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Comment by JdeBP | Hacker News Reader

It seems to have supported UTF-8 for at least a decade. Although it went the full-on ECMA-35 route of making that an optional switchable character set.

There was an issue back in 2016 where, ironically, it was coming up in Latin-1 mode with everything else around it talking UTF-8, and there have been other similar impedance mis-matches over the years. But they seem to hinge on it actually having UTF-8 support.

* https://github.com/cosmos72/twin/issues/4

* https://github.com/cosmos72/twin/issues/7

* https://github.com/cosmos72/twin/issues/8

However: There was no 256 colours support as of 2021.

* https://github.com/cosmos72/twin/issues/30

And in some places it even required IBM code page 437.

* https://github.com/cosmos72/twin/issues/22

And some of the doco seems to have never been incorporated.

* https://github.com/cosmos72/twin/issues/100

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Author here :)

I've been using Twin as my everyday terminal emulator and terminal multiplexer since ~2000, slowly adding features as my free time - and other interests - allowed.

As someone pointed out, the look-and-feel reminds Borland Turbo Vision. The reason is simple: I started writing in in the early '90s on DOS with a Borland C compiler, and I used the Borland Turbo Vision look-and-feel as a visual guideline (never actually looked at the code, though).

The porting to linux happened in 1999 (it was basically dormant before that), and Unicode support was progressively added around 2015-2016 (initially UCS-2 i.e. only the lowest 64k codepoints, then full UTF-32 internally, with terminal emulator accepting UTF-8). There are still some missing features, most notably: no grapheme clusters, no fullwidth (asian etc.) support, no right-to-left support.

Right now I'm adding truecolor support (see https://github.com/cosmos72/twin/tree/truecolor) - it's basically finished, I'm ironing out some remaining bugs, and thinking whether wire compatibility with older versions is worth adding.

And yes, documentation has been stalled for a very long time.

Retrospectively, I should have switched C -> C++ much earlier: lots of ugly preprocessor macros accumulated over time, and while I rewrote the C widget hierarchy as C++ classes, several warts remain.

Do symbols for legacy computing work with it? Especially the 1/8ths vertical/horizontal blocks?

If you mean the Unicode glyphs listed at https://en.m.wikipedia.org/wiki/Block_Elements they are supported - you just need a display driver that can render them. For example, `twin --hw=xft` (it's the default) or `twin --hw=X11`, both with a font that contains them

Xe means the Unicode block that is actually named "Symbols For Legacy Computing". It's not in the BMP. Some bloke named Bruce was doing TUI windows with scrollbars and sizer/menu boxes some years before TurboVision and code page 437. (-:

Indeed I meant these: https://en.wikipedia.org/wiki/Symbols_for_Legacy_Computing

I use them in some tiny hobby projects like these:

https://github.com/panzi/progress-pride-bar

https://github.com/panzi/bad-apple-terminal

https://github.com/panzi/js-unicode-bar-chart

https://github.com/panzi/js-unicode-plot

https://github.com/panzi/js-unicode-progress-bar

https://github.com/panzi/python-term-flags

Reading the flags one: Unscii has font coverage, if you want to try that out on the emulators whose fonts were problems.

* https://news.ycombinator.com/item?id=43812026

Given that it's drawing TUI windows, the MouseText characters for doing that very thing on the Apple IIe would seem even more pertinent.

* https://tty0.social/@JdeBP/114409020672330885

Alas, it's not finished. You've made the mistakes that all of us have made, and haven't caught up with us, must of us having fixed those mistakes, a few years back when implementing 24-bit RGB was in vogue.

This is not, as the function name suggests, a colon, but per ITU/IEC T.416 it should be:

https://github.com/cosmos72/twin/blob/truecolor/server/hw/hw...

And not only should this have colons too, but per ITU/IEC T.416 there's a colour space parameter that goes in there:

https://github.com/cosmos72/twin/blob/truecolor/server/hw/hw...

The unfortunate part is that when rendering to a terminal, you don't have any available mechanism apart from hand-decoding the family part of the TERM environment variable, and knowing who made which mistakes, to determine which of the 7 possible colour mechanisms are supported. They are:

1. ECMA-48 standard 8 colour, SGRs 30 to 37, 39, 40 to 47, and 49

2. AIXTerm 16 colour, ECMA-48 plus SGRs 90 to 97 and 100 to 107

3. XTerm 256 colour, ITU T.416 done wrongly with SGR 38;5;n and SGR 48;5;n

4. XTerm 256 colour corrected, ITU T.416 done right with SGR 38:5:n and SGR 48:5:n

5. 24-bit colour take 1, ITU T.416 done wrongly with SGR 38;2;r;g;b and SGR 48;2;r;g;b

6. 24-bit colour take 2, ITU T.416 done wrongly with SGR 38:2:r:g:b and SGR 48:2:r:g:b

7. 24-bit colour take 3, ITU T.416 done right with SGR 38:2::r:g:b::: and SGR 48:2::r:g:b:::

Few people support 4, and although quite a lot of us have finally got to supporting 7 it isn't quite universal. Egmont Koblinger, I, and others have been spreading the word where we can over the last few years.

This is where I was at in 2019:

https://github.com/jdebp/nosh/blob/trunk/source/TerminalCapa...

There a few updates to that that are going to come out in 1.41, but when it comes to colour they're mainly things like recognizing the "ms-terminal" and "netbsd6" terminal types in the right places.

Yep, I am well aware of the `;` vs `:` confusion in both 256 color and 24-bit color control sequences.

Short of hand-coding "which terminal supports which variant" I do not know any standard mechanism to detect that (beyond the well-known $TERM=...-256color and $COLORTERM=truecolor or $COLORTERM=24bit)

I guess I'll have to add command line options to choose among the variants 1...7 you helpfully listed above.

My main use it to render twin directly on X11, which avoids all these issues, and while rendering inside another terminal is important and is not going away, I am OK with a few minor color-related limitations (note: limitations, not bugs) in such setup, especially if the other terminal does not follow the relevant standards

> This is not, as the function name suggests, a colon, but per ITU/IEC T.416 it should be

Digressing, but I’m fascinated to see ODA still being referenced, even if only some small part of it

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