Show WFS layer with XML query

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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:arcgis_maps_sdk_flutter_samples/utils/sample_state_support.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

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

  @override
  State<ShowWfsLayerWithXmlQuery> createState() =>
      _ShowWfsLayerWithXmlQueryState();
}

class _ShowWfsLayerWithXmlQueryState extends State<ShowWfsLayerWithXmlQuery>
    with SampleStateSupport {
  // Create a controller for the map view.
  final _mapViewController = ArcGISMapView.createController();
  // A flag for when the map view is ready and controls can be used.
  var _ready = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Stack(
        children: [
          Column(
            children: [
              Expanded(
                // Add a map view to the widget tree and set a controller.
                child: ArcGISMapView(
                  controllerProvider: () => _mapViewController,
                  onMapViewReady: onMapViewReady,
                ),
              ),
            ],
          ),
          // Display a progress indicator and prevent interaction until state is ready.
          Visibility(
            visible: !_ready,
            child: const SizedBox.expand(
              child: ColoredBox(
                color: Colors.white30,
                child: Center(child: CircularProgressIndicator()),
              ),
            ),
          ),
        ],
      ),
    );
  }

  void onMapViewReady() async {
    // Create a map with the ArcGIS Navigation basemap style and set to the map view.
    final map = ArcGISMap.withBasemapStyle(BasemapStyle.arcGISNavigation);
    _mapViewController.arcGISMap = map;

    // Load the WFS layer with the XML query.
    await loadWfsLayerWithXmlQuery();

    // Set the ready state variable to true to enable the sample UI.
    setState(() => _ready = true);
  }

  Future<void> loadWfsLayerWithXmlQuery() async {
    const wfsFeatureTableUri =
        'https://dservices2.arcgis.com/ZQgQTuoyBrtmoGdP/arcgis/services/Seattle_Downtown_Features/WFSServer?service=wfs&amp;request=getcapabilities';

    // Create the WFS feature table from URI and name.
    final statesTable = WfsFeatureTable.withUriAndTableName(
      uri: Uri.parse(wfsFeatureTableUri),
      tableName: 'Seattle_Downtown_Features:Trees',
    )
      // Set the feature request mode and axis order.
      ..axisOrder = OgcAxisOrder.noSwap
      ..featureRequestMode = FeatureRequestMode.manualCache;

    // Create the feature layer from the feature table.
    final featureLayer = FeatureLayer.withFeatureTable(statesTable);
    await featureLayer.load();

    // Add the feature layer to the map.
    _mapViewController.arcGISMap?.operationalLayers.add(featureLayer);

    // Load the query string from the assets folder.
    final xmlQuery = await rootBundle.loadString('assets/wfs_query.xml');

    // Populate the features with the query string.
    await statesTable.populateFromServiceWithXml(
      xmlRequest: xmlQuery,
      clearCache: true,
    );

    // Zoom to the full extent of the feature layer.
    _mapViewController.setViewpointGeometry(featureLayer.fullExtent!);
  }
}