Re: Increase default `line-spacing' to 0.05, 0.10 or 0.15 [proposal]

[Daniele Nicolodi]

On 06/05/2021 18:29, Eli Zaretskii wrote:
>> Date: Thu, 06 May 2021 16:21:20 +0000
>> From: Gregory Heytings <gregory@heytings.org>
>> cc: jporterbugs@gmail.com, arstoffel@gmail.com, stefankangas@gmail.com, 
>>     emacs-devel@gnu.org
>>
>>>> \baselineskip=0pt means that the height and depth of a text line is 
>>>> equal to the maximal height and depth of the characters in that line. 
>>>> See the attached two screenshots that demonstrate the difference.
>>>
>>> That's what Emacs does as well, when line-spacing is nil, but Augusto 
>>> says they are different.
>>
>> Unless I'm missing something, that's not what Emacs does, no.  I attach 
>> two screenshots of the exact same text with the exact same font, one with 
>> Emacs (setq line-spacing nil) and the other with TeX (\baselineskip=0pt). 
>> The effect is very different.
> 
> Then your description of what TeX does is probably incomplete or
> inaccurate.
> 
> on the Emacs side, I can point you to the code which implements
> line-spacing, which clearly shows that if line-spacing is nil, the
> default, we add NOTHING (a.k.a. "zero") to the height of the line,
> leaving it at its computed value of the sum of the maximum ascent and
> maximum descent of the glyphs in that line.

I didn't look at the code, but I don't think this is true: on my Emacs,
lines containing only "." or containing only "l" have exactly the same
height, as I would expect. Also, lines containing only a new line
character (thus no printable characters) still have the same height as
lines with content, as expected.

Are you sure Emacs does not consider the maximum ascent and descent of
each _font_ contained in a line and not of each _glyph_?

Cheers,
Dan