Re: How to get the actual face attribute?

[Eli Zaretskii <eliz@gnu.org>]

> From: Yuan Fu <casouri@gmail.com>
> Date: Mon, 22 Jun 2020 13:21:15 -0400
> Cc: help-gnu-emacs@gnu.org, Stefan Monnier <monnier@iro.umontreal.ca>
> 
> I have a package that aligns org tables even for variable pitch text, CJK text, images, etc are in the table:
> 
> 
> 
> Some one reported that when they change the text size with text-scale-adjust, the alignment are messed up. That’s because the package aligns by calculating the pixel width of each cell, and when the text size are adjusted that width is no accurate anymore. I’m using this function to calculate the width of a glyph (which adds up to the width of a cell):
> 
> (let* ((p (or point (point))))
>     (if (eq (char-after point) ?\t)
>         (valign--tab-width (font-at p))
>       ;; (font-at 0 nil (buffer-substring p (1+ p))) doesn’t work, the
>       ;; font is sometimes wrong.  (font-at p) doesn’t work, because
>       ;; it requires the buffer to be visible.
>       (aref (aref (font-get-glyphs (font-at p) p (1+ p)) 0) 4)))

Did you try using window-text-pixel-size?