Browse WFS layers

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Sample viewer app

Browse a WFS service for layers and add them to the map.

screenshot

Use case

Services often have multiple layers available for display. For example, a feature service for a city might have layers representing roads, land masses, building footprints, parks, and facilities. A user can choose to only show the road network and parks for a park accessibility analysis.

How to use the sample

A list of layers in the WFS service will be shown. Select a layer to display.

Some WFS services return coordinates in X,Y order, while others return coordinates in lat/long (Y,X) order. If you don't see features rendered or you see features in the wrong location, click on "Swap Coordinate Order".

How it works

  1. Create a WfsService object with a URL to a WFS feature service.
  2. Obtain a list of WfsLayerInfo from WfsService::ServiceInfo.
  3. When a layer is selected, create a WfsFeatureTable from the WfsLayerInfo.
    • Set the axis order if necessary.
  4. Create a feature layer from the feature table.
  5. Add the feature layer to the map.

Relevant API

  • FeatureLayer
  • WfsFeatureTable
  • WfsFeatureTable::axisOrder
  • WfsLayerInfo
  • WfsService
  • WfsServiceInfo

About the data

The sample is configured with a sample WFS service, but you can load other WFS services if desired. The default service shows Seattle downtown features hosted on ArcGIS Online.

Tags

browse, catalog, feature, layers, OGC, service, web, WFS

Sample Code

BrowseWfsLayers.cppBrowseWfsLayers.cppBrowseWfsLayers.hBrowseWfsLayers.qml
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// [WriteFile Name=BrowseWfsLayers, Category=Layers]
// [Legal]
// Copyright 2019 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.
// [Legal]

#ifdef PCH_BUILD
#include "pch.hpp"
#endif // PCH_BUILD

#include "BrowseWfsLayers.h"

#include "Map.h"
#include "MapQuickView.h"
#include "WfsFeatureTable.h"
#include "FeatureLayer.h"
#include "QueryParameters.h"
#include "SimpleRenderer.h"
#include "SimpleLineSymbol.h"
#include "SimpleMarkerSymbol.h"
#include "WfsService.h"
#include "WfsLayerInfo.h"

using namespace Esri::ArcGISRuntime;

BrowseWfsLayers::BrowseWfsLayers(QObject* parent /* = nullptr */):
  QObject(parent),
  m_map(new Map(BasemapStyle::ArcGISTopographic, this))
{
  // create WFS Service
  m_wfsService = new WfsService(QUrl("https://dservices2.arcgis.com/ZQgQTuoyBrtmoGdP/arcgis/services/Seattle_Downtown_Features/WFSServer?service=wfs&request=getcapabilities"),this);

  // once WFS Service is loaded, populate QStringList with layer names for ComboBox
  connect(m_wfsService, &WfsService::doneLoading, this, [this](Error e)
  {
    if (!e.isEmpty())
      return;

      m_wfsLayersInfoList = m_wfsService->serviceInfo().layerInfos();
      for (const WfsLayerInfo& i : qAsConst(m_wfsLayersInfoList))
        m_layerInfoTitleList.append(i.title());

      emit layerInfoTitleListChanged();
  });
  m_wfsService->load();
}

BrowseWfsLayers::~BrowseWfsLayers() = default;

void BrowseWfsLayers::init()
{
  // Register the map view for QML
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<BrowseWfsLayers>("Esri.Samples", 1, 0, "BrowseWfsLayersSample");
}

MapQuickView* BrowseWfsLayers::mapView() const
{
  return m_mapView;
}

// Set the view (created in QML)
void BrowseWfsLayers::setMapView(MapQuickView* mapView)
{
  if (!mapView || mapView == m_mapView)
    return;

  m_mapView = mapView;
  m_mapView->setMap(m_map);

  emit mapViewChanged();
}

void BrowseWfsLayers::createWfsFeatureTable(int index, bool swap)
{
  if (m_wfsLayersInfoList.isEmpty())
    return;

  // if swapAxisOrder button is selected swap the axis otherwise reset to default(OgcAxisOrder::NoSwap or false)
  if (swap)
    m_swapAxis = !m_swapAxis;
  else
    m_swapAxis = false;

  // enable busy indicator
  m_loadingIndicator = true;
  emit isLoadingChanged();

  // clear previous layer
  m_map->operationalLayers()->clear();
  // create WFS Feature Table from selected layer
  m_wfsFeatureTable = new WfsFeatureTable(m_wfsLayersInfoList[index], this);

  // Set feature request mode to manual - only manual is supported at v100.5.
  // In this mode, you must manually populate the table - panning and zooming
  // won't request features automatically.
  m_wfsFeatureTable->setFeatureRequestMode(FeatureRequestMode::ManualCache);

  if (m_swapAxis)
    m_wfsFeatureTable->setAxisOrder(OgcAxisOrder::Swap);
  else
    m_wfsFeatureTable->setAxisOrder(OgcAxisOrder::NoSwap);

  // once WFS Feature Table is loaded, populate the table and add the layer to the map
  connect(m_wfsFeatureTable, &WfsFeatureTable::doneLoading, this, [this](Error e)
  {
    if(!e.isEmpty())
      return;

    populateWfsFeatureTable();
  });
  m_wfsFeatureTable->load();
}

void BrowseWfsLayers::populateWfsFeatureTable()
{
  if (!m_mapView || !m_wfsFeatureTable)
    return;

  // create query parameters
  QueryParameters params;
  params.setGeometry(m_mapView->visibleArea().extent());
  params.setSpatialRelationship(SpatialRelationship::Intersects);

  // query the service
  constexpr bool clearCache = false;
  const QStringList outFields {"*"};
  connect(m_wfsFeatureTable, &WfsFeatureTable::populateFromServiceCompleted, this, [this]()
  {
      addFeatureLayerToMap();
      m_mapView->setViewpointGeometry(m_wfsFeatureTable->extent());
  });
  m_wfsFeatureTable->populateFromService(params, clearCache, outFields);
}

void BrowseWfsLayers::addFeatureLayerToMap()
{
  // create feature layer from the feature table
  SimpleRenderer* sr = nullptr;
  SimpleMarkerSymbol* sms = nullptr;
  SimpleLineSymbol* sls = nullptr;

  // appropriate symbology for each corresponding geometry type
  switch (m_wfsFeatureTable->geometryType()) {
  case GeometryType::Point:
    sms = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle::Circle, QColor("green"), 3.0f, this);
    sr = new SimpleRenderer(sms, this);
    break;
  case GeometryType::Polygon:
    sls = new SimpleLineSymbol(SimpleLineSymbolStyle::Solid, QColor("blue"), 3.0f, this);
    sr = new SimpleRenderer(sls, this);
    break;
  case GeometryType::Polyline:
    sls = new SimpleLineSymbol(SimpleLineSymbolStyle::Solid, QColor("red"), 3.0f, this);
    sr = new SimpleRenderer(sls, this);
    break;
  default:
    qDebug() << "Error! No Renderer defined for this GeometryType";
    return;
  }

  // apply renderer to layer
  FeatureLayer* featureLayer = new FeatureLayer(m_wfsFeatureTable, this);
  featureLayer->setRenderer(sr);

  // add the layer to the map
  m_map->operationalLayers()->append(featureLayer);
  // disable busy indicator
  m_loadingIndicator = false;
  emit isLoadingChanged();
}

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