Re: Error when using Unifont and trying to launch M-x term

[Rodrigo Morales <me@rodrigomorales.site>]

Eli Zaretskii <eliz@gnu.org> writes:

> Maybe because you are setting up your fonts and fontsets incorrectly?
> For example, you cannot affect the default font, the one used for the
> ASCII characters, via set-fontset-font, at least not in the naïve way
> you are doing that.  Instead, you should do it the "traditional" way,
> by adding this:
>
>   (add-to-list 'default-frame-alist '(font . "Unifont"))
>
> to your init file, and then tell Emacs (again in the init file) that
> Unifont should be used for the entire Unicode space of non-ASCII
> characters:
>
>   (set-fontset-font t 'unicode "Unifont" nil 'prepend)
>
> In addition, you may need to customize face-font-family-alternatives,
> and specifically the alternatives for "Sans Serif" (not sure about
> this, but that's where the "-Sans-Serif" suffix above might be coming
> from), if the above two measures are still not enough.
>
> Please try the above, and if it also produces an error, report a bug
> using "M-x report-emacs-bug RET", with all the details.

Thanks. I wasn't aware of those methods for setting the default
font. The same error is still being thrown. I have reported a bug:
https://lists.gnu.org/archive/html/bug-gnu-emacs/2024-05/msg00953.html

> P.S. Let me just note, and I will only do this once, that doing all of
> that just to have all the lines in "M-x term" be the same height in
> 110% of cases is IMNSHO too much effort for a little gain.  Your time
> and energy will be spent much better by looking at fonts for
> characters that make the line height higher, then finding alternative
> fonts for those characters which don't have that effect, and
> configuring your fontset to use those better fonts for those
> problematic characters.  As a nice bonus, this will leave you with
> much nicer fonts than Unifont can ever be.

Thanks for the suggestion. I am afraid I didn't make my use case clear:
I value more efficiency over aesthetics so I don't care whether a bitmap
font looks ugly or not. I work with different scripts from different
languages in Emacs, some of these scripts contain characters with
minimal details. For example, consider the following pairs of
characters: 璧壁, 镱镜 and 畲畬. In order to easily different those
characters, I display them with a big size using a OpenType font. A big
font size for ASCII characters is not required, because ASCII characters
can be easily differentiated, so I use an extremely small bitmap font
for ASCII characters, a benefit of doing this is that the most number of
lines fit on my screen and I can read the most information without
scrolling.  A combination of big OpenType fonts and extremely small
bitmap fonts doesn't mix well inside *terminal* because it seems that
*terminal* assumes that all lines have the same height, so some
information in the *terminal* window is displayed out of the limits of
the window. Now, most of my work inside *terminal* involves displaying
ASCII characters so I want to make *terminal* use the extremely small
bitmap font, non-ASCII characters are hardly shown but if they are shown
I want the entire content of *terminal* still fit the window. Here's
another use case: when I am learning new things or I feel tired, I
change the extremely small bitmap font in *terminal* to an OpenType
font, whether a bitmap font or a OpenType font I want the entire
contents of *terminal* to fit the window.

So, the question I really want to solve is: Given one and only one
arbitrary font with an arbitrary size, how can I always ensure that the
information displayed in *terminal* fits the window in its entirety?

Some terminal emulators such as gnome-terminal and kitty are able to fit
the entire content regardless of the characters that are being shown (I
haven't done exhaustive testing on this, but I tried some scenarios). I
think they are able to do that by assigning the same height to all lines
and trying to fit all characters for that height.