Identify graphics

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Sample viewer app

Display an alert message when a graphic is clicked.

screenshot

Use case

A user may wish to select a graphic on a map to view relevant information about it.

How to use the sample

Select a graphic to identify it. You will see an alert message displayed.

How it works

  1. Create a GraphicsOverlay and add it to the MapView.
  2. Add a Graphic along with a SimpleFillSymbol to the graphics overlay.
  3. Create a Point from the location clicked on the map view by the user from the MapQuickView::mouseClicked signal.
  4. Identify the graphic on the map view with identifyGraphicsOverlay(graphicsOverlay, mouseEvent.x(), mouseEvent.y(), tolerance, returnPopupsOnly, max results).

Relevant API

  • Graphic
  • GraphicsOverlay
  • MapView

Tags

graphics, identify

Sample Code

IdentifyGraphics.cppIdentifyGraphics.cppIdentifyGraphics.hIdentifyGraphics.qml
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// [WriteFile Name=IdentifyGraphics, Category=DisplayInformation]
// [Legal]
// Copyright 2016 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 "IdentifyGraphics.h"

#include "Map.h"
#include "MapQuickView.h"
#include "SpatialReference.h"
#include "Basemap.h"
#include "GraphicsOverlay.h"
#include "SimpleFillSymbol.h"
#include "SimpleRenderer.h"
#include "PolygonBuilder.h"
#include "Graphic.h"
#include <QMouseEvent>
#include <QList>
#include <QUuid>
#include <memory>

using namespace Esri::ArcGISRuntime;

IdentifyGraphics::IdentifyGraphics(QQuickItem* parent) :
  QQuickItem(parent)
{
}

IdentifyGraphics::~IdentifyGraphics() = default;

void IdentifyGraphics::init()
{
  qmlRegisterType<MapQuickView>("Esri.Samples", 1, 0, "MapView");
  qmlRegisterType<IdentifyGraphics>("Esri.Samples", 1, 0, "IdentifyGraphicsSample");
}

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

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

  // Create a map using the topographic basemap
  m_map = new Map(BasemapStyle::ArcGISTopographic, this);
  // set map on the map view
  m_mapView->setMap(m_map);

  // create a new graphics overlay
  m_graphicsOverlay = new GraphicsOverlay(this);

  // assign a renderer to the graphics overlay
  SimpleFillSymbol* simpleFillSymbol = new SimpleFillSymbol(SimpleFillSymbolStyle::Solid, QColor(255, 255, 0, 180), this);
  SimpleRenderer* simpleRenderer = new SimpleRenderer(simpleFillSymbol, this);
  m_graphicsOverlay->setRenderer(simpleRenderer);

  // add the overlay to the mapview
  m_mapView->graphicsOverlays()->append(m_graphicsOverlay);

  // add polygon graphics
  addPolygonGraphic();

  // connect signals
  connectSignals();
}

// create the polygon geometry and graphic
void IdentifyGraphics::addPolygonGraphic()
{
  // create the polygon using the builder class
  PolygonBuilder polygonBuilder(SpatialReference::webMercator());
  polygonBuilder.addPoint(-20e5, 20e5);
  polygonBuilder.addPoint(20e5, 20e5);
  polygonBuilder.addPoint(20e5, -20e5);
  polygonBuilder.addPoint(-20e5, -20e5);

  // create the graphic and add to the graphics overlay
  Graphic* graphic = new Graphic(polygonBuilder.toGeometry(), this);
  m_graphicsOverlay->graphics()->append(graphic);
}

void IdentifyGraphics::connectSignals()
{
  //! [identify graphics api snippet]
  // connect to the mouse clicked signal on the MapQuickView
  connect(m_mapView, &MapQuickView::mouseClicked, this, [this](QMouseEvent& mouseEvent)
  {
    // call identify on the map view
    constexpr double tolerance = 5.0;
    constexpr bool returnPopupsOnly = false;
    constexpr int maximumResults = 1;

    m_mapView->identifyGraphicsOverlay(m_graphicsOverlay, mouseEvent.x(), mouseEvent.y(), tolerance, returnPopupsOnly, maximumResults);
  });

  // connect to the identifyLayerCompleted signal on the map view
  connect(m_mapView, &MapQuickView::identifyGraphicsOverlayCompleted, this, [this](QUuid, IdentifyGraphicsOverlayResult* rawIdentifyResult)
  {
    // Delete rawIdentifyResult on leaving scope.
    auto identifyResult = std::unique_ptr<IdentifyGraphicsOverlayResult>(rawIdentifyResult);

    if (identifyResult)
    {
      m_identifiedGraphicsCount = identifyResult->graphics().size();
      emit identifiedGraphicsCountChanged();
    }
  });
  //! [identify graphics api snippet]
}

int IdentifyGraphics::identifiedGraphicsCount()
{
  return m_identifiedGraphicsCount;
}

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