Offset Online

This sample demonstrates using an ESRI.ArcGIS.Client.Tasks GeometryService that takes an input graphic polygon and returns a buffered (or offset) graphic polygon. To obtain the input graphic polygon, a user makes a single mouse click that generates a graphic which is turned into an MapPoint object. The MapPoint object has a SpatialReference applied and is used as an input into the FindGraphicsInHostCoordinates Method which generates the input graphic polygon.

To use the sample, click on a parcel to generate an offset (cyan).

XAML

<UserControl x:Class="ArcGISWPFSDK.Offset"
    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:SimpleFillSymbol x:Key="BlueFillSymbol" Fill="#990000FF" BorderBrush="Blue" />
            <esri:SimpleFillSymbol x:Key="CyanFillSymbol" Fill="#4400FFFF"  BorderBrush="Cyan"/>
            <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="-9275076.4794,5253225.9406,-9274273.6411,5253885.6155" >
            <esri:ArcGISTiledMapServiceLayer ID="StreetMapLayer" 
                Url="http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer" />
            <esri:GraphicsLayer ID="ParcelsGraphicsLayer" />
            <esri:GraphicsLayer ID="OffsetGraphicsLayer" />
        </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" />
            <TextBlock x:Name="ResponseTextBlock" Text="Click on a parcel to generate an offset (cyan)." 
                       Width="200" TextAlignment="Left" Margin="30,20,20,30" TextWrapping="Wrap" Foreground="Black" />
        </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.Media;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.Tasks;
using ESRI.ArcGIS.Client.Geometry;

namespace ArcGISWPFSDK
{
    public partial class Offset : UserControl
    {
        private Draw MyDrawObject;
        private GraphicsLayer parcelGraphicsLayer;
        private GraphicsLayer offsetGraphicsLayer;
        private GeometryService geometryService;

        public Offset()
        {
            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;
            offsetGraphicsLayer = MyMap.Layers["OffsetGraphicsLayer"] 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 = new Envelope(-83.3188395774275, 42.61428312652851, -83.31295664068958, 42.61670913269855);
                query.ReturnGeometry = true;
                query.OutSpatialReference = MyMap.SpatialReference;
                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)
        {
            MyDrawObject.IsEnabled = false;
            offsetGraphicsLayer.ClearGraphics();

            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);

            List<Graphic> selectedList = selected.ToList();
            if (selectedList.Count < 1)
            {
                MyDrawObject.IsEnabled = true;
                return;
            }

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

            geometryService.OffsetCompleted += GeometryService_OffsetCompleted;
            geometryService.Failed += GeometryService_Failed;

            OffsetParameters offsetParameters = new OffsetParameters()
            {
                BevelRatio = 1.1,
                OffsetDistance = -30,
                OffsetHow = GeometryOffset.Bevelled,
                OffsetUnit = LinearUnit.Meter,
                Simplify = true
            };

            geometryService.OffsetAsync(selectedList, offsetParameters);
        }

        void GeometryService_OffsetCompleted(object sender, GraphicsEventArgs e)
        {
            foreach (Graphic g in e.Results)
            {
                g.Symbol = LayoutRoot.Resources["CyanFillSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol;
                offsetGraphicsLayer.Graphics.Add(g);
            }
            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.Media
Imports ESRI.ArcGIS.Client
Imports ESRI.ArcGIS.Client.Tasks
Imports ESRI.ArcGIS.Client.Geometry

Namespace ArcGISWPFSDK
    Partial Public Class Offset
        Inherits UserControl
        Private MyDrawObject As Draw
        Private parcelGraphicsLayer As GraphicsLayer
        Private offsetGraphicsLayer As GraphicsLayer
        Private geometryService As GeometryService

        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)
            offsetGraphicsLayer = TryCast(MyMap.Layers("OffsetGraphicsLayer"), 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 = New Envelope(-83.3188395774275, 42.6142831265285, -83.3129566406896, 42.6167091326986)
                query.ReturnGeometry = True
                query.OutSpatialReference = MyMap.SpatialReference
                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)
            MyDrawObject.IsEnabled = False
            offsetGraphicsLayer.ClearGraphics()

            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)

            Dim selectedList As List(Of Graphic) = selected.ToList()
            If selectedList.Count < 1 Then
                MyDrawObject.IsEnabled = True
                Return
            End If

            geometryService = New GeometryService("http://tasks.arcgisonline.com/ArcGIS/rest/services/Geometry/GeometryServer")

            AddHandler geometryService.OffsetCompleted, AddressOf GeometryService_OffsetCompleted
            AddHandler geometryService.Failed, AddressOf GeometryService_Failed

            Dim offsetParameters As New OffsetParameters() With { _
             .BevelRatio = 1.1, _
             .OffsetDistance = -30, _
             .OffsetHow = GeometryOffset.Bevelled, _
             .OffsetUnit = LinearUnit.Meter, _
             .Simplify = True _
            }

            geometryService.OffsetAsync(selectedList, offsetParameters)
        End Sub

        Private Sub GeometryService_OffsetCompleted(sender As Object, e As GraphicsEventArgs)
            For Each g As Graphic In e.Results
                g.Symbol = TryCast(LayoutRoot.Resources("CyanFillSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
                offsetGraphicsLayer.Graphics.Add(g)
            Next
            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