topic Re: Inside Polygon Buffer and QueryTask Crossing Polygons in ArcGIS API for Silverlight Questions

Inside Polygon Buffer and QueryTask Crossing Polygons

BradBarnell — Mon, 14 Feb 2011 17:22:08 GMT

I have two questions:

1) Is there a way to use the Geometry Service with a negative buffer distance? I am trying to create an inside buffer polygon. Is there a workaround for this problem?

2) Is there a workaround for the QueryTask to make it crash more gracefully when its geometry property is set to a polygon with crossing linework? For example, if a user draws a figure 8 polygon and trys to query for features based on this polygon it crashes.

Re: Inside Polygon Buffer and QueryTask Crossing Polygons

JenniferNery — Mon, 14 Feb 2011 17:45:03 GMT

#1 - The error you are seeing is from the service.

{"error":{"code":400,"message":"Unable to complete Buffer operation.","details":["An error occured while buffering geometry. Unable to complete the operation.","The coordinates or measures are out of bounds."]}}

You may need to call Simplify and use the simplified geometry instead.

#2 - I could not replicate the crashing when using this SDK sample: http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#SpatialQuery
I get results whether the polygon I create has hole in it or not.

For both cases, GeometryService and QueryTask, you can subscribe and handle Failed events. Also, to ensure that you are sending a valid geometry for your query, call Simplify on it first. Here's an example: http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#Simplify

Re: Inside Polygon Buffer and QueryTask Crossing Polygons

BradBarnell — Mon, 14 Feb 2011 19:04:15 GMT

Yes, the ESRI sample does work. Not sure why mine does not. I will log an incident.