Simplify Online

This sample demonstrates use of a GeometryService to simplify a polygon, and demonstrates the importance of simplification. To use the sample, click the Query with Original Polygon button. Observe the results include parcels that are not wholly within the red polygon. Then click the Simplify Polygon, then Query button. Observe the results parcels are now wholly within the red polygon.

XAML

<UserControl x:Class="ArcGISWPFSDK.Simplify"
    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:SimpleFillSymbol x:Key="ParcelFillSymbol" Fill="#660000FF" BorderBrush="Blue" BorderThickness="2" />
            <esri:SimpleFillSymbol x:Key="PolygonFillSymbol" Fill="#66FF0000" BorderBrush="Red" BorderThickness="2" />
            <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="-9270434.248,5246977.326,-9269261.417,5247569.712" >
            <esri:ArcGISTiledMapServiceLayer ID="StreetMapLayer" 
                      Url="http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer" />
            <esri:GraphicsLayer ID="MyGraphicsLayer" />
        </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" Margin="30,20,25,30" >
                <TextBlock x:Name="ResponseText" Text="Many spatial operations require topologically correct geometry.  If you try to use the self-intersecting geometry below without simplifying it you will get incorrect results.  The query's spatial relationship is Contains, which should only return the parcels that the polygon contains." 
                           Width="550" TextAlignment="Left"  TextWrapping="Wrap" Foreground="Black" />
                <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" >
                    <Button Content="Query with Original Polygon" Margin="0,5,5,0" x:Name="QueryOnlyButton" Click="QueryOnlyButton_Click" />
                    <Button Content="Simplify Polygon, then Query" x:Name="SimplifyAndQueryButton" Click="SimplifyAndQueryButton_Click"  Margin="5,5,0,0" />
                </StackPanel>
            </StackPanel>
        </Grid>

    </Grid>
</UserControl>

C#

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.Geometry;
using ESRI.ArcGIS.Client.Tasks;

namespace ArcGISWPFSDK
{
    public partial class Simplify : UserControl
    {
        private Graphic _unsimplifiedGraphic = new Graphic();

        public Simplify()
        {
            InitializeComponent();

            MyMap.Layers.LayersInitialized += Layers_LayersInitialized;
        }

        void Layers_LayersInitialized(object sender, EventArgs args)
        {
            if ((MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer).Graphics.Count < 1)
                drawPolygon();
        }

        private void drawPolygon()
        {
            MapPoint center = MyMap.Extent.GetCenter();
            double lat = center.Y;
            double lon = center.X + 300;
            double latOffset = 300;
            double lonOffset = 300;
            ESRI.ArcGIS.Client.Geometry.PointCollection points = new ESRI.ArcGIS.Client.Geometry.PointCollection()
            {
                new MapPoint(lon - lonOffset, lat),
                new MapPoint(lon, lat + latOffset),
                new MapPoint(lon + lonOffset, lat),
                new MapPoint(lon, lat - latOffset),
                new MapPoint(lon - lonOffset, lat),
                new MapPoint(lon - 2 * lonOffset, lat + latOffset),
                new MapPoint(lon - 3 * lonOffset, lat),
                new MapPoint(lon - 2 * lonOffset, lat - latOffset),
                new MapPoint(lon - 1.5 * lonOffset, lat + latOffset),
                new MapPoint(lon - lonOffset, lat)
            };
            ESRI.ArcGIS.Client.Geometry.Polygon polygon = new ESRI.ArcGIS.Client.Geometry.Polygon();
            polygon.Rings.Add(points);
            polygon.SpatialReference = MyMap.SpatialReference;
            _unsimplifiedGraphic.Geometry = polygon;

