VS2010 extension, using MEF tagger, want to use code model

I want to write a visual studio 2010 extension displaying a margin glyph on each class, method, property, field and event definition (tooltip/popup window on click with addition开发者_如何学JAVAal info).

The new MEF based framework is really neat but the only thing I can tag in order to create margin glyphs are snapshotspans. unfortunately they dont have any sort of code model or structuring and i am forced to search for class names, etc. by string parsing => absolutely not what i want to do.

We found out that we can use

[Import]
internal SVsServiceProvider ServiceProvider;

to retreive a DTE object for the current document. Unfortunately we still have problems to call fileCodeModel.CodeElementFromPoint() because we have no TextPoint object.

Does somebody know how to convert a SnapshotSpan to a TextPoint?

Is there any other way to directly tag the code model instead of the text? Only thing I found on google has been: Visual Studio Extensibility / Margins - also forgeting about how to convert from SnapshotSpan to TextPoint : (

Best regards. D.R.

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I don't know how to do this myself, but you might be able to figure it out by looking at the code to RapidMEF.