notcurses VS libsixel

> The only reason we don't have animation frameworks for the terminal is because it's not possible

https://nick-black.com/dankwiki/index.php/Notcurses

Notcurses. Install it and run notcurses-demo to be suitably impressed.

Same for me, I would be much more motivated if there was something like textual for Rust. Given the capability of terminal emulators now I think Rust is lacking behind in the TUI field. Just checkout what can be done with something like notcurses

On the application side of rendering, see notcurses, it is at the leading edge: https://github.com/dankamongmen/notcurses

Other TUI libraries of note: https://github.com/dankamongmen/notcurses/blob/master/doc/OT...

The broader world probably knows him best for the terminal handling library Notcurses[1] and a lot of telling terminal emulator authors to get their shit together.

I’ve had his grad-school project libtorque[2] (HotPar ’10), an event-handling and scheduling library, on my to-read list for years, but I can’t seem to figure out how it accomplishes the interesting things it does.

[1] https://nick-black.com/dankwiki/index.php/Notcurses, https://github.com/dankamongmen/notcurses/

[2] https://nick-black.com/dankwiki/index.php/Libtorque

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...

And there's also the notcurses library:

Library you can use to generate these images:

https://github.com/saitoha/libsixel

Plenty of links to other projects.

Sixels are pixels and enjoy a wide support due to how old it is.

Kitty protocol is PNG or primitives - which BTW would make it great for a GUI library.

Different tools for different needs, but if you are going for a wide support you want something simple that doesn't have 5 different types you have to separately implement and test:

> d: Direct (the data is transmitted within the escape code itself)

> f: A simple file (regular files only, not named pipes or similar)

> t: A temporary file, the terminal emulator will delete the file after reading the pixel data. For security reasons the terminal emulator should only delete the file if it is in a known temporary directory, such as /tmp, /dev/shm, TMPDIR env var if present and any platform specific temporary directories and the file has the string tty-graphics-protocol in its full file path.

> s: A shared memory object, which on POSIX systems is a POSIX shared memory object and on Windows is a Named shared memory object. The terminal emulator must read the data from the memory object and then unlink and close it on POSIX and just close it on Windows.

> What nonsense, it takes literally 15 lines of code without using anything beyond the standard library to write a client

Conveniently taking a preencoded PNG and assuming away the necessary queries of supported protocol:

> Since a client has no a-priori knowledge of whether it shares a filesystem/shared memory with the terminal emulator, it can send an id with the control data, using the i key (which can be an arbitrary positive integer up to 4294967295, it must not be zero).

> for the kitty graphics protocol. I challenge you to match that for sixel

https://github.com/saitoha/libsixel/tree/master/perl

    use Image::LibSIXEL;

Also:

https://github.com/saitoha/libsixel

contains img2sixel, which lets you dump images to the terminal. It can also do animated GIFs.

Video:

https://github.com/saitoha/FFmpeg-SIXEL

GUI apps:

https://github.com/saitoha/SDL1.2-SIXEL

and more, linked from the libsixel repository.

Not sure of Terminal emulator capabilities on Apple devices, but thanks to https://github.com/saitoha/libsixel , several applications, including emacs very much support image output in terminals.

You don't have multi-colored terminal output? Even legacy systems have long had Sixel support.

> SIXEL is one of image formats for printer and terminal imaging introduced by Digital Equipment Corp. (DEC). Its data scheme is represented as a terminal-friendly escape sequence. So if you want to view a SIXEL image file, all you have to do is "cat" it to your terminal

https://github.com/saitoha/libsixel