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From: Eli Zaretskii <eliz@gnu.org>
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Subject: Re: How to get the actual face attribute?
Date: Sun, 21 Jun 2020 17:52:46 +0300
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In-Reply-To: <60C41409-88B0-4F21-AC6D-2F18394A7C46@gmail.com> (message from
 Yuan Fu on Sun, 21 Jun 2020 00:01:37 -0400)
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> From: Yuan Fu <casouri@gmail.com>
> Date: Sun, 21 Jun 2020 00:01:37 -0400
> 
> When writing my package I need to get height of the face at point. But `face-attribute` doesn’t take face remapping into account, which gives wrong answers. Is there a reliable way to get the actual face attribute that’s used for display? Thanks.

>From Lisp or from C?

In general, you cannot know that except by displaying that text or
emulating its display, because the face is fully realized only while
displaying text that is affected by the face.