Re: How to get the actual face attribute?

[Yuan Fu <casouri@gmail.com>]

> On Jun 22, 2020, at 3:49 PM, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
> 
>>>> Some one reported that when they change the text size with
>>>> text-scale-adjust, the alignment are messed up.
>>> If the alignment is done before changing the text-scale, then it's no
>>> big surprise, since text-scale won't scale everything by the same factor.
>> I see. I calculate the text size base on the assumption that the text scale
>> is the same for all glyphs. That explains why my measuring are off.
> 
> I don't know what that means.  The text-scale does apply globally.
> But it doesn't necessarily scale by the same factor horizontally and
> vertically, nor does it necessarily scale by the same factor for
> different fonts.  It's "more or less equal" but not exactly.  And of
> course, it won't affect those glyphs whose size is not relative to the
> base `default` face (e.g. images or glyphs to which a face is applied
> which sets an absolute rather than relative size).
> 
> IOW it needs to be recomputed from scratch when the text-scale is changed.

How should I recompute the text scale? Currently I calculate it from

(expt text-scale-mode-step text-scale-mode-amount)

Which is what text-scale-mode uses. (Face remap is hard to calculate so I thought I can just support text-scale-mode.)

Yuan