ARCGIS FOR SILVERLIGHT Layer

原文地址：http://blog.163.com/zwx_gis/blog/static/32434435201122194352393/

五、Graphics layer

1、新增Graphics layer

Graphics layer用於顯示用戶自定義繪制的點、線、面圖形。使用時確保xaml文件中Graphics layer定義在其它圖層的下面，以確保它能顯示在其它圖層的上面。

<esri:Map x:Name="MyMap" Extent=", , , " >

       <esri:Map.Layers>                      

<esri:ArcGISTiledMapServiceLayerID="."Url="http://../rest/./MapServer"/>

              <esri:GraphicsLayer ID=”.” />

       </esri:Map.Layers>

</esri:Map>

 

2、管理Graphics features

在Graphics layer上創建Graphics的步驟一般如下：

（1）獲取Graphics layer

（2）創建或獲取Graphic

（3）設置Graphic的Geometry

（4）應用Graphic的Symbol

（5）將Graphic添加到Graphics layers

代碼如下：

GraphicsLayer graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;

foreach (Graphic graphic in graphicsList)

{

    graphic.Symbol = MySymbol;

    graphicsLayer.Graphics.Add(graphic);

}

 

3、使用Draw surface

Draw surface用於獲取Geometries，Geometries可添加到Graphics Layer或用作identify和buffer操作。

       使用Draw surface，你必須

（1）設置繪圖操作的Symbols

（2）設置Draw surface的地圖

（3）執行邏輯以激活|解除surface

（4）處理Geometries，以在surface上繪圖

示例代碼如下：

xaml文件：

<Grid x:Name="LayoutRoot" Background="White">

              <Grid.Resources>

                     <esriSymbols:SimpleFillSymbol x:Name="RedFillSymbol" Fill="#66FF0000" BorderBrush="Red" BorderThickness="2" />

              </Grid.Resources>

              <esri:Map …>

…

cs文件：

MyDrawObject = new Draw(MyMap)

{ LineSymbol =LayoutRoot.Resources["DrawLineSymbol"] as LineSymbol,

FillSymbol =LayoutRoot.Resources["DrawFillSymbol"] as FillSymbol };

MyDrawObject.DrawComplete += MyDrawObject_DrawComplete;

MyDrawObject.DrawMode = DrawMode.Polygon;

MyDrawObject.IsEnabled = true;

private void MyDrawObject_DrawComplete(object sender, ESRI.ArcGIS.Client.DrawEventArgs args)

{

    Graphic graphic = new Graphic() { Geometry = args.Geometry, Symbol = RedFillSymbol };

GraphicsLayer graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;

graphicsLayer.Graphics.Add(graphic);

}

 

4、Symbols和Renderers

       Symbols定義了Graphic的非幾何學方面的顯示特性，如顏色、邊框寬度、透明度等。

       Renderers定義了一個或多個應用於Graphics layer的Symbols，指定哪些Graphics屬性與哪個Symbol相符。

Symbols和Geometries類型：

Symbol	Geometry	描述
SimpleMarkerSymbol	Point	用簡單形狀來表現點
PictureMarkerSymbol	Point	用images來表現點
SimpleLineSymbol	Polyline	用預定義的風格來表現線
CartographicLineSymbol	Polyline	用定制的風格來表現線
SimpleFillSymbol	Polygon	用Silverlight Brush來填充多邊形
PictureFillSymbol	Polygon	用images填充多邊形

 

 

通常，視覺定義在xaml文件中，行為邏輯定義在.cs文件中，讓表現層和業務邏輯層分開，使得應用程序更容易開發、維護和擴展。

 

Symbol的使用：

（1）添加命名空間：symbol類定義在ESRI.ArcGIS.Client.Symbols命名空間中（ESRI.ArcGIS.Client集）

xmlns:esriSymbols="clr-namespace:ESRI.ArcGIS.Client.Symbols;assembly=ESRI.ArcGIS.Client"

（2）xaml文件中定義Symbol

<Grid.Resources>

<esriSymbols:SimpleFillSymbol x:Name="MyRedFillSymbol" Fill="#66FF0000" BorderBrush="Red" BorderThickness="2" />

</Grid.Resources>

//Symbol運用於FeatureLayer

<esri:FeatureLayer ID="." Where="1=1" FeatureSymbol="{StaticResource MyRedFillSymbol}"

