Learn how to use a URL to access and display a feature layer in a map.
A map contains layers of geographic data. A map contains a basemap layer and, optionally, one or more data layers. This tutorial shows you how to access and display a feature layer in a map. You access feature layers with an item ID or URL. You will use URLs to access the Trailheads, Trails, and Parks and Open Spaces feature layers and display them in a map.
A feature layer is a dataset in a feature service hosted in ArcGIS. Each feature layer contains features with a single geometry type (point, line, or polygon), and a set of attributes. You can use feature layers to store, access, and manage large amounts of geographic data for your applications.
Prerequisites
The following are required for this tutorial:
- An ArcGIS account to access API keys. If you don't have an account, sign up for free.
- Your system meets the system requirements.
- The ArcGIS Maps SDK for Qt, version 200.4.0 or later is installed.
- The Qt 6.5.1 software development framework is installed.
Open the project in Qt Creator
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To start this tutorial, complete the Display a map tutorial or download and unzip the solution.
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Open the display_a_map project in Qt Creator.
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If you downloaded the Display a map solution, set your API key.
An API Key enables access to services, web maps, and web scenes hosted in ArcGIS Online.
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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.
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In the Projects window, in the Sources folder, open the main.cpp file.
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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.cppUse dark colors for code blocks Change line // 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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Include header files
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Double click on Sources > Display_a_map.cpp to open the file. Include these header files to be able to create
ServiceFeatureTable
andFeatureLayer
instances.Display-a-map.cppUse dark colors for code blocks Add line. Add line. Add line. #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> #include "LayerListModel.h" #include "ServiceFeatureTable.h" #include "FeatureLayer.h"
Add a polygon feature layer
This tutorial will draw the map in following order:
- ArcGISTopographic basemap style layer
- Parks and Open Spaces (polygons)
- Trails (lines)
- Trailheads (points)
It is important to add feature layers in the correct order so features are displayed correctly. Polygon feature layers are typically created before lines or points, so that those features are not obscured by the polygons.
Use the FeatureLayer
class to reference the Parks and Open Spaces URL and add features to the map.
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Go to the Parks and Open Spaces URL and browse the properties of the layer. You may want to explore the Name, Type, Drawing Info, and Fields properties.
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Within the
setup
method, add the following code. Create aViewpoint QUrl
instance namedpolygon
using an ArcGIS feature server as the feature data source. Then create aFeature Url ServiceFeatureTable
namedpolygon_
from thatfeature_ table QUrl
.Display-a-map.cppUse dark colors for code blocks Add line. Add line. void Display_a_map::setupViewpoint() { const Point center(-118.80543, 34.02700, SpatialReference::wgs84()); const Viewpoint viewpoint(center, 100000.0); m_mapView->setViewpointAsync(viewpoint); const QUrl polygonFeatureUrl("https://services3.arcgis.com/GVgbJbqm8hXASVYi/ArcGIS/rest/services/Parks_and_Open_Space/FeatureServer/0"); ServiceFeatureTable* polygon_feature_table = new ServiceFeatureTable(polygonFeatureUrl, this);
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Create a
FeatureLayer
instance namedpolygon_
, passing infeature_ layer polygon_
as the argument. Then append your newfeature_ table polygon_
to thefeature_ layer Map
instance namedm_
.map Display-a-map.cppUse dark colors for code blocks Add line. Add line. const QUrl polygonFeatureUrl("https://services3.arcgis.com/GVgbJbqm8hXASVYi/ArcGIS/rest/services/Parks_and_Open_Space/FeatureServer/0"); ServiceFeatureTable* polygon_feature_table = new ServiceFeatureTable(polygonFeatureUrl, this); FeatureLayer* polygon_feature_layer = new FeatureLayer(polygon_feature_table, this); m_map->operationalLayers()->append(polygon_feature_layer);
Press Ctrl + R to run the app.
You should see a map view centered in the Santa Monica Mountains, with your feature layer showing the Parks and Open Spaces layer in the map.
Add a line feature layer
Line features are typically displayed in a feature layer before points. Use the FeatureLayer
class to reference the Trails URL and add features to the map, as described next.
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Add the following code to create a
QUrl
instance namedline
using the ArcGIS feature server as the feature data source, in this case,Feature Url Trails_
. Then create aStyled ServiceFeatureTable
namedline_
from thatfeature_ table QUrl
.Display-a-map.cppUse dark colors for code blocks Add line. Add line. FeatureLayer* polygon_feature_layer = new FeatureLayer(polygon_feature_table, this); m_map->operationalLayers()->append(polygon_feature_layer); const QUrl lineFeatureUrl("https://services3.arcgis.com/GVgbJbqm8hXASVYi/ArcGIS/rest/services/Trails/FeatureServer/0"); ServiceFeatureTable* line_feature_table = new ServiceFeatureTable(lineFeatureUrl, this);
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Create a
FeatureLayer
instance namedline_
, passing infeature_ layer line_
as the argument. Then append your newfeature_ table line_
to thefeature_ layer Map
instance namedm_
.map Display-a-map.cppUse dark colors for code blocks Add line. Add line. const QUrl lineFeatureUrl("https://services3.arcgis.com/GVgbJbqm8hXASVYi/ArcGIS/rest/services/Trails/FeatureServer/0"); ServiceFeatureTable* line_feature_table = new ServiceFeatureTable(lineFeatureUrl, this); FeatureLayer* line_feature_layer = new FeatureLayer(line_feature_table, this); m_map->operationalLayers()->append(line_feature_layer);
Press Ctrl + R to run the app.
The map view should display the Parks and Open Spaces layer (polygons) and the Trails (lines) layer.
Add a point feature layer
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Add the following code to create a
QUrl
instance namedpoint
using the ArcGIS feature server as the feature data source, in this case,Feature Url Trailheads
. Then create aServiceFeatureTable
namedpoint_
from thatfeature_ table QUrl
.Display-a-map.cppUse dark colors for code blocks Add line. Add line. FeatureLayer* line_feature_layer = new FeatureLayer(line_feature_table, this); m_map->operationalLayers()->append(line_feature_layer); const QUrl pointFeatureUrl("https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0"); ServiceFeatureTable* point_feature_table= new ServiceFeatureTable(pointFeatureUrl, this);
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Add the following two lines of code to create a
FeatureLayer
, passing inpoint_
as the argument. Then append yourfeature_ table FeatureLayer
to theMap
instance namedm_
.map Display-a-map.cppUse dark colors for code blocks Add line. Add line. const QUrl pointFeatureUrl("https://services3.arcgis.com/GVgbJbqm8hXASVYi/arcgis/rest/services/Trailheads/FeatureServer/0"); ServiceFeatureTable* point_feature_table= new ServiceFeatureTable(pointFeatureUrl, this); FeatureLayer* point_feature_layer = new FeatureLayer(point_feature_table, this); m_map->operationalLayers()->append(point_feature_layer);
Press Ctrl + R to run the app.
The map view should display all three feature layers in the map. Double-click, drag, and scroll the mouse wheel over 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: