topic LabelPoints from GeometryService, am I missing something? in ArcGIS API for Silverlight Questions

LabelPoints from GeometryService, am I missing something?

PaulAbbott — Wed, 13 Oct 2010 19:54:31 GMT

I am attempting to label some selected polygon features using the following process:

1) Send the list of selected polygon features to a geometry service
2) Get the returned label points
3) For each returned point, add text based on the polygon's attributes to a graphics layer

So far 1 and 2 work fine, but the returned label points have no attributes! I would have expected the geometry service to return the label point with all of the polygon's attributes intact so I would have something to label with, or at least the very least keep the ObjectID so I can go look up what I need.

How do I know which returned label point corresponds to which polygon, so I can retrieve the attributes needed for the label text?

Re: LabelPoints from GeometryService, am I missing something?

AliMirzabeigi — Thu, 14 Oct 2010 17:32:19 GMT

The LabelPointsAsync() method of the GeometryService has a second parameter "userToken". When invoking this method also include your graphics list in the second parameter:

geometryService.LabelPointsAsync(graphicsList, graphicsList);

Then on LabelPointsCompleted event handler get the list of your graphics (with attributes) using "UserState" property of the GraphicsEventArgs, ie:

IList<Graphic> graphicsWithAttributes = e.UserState as IList<Graphic>;

The sequence of graphics in e.Results matches e.UserState hence, you just need to grab the attributes from the corresponding graphic in graphicsWithAttributes in above code snippet.