问题提出：
在实际中通常会遇到这样的情况，如果地图范围小，而且需要在地图上展示的元素又比较多的时候（在展现元素符号的同时，还展示元素名称或其他属性值等），这样如果在首次加载地图的时候一次性全部显示，必然会出现严重的重叠现象，怎么解决？
解决思路：
我想大家首先想到的就是分层显示，不错，其实这就是一个方便可行的思路。为数据库表中增加一个显示层次的字段，比如叫ShowLevel，默认是0-第一层显示，1-第二层显示...,然后在Map的Layers中添加多个Graphics，有几层就设置多少个，然后在后台程序中通过判断元素是ShowLevel属性，将元素添加到各自不同的Graphics当中去，最后处理Map的ExtendChanged事件，找到一个显示的边界值，然后通过判断当前的缩放比例是否达到了这个边界值，如果达到了，就显示第二层，如果没有达到就隐藏。
具体实现及部分代码如下：
1、首先数据库中增加一个字段，ShowLevel，默认值为0
2、在MainPage.xaml中多增加几个Graphics
<esri:Map.Layers> <esri:Graphicslayer ID="MyGraphicslayer"> </esri:Graphicslayer> <esri:Graphicslayer ID="MyGraphicslayer3"> </esri:Graphicslayer> <!--站点名称--> <esri:Graphicslayer ID="Graphicslayer1"> </esri:Graphicslayer> <esri:Graphicslayer ID="Graphicslayer11"> </esri:Graphicslayer> <!--站点数据--> <esri:Graphicslayer ID="Graphicslayer2"> </esri:Graphicslayer> <esri:Graphicslayer ID="Graphicslayer22"> </esri:Graphicslayer> <!--站点编码--> <esri:Graphicslayer ID="Graphicslayer3"> </esri:Graphicslayer> <esri:Graphicslayer ID="Graphicslayer33"> </esri:Map.Layers>
3、MainPage.xaml.cs中根据ShowLevel字段值，分别添加到各自的Graphics中
ESRI.ArcGIS.ClIEnt.Projection.WebMercator mercator = new ESRI.ArcGIS.ClIEnt.Projection.WebMercator(); //每次加载时先清空地图上数据 Graphicslayer graphicslayer = myMap.Layers["MyGraphicslayer"] as Graphicslayer; graphicslayer.Cleargraphics(); Graphicslayer graphicslayer0 = myMap.Layers["MyGraphicslayer3"] as Graphicslayer; graphicslayer0.Cleargraphics(); Graphicslayer graphicslayer1 = myMap.Layers["Graphicslayer1"] as Graphicslayer; graphicslayer1.Cleargraphics(); Graphicslayer graphicslayer2 = myMap.Layers["Graphicslayer2"] as Graphicslayer; graphicslayer2.Cleargraphics(); Graphicslayer graphicslayer3 = myMap.Layers["Graphicslayer3"] as Graphicslayer; graphicslayer3.Cleargraphics(); Graphicslayer graphicslayer11 = myMap.Layers["Graphicslayer11"] as Graphicslayer; graphicslayer11.Cleargraphics(); Graphicslayer graphicslayer22 = myMap.Layers["Graphicslayer22"] as Graphicslayer; graphicslayer22.Cleargraphics(); Graphicslayer graphicslayer33 = myMap.Layers["Graphicslayer33"] as Graphicslayer; graphicslayer33.Cleargraphics(); //获取到所有的山洪雨量点 ObservableCollection<RainFall> Lists = e.Result; //从集合中找出最大值对应的经纬度坐标 RainFall max = Lists.OrderByDescending(s => s.YL24).FirstOrDefault(); //动态添加点到地图上 Graphic graphic = null; //第一层 Graphic graphic2 = null; //第二层 foreach (RainFall item in Lists) { if (!string.IsNullOrEmpty(item.Latitute.ToString()) && !string.IsNullOrEmpty(item.Longitute.ToString())) { //有坐标值时，将该监测点添加到地图上去 if (max.YLZBM == item.YLZBM) { if (max.YL24 != 0) { //最大值不为0,红点闪烁 graphic = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim()),double.Parse(item.Longitute.ToString().Trim()))),Symbol = LayoutRoot.Resources["DefaultMarkerSymbol"] as Symbol }; } else { //保持原来的蓝色标记点符号 graphic = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim()),Symbol = LayoutRoot.Resources["BlueMarkerSymbol"] as Symbol }; } //保存属性 graphic.Attributes["YLZBM"] = item.YLZBM; //雨量站编码 graphic.Attributes["YLZMC"] = item.ZDMC; //雨量站名称 graphic.Attributes["YL24"] = item.YL24; //２４小时雨量 graphic.Attributes["DTNow"] = item.DTNow; //当前时间 graphic.Attributes["Latitute"] = item.Latitute; //纬度 graphic.Attributes["Longitute"] = item.Longitute; //经度 //将该Graphics添加到Graphicslayer中去 graphicslayer.Graphics.Add(graphic); graphicslayer.Opacity = 1; //鼠标移入事件 graphic.MouseEnter += new MouseEventHandler(sh_graphic_MouseEnter); graphic.MouseLeave += new MouseEventHandler(sh_graphic_MouseLeave); //鼠标点击事件 #region 站点名称 //动态添加文本 TextSymbol textSymbol = new TextSymbol() { FontFamily = new System.windows.Media.FontFamily("Microsoft YaHei"),Foreground = new