqueValue(
      description: 'West South Central Region',
      label: 'West South Central',
      symbol: westSouthCentralFillSymbol,
      values: ['West South Central'],
    );

    final defaultFillSymbol = SimpleFillSymbol(
      style: SimpleFillSymbolStyle.cross,
      color: Colors.grey,
      outline: null,
    );

    // Create a unique value renderer with the unique values.
    return UniqueValueRenderer(
      fieldNames: ['SUB_REGION'],
      uniqueValues: [
        pacificValue,
        mountainValue,
        westSouthCentralValue,
      ],
      defaultLabel: 'Other',
      defaultSymbol: defaultFillSymbol,
    );
  }
}