ArcGIS API for Silverlight代码中使用Template模板

       在项目开发中，会遇到点选中聚焦闪烁效果，但是因为在使用Symbol的时候，会设置一定的OffSetX和OffSetY，所以聚焦闪烁的时候，有些情况下，会出现闪烁点的位置和Symbol的位置不重叠现象，下面的方法就是解决这个问题的。
1、在Silverlight项目中新建一个文件夹Template，新建一个DefaultMarkerSymbol.xaml的Silverlight资源字典文件，如下图：



2、打开DefaultMarkerSymbol.xaml文件，删掉里面的内容，拷贝如下的内容：
<ControlTemplate
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:vsm="clr-namespace:System.Windows;assembly=System.Windows"
xmlns:esri="http://schemas.esri.com/arcgis/client/2009"
>
<Canvas>
<vsm:VisualStateManager.VisualStateGroups>
<vsm:VisualStateGroup x:Name="CommonStates">
<vsm:VisualState x:Name="Normal">
<Storyboard RepeatBehavior="Forever">
<DoubleAnimation BeginTime="00:00:00" Storyboard.TargetName="ellipse" Storyboard.TargetProperty="(UIElement.RenderTransform).(ScaleTransform.ScaleX)" From="1" To="5" Duration="00:00:01" />
<DoubleAnimation BeginTime="0:0:0" Storyboard.TargetName="ellipse" Storyboard.TargetProperty="(UIElement.RenderTransform).(ScaleTransform.ScaleY)" From="1" To="5" Duration="00:00:01" />
<DoubleAnimation BeginTime="00:00:00" Storyboard.TargetName="ellipse" Storyboard.TargetProperty="(UIElement.Opacity)" From="1" To="0" Duration="00:00:01" />
</Storyboard>
</vsm:VisualState>
</vsm:VisualStateGroup>
</vsm:VisualStateManager.VisualStateGroups>
<Ellipse Height="25" Width="25" Canvas.Left="0" Canvas.Top="0" RenderTransformOrigin="0.5,0.5" x:Name="ellipse" IsHitTestVisible="False">
<Ellipse.RenderTransform>
<ScaleTransform />
</Ellipse.RenderTransform>
<Ellipse.Fill>
<RadialGradientBrush>
<GradientStop Color="#00FF0000" />
<GradientStop Color="#FFFF0000" Offset="0.25" />
<GradientStop Color="#00FF0000" Offset="0.5" />
<GradientStop Color="#FFFF0000" Offset="0.75" />
<GradientStop Color="#00FF0000" Offset="1" />
</RadialGradientBrush>
</Ellipse.Fill>
</Ellipse>
<Ellipse Height="20" Width="20" Canvas.Left="0" Canvas.Top="0" Fill="#FFFF0000" x:Name="ellipse1" />
</Canvas>
</ControlTemplate >

3、Silverlight程序代码中使用，这里是通过选中ListBox中的站点名称，进行聚焦显示，方法如下： private void lbSearchSite_SelectionChanged(object sender, System.Windows.Controls.SelectionChangedEventArgs e)
{
RainFall findResult = e.AddedItems[0] as RainFall;
Graphic g = new Graphic()
{
Geometry = mercator.FromGeographic(new MapPoint(double.Parse(findResult.Latitute.ToString().Trim()), double.Parse(findResult.Longitute.ToString().Trim())))
};
MarkerSymbol symbol = new MarkerSymbol();
string contentStr = new StreamReader(
Application.GetResourceStream(
new Uri("/MapClient;component/Template/DefaultMarkerSymbol.xaml", UriKind.Relative)
).Stream).ReadToEnd();
symbol.ControlTemplate = (ControlTemplate)XamlReader.Load(contentStr);
symbol.OffsetX = 10;
symbol.OffsetY = 10;
g.Symbol = symbol;

ESRI.ArcGIS.Client.Geometry.Envelope selectedFeatureExtent = mercator.ToGeographic(g.Geometry).Extent; //选中点的位置
double expandPercentage = 10;

//加数值后，聚焦（这里需要注意，进行地理坐标和墨卡托坐标的转换）
double widthExpand = (selectedFeatureExtent.Width + 5) * (expandPercentage / 100);
double heightExpand = (selectedFeatureExtent.Height + 5) * (expandPercentage / 100);
ESRI.ArcGIS.Client.Geometry.Envelope displayExtent = new Envelope(WKIDConvert.lonlat2mercator(new MapPoint(selectedFeatureExtent.XMin - (widthExpand / 2), selectedFeatureExtent.YMin - (heightExpand / 2))), WKIDConvert.lonlat2mercator(new MapPoint(selectedFeatureExtent.XMax + (widthExpand / 2), selectedFeatureExtent.YMax + (heightExpand / 2))))
{
SpatialReference = new SpatialReference(102100)
};
try
{
//聚焦
myMap.ZoomTo(displayExtent);
ShowFocus(g);
}
catch (Exception)
{
}
}

/// <summary>
/// 显示聚焦点
/// </summary>
public void ShowFocus(Graphic g)
{
GraphicsLayer graphicsLayerSW = myMap.Layers["GraphicsLayerRed"] as GraphicsLayer;
//产生红色光晕
if (graphicsLayerSW.Graphics.Count < 1)
{
graphicsLayerSW.Graphics.Add(g);
}
else
{
graphicsLayerSW.Graphics.RemoveAt(0);
graphicsLayerSW.Graphics.Add(g);
}
}

4、效果图如下：