arcgis api for silverlight开发系列之六：缓冲区分析实现及Geometry service服务发布

缓冲区分析的需求：有时候我们需要在地图某个点上，画出方圆5公里的区域，目的是查看该点所影响的地区。那么直接先看看效果：

源码：

    <Grid x:Name="LayoutRoot">
       
        <Grid.resources>
            <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="0,10,0" >
            <Rectangle Fill="#77919191" stroke="Gray"  RadiusX="10" RadiusY="10" Margin="0,5" >
             <Rectangle.Effect>
              <DropShadowEffect/>
             </Rectangle.Effect>
            </Rectangle>
            <Rectangle Fill="#FFFFFFFF" stroke="DarkGray" RadiusX="5" RadiusY="5" Margin="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" />
        </Grid>
       
    </Grid>

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);
        }

相信大部分代码大家都会明白，只是其中Geometryservice是什么东东，其实它是arcgis server一种服务，用于协助应用程序执行各种几何计算，如缓冲区、简化、面积和长度计算以及投影。简单浏览一下arcgis server提供的各种服务：

那么如何发布几何服务（Geometry service）呢 ？

其实发布Geometry service是最简单的，因为它不需要任何地图资源。

1、打开ArcCatalog，添加服务

2、类型选择Geometry service，名称必须用"Geometry"命名。