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ArcGIS Runtime SDK for Qt

Display annotation

Sample Viewer View Sample on GitHub

Display annotation from a feature service URL.

Use case

Annotation is useful for displaying text that you don't want to move or resize when the map is panned or zoomed (unlike labels which will move and resize). You can use annotation to place text at a fixed size, position, orientation, font, and so on. You may choose to do this for cartographic reasons or because the exact placement of the text is important.

How to use the sample

Pan and zoom to see names of waters and burns in a small region of Scotland.

How it works

  1. Create a Map with a light gray canvas and a viewpoint near the data.
  2. Create an AnnotationLayer from a feature service URL.
  3. Add both layers to the operational layers of the map and add it to a MapView.

Relevant API

  • AnnotationLayer
  • FeatureLayer
  • ServiceFeatureTable

About the data

Data derived from Ordnance Survey OpenRivers. Contains OS data © Crown copyright and database right 2018.

The annotation layer contains two sublayers of rivers in East Lothian, Scotland, which were set by the author to only be visible within the following scale ranges:

  • Water (1:50,000 - 1:100,000) - A large stream, as defined in the Scots language
  • Burn (1:25,000 - 1:75,000) - A brook or small stream, as defined in the Scots language

Additional information

Annotation is only supported from feature services hosted on an ArcGIS Enterprise server.

Tags

annotation, cartography, labels, placement, reference scale, text, utility

Sample Code

import QtQuick 2.6
import QtQuick.Controls 2.2
import Esri.Samples 1.0

Item {

    // add a mapView component
    MapView {
        id: view
        anchors.fill: parent
    }

    // Declare the C++ instance which creates the scene etc. and supply the view
    DisplayAnnotationSample {
        id: model
        mapView: view
    }
}
#ifdef PCH_BUILD
#include "pch.hpp"
#endif // PCH_BUILD

#include "DisplayAnnotation.h"

#include "AnnotationLayer.h"
#include "FeatureLayer.h"
#include "Map.h"
#include "MapQuickView.h"
#include "ServiceFeatureTable.h"

using namespace Esri::ArcGISRuntime;

namespace
{
const QUrl url("https://services1.arcgis.com/6677msI40mnLuuLr/arcgis/rest/services/East_Lothian_Rivers/FeatureServer/0");
const QUrl annotationUrl("https://sampleserver6.arcgisonline.com/arcgis/rest/services/RiversAnnotation/FeatureServer/0");
}

DisplayAnnotation::DisplayAnnotation(QObject* parent /* = nullptr */):
  QObject(parent),
  m_map(new Map(Basemap::lightGrayCanvas(this), this))
{
  const Point center(-2.725610, 55.882436, SpatialReference::wgs84());
  const Viewpoint viewpoint(center, 50000);
  m_map->setInitialViewpoint(viewpoint);

  ServiceFeatureTable* riverFeaturetable = new ServiceFeatureTable(url, this);
  FeatureLayer* riverFeatureLayer = new FeatureLayer(riverFeaturetable, this);
  m_map->operationalLayers()->append(riverFeatureLayer);

  ServiceFeatureTable* riverAnnotationtable = new ServiceFeatureTable(annotationUrl, this);
  AnnotationLayer* riverAnnotationLayer = new AnnotationLayer(riverAnnotationtable, this);
  m_map->operationalLayers()->append(riverAnnotationLayer);
}

DisplayAnnotation::~DisplayAnnotation() = default;

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

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

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

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

  emit mapViewChanged();
}
#ifndef DISPLAYANNOTATION_H
#define DISPLAYANNOTATION_H

namespace Esri
{
namespace ArcGISRuntime
{
class Map;
class MapQuickView;
}
}

#include <QObject>

class DisplayAnnotation : public QObject
{
  Q_OBJECT

  Q_PROPERTY(Esri::ArcGISRuntime::MapQuickView* mapView READ mapView WRITE setMapView NOTIFY mapViewChanged)

public:
  explicit DisplayAnnotation(QObject* parent = nullptr);
  ~DisplayAnnotation();

  static void init();

signals:
  void mapViewChanged();

private:
  Esri::ArcGISRuntime::MapQuickView* mapView() const;
  void setMapView(Esri::ArcGISRuntime::MapQuickView* mapView);

  Esri::ArcGISRuntime::Map* m_map = nullptr;
  Esri::ArcGISRuntime::MapQuickView* m_mapView = nullptr;
};

#endif // DISPLAYANNOTATION_H