True Color support in both GUI and console application

[XVilka]

See the support/patches for original VIm https://bitbucket.org/ZyX_I/vim/commits/branch/24-bit-xterm
Also, ncurses is not going to have support for that (thanks its author!).
And now it is supported by major part of terminal applications.
Here is the addition info about true colors:

Colors in terminal

It's a common confusion about terminal colors... Actually we have this:

• plain ascii
• ansi escape codes (16 color codes with bold/italic and background)
• 256 color palette (216 colors+16gray + ansi) (colors are 24bit)
• 24bit true color (888 colors (aka 16 milion))

The 256 color palete is configured at start, and it's a 666 cube of
colors, each of them defined as a 24bit (888 rgb) color.

This means that current support can only display 256 different colors
in the terminal, while truecolor means that you can display 16 milion
different colors at the same time.

Truecolor escape codes doesnt uses a color palete. It just specifies the
color itself.

Here's a test case:

printf "\x1b[38;2;255;100;0mTRUECOLOR\x1b[0m\n"

• or http://github.com/robertknight/konsole/tree/master/tests/color-spaces.pl
• or https://git.gnome.org/browse/vte/tree/perf/img.sh?h=vte-0-36

Keep in mind that it is possible to use both ';' and ':' as parameters delimiter.

According to Wikipedia[1], this is only supported by xterm and konsole.

[1] https://en.wikipedia.org/wiki/ANSI_color

Here are terminals discussions:

Now supporting truecolor

• st (from suckless) [delimeter: semicolon] - http://lists.suckless.org/dev/1307/16688.html
• konsole [delimeter: colon, semicolon] - https://bugs.kde.org/show_bug.cgi?id=107487
• iterm2 [delimeter: colon, semicolon] - only in the nighties https://code.google.com/p/iterm2/issues/detail?id=218
• qterminal [delimeter: semicolon] - Colons support in RGB definition lxqt/qterminal#78
• Tera Term [delimeter: colon, semicolon] - Windows platform
• FinalTerm [delimeter: semicolon]
• all libvte based terminals (since 0.36 version) [delimeter: colon, semilocon] - https://bugzilla.gnome.org/show_bug.cgi?id=704449
  • libvte-based Gnome Terminal
  • libvte-based sakura
  • libvte-based Terminator
  • libvte-based Lilyterm - since commit Tetralet/LilyTerm@72536e7
  • libvte-based ROXTerm
  • libvte-based evilvte - no release yet, version from git https://github.com/caleb-/evilvte
  • libvte-based Termit
  • libvte-based Termite
  • libvte-based Tilda
  • libvte-based tinyterm
  • libvte-based lxterminal - with --enable-gtk3 configure flag.

But there are bunch of libvte-based terminals for GTK2 so they are listed in the another section.

Parsing ANSI color sequences, but approximating them to 256 palette

• xterm (though doing it wrong: "it uses nearest colour in RGB colour space, with a usualfalse assumption about orthogonal axes")
• mlterm - http://sourceforge.net/mailarchive/message.php?msg_id=31828705

Note about colour differences: a) RGB axes are not orthogonal, so you cannot use sqrt(R^2+G^2+B^2) formula, b) for colour differences there is more correct (but much more complex) CIEDE2000 formula (which may easily blow up performance if used blindly) [2].

[2] #793 (comment)

NOT supporting truecolor

• urxvt - http://lists.schmorp.de/pipermail/rxvt-unicode/2013q3/001826.html
• Terminlogy (E17) - https://phab.enlightenment.org/T746
• mrxvt - https://sourceforge.net/p/materm/feature-requests/41/
• aterm - https://sourceforge.net/p/aterm/feature-requests/23/
• mintty (Cygwin and MSYS) - https://code.google.com/p/mintty/issues/detail?id=431
• fbcon (from linux kernel) - https://bugzilla.kernel.org/show_bug.cgi?id=79551
• FreeBSD console - https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=191652
• libvte and GTK2 - based:
  • libvte-based GTKTerm2
  • libvte-based stjerm - GTK3 and lbvte >= 0.3x support stjerm/stjerm#39

Terminal multiplexers

• tmux (have workaround[3]) - https://sourceforge.net/p/tmux/tickets/140/ and https://www.mail-archive.com/tmux-users@lists.sourceforge.net/msg04720.html
• screen

[3] Currently you can use tmux_escape option as a workaround if you want true color in shell run under tmux. No true color in tmux statusline though.

Here are another console programs discussions:

Supporting True Color:

• irssi - 256 colour support for Irssi irssi/irssi#48

Not supporting True Color:

• mutt - http://dev.mutt.org/trac/ticket/3674
• mc - http://www.midnight-commander.org/ticket/3145#comment:1 - demo patches attached
• s-lang library - http://lists.jedsoft.org/lists/slang-users/2014/0000002.html
• ncurses library - https://lists.gnu.org/archive/html/bug-ncurses/2013-10/msg00007.html
• termbox library - 24 bit colors support (true colors) nsf/termbox#37
• mcabber - https://bitbucket.org/McKael/mcabber-crew/issue/126/support-for-true-color-16-millions-colors
• emacs - http://emacs.1067599.n5.nabble.com/RFC-Add-tty-True-Color-support-td299962.html
• vim - https://bitbucket.org/ZyX_I/vim/commits/branch/24-bit-xterm
• tig - Support for True Color (16 millions colors) jonas/tig#227

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[tarruda]

@XVilka these concerns will go in other projects. neovim will simply emit color information embedded in msgpack objects, its up to the UI to parse those and display to the user in whatever way it can.

After the msgpack UI is finished, a new project for hosting a ncurses UI will be created.

[leonerd]

I should also add that my own libvterm / pangoterm also supports the standard SGR 38:2:rrr:ggg:bbb format for RGB8 colour handling.
http://www.leonerd.org.uk/code/libvterm/
http://www.leonerd.org.uk/code/pangoterm/

[justinmk]

@leonerd Would it be reasonable to use libvterm as a replacement for ncurses, or is it lower level?

Does anyone have experience with termbox?

slang (better ncurses alternative)

slang is probably not an option since it's GPL: http://www.jedsoft.org/slang/

[leonerd]

@leonerd Would it be reasonable to use libvterm as a replacement for ncurses, or is it lower level?

I think you mean libtickit. :) But yes; it's quite similar.

For neovim you'll likely want to use the highest layer that currently exists in the C library; the renderbuffer layer. See http://home.leonerd.org.uk/code/libtickit/doc/tickit_renderbuffer.7.html.

At some point later, I may have a porting of the Window layer from the Perl library. This will help manage rendering nested/overlapping/etc.. regions using the renderbuffer, and routes input events via focus management. Some of those issues might not be important for neovim - maybe renderbuffer will be sufficient.

[justinmk]

@leonerd Good info as usual, thanks.

[ZyX-I]

@leonerd I am wondering whether you support incompatible 38;2;r*;g*;b*? Konsole does not support colons there and semicolons are supported by almost all terminals. Or is there any way to automatically deduce what format (colons/semicolons) is supported (e.g. via terminfo)?

It may appear that somebody (libtickit?) will have to write a set of hacks just to answer the last question.

[ZyX-I]

@leonerd By the way, why this list:

A full set of terminal rendering attributes; bold, italics_, underline, reverse, strikethough_, alternate font*

is lacking blink attribute (echo -e "Normal \e[5mBlink", is supported by xterm)? It is super useful for making user mad and fix blinking as fast as possible! And it can be emulated if needed.

[leonerd]

@ZyX-I I suspect the choice of colon or semicolon format for SGR colours can be determined by using DECRQSS on SGR, and parsing the result. This is also handy for detecting if the terminal supports 256 palette or 24bit RGB8 modes in the first place. I'll see what I can come up with; though in the short term I doubt I'll manage to get very much in.

As to the lack of blink, that's an easy one to add - it's just another set of bits on top of what it already has.

[leonerd]

@ZyX-I libtickit now supports blink, as of last night.

[Gaelan]

No Terminal.app support either.

[sebroeder]

Now that the new tui has been merged, what else is needed to support true color nvim in the terminal?

[tarruda]

Now that the new tui has been merged, what else is needed to support true color nvim in the terminal?

This PR 😄

[sebroeder]

This is awesome @tarruda, thank you so much! I wanted to donate to the Neovim project for a long time and this it the perfect opportunity 😄

[grawity]

Linux v3.13 parses and discards extended color codes: torvalds/linux@3415097

Linux v3.16 translates them to the closest VGA color: torvalds/linux@cec5b2a

tmux v2.2 appears to have gained support: ThomasAdam/tmux@427b820

[valpackett]

yeah it works in tmux now, please update the list