Offset

This sample demonstrates using the ArcGIS Runtime SDK for WPF to perform a geometry operation 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.LocalOffset"
    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="-15000000,2000000,-7000000,8000000" Background="#FFE3E3E3" >
            <esri:ArcGISLocalTiledLayer ID="BaseMap" Path="..\\Data\\TPKs\\Topographic.tpk"/>
            <esri:GraphicsLayer ID="ParcelsGraphicsLayer" x:Name="_ParcelsGraphicsLayer"/>
            <esri:GraphicsLayer ID="OffsetGraphicsLayer" x:Name="_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.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.Tasks;
using ESRI.ArcGIS.Client.Local;

namespace ArcGISWPFSDK
{
    public partial class LocalOffset : UserControl
    {
        private Draw _drawObject;
        GeometryService _geometryTask;

        public LocalOffset()
        {
            InitializeComponent();

            MyMap.Layers.LayersInitialized += (s, e) =>
            {
                LocalMapService.GetServiceAsync("..\\Data\\MPKS\\USCitiesStates.mpk", (localMapService) =>
                {
                    QueryTask _queryTask = new QueryTask();
                    _queryTask.Url = localMapService.UrlMapService + "/2";
                    Query query = new Query();
                    query.Geometry = MyMap.Extent;
                    query.ReturnGeometry = true;
                    query.OutSpatialReference = MyMap.SpatialReference;
                    _queryTask.ExecuteCompleted += queryTask_ExecuteCompleted;
                    _queryTask.Failed += queryTask_Failed;
                    _queryTask.ExecuteAsync(query);
                });

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

            LocalGeometryService.GetServiceAsync(lgs =>
            {
                _geometryTask = new GeometryService();
                _geometryTask.Url = lgs.UrlGeometryService;
                _geometryTask.OffsetCompleted += GeometryService_OffsetCompleted;
                _geometryTask.Failed += GeometryService_Failed;

            });
        }

        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;
                _ParcelsGraphicsLayer.Graphics.Add(g);
            }
            _drawObject.IsEnabled = true;
        }

        private void DrawObject_DrawComplete(object sender, DrawEventArgs args)
        {
            _drawObject.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 =
                _ParcelsGraphicsLayer.FindGraphicsInHostCoordinates(transformScreenPnt);

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

            OffsetParameters offsetParameters = new OffsetParameters()
            {
                BevelRatio = 1.1,
                OffsetDistance = -300,
                OffsetHow = GeometryOffset.Bevelled,
                OffsetUnit = LinearUnit.Kilometer,
                Simplify = true
            };

            _geometryTask.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);
            }
            _drawObject.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
Imports ESRI.ArcGIS.Client.Local

Namespace ArcGISWPFSDK
    Partial Public Class LocalOffset
        Inherits UserControl
        Private MyDrawObject As Draw
        Private parcelGraphicsLayer As GraphicsLayer
        Private offsetGraphicsLayer As GraphicsLayer
        Private _geometryService As GeometryService
        Private _queryTask As QueryTask
        Private _mapService As LocalMapService

        Public Sub New()
            InitializeComponent()

            LocalMapService.GetServiceAsync("..\Data\MPKS\USCitiesStates.mpk", Function(localMapService__1)
                                                                                   _mapService = localMapService__1
                                                                                   _queryTask = New QueryTask()
                                                                                   _queryTask.Url = _mapService.UrlMapService & "/2"
                                                                                   Dim query As New Query()
                                                                                   query.Geometry = MyMap.Extent
                                                                                   query.ReturnGeometry = True
                                                                                   query.OutSpatialReference = MyMap.SpatialReference
                                                                                   AddHandler _queryTask.ExecuteCompleted, AddressOf queryTask_ExecuteCompleted
                                                                                   AddHandler _queryTask.Failed, AddressOf queryTask_Failed
                                                                                   _queryTask.ExecuteAsync(query)

                                                                               End Function)

            Dim localGeometryService As New LocalGeometryService()
            AddHandler localGeometryService.StartCompleted, Function(sender, eventargs)
                                                                Dim lgs As LocalGeometryService = TryCast(sender, LocalGeometryService)
                                                                _geometryService = New GeometryService()
                                                                _geometryService.Url = lgs.UrlGeometryService
                                                                MyMap.IsEnabled = True
                                                                AddHandler _geometryService.OffsetCompleted, AddressOf GeometryService_OffsetCompleted
                                                                AddHandler _geometryService.Failed, AddressOf GeometryService_Failed
                                                                MyDrawObject = New Draw(MyMap) With { _
                                                                 .DrawMode = DrawMode.Point, _
                                                                 .IsEnabled = False _
                                                                }

                                                                AddHandler MyDrawObject.DrawComplete, AddressOf MyDrawObject_DrawComplete

                                                            End Function
            localGeometryService.StartAsync()

            parcelGraphicsLayer = TryCast(MyMap.Layers("ParcelsGraphicsLayer"), GraphicsLayer)
            offsetGraphicsLayer = TryCast(MyMap.Layers("OffsetGraphicsLayer"), GraphicsLayer)
        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


            Dim offsetParameters As New OffsetParameters() With { _
             .BevelRatio = 1.1, _
             .OffsetDistance = -300, _
             .OffsetHow = GeometryOffset.Bevelled, _
             .OffsetUnit = LinearUnit.Kilometer, _
             .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