            GraphicsLayer graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;
            _unsimplifiedGraphic.Symbol = LayoutRoot.Resources["PolygonFillSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol;
            graphicsLayer.Graphics.Add(_unsimplifiedGraphic);
        }

        private void QueryOnlyButton_Click(object sender, RoutedEventArgs e)
        {
            doQuery(_unsimplifiedGraphic.Geometry);
        }

        private void SimplifyAndQueryButton_Click(object sender, RoutedEventArgs e)
        {
            GeometryService geometryService =
                new GeometryService("http://tasks.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer");
            geometryService.SimplifyCompleted += GeometryService_SimplifyCompleted;
            geometryService.Failed += GeometryService_Failed;

            List<Graphic> graphicList = new List<Graphic>();
            graphicList.Add(_unsimplifiedGraphic);
            geometryService.SimplifyAsync(graphicList);
        }

        private void GeometryService_SimplifyCompleted(object sender, GraphicsEventArgs args)
        {
            doQuery(args.Results[0].Geometry);
        }

        private void doQuery(ESRI.ArcGIS.Client.Geometry.Geometry geometry)
        {
            QueryTask queryTask = new QueryTask("http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/BloomfieldHillsMichigan/Parcels/MapServer/2");
            queryTask.ExecuteCompleted += QueryTask_ExecuteCompleted;
            queryTask.Failed += QueryTask_Failed;

            ESRI.ArcGIS.Client.Tasks.Query query = new ESRI.ArcGIS.Client.Tasks.Query()
            {
                Geometry = geometry,
                SpatialRelationship = SpatialRelationship.esriSpatialRelContains,
                OutSpatialReference = MyMap.SpatialReference,
                ReturnGeometry = true
            };
            query.OutFields.Add("*");
            queryTask.ExecuteAsync(query);
        }

        private void QueryTask_ExecuteCompleted(object sender, QueryEventArgs args)
        {
            if (args.FeatureSet == null)
                return;
            FeatureSet featureSet = args.FeatureSet;
            GraphicsLayer graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;
            graphicsLayer.ClearGraphics();

            if (featureSet != null && featureSet.Features.Count > 0)
            {
                foreach (Graphic feature in featureSet.Features)
                {
                    ESRI.ArcGIS.Client.Graphic graphic = new ESRI.ArcGIS.Client.Graphic()
                    {
                        Geometry = feature.Geometry,
                        Symbol = LayoutRoot.Resources["ParcelFillSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol
                    };
                    graphicsLayer.Graphics.Add(graphic);
                }
            }
            graphicsLayer.Graphics.Add(_unsimplifiedGraphic);
        }

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

        private void QueryTask_Failed(object sender, TaskFailedEventArgs e)
        {
            MessageBox.Show("Query failed: " + e.Error);
        }
    }
}

VB.NET

Imports System.Collections.Generic
Imports System.Windows
Imports System.Windows.Controls
Imports ESRI.ArcGIS.Client
Imports ESRI.ArcGIS.Client.Geometry
Imports ESRI.ArcGIS.Client.Tasks

Namespace ArcGISWPFSDK
    Partial Public Class Simplify
        Inherits UserControl
        Private _unsimplifiedGraphic As New Graphic()

        Public Sub New()
            InitializeComponent()

            AddHandler MyMap.Layers.LayersInitialized, AddressOf Layers_LayersInitialized
        End Sub

        Private Sub Layers_LayersInitialized(sender As Object, args As EventArgs)
            If TryCast(MyMap.Layers("MyGraphicsLayer"), GraphicsLayer).Graphics.Count < 1 Then
                drawPolygon()
            End If
        End Sub

