Style WMS layer

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Change the style of a Web Map Service (WMS) layer.

screenshot

Use case

Layers hosted on WMS may have different pre-set styles available to apply to them. Swapping between these styles can help during visual examination of the data. For example, increasing the contrast of satellite images can help in identifying urban and agricultural areas within forested areas.

How to use the sample

Select one of the styles and the map will update the display with the selected style.

How it works

  1. Create a WmsLayer specifying the URL of the service and the layer names you want new WmsLayer(url, names).
  2. When the layer is done loading, get it's list of style strings using wmsLayer::sublayers()::at(0)::sublayerInfo()::styles().
  3. Set one of the styles using wmsLayer::sublayers()::at(0)::setCurrentStyle(styleString).

Relevant API

  • WmsLayer
  • WmsSublayer
  • WmsSublayer::currentStyle
  • WmsSublayerInfo

About the data

This sample uses a public service managed by the State of Minnesota and provides composite imagery for the state and the surrounding areas.

Tags

imagery, styles, visualization, WMS

Sample Code

StyleWmsLayer.cppStyleWmsLayer.cppStyleWmsLayer.hStyleWmsLayer.qml
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// [WriteFile Name=StyleWmsLayer, Category=Layers]
// [Legal]
// Copyright 2018 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 "StyleWmsLayer.h"

#include "Map.h"
#include "MapQuickView.h"
#include "SpatialReference.h"
#include "WmsLayer.h"
#include "WmsSublayer.h"
#include "WmsLayerInfo.h"

using namespace Esri::ArcGISRuntime;

StyleWmsLayer::StyleWmsLayer(QQuickItem* parent /* = nullptr */):
  QQuickItem(parent)
{
}

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

void StyleWmsLayer::componentComplete()
{
  QQuickItem::componentComplete();

  // find QML MapView component
  m_mapView = findChild<MapQuickView*>("mapView");

  // Create a map with spatial reference appropriate for the WMS service (North American Datum 83)
  m_map = new Map(SpatialReference(26915), this);
  m_map->setMinScale(7'000'000);

  // Add a WMS Layer
  WmsLayer* wmsLayer = new WmsLayer(QUrl("https://imageserver.gisdata.mn.gov/cgi-bin/mncomp?SERVICE=WMS&VERSION=1.3.0&REQUEST=GetCapabilities"), QStringList{"mncomp"}, this);
  m_map->operationalLayers()->append(wmsLayer);

  // connect to the doneLoading signal of the WMS Layer
  connect(wmsLayer, &WmsLayer::doneLoading, this, [this, wmsLayer](Error e)
  {
    if (!e.isEmpty())
      return;

    // zoom to the layer
    m_mapView->setViewpointGeometry(wmsLayer->fullExtent());

    // get the subLayer
    if (!wmsLayer->subLayers().empty())
      m_wmsSublayer = wmsLayer->subLayers().at(0);
  });

  // Set map to map view
  m_mapView->setMap(m_map);
}

void StyleWmsLayer::setCurrentStyle(int index)
{
  if (!m_wmsSublayer)
    return;

  // get the styles
  const QStringList styles = m_wmsSublayer->sublayerInfo().styles();
  if (styles.length() < index + 1)
    return;

  // get the style
  const QString style = styles.at(index);

  // set the style on the WMS Sublayer
  m_wmsSublayer->setCurrentStyle(style);
}

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