Display a map

Learn how to create and display a map with a basemap layer.

A map contains layers of geographic data. A map contains a basemap layer and, optionally, one or more data layers. You can display a specific area of a map by using a map view and setting the location and zoom level.

In this tutorial, you create and display a map of the Santa Monica Mountains in California using the topographic basemap layer.

The map and code will be used as the starting point for other 2D tutorials.

Prerequisites

Create a new ArcGIS Maps Qt Creator Project

Use Qt Creator to create an app that displays a Map centered on the Santa Monica Mountains.

1. Start Qt Creator.

2. Click File > New File or Project. Under Projects, select ArcGIS.

3. Select the ArcGIS Maps 200.4.0 Qt Quick C++ app project template (or a later version) and click Choose.

   More info

   You may have several selections for the ArcGIS project type. Be sure to select ArcGIS Maps 200.4.0 Qt Quick C++ app (or a later version).

4. In the Project Location dialog, name your project display_a_map. Click Next.

5. In the Define Build System dialog, select qmake for your build system. Click Next.

6. In the Define Project Details dialog, give this app a description or leave as is. Leave the rest of this dialog as is.

7. Leave the 3D project box unchecked. At the ArcGIS Online Basemap dropdown menu, select Topographic. Then click Next.

8. On the Kit Selection dialog, check the kit(s) you previously set up when you installed the API. You should select a Desktop kit to run this tutorial. Then click Next.

9. At the Project Management dialog, the option to Add as a subproject to root project is only available if you have already created a root project. Ignore this dialog for this tutorial. Click Next.

Set your API key

An API key is required to enable access to services, web maps, and web scenes hosted in ArcGIS Online.

If you haven't already, go to your developer dashboard to get your API key. For these tutorials, use your default API key. It is scoped to include all of the services demonstrated in the tutorials.

1. In the Projects window, in the Sources folder, open the main.cpp file. Modify the code to set the API key. Paste the API key, acquired from your dashboard, between the quotes. Then save and close the file.

   main.cpp

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       // 2. API key authentication: Get a permanent key that gives your application access to Esri
       // location services. Create a new API key or access existing API keys from
       // your ArcGIS for Developers dashboard (https://links.esri.com/arcgis-api-keys).
   
       const QString apiKey = QString("");
   

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Add a map

Use the map view to display a map centered on the Santa Monica Mountains in California. The map will contain a layer built from the ArcGISTopographic BasemapStyle.

1. In the Projects window, open the Headers folder. Double-click the file display_a_map.h to open it.

2. Add the declaration void setupViewpoint(); under private:. Then save and close the file.

   Display_a_map.h

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

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3. In the Projects window, open the Sources folder. Open the display_a_map.cpp file.

4. Add the following #include statements.

   Display_a_map.cpp

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   #include "Display_a_map.h"
   #include "Map.h"
   #include "MapTypes.h"
   #include "MapQuickView.h"
   
   #include "Point.h"
   #include "Viewpoint.h"
   #include "SpatialReference.h"
   #include <QFuture>
   

Create the view point

1. Add code to implement the setupViewpoint method. This method creates a center Point based on a SpatialReference along with longitude and latitude. It also creates a Viewpoint based on center and sets scale. Lastly, it asynchronously sets the initial Map viewpoint.

   More info

   The center Point and scale value keep the initial Viewpoint centered and focused on the Santa Monica Mountains. The scale value sets the level of detail to focus on the area of interest.

   The spatial reference created above is set to use World Geodetic System 1984 (WGS84), the spatial reference commonly used for GPS, and it has the well known id 4326. To learn more, see Spatial References in the ArcGIS Maps SDK for Qt Guide.

   Display_a_map.cpp

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   MapQuickView* Display_a_map::mapView() const
   {
       return m_mapView;
   }
   
   void Display_a_map::setupViewpoint()
   {
   
       const Point center(-118.80543, 34.02700, SpatialReference::wgs84());
       const Viewpoint viewpoint(center, 100000.0);
       m_mapView->setViewpointAsync(viewpoint);
   
   }
   
   
   More info

   The setMapView method appearing later in this file gets a handle to the MapView object that was declared in QML code and sets the Map on the MapView for display. This code is installed by the templates that ArcGIS provides when creating a new project in Qt. You should not modify it.

2. Add the following line of code to call setupViewpoint.

   Display_a_map.cpp

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   // Set the view (created in QML)
   void Display_a_map::setMapView(MapQuickView* mapView)
   {
       if (!mapView || mapView == m_mapView)
       {
           return;
       }
   
       m_mapView = mapView;
   
       m_mapView->setMap(m_map);
   
       setupViewpoint();
   

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3. Press Ctrl + R to run the app.

You should see a map with the topographic basemap layer centered on the Santa Monica Mountains in California. Zoom in and out, and drag the map view to explore the map.

What's next?

Learn how to use additional API features, ArcGIS location services, and ArcGIS tools in these tutorials:

• Add a point, line, and polygon
• Add a feature layer
• Search for an address
• Find a route and directions
• Display a web map
• Display a scene