arcgis for silverlight 控制图层显示级别

  在GIS项目中，如果加载两个图层，一个为切片图层（做为底图），另一个为动态图层，动态图层一般没有设置能够缩放到的比例，就会出现底图空白的情况，那么，是什么原因出现底图为空白的呢？

  切片图层早已规定好能够达到的最大比例尺以及最小比例尺，级别已经是固定的了。所以在动态底图里面放大或缩小时就会出现空白。

  解决方式：

  根据切片图层来控制整个地图能够进行放大或缩小的范围：重载ArcGISTiledMapServiceLayer类

  后台代码：

public class ControlArcGiSTitleLayerLevel : ArcGISTiledMapServiceLayer
    {
        //最小Level
        private int MinLevel = 0;
        //最大Level
        private int MaxLevel = 1;

        //目前使用的rest服务共有11个级别 MaxLevel 最大可到10

        public override void Initialize()
        {
            base.Initialize();

            //实际使用中可以不注册此事件 ，只是看Level数值
            this.TileLoading -= new EventHandler<TileLoadEventArgs>(ControlArcGiSTitleLayerLevel_TileLoading);
            this.TileLoading += new EventHandler<TileLoadEventArgs>(ControlArcGiSTitleLayerLevel_TileLoading);

            this.Map.Loaded -= new RoutedEventHandler(Map_Loaded);
            this.Map.Loaded += new RoutedEventHandler(Map_Loaded);
        }

        void Map_Loaded(object sender, RoutedEventArgs e)
        {
            //this.TileInfo.Lods 代表有多少个Level级别
            //控制
            Lod[] lod = this.TileInfo.Lods.Clone() as Lod[];
            Lod[] newlod = new Lod[MaxLevel + 1];
            //Resolution 随着比例尺的逐渐变大而更小
            for (int i = 0; i < newlod.Length; i++)
            {
                newlod[i] = lod[i];
                if (i == MinLevel) //Resolution 随着Level的逐渐变大而更小 所以Level越小 Resolution 越大
                    this.Map.MaximumResolution = lod[i].Resolution;
                if (i == MaxLevel) //Resolution 随着Level的逐渐变大而更小 所以Level越大 Resolution 越小
                    this.Map.MinimumResolution = lod[i].Resolution;
            }
            this.TileInfo.Lods = newlod;
        }

        void ControlArcGiSTitleLayerLevel_TileLoading(object sender, TiledLayer.TileLoadEventArgs e)
        {
            string message = string.Concat("Level:", e.Level, ",Scale:", this.Map.Scale, ",Resolution:", this.Map.Resolution);
            System.Diagnostics.Debug.WriteLine(message);
        }
    }

Xaml：

<UserControl x:Class="ControlMapLevel.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    xmlns:esri="clr-namespace:ESRI.ArcGIS.Client;assembly=ESRI.ArcGIS.Client"
    xmlns:local="clr-namespace:ControlMapLevel"
    d:DesignHeight="300" d:DesignWidth="400">
    <Grid x:Name="LayoutRoot" Background="White">
        <esri:Map x:Name="mapctl">
            <esri:Map.Layers>
                <local:ControlArcGiSTitleLayerLevel Url="http://localhost/arcgis/rest/services/ScSummaryService/MapServer"></local:ControlArcGiSTitleLayerLevel>
                <esri:ArcGISDynamicMapServiceLayer Url="http://localhost/arcgis/rest/services/testdymic/MapServer"></esri:ArcGISDynamicMapServiceLayer>
            </esri:Map.Layers>
        </esri:Map>
    </Grid>
</UserControl>