How to change a layer property with C# code?

[Anonymous User]

Original User: huangs3

Hi Experts:

    I am using the Silverlight/WPF API to implement a magnifying glass on a map.
    Attached pictures are the XAML code and C# code I am using.
    The C# code (shown in errNewTiledMapServiceLyr.png file) tries to dynamically change the Layer property of the magnifying glass, but it failed. From the error message, seems it is because of unapporiate initialization of ArcGISTiledMapServiceLayer object. However, I follows the method in http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#AddLayerDynamically
and I couldn't find out how I should fix it.
    Can you give me some suggestion?
    Thank you.

[JenniferNery]

What version of the API are you using?

I cannot replicate the issue with the following code using v2.1 Final (Silverlight aplication):

xmlns:esri="http://schemas.esri.com/arcgis/client/2009">
<Grid x:Name="LayoutRoot" Background="White">
 <esri:Map x:Name="MyMap"/>
 <Grid HorizontalAlignment="Right" VerticalAlignment="Top" Margin="10" >
  <Rectangle Fill="#77919191" Stroke="Gray"  RadiusX="10" RadiusY="10" Margin="0" >
   <Rectangle.Effect>
    <DropShadowEffect/>
   </Rectangle.Effect>
  </Rectangle>
  <StackPanel Orientation="Horizontal" HorizontalAlignment="Right" Background="Transparent" Margin="10">
   <RadioButton x:Name="StreetsRadioButton" 
                        Tag="http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer"
                         IsChecked="true" Margin="5,0,0,0" Foreground="White"
                         GroupName="Layers" Content="Streets" Click="RadioButton_Click"/>
   <RadioButton x:Name="TopoRadioButton" 
                         Tag="http://services.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer" 
                         Margin="5,0,0,0" Foreground="White" 
                         GroupName="Layers" Content="Topo" Click="RadioButton_Click"/>
   <RadioButton x:Name="ImageryRadioButton" 
                         Tag="http://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer" 
                         Margin="5,0,0,0" Foreground="White" 
                         GroupName="Layers" Content="Imagery" Click="RadioButton_Click"/>
  </StackPanel>
 </Grid>
 <esri:MagnifyingGlass x:Name="MyMagnifyingGlass" Visibility="Visible" 
                                         HorizontalAlignment="Left" VerticalAlignment="Top"
                                         Map="{Binding ElementName=MyMap}" >
  <esri:MagnifyingGlass.Layer>
   <esri:ArcGISTiledMapServiceLayer ID="StreetMapLayer" 
                    Url="http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer"/>
  </esri:MagnifyingGlass.Layer>
 </esri:MagnifyingGlass>
</Grid>

private void RadioButton_Click(object sender, RoutedEventArgs e)
{   
 MyMagnifyingGlass.Layer = new ArcGISTiledMapServiceLayer() { Url = ((RadioButton)sender).Tag as string };   
}

[Anonymous User · Accepted solution]

Original User: huangs3

Hi Jenniferdnery:

    Thank you for your test.
    I re-checked my code and found that the issue happens at program startup because at that time the MagnifyingGlass object is not initialized yet.
    I changed the event handler to the following and it works:

*************************************
private void RadioButton_Checked(object sender, RoutedEventArgs e)
{
   if (MagnifyingGlass != null)
   {
        ArcGISTiledMapServiceLayer newMagnifyingGlassLayer = new ArcGISTiledMapServiceLayer();
        newMagnifyingGlassLayer.Url = "http://xyz";
        MagnifyingGlass.Layer = newMagnifyingGlassLayer;
    }
}
**************************************