Union Online

This sample demonstrates using an ESRI.ArcGIS.Client.Tasks GeometryService that takes two or more input polygons and returns a polygon that is the union of the inputs. The input polygons do not have to be contiguous (i.e. touching) to be unioned. Polygons that are spatially disparate, like islands, can be unioned into one polygon.

To use the sample, click on the parcel polygons to select or unselect graphic features. Click on the Union button to union selected parcels.

XAML

<UserControl x:Class="ArcGISWPFSDK.Union"
    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/client/2009">
    <Grid x:Name="LayoutRoot">

        <Grid.Resources>
            <esri:SimpleLineSymbol x:Key="RedLineSymbol" Color="Red" Width="4" Style="Solid" />
            <esri:FillSymbol x:Key="BlueFillSymbol">
                <esri:FillSymbol.ControlTemplate>
                    <ControlTemplate x:Name="CustomPolygonTemplate">
                        <Grid>
                            <VisualStateManager.VisualStateGroups>
                                <VisualStateGroup x:Name="CommonStates">
                                    <VisualState x:Name="Unselected" />
                                    <VisualState x:Name="Selected">
                                        <Storyboard>
                                            <ColorAnimation Storyboard.TargetName="Element"
                                                Storyboard.TargetProperty="(Fill).(Color)"
                                                To="#99FFFF00" Duration="0:0:0.1" />
                                        </Storyboard>
                                    </VisualState>
                                </VisualStateGroup>
                            </VisualStateManager.VisualStateGroups>
                            <Path x:Name="Element" Stroke="Red" Fill="#660000FF"
                                StrokeStartLineCap="Round" StrokeThickness="2" 
                                StrokeLineJoin="Round" StrokeEndLineCap="Round" />
                        </Grid>
                    </ControlTemplate>
                </esri:FillSymbol.ControlTemplate>
            </esri:FillSymbol>
            <LinearGradientBrush x:Key="PanelGradient" EndPoint="0.5,1" StartPoint="0.5,0">
                <LinearGradientBrush.RelativeTransform>
                    <TransformGroup>
                        <ScaleTransform CenterY="0.5" CenterX="0.5"/>
                        <SkewTransform CenterY="0.5" CenterX="0.5"/>
                        <RotateTransform Angle="176" CenterY="0.5" CenterX="0.5"/>
                        <TranslateTransform/>
                    </TransformGroup>
                </LinearGradientBrush.RelativeTransform>
                <GradientStop Color="#FF145787" Offset="0.16"/>
                <GradientStop Color="#FF3D7FAC" Offset="0.502"/>
                <GradientStop Color="#FF88C5EF" Offset="0.984"/>
            </LinearGradientBrush>
        </Grid.Resources>

        <esri:Map x:Name="MyMap" Extent="-83.3188395774275,42.61428312652851,-83.31295664068958,42.61670913269855" >
            <esri:ArcGISTiledMapServiceLayer ID="StreetMapLayer" 
                Url="http://services.arcgisonline.com/ArcGIS/rest/services/ESRI_StreetMap_World_2D/MapServer" />
            <esri:GraphicsLayer ID="ParcelsGraphicsLayer" />
        </esri:Map>

        <Grid HorizontalAlignment="Right" VerticalAlignment="Top" Margin="0,10,10,0" >
            <Rectangle Fill="{StaticResource PanelGradient}" Stroke="Gray"  RadiusX="10" RadiusY="10" Margin="0,0,0,5" >
                <Rectangle.Effect>
                    <DropShadowEffect/>
                </Rectangle.Effect>
            </Rectangle>
            <Rectangle Fill="#FFFFFFFF" Stroke="DarkGray" RadiusX="5" RadiusY="5" Margin="10,10,10,15" />
            <StackPanel Orientation="Vertical" HorizontalAlignment="Center" Margin="30,20,20,30" >
                <TextBlock x:Name="ResponseTextBlock" Width="200"
                           Text="Click on the parcel polygons to select or unselect graphic features.  Click on the Union button to union selected parcels." 
                       TextAlignment="Left" TextWrapping="Wrap" Foreground="Black"/>
                <Button Content="Union" Margin="0,5,5,0" x:Name="UnionButton" Width="100"
                             Click="UnionButton_Click" IsEnabled="False" />
            </StackPanel>
        </Grid>