System.windows.Media.solIDcolorBrush(color.FromArgb(255,117,20,99)),FontSize = 12,Text = item.ZDMC,OffsetX = 12,OffsetY = -5 }; Graphic graphicText1 = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim(),System.Globalization.CultureInfo.InvariantCulture),double.Parse(item.Longitute.ToString().Trim(),System.Globalization.CultureInfo.InvariantCulture))),Symbol = textSymbol }; graphicText1.Attributes["TextYLZMC"] = item.ZDMC; graphicslayer1.Graphics.Add(graphicText1); #endregion #region 水位/雨量 数值 if (item.YL24 != 0) { TextSymbol textSymbol2 = new TextSymbol() { FontFamily = new System.windows.Media.FontFamily("Microsoft YaHei"),255,0)),FontSize = 14,Text = item.YL24.ToString(),OffsetX = 10,OffsetY = 23 }; Graphic graphicText2 = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim(),Symbol = textSymbol2 }; graphicText2.Attributes["TextYL"] = item.YL24; graphicslayer2.Graphics.Add(graphicText2); } #endregion #region 站点编码 //动态添加站点编码 TextSymbol textSymbol3 = new TextSymbol() { FontFamily = new System.windows.Media.FontFamily("Microsoft YaHei"),Text = item.YLZBM,OffsetX = 27,OffsetY = 23 }; Graphic graphicText3 = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim(),Symbol = textSymbol3 }; graphicText3.Attributes["TextYLZBM"] = item.YLZBM; graphicslayer3.Graphics.Add(graphicText3); graphicslayer3.Visible = false; #endregion //左键点击事件 graphic.MouseleftbuttonDown += new MousebuttonEventHandler(sh_graphic_MouseleftbuttonDown); graphic.MouseleftbuttonUp += new MousebuttonEventHandler(sh_graphic_MouseleftbuttonUp); } else { //这里判断显示层数 if (item.ShowLevel == 0) { #region 显示第一层数据 graphic = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim()),Symbol = LayoutRoot.Resources["BlueMarkerSymbol"] as Symbol }; //保存属性 graphic.Attributes["YLZBM"] = item.YLZBM; //雨量站编码 graphic.Attributes["YLZMC"] = item.ZDMC; //雨量站名称 graphic.Attributes["YL24"] = item.YL24; //２４小时雨量 graphic.Attributes["DTNow"] = item.DTNow; //当前时间 graphic.Attributes["Latitute"] = item.Latitute; //纬度 graphic.Attributes["Longitute"] = item.Longitute; //经度 //将该Graphics添加到Graphicslayer中去 graphicslayer.Graphics.Add(graphic); graphicslayer.Opacity = 1; //鼠标移入事件 graphic.MouseEnter += new MouseEventHandler(sh_graphic_MouseEnter); graphic.MouseLeave += new MouseEventHandler(sh_graphic_MouseLeave); //鼠标点击事件 #region 站点名称 //动态添加文本 TextSymbol textSymbol = new TextSymbol() { FontFamily = new System.windows.Media.FontFamily("Microsoft YaHei"),OffsetY = -5 }; Graphic graphicText1 = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim(),Symbol = textSymbol }; graphicText1.Attributes["TextYLZMC"] = item.ZDMC; graphicslayer1.Graphics.Add(graphicText1); #endregion #region 水位/雨量 数值 if (item.YL24 != 0) { TextSymbol textSymbol2 = new TextSymbol() { FontFamily = new System.windows.Media.FontFamily("Microsoft YaHei"),OffsetY = 23 }; Graphic graphicText2 = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim(),Symbol = textSymbol2 }; graphicText2.Attributes["TextYL"] = item.YL24; graphicslayer2.Graphics.Add(graphicText2); } #endregion #region 站点编码 //动态添加站点编码 TextSymbol textSymbol3 = new TextSymbol() { FontFamily = new System.windows.Media.FontFamily("Microsoft YaHei"),OffsetY = 23 }; Graphic graphicText3 = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim(),Symbol = textSymbol3 }; graphicText3.Attributes["TextYLZBM"] = item.YLZBM; graphicslayer3.Graphics.Add(graphicText3); graphicslayer3.Visible = false; #endregion //左键点击事件 graphic.MouseleftbuttonDown += new MousebuttonEventHandler(sh_graphic_MouseleftbuttonDown); graphic.MouseleftbuttonUp += new MousebuttonEventHandler(sh_graphic_MouseleftbuttonUp); #endregion } else { #region 显示第二层数据 graphic2 = new Graphic() { Geometry = mercator.FromGeographic(new MapPoint(double.Parse(item.Latitute.ToString().Trim()),Symbol = LayoutRoot.Resources["BlueMarkerSymbol"] as Symbol }; //保存属性 graphic2.Attributes["YLZBM"] = item.YLZBM; //雨量站编码 graphic2.Attributes["YLZMC"] = item.ZDMC; //雨量站名称 graphic2.Attributes["YL24"] = item.YL24; //２４小时雨量 graphic2.Attributes["DTNow"] = item.DTNow; //当前时间 graphic2.Attributes["Latitute"] = item.Latitute; //纬度 graphic2.Attributes["Longitute"] = item.Longitute; //经度 //将该Graphics添加到Graphicslayer中去 graphicslayer0.Graphics.Add(graphic2); graphicslayer0.Opacity = 1; if (currentValue > tip_Base.sIDeValue) { graphicslayer0.Visible = false; } else { graphicslayer0.Visible = true; } //鼠标移入事件 graphic2.MouseEnter += new MouseEventHandler(sh_graphic_MouseEnter); graphic2.MouseLeave += new MouseEventHandler(sh_graphic_MouseLeave); //鼠标点击事件 #region 站点名称 //动态添加文本 TextSymbol textSymbol = new TextSymbol() { FontFamily = new System.windows.Media.FontFamily("Microsoft YaHei"),Symbol = textSymbol }; graphicText1.Attributes["TextYLZMC"] = item.ZDMC; graphicslayer11.Graphics.Add(graphicText1); if (currentValue > tip_Base.sIDeValue) { graphicslayer11.Visible = false; } else { graphicslayer11.Visible = true; } #endregion #region 水位/雨量 数值 if (item.YL24 != 0) { TextSymbol textSymbol2 = new TextSymbol() { FontFamily = new System.windows.Media.FontFamily("Microsoft YaHei"),Symbol = textSymbol2 }; graphicText2.Attributes["TextYL"] = item.YL24; graphicslayer22.Graphics.Add(graphicText2); if (currentValue > tip_Base.sIDeValue) { graphicslayer22.Visible = false; } else { graphicslayer22.Visible = true; } } #endregion #region 站点编码 //动态添加站点编码 TextSymbol textSymbol3 = new TextSymbol() { FontFamily = new System.windows.Media.FontFamily("Microsoft YaHei"),Symbol = textSymbol3 }; graphicText3.Attributes["TextYLZBM"] = item.YLZBM; graphicslayer33.Graphics.Add(graphicText3); graphicslayer33.Visible = false; #endregion //左键点击事件 graphic2.MouseleftbuttonDown += new MousebuttonEventHandler(sh_graphic_MouseleftbuttonDown); graphic2.MouseleftbuttonUp += new MousebuttonEventHandler(sh_graphic_MouseleftbuttonUp); #endregion } } } else { //不做任何处理，不添加任何点信息 } } 4、在Map的ExtendChanged事件中处理
private voID myMap_ExtentChanged(object sender,ExtentEventArgs e){ currentValue = (e.NewExtent.XMax - e.NewExtent.XMin) / (myMap.Layers.GetFullExtent().XMax - myMap.Layers.GetFullExtent().XMin); ShowSiteByGrade();} /// <summary> /// 判断是在第一层还是第二层显示 /// </summary> private voID ShowSiteByGrade() { if (currentValue >= tip_Base.sIDeValue) { Graphicslayer graphicslayer0 = myMap.Layers["MyGraphicslayer3"] as Graphicslayer; graphicslayer0.Visible = false; Graphicslayer graphicslayer2 = myMap.Layers["Graphicslayer11"] as Graphicslayer; graphicslayer2.Visible = false; Graphicslayer graphicslayer3 = myMap.Layers["Graphicslayer22"] as Graphicslayer; graphicslayer3.Visible = false; Graphicslayer graphicslayer4 = myMap.Layers["Graphicslayer33"] as Graphicslayer; graphicslayer4.Visible = false; } else { Graphicslayer graphicslayer = myMap.Layers["MyGraphicslayer3"] as Graphicslayer; graphicslayer.Visible = true; Graphicslayer graphicslayer2 = myMap.Layers["Graphicslayer11"] as Graphicslayer; graphicslayer2.Visible = true; Graphicslayer graphicslayer3 = myMap.Layers["Graphicslayer22"] as Graphicslayer; graphicslayer3.Visible = true; Graphicslayer graphicslayer4 = myMap.Layers["Graphicslayer33"] as Graphicslayer; graphicslayer4.Visible = false; } } 总结 以上是内存溢出为你收集整理的ArcGIS API for Silverlight 解决众多密集点分层显示全部内容，希望文章能够帮你解决ArcGIS API for Silverlight 解决众多密集点分层显示所遇到的程序开发问题。
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