Url="http://./ArcGIS/rest/services/./MapServer/5" >

<esri:FeatureLayer.OutFields>

<sys:String>POP07_SQMI</sys:String>

       </esri:FeatureLayer.OutFields>

</esri:FeatureLayer>

（3）cs文件中動態生成

SimpleFillSymbol fillSymbol = new SimpleFillSymbol()

  {

     BorderBrush = new SolidColorBrush(Color.FromArgb(0, 255, 0, 0)),

     BorderThickness = 2,

     Fill = new SolidColorBrush(Color.FromArgb(alphaVal, redVal, greenVal, blueVal))

  };

//Symbol運用於GraphicsLayer的每一個graphic

GraphicsLayer graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;

foreach (Graphic graphic in graphicsLayer.Graphics)

graphic.Symbol = fillSymbol;

 

創建Unique Value Renderer：

<Grid.Resources>

<esriSymbols:SimpleFillSymbol x:Name="a" Fill=""BorderBrush=""BorderThickness="" />

<esriSymbols:SimpleFillSymbol x:Name="b" Fill=""BorderBrush=""BorderThickness="" />

<esriSymbols:SimpleFillSymbol x:Name="c" Fill=""BorderBrush=""BorderThickness="" />

       <esri:UniqueValueRenderer x:Name="abcRenderer" Attribute="STATE_NAME" >

              <esri:UniqueValueRenderer.Infos>

                     <esri:UniqueValueInfo Value="California" Symbol="{StaticResource  a}" />

                     <esri:UniqueValueInfo Value="New York" Symbol="{StaticResource  b}" />

                     <esri:UniqueValueInfo Value="Kansas" Symbol="{StaticResource    c}" />

              </esri:UniqueValueRenderer.Infos>

       </esri:UniqueValueRenderer>

</Grid.Resources>

// FeatureLayer中，指定一個過濾，僅僅California、New York、Kansas被繪制

//並且將其STATE_NAME字段的值顯示在layer的Graphics中

<esri:FeatureLayer ID=""

Where="(STATE_NAME='California') OR (STATE_NAME='New York') OR (STATE_NAME = 'Kansas')"

Renderer="{StaticResource  abcRenderer}"

       Url="http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/5" >

       <esri:FeatureLayer.OutFields>

              <sys:String>STATE_NAME</sys:String>

       </esri:FeatureLayer.OutFields>

</esri:FeatureLayer>

 

創建Class Breaks Renderer：即將symbol應用於一組指定范圍的graphics中。

<Grid.Resources>

<esriSymbols:SimpleFillSymbol x:Name="a" Fill="" BorderBrush=""BorderThickness="" />

<esriSymbols:SimpleFillSymbol x:Name="b" Fill="" BorderBrush=""BorderThickness="" />

<esriSymbols:SimpleFillSymbol x:Name="c" Fill="" BorderBrush=""BorderThickness="" />

       <esri:ClassBreaksRenderer x:Name="abcRenderer" Attribute="POP07_SQMI" >

              <esri:ClassBreaksRenderer.Classes>

                     <esri:ClassBreakInfo MinimumValue="0" MaximumValue="50" Symbol="{StaticResource  a}" />

                     <esri:ClassBreakInfo MinimumValue="51" MaximumValue="125" Symbol="{StaticResource  b}" />

                     <esri:ClassBreakInfo MinimumValue="125" MaximumValue="2000" Symbol="{StaticResource  c}" />

              </esri:ClassBreaksRenderer.Classes>

       </esri:ClassBreaksRenderer>

</Grid.Resources>

// FeatureLayer中，將renderer和Feature layer聯系起來，進行地圖繪制

//並且將其POP07_SQMI字段的值顯示在layer的Graphics中

<esri:FeatureLayer ID="" Where="1=1" Renderer="{StaticResource abcRenderer}"

Url="http://./ArcGIS/rest/services/./MapServer/5" >

       <esri:FeatureLayer.OutFields>

              <sys:String>POP07_SQMI</sys:String>

       </esri:FeatureLayer.OutFields>

</esri:FeatureLayer>

 