    </Grid>
</UserControl>

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.Tasks;

namespace ArcGISWPFSDK
{
    public partial class Union : UserControl
    {
        private Draw MyDrawObject;
        private GraphicsLayer parcelGraphicsLayer;
        List<Graphic> selectedGraphics = new List<Graphic>();

        public Union()
        {
            InitializeComponent();

            MyMap.Layers.LayersInitialized += Layers_LayersInitialized;

            MyMap.MinimumResolution = double.Epsilon;

            MyDrawObject = new Draw(MyMap)
            {
                DrawMode = DrawMode.Point,
                IsEnabled = false,
            };
            MyDrawObject.DrawComplete += MyDrawObject_DrawComplete;

            parcelGraphicsLayer = MyMap.Layers["ParcelsGraphicsLayer"] as GraphicsLayer;
        }

        void Layers_LayersInitialized(object sender, EventArgs args)
        {
            if (parcelGraphicsLayer != null && parcelGraphicsLayer.Graphics.Count == 0)
            {
                QueryTask queryTask =
                    new QueryTask("http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/TaxParcel/AssessorsParcelCharacteristics/MapServer/1");
                Query query = new Query();
                query.Geometry = MyMap.Extent;
                query.ReturnGeometry = true;
                queryTask.ExecuteCompleted += queryTask_ExecuteCompleted;
                queryTask.Failed += queryTask_Failed;
                queryTask.ExecuteAsync(query);
            }
        }

        void queryTask_Failed(object sender, TaskFailedEventArgs e)
        {
            MessageBox.Show("Query error: " + e.Error);
        }

        void queryTask_ExecuteCompleted(object sender, QueryEventArgs e)
        {
            foreach (Graphic g in e.FeatureSet.Features)
            {
                g.Symbol = LayoutRoot.Resources["BlueFillSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol;
                g.Geometry.SpatialReference = MyMap.SpatialReference;
                parcelGraphicsLayer.Graphics.Add(g);
            }
            MyDrawObject.IsEnabled = true;
        }

        private void MyDrawObject_DrawComplete(object sender, DrawEventArgs args)
        {
            ESRI.ArcGIS.Client.Geometry.MapPoint point = args.Geometry as ESRI.ArcGIS.Client.Geometry.MapPoint;
            point.SpatialReference = MyMap.SpatialReference;
            System.Windows.Point screenPnt = MyMap.MapToScreen(point);

            // Account for difference between Map and application origin
            GeneralTransform generalTransform = MyMap.TransformToVisual(Application.Current.MainWindow);
            System.Windows.Point transformScreenPnt = generalTransform.Transform(screenPnt);

            IEnumerable<Graphic> selected =
                parcelGraphicsLayer.FindGraphicsInHostCoordinates(transformScreenPnt);

            foreach (Graphic g in selected)
                if (g.Selected) { g.UnSelect(); selectedGraphics.Remove(g); }
                else { g.Select(); selectedGraphics.Add(g); }

            if (selectedGraphics.Count > 1)
                UnionButton.IsEnabled = true;
            else
                UnionButton.IsEnabled = false;
        }

        private void UnionButton_Click(object sender, RoutedEventArgs e)
        {
            UnionButton.IsEnabled = false;
            MyDrawObject.IsEnabled = false;

            GeometryService geometryService =
                        new GeometryService("http://tasks.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer");
            geometryService.UnionCompleted += GeometryService_UnionCompleted;
            geometryService.Failed += GeometryService_Failed;

            geometryService.UnionAsync(selectedGraphics);
        }

        void GeometryService_UnionCompleted(object sender, GeometryEventArgs e)
        {
            foreach (Graphic g in selectedGraphics)
                parcelGraphicsLayer.Graphics.Remove(g);
            selectedGraphics.Clear();

            parcelGraphicsLayer.Graphics.Add(new Graphic() { Geometry = e.Result, Symbol = LayoutRoot.Resources["BlueFillSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol });

            MyDrawObject.IsEnabled = true;
        }

        private void GeometryService_Failed(object sender, TaskFailedEventArgs e)
        {
            MessageBox.Show("Geometry Service error: " + e.Error);
        }
    }
}

VB.NET

Imports System.Collections.Generic
Imports System.Linq
Imports System.Net
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Animation
Imports System.Windows.Shapes
Imports ESRI.ArcGIS.Client
Imports ESRI.ArcGIS.Client.Tasks

Namespace ArcGISWPFSDK
    Partial Public Class Union
        Inherits UserControl
        Private MyDrawObject As Draw
        Private parcelGraphicsLayer As GraphicsLayer
        Private selectedGraphics As New List(Of Graphic)()

