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// Copyright 2021 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.
using ArcGISRuntime;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI.Controls;
using Foundation;
using System;
using UIKit;
using Color = System.Drawing.Color;
namespace ArcGISRuntimeXamarin.Samples.DisplayOACollection
{
[Register("DisplayOACollection")]
[ArcGISRuntime.Samples.Shared.Attributes.Sample(
name: "Display OGC API collection",
category: "Layers",
description: "Display an OGC API feature collection and query features while navigating the map view.",
instructions: "Pan the map and observe how new features are loaded from the OGC API feature service.",
tags: new[] { "OGC", "OGC API", "feature", "feature layer", "feature table", "service", "table", "web" })]
public class DisplayOACollection : UIViewController
{
// Hold references to UI controls.
private MapView _myMapView;
private UIActivityIndicatorView _loadingProgressBar;
// Hold a reference to the OGC feature collection table.
private OgcFeatureCollectionTable _featureTable;
// Constants for the service URL and collection id.
private const string ServiceUrl = "https://demo.ldproxy.net/daraa";
// Note that the service defines the collection id which can be accessed via OgcFeatureCollectionInfo.CollectionId.
private const string CollectionId = "TransportationGroundCrv";
public DisplayOACollection()
{
Title = "Display OGC API collection";
}
private async void Initialize()
{
// Create the map with topographic basemap.
_myMapView.Map = new Map(BasemapStyle.ArcGISTopographic);
try
{
// Create the feature table from URI and collection id.
_featureTable = new OgcFeatureCollectionTable(new Uri(ServiceUrl), CollectionId);
// Set the feature request mode to manual (only manual is currently supported).
// In this mode, you must manually populate the table - panning and zooming won't request features automatically.
_featureTable.FeatureRequestMode = FeatureRequestMode.ManualCache;
// Load the table.
await _featureTable.LoadAsync();
// Create a feature layer to visualize the OAFeat features.
FeatureLayer ogcFeatureLayer = new FeatureLayer(_featureTable);
// Apply a renderer.
ogcFeatureLayer.Renderer = new SimpleRenderer(new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Color.Blue, 3));
// Add the layer to the map.
_myMapView.Map.OperationalLayers.Add(ogcFeatureLayer);
// Use the navigation completed event to populate the table with the features needed for the current extent.
_myMapView.NavigationCompleted += MapView_NavigationCompleted;
// Zoom to a small area within the dataset by default.
Envelope datasetExtent = _featureTable.Extent;
if (datasetExtent != null && !datasetExtent.IsEmpty)
{
await _myMapView.SetViewpointGeometryAsync(new Envelope(datasetExtent.GetCenter(), datasetExtent.Width / 3, datasetExtent.Height / 3));
}
}
catch (Exception ex)
{
new UIAlertView("Error.", ex.Message, (IUIAlertViewDelegate)null, "OK", null).Show();
}
}
private void MapView_NavigationCompleted(object sender, EventArgs e) => UpdateForExtent();
private async void UpdateForExtent()
{
// Show the loading bar.
_loadingProgressBar.StartAnimating();
// Get the current extent.
Envelope currentExtent = _myMapView.VisibleArea.Extent;
// Create a query based on the current visible extent.
QueryParameters visibleExtentQuery = new QueryParameters();
visibleExtentQuery.Geometry = currentExtent;
visibleExtentQuery.SpatialRelationship = SpatialRelationship.Intersects;
// Set a limit of 5000 on the number of returned features per request,
// because the default on some services could be as low as 10.
visibleExtentQuery.MaxFeatures = 5000;
try
{
// Populate the table with the query, leaving existing table entries intact.
// Setting outFields to null requests all fields.
await _featureTable.PopulateFromServiceAsync(visibleExtentQuery, false, null);
}
catch (Exception ex)
{
new UIAlertView("Couldn't populate table.", ex.Message, (IUIAlertViewDelegate)null, "OK", null).Show();
}
finally
{
// Hide the loading bar.
_loadingProgressBar.StopAnimating();
}
}
public override void LoadView()
{
// Create the views.
View = new UIView() { BackgroundColor = ApplicationTheme.BackgroundColor };
_myMapView = new MapView();
_myMapView.TranslatesAutoresizingMaskIntoConstraints = false;
_loadingProgressBar = new UIActivityIndicatorView(UIActivityIndicatorViewStyle.WhiteLarge)
{
HidesWhenStopped = true,
BackgroundColor = UIColor.FromWhiteAlpha(0, .6f),
TranslatesAutoresizingMaskIntoConstraints = false
};
UILabel helpLabel = new UILabel
{
Text = "Pan and zoom to see features.",
AdjustsFontSizeToFitWidth = true,
TextAlignment = UITextAlignment.Center,
BackgroundColor = UIColor.FromWhiteAlpha(0, .6f),
TextColor = UIColor.White,
Lines = 1,
TranslatesAutoresizingMaskIntoConstraints = false
};
// Add the views.
View.AddSubviews(_myMapView, helpLabel, _loadingProgressBar);
// Lay out the views.
NSLayoutConstraint.ActivateConstraints(new[]
{
_myMapView.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
_myMapView.BottomAnchor.ConstraintEqualTo(View.BottomAnchor),
_myMapView.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
_myMapView.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
helpLabel.TopAnchor.ConstraintEqualTo(_myMapView.TopAnchor),
helpLabel.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
helpLabel.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
helpLabel.HeightAnchor.ConstraintEqualTo(40),
_loadingProgressBar.TopAnchor.ConstraintEqualTo(helpLabel.BottomAnchor),
_loadingProgressBar.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
_loadingProgressBar.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
_loadingProgressBar.HeightAnchor.ConstraintEqualTo(40)
});
}
public override void ViewDidLoad()
{
base.ViewDidLoad();
Initialize();
}
public override void ViewWillAppear(bool animated)
{
base.ViewWillAppear(animated);
// Subscribe to events.
_myMapView.NavigationCompleted += MapView_NavigationCompleted;
}
public override void ViewDidDisappear(bool animated)
{
base.ViewDidDisappear(animated);
// Unsubscribe from events, per best practice.
_myMapView.NavigationCompleted -= MapView_NavigationCompleted;
}
}
}
