ArcObjects: How to get from IFeatureClass on annotation feature class to IAnnoClass?

Question

I am working in Python 2.6 and ArcGIS 10.0 through comtypes, so I have full ArcObjects access. (See the answer I tacked onto the related question "How do I access arcobjects from python?") That makes this strictly an object model traversal question.

I have an IFeatureClass on an annotation feature class. I need to get to IAnnoClass to get the ReferenceScale property. How do I do that?

I'm guessing that it starts with the Extension property inherited from IClass, but I may be way off base. Thank you, all.

Cheers, Ti

Answer 1

If a feature class is an annotation class, its IFeatureClass.Extension will be a reference to the AnnotationFeatureClassExtension coclass instance. It can be directly cast to IAnnoClass interface.

In short, you are right, the Extension property will be an object which implements IAnnoClass.