Re: [dev] [tabbed] utf8 characters not displayed in tabs

From: NRK <nrk_AT_disroot.org>
Date: Wed, 31 Aug 2022 22:38:58 +0600

On Tue, Aug 30, 2022 at 10:47:46PM +0200, Storkman wrote:
> but more generally,
> the "set of fonts covering as wide variety of code-points as possible"
> ...is just the set of all installed fonts, isn't it?

Not entirely. Let's say a system has 3 fonts installed: A, B and C. A
and B both *only* cover English characters and C covers Chinese ones.

In that case, our list would be [A, C]. B can be eliminated from the
fallback-list since it doesn't add anything new. (Or it could be [B, C]
with A eliminated).

We could of course add a reasonable upper-limit to this list, say
128/196 or something along those lines.

And just so everyone is on the same page: drw ALREADY maintains such a
list. I'm only proposing we change *how* we construct the list (assuming
it's possible).

This is roughly how things currently work:

        0. at startup push the user specified fonts (in config.h) to the list
        // list = [ userfont0, userfont1 ]
        foreach code-point:
                1. walk the list to find a font that can render the code-point.
                   if any of the fonts in the list can render it, just use that.
                2. if not, then run XftFontMatch() to see if we can find
                   a match.
                3. If XftFontMatch() finds a match then append the
                   matched font to the list (so that step 1 can find it
                   next time around).
                   // list = [ userfont0, userfont1, matchedfont0, matchedfont1 ... ]

My idea is to simply remove step 2 and 3 from the loop and construct the
list at startup so we don't have to constantly keep calling
XftFontMatch() inside the loop for each unknown code-point.

> I'm a big fan of pre-calculating this list before compiling the program.

I was talking about doing it on program startup since I don't think you
should have to recompile the program every time you install a new font
for font fallback to work.

> If your question is simply "which code-points ARE NOT supported by ANY font",

Wasn't exactly what I was looking for but even this *could be* an
improvement over the current system if it can be done in reasonable
space, speed and code-size.

- NRK
Received on Wed Aug 31 2022 - 18:38:58 CEST