        Private Sub drawPolygon()
            Dim center As MapPoint = MyMap.Extent.GetCenter()
            Dim lat As Double = center.Y
            Dim lon As Double = center.X + 300
            Dim latOffset As Double = 300
            Dim lonOffset As Double = 300
            Dim points As New ESRI.ArcGIS.Client.Geometry.PointCollection() From { _
             New MapPoint(lon - lonOffset, lat), _
             New MapPoint(lon, lat + latOffset), _
             New MapPoint(lon + lonOffset, lat), _
             New MapPoint(lon, lat - latOffset), _
             New MapPoint(lon - lonOffset, lat), _
             New MapPoint(lon - 2 * lonOffset, lat + latOffset), _
             New MapPoint(lon - 3 * lonOffset, lat), _
             New MapPoint(lon - 2 * lonOffset, lat - latOffset), _
             New MapPoint(lon - 1.5 * lonOffset, lat + latOffset), _
             New MapPoint(lon - lonOffset, lat) _
            }
            Dim polygon As New ESRI.ArcGIS.Client.Geometry.Polygon()
            polygon.Rings.Add(points)
            polygon.SpatialReference = MyMap.SpatialReference
            _unsimplifiedGraphic.Geometry = polygon

            Dim graphicsLayer As GraphicsLayer = TryCast(MyMap.Layers("MyGraphicsLayer"), GraphicsLayer)
            _unsimplifiedGraphic.Symbol = TryCast(LayoutRoot.Resources("PolygonFillSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
            graphicsLayer.Graphics.Add(_unsimplifiedGraphic)
        End Sub

        Private Sub QueryOnlyButton_Click(sender As Object, e As RoutedEventArgs)
            doQuery(_unsimplifiedGraphic.Geometry)
        End Sub

        Private Sub SimplifyAndQueryButton_Click(sender As Object, e As RoutedEventArgs)
            Dim geometryService As New GeometryService("http://tasks.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer")
            AddHandler geometryService.SimplifyCompleted, AddressOf GeometryService_SimplifyCompleted
            AddHandler geometryService.Failed, AddressOf GeometryService_Failed

            Dim graphicList As New List(Of Graphic)()
            graphicList.Add(_unsimplifiedGraphic)
            geometryService.SimplifyAsync(graphicList)
        End Sub

        Private Sub GeometryService_SimplifyCompleted(sender As Object, args As GraphicsEventArgs)
            doQuery(args.Results(0).Geometry)
        End Sub

        Private Sub doQuery(geometry As ESRI.ArcGIS.Client.Geometry.Geometry)
            Dim queryTask As New QueryTask("http://sampleserver3.arcgisonline.com/ArcGIS/rest/services/BloomfieldHillsMichigan/Parcels/MapServer/2")
            AddHandler queryTask.ExecuteCompleted, AddressOf QueryTask_ExecuteCompleted
            AddHandler queryTask.Failed, AddressOf QueryTask_Failed

            Dim query As New ESRI.ArcGIS.Client.Tasks.Query() With { _
             .Geometry = geometry, _
             .SpatialRelationship = SpatialRelationship.esriSpatialRelContains, _
             .OutSpatialReference = MyMap.SpatialReference, _
             .ReturnGeometry = True _
            }
            query.OutFields.Add("*")
            queryTask.ExecuteAsync(query)
        End Sub

        Private Sub QueryTask_ExecuteCompleted(sender As Object, args As QueryEventArgs)
            If args.FeatureSet Is Nothing Then
                Return
            End If
            Dim featureSet As FeatureSet = args.FeatureSet
            Dim graphicsLayer As GraphicsLayer = TryCast(MyMap.Layers("MyGraphicsLayer"), GraphicsLayer)
            graphicsLayer.ClearGraphics()

            If featureSet IsNot Nothing AndAlso featureSet.Features.Count > 0 Then
                For Each feature As Graphic In featureSet.Features
                    Dim graphic As New ESRI.ArcGIS.Client.Graphic() With { _
                     .Geometry = feature.Geometry, _
                     .Symbol = TryCast(LayoutRoot.Resources("ParcelFillSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol) _
                    }
                    graphicsLayer.Graphics.Add(graphic)
                Next
            End If
            graphicsLayer.Graphics.Add(_unsimplifiedGraphic)
        End Sub

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

        Private Sub QueryTask_Failed(sender As Object, e As TaskFailedEventArgs)
            MessageBox.Show("Query failed: " & Convert.ToString(e.[Error]))
        End Sub
    End Class
End Namespace