melatonin_audio_sparklines VS lsix

You found the Achilles' heel of my project! I don't mind the fonts being different sizes or not monospaced, but the fact that there's a difference in height in the font rendering between ⎺ and ‾ on different platforms is a bummer. I have a flag in the C++ implementation so they can still be rendered "correctly" in IDEs like Xcode [1].

I felt doomed to Unicode in this case because of the number of places I wanted them to show up (CLion lldb integration, GitHub actions output, terminal). I would have loved to actually render graphics! I actually never thought about how they would render on a blog article, I wouldn't generally wouldn't use them for blogging...

1. https://github.com/sudara/melatonin_audio_sparklines/blob/ma...

Nice! I became obsessed with rendering sparkline representations of chunks of audio for the same reason: to inspect failures when writing tests / refactoring. https://github.com/sudara/melatonin_audio_sparklines

In XTerm, this (rightly) makes no difference. In Foot and Contour however, you still end up a line resp. a screen below where you started, if now with the correct horizontal position.

So it seems to me like what you want should work by default, except it doesn’t.

It should be possible to instead just treat the whole thing as a graphical overlay (by computing or directly asking for the character cell size, as Kirill Panov rightly admonishes me is possible with XTWINOPS) without touching the cursor; that’s what the “sixel scrolling” setting (DECSDM) is supposed to do. Then you can just manually move the cursor forward however many positions after you’re done drawing.

Except apparently the DEC manual (the VT330/340 one above) and DEC hardware contradict each other as to which setting of DECSDM (set or reset) corresponds to which scrolling state (enabled or disabled), and XTerm has implemented it according to the manual not the VT3xx[1,2,3]—then most other emulators followed suit[4]—then XTerm switched to following the hardware[5,6] (unless you and that’s what I’m seeing on my machine right now. So now you need to check if you’re on XTerm ≥ 369 or not[7]. If I’m reading the Notcurses code right, other terminals have followed suit[8].

Again, ouch.

P.S. It seems DEC had an internal doc for how their terminals should operate (DEC STD 070) [9]. It does not document DECSDM at all.

[1] https://github.com/wez/wezterm/issues/217#issuecomment-86449...

[2] https://github.com/hackerb9/lsix/issues/41

[3] https://github.com/dankamongmen/notcurses/issues/1782

[4] https://github.com/arakiken/mlterm/pull/23

[5] https://invisible-island.net/xterm/xterm.log.html#xterm_369

[6] https://invisible-island.net/xterm/ctlseqs/ctlseqs.html#h3-T...

[7] https://github.com/dankamongmen/notcurses/commit/0918fa251e2... (the correct version cutoff is 369 not 359, the patch contains a now-fixed bug)

[8] https://github.com/dankamongmen/notcurses/blob/master/src/li... (look for mentions of invertsixel)

[9] http://www.bitsavers.org/pdf/dec/standards/EL-SM070-00_DEC_S...

Sixel - Sixel is a standard from the 1970's/1980's DEC VT series. It has enjoyed a tremendous resurgence in popularity thanks largely to saitoha's libsixel project. Many projects are now using sixel; a few you may have heard of include lsix, chafa, and notcurses.

I would point out that sixels[0] exist. There is a nice library, libsixel[1] for working with it, which includes bindings into many languages. If the author of sixel-tmux[2][3] is to be believed[4], the relative lack of adoption is a result of unwillingness on the part of maintainers of some popular open source terminal libraries to implement sixel support.

I can't comment on that directly, but I will say, it's pretty damn cool to see GnuPlot generating output right into one's terminal. lsix[5] is also pretty handy as well.

But yeah, I agree, I'm not a fan of all the work that has gone into "terminal graphics" that are based on unicode. It's a dead-end, as was clear to DEC even back in '87 (and that's setting aside that the VT220[6] had it's own drawing capabilities, though they were more limited). Maybe sixel isn't the best possible way of handling this, but it does have the benefit of 34 years of backwards-compatibility, and with the right software, you can already use it _now_.

0 - https://en.wikipedia.org/wiki/Sixel

1 - https://saitoha.github.io/libsixel/

2 - https://github.com/csdvrx/sixel-tmux

3 - https://news.ycombinator.com/item?id=28756701

4 - https://github.com/csdvrx/sixel-tmux/blob/main/RANTS.md

5 - https://github.com/hackerb9/lsix

6 - https://en.wikipedia.org/wiki/VT220

no, I found it and it's called lsix