DgnPlatformNet API for C# Developers
[quote user="djeten"]A bit of background : this function is part of old vba code (aprox 10 years old), that I'm trying to rework to c# [/quote]
MicroStation CONNECT provides the C# DgnPlatformNet API. Having said that, I don't see any mention in the DgnPlatformNet help of a method to measure area or volume properties. Perhaps someone from Bentley Systems can suggest how to achieve that.
VBA ClosedElement Interface
[quote user="djeten"]I'm not aware of VBA functions that calculates these kind of information ?[/quote]
VBA provides the ClosedElement interface. If an element implements that interface then you can take measurements.
There's also the Property Handler API, which may be useful to you.
C Expressions in CONNECT
You're not the first to notice that C Expressions don't work in CONNECT VBA. C Expressions rely on some internal book-keeping where MDL functions were published in a way that they could be interpreted by the C Expression handler. That internal book-keeping seems deficient.
Reports, Tables and Item Types
You should investigate Reports in CONNECT. The report tools let you gather element information. Once created, a report can be used to build a Table or sent to an external file such as CSV or XML. By defining your own Item Types for business data, and attaching item data to graphical elements, you can add custom information to those reports. In other words, you may not need to write any code.