Difference

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Description

Example of using the GeometryEngine.Difference or GeometryEngine.SymmetricDifference methods to calculate the geometric difference between feature geometries and a user defined geometry. To use this sample, the user draws a polygon over the feature polygons and the system then calculates the difference between the intersecting feature geometries and displays the resulting polygons in a graphics layer on the map.

"Desktop" "Store" "Phone" Available for Desktop, Store, Phone

Sample Code

<UserControl x:Class="ArcGISRuntime.Samples.Desktop.Difference"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:esri="http://schemas.esri.com/arcgis/runtime/2013">
    <Grid x:Name="layoutGrid">
        <Grid.Resources>
            <BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter"/>

            <esri:SimpleFillSymbol x:Key="FillSymbol" Color="#660000FF" Style="Solid">
                <esri:SimpleFillSymbol.Outline>
                    <esri:SimpleLineSymbol Color="Blue" Width="2" />
                </esri:SimpleFillSymbol.Outline>
            </esri:SimpleFillSymbol>
        </Grid.Resources>

        <esri:MapView x:Name="MyMapView" WrapAround="True">
			<esri:Map InitialViewpoint="-15053000,2749000,-6540000,6590000">
				<esri:ArcGISTiledMapServiceLayer
                    ServiceUri="http://services.arcgisonline.com/ArcGIS/rest/services/Canvas/World_Light_Gray_Base/MapServer" />
			</esri:Map>
			<esri:MapView.GraphicsOverlays>
				<esri:GraphicsOverlay ID="resultsOverlay" />
			</esri:MapView.GraphicsOverlays>
        </esri:MapView>

		<Border Background="White" BorderBrush="Black" BorderThickness="1"
				 HorizontalAlignment="Right" VerticalAlignment="Top"
				 Margin="30" Padding="20">
			<Border.Effect>
				<DropShadowEffect/>
			</Border.Effect>
			<StackPanel>
                <TextBlock Text="Click the 'Difference' button to digitize a polygon and calculate the geometric difference between polygon features and the digitized polygon. Resulting difference polygons will be shown as blue graphics."
                           Width="400" TextAlignment="Left" TextWrapping="Wrap" />
                <StackPanel Margin="12,12,12,0" HorizontalAlignment="Center">
                    <Button Content="Difference" Click="DifferenceButton_Click" />
                    <CheckBox x:Name="useSymmetricDifference" Content="Use Symmetric Difference" Margin="12,12,12,0" HorizontalAlignment="Center" />
                </StackPanel>
            </StackPanel>
        </Border>

        <Border Background="White" BorderBrush="Black" BorderThickness="2" Margin="25"
                HorizontalAlignment="Center" VerticalAlignment="Bottom"
                Visibility="{Binding ElementName=MyMapView, Path=Editor.IsActive, Converter={StaticResource BooleanToVisibilityConverter}}">
            <TextBlock Text="Draw a polygon on the map." Margin="8" FontSize="14" />
        </Border>
    </Grid>
</UserControl>
using Esri.ArcGISRuntime.Controls;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Layers;
using Esri.ArcGISRuntime.Symbology;
using System;
using System.Linq;
using System.Windows;
using System.Windows.Controls;

namespace ArcGISRuntime.Samples.Desktop
{
    /// <summary>
    /// Example of using the GeometryEngine.Difference or GeometryEngine.SymmetricDifference methods to calculate the geometric difference between feature geometries and a user defined geometry. To use this sample, the user draws a polygon over the feature polygons and the system then calculates the difference between the intersecting feature geometries and displays the resulting polygons in a graphics layer on the map.
    /// </summary>
    /// <title>Difference</title>
	/// <category>Geometry</category>
	public partial class Difference : UserControl
    {
        private const string GDB_PATH = @"..\..\..\samples-data\maps\usa.geodatabase";

        private Symbol _fillSymbol;
        private FeatureLayer _statesLayer;
		private GraphicsOverlay _differenceGraphics;

        /// <summary>Construct Difference sample control</summary>
        public Difference()
        {
            InitializeComponent();

            _fillSymbol = layoutGrid.Resources["FillSymbol"] as Symbol;
			_differenceGraphics = MyMapView.GraphicsOverlays["resultsOverlay"];
            CreateFeatureLayers();
        }

        // Creates a feature layer from a local .geodatabase file
		private async void CreateFeatureLayers()
        {
            try
            {
                var gdb = await Geodatabase.OpenAsync(GDB_PATH);

                var table = gdb.FeatureTables.First(ft => ft.Name == "US-States");
                _statesLayer = new FeatureLayer() { ID = table.Name, FeatureTable = table };
                MyMapView.Map.Layers.Add(_statesLayer);
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error creating feature layer: " + ex.Message, "Geometry Difference Sample");
            }
        }

        // Calculates a geometric difference between features and user defined geometry
        private async void DifferenceButton_Click(object sender, RoutedEventArgs e)
        {
            try
            {
				_differenceGraphics.Graphics.Clear();

                // wait for user to draw difference polygon
                Polygon userpoly = await MyMapView.Editor.RequestShapeAsync(DrawShape.Polygon) as Polygon;

				// Take account of WrapAround
				Polygon poly = GeometryEngine.NormalizeCentralMeridian(userpoly) as Polygon;

                // Adjust user polygon for backward digitization
                poly = GeometryEngine.Simplify(poly) as Polygon;

                // get intersecting features from the feature layer
                SpatialQueryFilter filter = new SpatialQueryFilter();
                filter.Geometry = GeometryEngine.Project(poly, _statesLayer.FeatureTable.SpatialReference);
                filter.SpatialRelationship = SpatialRelationship.Intersects;
                filter.MaximumRows = 52;
                var stateFeatures = await _statesLayer.FeatureTable.QueryAsync(filter);

                // Calc difference between feature geometries and user polygon and add results to graphics layer
                var states = stateFeatures.Select(feature => feature.Geometry);

                var diffGraphics = states
                    .Select(state => ((bool)useSymmetricDifference.IsChecked) 
                        ? GeometryEngine.SymmetricDifference(state, poly) 
                        : GeometryEngine.Difference(state, poly))
                    .Select(geo => new Graphic(geo, _fillSymbol));

				_differenceGraphics.Graphics.AddRange(diffGraphics);
            }
            catch (Exception ex)
            {
                MessageBox.Show("Difference Error: " + ex.Message, "Geometry Difference Sample");
            }
        }
    }
}
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