Re: master a739cab6637 2/2: ; * doc/lispref/display.texi (Image Descriptors): Insert missing text.

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: rpluim@gmail.com,  emacs-devel@gnu.org
> Date: Fri, 07 Jun 2024 08:14:36 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > And I would like to explain more about "computing the scaling factor
> > based on pixel size of the font used by the frame's default face", and
> > what happens if the default font's width is 10 pixels or below, but
> > your text doesn't really tell that story.  I think it should.  (Btw,
> > the default width of the font in "emacs -Q" on Windows is 8, so it
> > will always hit the case which was left unexplained.)
> 
> Below 10 pixels, the image is not scaled unless a numeric scale be
> provided in image-scaling-factor.  As for the reasoning behind this
> arbitrary value, you'll need to ask Lars, whose code I've merely
> reproduced in C.

So this means at least on Windows, where the default font's width is
8, the image will never be scaled in "emacs -Q", am I right?

I think on macOS the default width is 7, so the same will happen there
as well?

What is the default width of the font on GNU/Linux?

And finally, can you tell more about how the scale factor is computed
"based on the font's pixel size"?  Or point me to the code which does
that?  I think some of that should be in the manual, to give the users
some idea of what will happen.

Thanks.