5、使用Clustering（聚類分組，用於render的數量很大時）

當點很多和密集時，使用Clustering將點分組，使得在cluster distance內的多個點用一個點代替。Clustering可用於GraphicsLayer和Feature Layer。

（1）使用FlareClusterer

FlareClusterer可按如下方式添加到GraphicsLayer和FeatureLayer中：

<esri:GraphicsLayer ID="MyGraphicsLayer">

   <esri:GraphicsLayer.Clusterer>

      <esri:FlareClusterer />

   </esri:GraphicsLayer.Clusterer>

</esri:GraphicsLayer>

效果如下圖：

FlareClusterer的屬性如下表：

FlareClusterer屬性	描述
FlareBackground	填充的背景顏色（默認紅色）
FlareForeground	邊界和文字顏色（默認白色）
MaximumFlareCount	當鼠標移動到cluster時，各小點是否展開的最大數量界限 小於此值時，鼠標移上去會展開各小點；大於此值時，稱為large clusters，其顏色和大小會根據點多少變化。（默認=10）
Radius	被cluster的半徑，單位pixels（默認20）
Gradient	LinearGradientBrush線性漸變刷用於large clusters （默認：Default = LinearGradientBrush; MappingMode = RelativeToBoundingBox; GradientStop1: Offset = 0, Argb = 127,255,255,0, GradientStop2: Offset = 1, Argb = 127,255,0,0)

示例：修改FlareClusterer的默認屬性

<Grid.Resources>

<LinearGradientBrush x:Name="aGradient" MappingMode="RelativeToBoundingBox" >

              <GradientStop Color="#990011FF" Offset="0"/>

              <GradientStop Color="#990055FF" Offset="0.25"/>

              <GradientStop Color="#990099FF" Offset="0.5"/>

              <GradientStop Color="#9900CCFF" Offset="0.75"/>

              <GradientStop Color="#9900FFFF" Offset="1"/>

    </LinearGradientBrush>

</Grid.Resources>

<esri:Map x:Name="MyMap">

    <esri:Map.Layers>

          <esri:GraphicsLayer ID="MyGraphicsLayer">

           <esri:GraphicsLayer.Clusterer>

                     <esri:FlareClusterer FlareBackground="Yellow" FlareForeground="#99000000"

              MaximumFlareCount="5" Radius="15" Gradient="{StaticResource aGradient}" />

           </esri:GraphicsLayer.Clusterer>

          </esri:GraphicsLayer>

    </esri:Map.Layers>

</esri:Map>

 

（2）擴展GraphicsClusterer

為了定制cluster的外觀，你可以創建一個繼承自ESRI.ArcGIS.Client.GraphicsClusterer的類，並重寫OnCreateGraphic()方法來定義cluster graphic。示例代碼如下：

public class SumClusterer : GraphicsClusterer

{

    public SumClusterer()

    {

        MinimumColor = Colors.Red;

        MaximumColor = Colors.Yellow;

        SymbolScale = 1;

        base.Radius = 50;

    }

    public string AggregateColumn { get; set; }

    public double SymbolScale { get; set; }

    public Color MinimumColor { get; set; }

    public Color MaximumColor { get; set; }

    protected override Graphic OnCreateGraphic(GraphicCollection cluster, MapPoint point, int maxClusterCount)

    {

        if (cluster.Count == 1) return cluster[0];

        Graphic graphic = null;

        double sum = 0;

        foreach (Graphic g in cluster)

        {

            if (g.Attributes.ContainsKey(AggregateColumn))

            {try{sum += Convert.ToDouble(g.Attributes[AggregateColumn]); }}

        }

        double size = (sum + 450) / 30;

        size = (Math.Log(sum * SymbolScale / 10) * 10 + 20);

        if (size < 12) size = 12;

        graphic=new Graphic(){Symbol=new ClusterSymbol() {Size = size},Geometry= point};

        graphic.Attributes.Add("Count", sum);

        graphic.Attributes.Add("Size", size);

        graphic.Attributes.Add("Color", InterpolateColor(size - 12, 100));

        return graphic;

}

    private static Brush InterpolateColor(double value, double max)

    {

        value = (int)Math.Round(value * 255.0 / max);

        if (value > 255) value = 255;

        else if (value < 0) value = 0;

        return new SolidColorBrush(Color.FromArgb(127, 255, (byte)value, 0));

    }

}