ArcGIS 中UniqueValueRenderer和SimpleRenderer的异同点

    唯一值渲染器：UniqueValueRenderer用符号表示一组有匹配属性的图形，这通常用于名词或字符串数据。SimpleRenderer是使用单一符号进行着色分类，不涉及对要素的数据进行处理。这种专题图同一个图层内的所有元素都是一种符号。通过SimpleRenderer对象对Symbol进行设置后，赋予FeatureLayer接口的Renderer属性就可以了。

ESRI.ArcGIS.Client.UniqueValueInfo info = new UniqueValueInfo();
            info.Value = "0";
            info.Symbol = this.CreateSymbolFromEmbedFile("GQYPGIS.MapElement.Symbols.BayonetSymbol.xml");

            ESRI.ArcGIS.Client.UniqueValueInfo info1 = new UniqueValueInfo();
            info.Value = "1";
            info.Symbol = this.CreateSymbolFromEmbedFile("GQYPGIS.MapElement.Symbols.CameraSymbol.xml");


            ESRI.ArcGIS.Client.UniqueValueInfo info2 = new UniqueValueInfo();
            info.Value = "2";
            info.Symbol = this.CreateSymbolFromEmbedFile("GQYPGIS.MapElement.Symbols.CameraSymbol.xml");

          
            ESRI.ArcGIS.Client.UniqueValueInfo info3 = new UniqueValueInfo();
            info.Value = "3";
            info.Symbol = this.CreateSymbolFromEmbedFile("GQYPGIS.MapElement.Symbols.CameraSymbol.xml");


            ESRI.ArcGIS.Client.UniqueValueRenderer renderer = new ESRI.ArcGIS.Client.UniqueValueRenderer();
            renderer.Field = "CAMERATYPE";
            renderer.Infos.Add(info);

            this.Renderer = renderer;  

            public Symbol CreateSymbolFromEmbedFile(string embedFile)
        {
            Assembly ass = Assembly.GetExecutingAssembly();
            System.IO.UnmanagedMemoryStream ums = ass.GetManifestResourceStream(embedFile) as System.IO.UnmanagedMemoryStream;
            byte[] bytes = new byte[ums.Length];
            ums.Read(bytes, 0, (int)ums.Length);
            string xmlString = System.Text.Encoding.UTF8.GetString(bytes);
            xmlString = System.Text.RegularExpressions.Regex.Replace(xmlString, "^[^<]", "");
            byte[] datas = System.Text.Encoding.ASCII.GetBytes(xmlString);
            System.IO.MemoryStream ms = new MemoryStream(datas);
            MarkerSymbol symbol = new MarkerSymbol();
            symbol.ControlTemplate = (ControlTemplate)System.Windows.Markup.XamlReader.Load(ms);
            return symbol;

        }

在上述的例子中，this代表的是一个继承自FeatureLayer的摄像机图层，这里也列出 GQYPGIS.MapElement.Symbols.CameraSymbol.xml里面的具体内容，这里面把从该xml文件读取相应的ControlTemplate并作为UniqueValueInfo的Symbol

<ControlTemplate
  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>
    <VisualStateManager.VisualStateGroups>
      <VisualStateGroup x:Name="CommonStates">
        <VisualState x:Name="Normal" />
        <VisualState x:Name="MouseOver">        
        </VisualState>
      </VisualStateGroup>
      <VisualStateGroup x:Name="SelectionStates">
        <VisualState x:Name="Unselected" />
        <VisualState x:Name="Selected">
          <Storyboard>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="MarkerSymbolVideoImg1">
              <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}"/>
            </ObjectAnimationUsingKeyFrames>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="MarkerSymbolVideoImg2">
              <DiscreteObjectKeyFrame KeyTime="0"  Value="{x:Static Visibility.Visible}"/>
            </ObjectAnimationUsingKeyFrames>
          </Storyboard>
        </VisualState>
      </VisualStateGroup>
    </VisualStateManager.VisualStateGroups>
    <Image Name="MarkerSymbolVideoImg1" Source="/GQYPGIS;component/Source/Image/point_video.png" Visibility="Visible" Width="6"  Height="6" />
    <Image Name="MarkerSymbolVideoImg2" Source="/GQYPGIS;component/Source/Image/point_video_hit.png" Visibility="Hidden" Width="6" Height="6" />
  </Grid>
  
</ControlTemplate>

   这里必须注意的是要把该xml文件设置成一种嵌入式资源来进行使用，否则是不能正常使用的。其实SimpleRender的用法差不错，也是将获取到的Symbol赋值给SimpleRender的一个对象，下面贴出部分代码。 

Assembly ass = Assembly.GetExecutingAssembly();
            System.IO.UnmanagedMemoryStream ums = ass.GetManifestResourceStream("ServerShell.ServerWindows.IGIS.MapElement.Symbols.BayonetSymbol.xml") as System.IO.UnmanagedMemoryStream;
            byte[] bytes = new byte[ums.Length];
            ums.Read(bytes, 0, (int)ums.Length);
            string xmlString = System.Text.Encoding.UTF8.GetString(bytes);
            xmlString = System.Text.RegularExpressions.Regex.Replace(xmlString, "^[^<]", "");
            xmlString = xmlString.Replace("Width="6"", "Width="" + size.ToString() + """);
            xmlString = xmlString.Replace("Height="6"", "Height="" + size.ToString() + """);

            byte[] datas = System.Text.Encoding.ASCII.GetBytes(xmlString);
            System.IO.MemoryStream ms = new System.IO.MemoryStream(datas);
            MarkerSymbol symbol = new MarkerSymbol();
            symbol.ControlTemplate = (System.Windows.Controls.ControlTemplate)System.Windows.Markup.XamlReader.Load(ms);
            this.Renderer = new SimpleRenderer()
            {
                Symbol = symbol
            };

<ControlTemplate
  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>
    <VisualStateManager.VisualStateGroups>
      <VisualStateGroup x:Name="CommonStates">
        <VisualState x:Name="Normal" />
        <VisualState x:Name="MouseOver">
        </VisualState>
      </VisualStateGroup>
      <VisualStateGroup x:Name="SelectionStates">
        <VisualState x:Name="Unselected" />
        <VisualState x:Name="Selected">
          <Storyboard>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="MarkerSymbolCheckPointImg1">
              <DiscreteObjectKeyFrame KeyTime="0" Value="{x:Static Visibility.Hidden}"/>
            </ObjectAnimationUsingKeyFrames>
            <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Visibility)" Storyboard.TargetName="MarkerSymbolCheckPointImg2">
              <DiscreteObjectKeyFrame KeyTime="0"  Value="{x:Static Visibility.Visible}"/>
            </ObjectAnimationUsingKeyFrames>
          </Storyboard>
        </VisualState>
      </VisualStateGroup>
    </VisualStateManager.VisualStateGroups>

    <Image Name="MarkerSymbolCheckPointImg1" Source="/ServerShell;component/Source/Image/point_checkpoint.png" Visibility="Visible" Width="6"  Height="6"/>
    <Image Name="MarkerSymbolCheckPointImg2" Source="/ServerShell;component/Source/Image/point_checkpoint_hit.png" Visibility="Hidden" Width="6"  Height="6"/>
  </Grid>
  
</ControlTemplate>

    其实采用上面的两种方式都是差不多的，都能够将相应的图片添加到相应地图层上面去，另外通过读取xml的这种方式能够通过代码的方式去控制添加图片的宽度和高度，这个也是非常好的一种方式，如果直接在前台进行代码的书写，那么在程序中将非常不好更改，这一点采用xml的方式会比较灵活的。