        Public Sub New()
            InitializeComponent()

            AddHandler MyMap.Layers.LayersInitialized, AddressOf Layers_LayersInitialized

            MyMap.MinimumResolution = Double.Epsilon

            MyDrawObject = New Draw(MyMap) With { _
             .DrawMode = DrawMode.Point, _
             .IsEnabled = False _
            }
            AddHandler MyDrawObject.DrawComplete, AddressOf MyDrawObject_DrawComplete

            parcelGraphicsLayer = TryCast(MyMap.Layers("ParcelsGraphicsLayer"), GraphicsLayer)
        End Sub

        Private Sub Layers_LayersInitialized(sender As Object, args As EventArgs)
            If parcelGraphicsLayer IsNot Nothing AndAlso parcelGraphicsLayer.Graphics.Count = 0 Then
                Dim queryTask As New QueryTask("http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/TaxParcel/AssessorsParcelCharacteristics/MapServer/1")
                Dim query As New Query()
                query.Geometry = MyMap.Extent
                query.ReturnGeometry = True
                AddHandler queryTask.ExecuteCompleted, AddressOf queryTask_ExecuteCompleted
                AddHandler queryTask.Failed, AddressOf queryTask_Failed
                queryTask.ExecuteAsync(query)
            End If
        End Sub

        Private Sub queryTask_Failed(sender As Object, e As TaskFailedEventArgs)
            MessageBox.Show("Query error: " & Convert.ToString(e.[Error]))
        End Sub

        Private Sub queryTask_ExecuteCompleted(sender As Object, e As QueryEventArgs)
            For Each g As Graphic In e.FeatureSet.Features
                g.Symbol = TryCast(LayoutRoot.Resources("BlueFillSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
                g.Geometry.SpatialReference = MyMap.SpatialReference
                parcelGraphicsLayer.Graphics.Add(g)
            Next
            MyDrawObject.IsEnabled = True
        End Sub

        Private Sub MyDrawObject_DrawComplete(sender As Object, args As DrawEventArgs)
            Dim point As ESRI.ArcGIS.Client.Geometry.MapPoint = TryCast(args.Geometry, ESRI.ArcGIS.Client.Geometry.MapPoint)
            point.SpatialReference = MyMap.SpatialReference
            Dim screenPnt As System.Windows.Point = MyMap.MapToScreen(point)

            ' Account for difference between Map and application origin
            Dim generalTransform As GeneralTransform = MyMap.TransformToVisual(Application.Current.MainWindow)
            Dim transformScreenPnt As System.Windows.Point = generalTransform.Transform(screenPnt)

            Dim selected As IEnumerable(Of Graphic) = parcelGraphicsLayer.FindGraphicsInHostCoordinates(transformScreenPnt)

            For Each g As Graphic In selected
                If g.Selected Then
                    g.UnSelect()
                    selectedGraphics.Remove(g)
                Else
                    g.[Select]()
                    selectedGraphics.Add(g)
                End If
            Next

            If selectedGraphics.Count > 1 Then
                UnionButton.IsEnabled = True
            Else
                UnionButton.IsEnabled = False
            End If
        End Sub

        Private Sub UnionButton_Click(sender As Object, e As RoutedEventArgs)
            UnionButton.IsEnabled = False
            MyDrawObject.IsEnabled = False

            Dim geometryService As New GeometryService("http://tasks.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer")
            AddHandler geometryService.UnionCompleted, AddressOf GeometryService_UnionCompleted
            AddHandler geometryService.Failed, AddressOf GeometryService_Failed

            geometryService.UnionAsync(selectedGraphics)
        End Sub

        Private Sub GeometryService_UnionCompleted(sender As Object, e As GeometryEventArgs)
            For Each g As Graphic In selectedGraphics
                parcelGraphicsLayer.Graphics.Remove(g)
            Next
            selectedGraphics.Clear()

            parcelGraphicsLayer.Graphics.Add(New Graphic() With { _
             .Geometry = e.Result, _
             .Symbol = TryCast(LayoutRoot.Resources("BlueFillSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol) _
            })

            MyDrawObject.IsEnabled = True
        End Sub

        Private Sub GeometryService_Failed(sender As Object, e As TaskFailedEventArgs)
            MessageBox.Show("Geometry Service error: " & Convert.ToString(e.[Error]))
        End Sub
    End Class
End Namespace