title: How to use ArcGIS for WPF custom symbol with data binding?
body: <p>Esri's ArcGIS for WPF does not seem to have any real MVVM support or binding support; unless I'm mistaken. </p>
  
  <p>Anyway, I am creating a tracking application and it needs to track objects via GPS coordinates.</p>
  
  <p>I have implemented a custom <code>IGeoPositionWatcher&lt;GeoCoordinate&gt;</code> which is used with the <code>GpsLayer</code>. This all works perfectly. I can modify the GPS coordinates and my little dot on the map moves smoothly to it's final resting place. My problem is that I can't use the little dot and arrow that comes with the <code>GpsLayer</code>. I need a custom <code>MarkerSymbol</code> to be something similar to the following:</p>
  
  <pre><code>&lt;Grid&gt;
     &lt;Image Source="{Binding Pogostick.HeightImage}" /&gt;
     &lt;TextBlock Text="{Binding Pogostick.PogoId}" /&gt;
  &lt;/Grid&gt;
  </code></pre>
  
  <p>I have a list (amount unknown and changes at any given moment) of these "pogosticks" which are always tracking by GPS and need to have the symbol update according to its status. The problem is that I can't get the <code>Pogostick</code> object to be the <code>DataContext</code> for the custom <code>MarkerSymbol.ControlTemplate</code> and there for my image source and text do not show.</p>
  
  <p>I'm trying to avoid using a <code>Graphic</code> in a <code>GraphicLayer</code> and would like this to work with the <code>GpsLayer</code>. Is there a way to do this at all? Am I even approaching this correctly... should I be using a <code>GraphicLayer</code> or a <code>FeatureLayer</code>?</p>
  
  <p>I want to render these tracked pogosticks on the user's desktop app and not by editing layers or features on the map service. Perhaps I should be using a custom renderer?</p>