Buffer a Point Online

This sample demonstrates use of a GeometryService to calculate a buffer. To use the sample, simply click a point on the map. The click point and a buffer of 5 miles around the point will be shown.

In the code-behind, a GeometryService is used to buffer the point. Note that, for accurate results, the BufferSpatialReference is set based on the area of interest.

XAML

<UserControl x:Class="ArcGISWPFSDK.BufferPoint"
    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>
            <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>
            <esri:PictureMarkerSymbol x:Key="DefaultClickSymbol" OffsetX="11" OffsetY="39" Source="/Assets/Images/i_pushpin.png" />
            <esri:SimpleFillSymbol x:Key="DefaultBufferSymbol" Fill="#660000FF" BorderBrush="Blue" BorderThickness="2"  />
        </Grid.Resources>

        <esri:Map x:Name="MyMap" Extent="-10863035.970,3838021.340,-10744801.344,3887145.299" MouseClick="MyMap_MouseClick" >
            <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" />
            <TextBlock x:Name="InformationTextBlock" Text="Click on map to set a location. A buffer of 5 miles will be displayed." 
                       Width="200" TextAlignment="Left" Margin="30,20,25,30" TextWrapping="Wrap" Foreground="Black" />
        </Grid>

    </Grid>
</UserControl>

C#

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 BufferPoint : UserControl
    {
        public BufferPoint()
        {
            InitializeComponent();
        }

        private void MyMap_MouseClick(object sender, ESRI.ArcGIS.Client.Map.MouseEventArgs e)
        {
            GraphicsLayer graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;
            graphicsLayer.ClearGraphics();

            e.MapPoint.SpatialReference = MyMap.SpatialReference;
            Graphic graphic = new ESRI.ArcGIS.Client.Graphic()
            {
                Geometry = e.MapPoint,
                Symbol = LayoutRoot.Resources["DefaultClickSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol
            };
            graphic.SetZIndex(1);
            graphicsLayer.Graphics.Add(graphic);

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

            // If buffer spatial reference is GCS and unit is linear, geometry service will do geodesic buffering
            BufferParameters bufferParams = new BufferParameters()
            {
                Unit = LinearUnit.StatuteMile,
                BufferSpatialReference = new SpatialReference(4326),
                OutSpatialReference = MyMap.SpatialReference
            };
            bufferParams.Features.Add(graphic);
            bufferParams.Distances.Add(5);

            geometryService.BufferAsync(bufferParams);
        }

        void GeometryService_BufferCompleted(object sender, GraphicsEventArgs args)
        {
            IList<Graphic> results = args.Results;
            GraphicsLayer graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;

            foreach (Graphic graphic in results)
            {
                graphic.Symbol = LayoutRoot.Resources["DefaultBufferSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol;
                graphicsLayer.Graphics.Add(graphic);
            }
        }

        private void GeometryService_Failed(object sender, TaskFailedEventArgs e)
        {
            MessageBox.Show("Geometry Service error: " + 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 BufferPoint
        Inherits UserControl
        Public Sub New()
            InitializeComponent()
        End Sub

        Private Sub MyMap_MouseClick(sender As Object, e As ESRI.ArcGIS.Client.Map.MouseEventArgs)
            Dim graphicsLayer As GraphicsLayer = TryCast(MyMap.Layers("MyGraphicsLayer"), GraphicsLayer)
            graphicsLayer.ClearGraphics()

            e.MapPoint.SpatialReference = MyMap.SpatialReference
            Dim graphic As Graphic = New ESRI.ArcGIS.Client.Graphic() With { _
             .Geometry = e.MapPoint, _
             .Symbol = TryCast(LayoutRoot.Resources("DefaultClickSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol) _
            }
            graphic.SetZIndex(1)
            graphicsLayer.Graphics.Add(graphic)

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

            ' If buffer spatial reference is GCS and unit is linear, geometry service will do geodesic buffering
            Dim bufferParams As New BufferParameters() With { _
             .Unit = LinearUnit.StatuteMile, _
             .BufferSpatialReference = New SpatialReference(4326), _
             .OutSpatialReference = MyMap.SpatialReference _
            }
            bufferParams.Features.Add(graphic)
            bufferParams.Distances.Add(5)

            geometryService.BufferAsync(bufferParams)
        End Sub

        Private Sub GeometryService_BufferCompleted(sender As Object, args As GraphicsEventArgs)
            Dim results As IList(Of Graphic) = args.Results
            Dim graphicsLayer As GraphicsLayer = TryCast(MyMap.Layers("MyGraphicsLayer"), GraphicsLayer)

            For Each graphic As Graphic In results
                graphic.Symbol = TryCast(LayoutRoot.Resources("DefaultBufferSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
                graphicsLayer.Graphics.Add(graphic)
            Next
        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