topic Re: Accessing AutoCAD's COM api from .Net framework in .NET Forum

Accessing AutoCAD's COM api from .Net framework

TK_Rao5AR2 — Fri, 11 Apr 2025 05:20:36 GMT

Accessing AutoCAD's COM api from out-of-process is not a challenge (I am using .Net framework 4.8). However when I react to events such as ObjectAdded, ObjectModified etc., they are executed in a worker thread.

There is a need to keep these events on the Main thread. Any ideas on how to achieve this?

Thanks,

Re: Accessing AutoCAD's COM api from .Net framework

ActivistInvestor — Fri, 11 Apr 2025 18:35:32 GMT

I don't think there's any option for configuring what thread the events are raised on, as that's determined by the server.

You can deal with it using Control.Invoke() or SynchronizationContext.Post().

I would also point out that events like those you cite can fire at a very high frequency, and when handling them from an out-of-process client, there will be significant overhead imposed on the end user. Given the other options for AutoCAD development, handling high-frequency events in an out-of-process client is not something I would recommend.

Re: Accessing AutoCAD's COM api from .Net framework

TK_Rao5AR2 — Wed, 16 Apr 2025 05:29:27 GMT

Thank you. I ended up using SynchronizationContext.Post().

There is no choice but to use it out-of-process as another application is launching and controlling autocad. That other application works well when AutoCAD is on the Main Thread. Its a requirement.

-TK