Bringing Feature Selection To Top using ArcObjects?

Question

I'm using IFeatureSelection.SelectFeatures() to select parcel polygons in my parcel layer.

It works fine until I create a ClassBreaksRenderer to apply a color ramp based on a field in the feature.

The selection proceeds without error but does not draw on top of the renderer.

Is there a way to ensure that the feature selection draws on top?

Answer 1

Try calling IActiveView.PartialRefresh, passing in the esriViewGeoSelection draw phase -- once before, and once after selecting the features.

• Chaz: I can select an area correctly and then apply the renderer and the area remains selected. In addition I have discovered that the only the UniqueRenderer completely prevents the selection. The ClassBreaksRenderer works correctly (with the PartialRefresh) for some of the selection - but not all! For example: in one case the SelectionSet said that the SelectFeatures() query returned 11 and the map only selected 8!

Answer 2

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One way to do it is to is with IScreenDisplay.Invalidate, see code here.

• Chaz: Tried this also and it failed. Could this be a real bug? The fact that it works randomly is disturbing? Does anyone know how to track the ArcGIS bugs - is there a site where they are listed?
• Kirk Kuykendall: @chaz I've seen random draw bugs in situations where there's an exception after IDisplay.StartDrawing but before IDisplay.FinishDrawing is called. In this situation the screen caches get into an unstable state I wonder if somehow the renderer has an unhandled exception internally. Are you using a custom renderer anywhere?
• Chaz: No custom renderer, just classbreaks and unique but I have been curious about the "NullReferenceExceptions" I see in the output window while I'm running the program - but this happens with no renderers defined. (And I have tried to track down everything that needed to be released.)
• Kirk Kuykendall: Have you run in debug mode after setting Debug>Exceptions> and check CLR and C++ for thrown exceptions?
• Chaz: Thanks! Found out was was causing the null reference exception (Enabled is called without class instantiation?) But I still can't do a select on top of a classified layer.