Emoji and decrqm_unicode

[gwenn]

Hi,
I am trying to solve emoji rendering for rustyline.
And libvaxis seems to use this sequence:

libvaxis/src/ctlseqs.zig

Line 9 in 6285467

pub const decrqm_unicode = "\x1b[?2027$p";

to check how the current terminal behaves.
So I tried zig build example -Dexample=cli.
But some terminals don't behave correctly.

• alacritty => OK
  
• iterm2 => KO
  
• kitty => KO
  
• Terminal.app => KO
  
• wezterm => OK
  

Those terminals answer to decrqm_unicode like:

• alacritty

[27, 91, 63, 50, 48, 50, 55, 59, 48, 36, 121]
[decrpm] 2027 => Some("Mode not recognized"`

• iterm2

[27, 91, 63, 50, 48, 50, 55, 59, 52, 36, 121]
[decrpm] 2027 => Some("Permanently reset")

• kitty

[27, 91, 63, 50, 48, 50, 55, 59, 48, 36, 121]
[decrpm] 2027 => Some("Mode not recognized")

• Terminal.app
  garbage (sequence not supported?)
• wezterm

[27, 91, 63, 50, 48, 50, 55, 59, 51, 36, 121]
[decrpm] 2027 => Some("Permanently set")

How to check that DECRQM is not supported (by Mac Terminal) ?
How to handle kitty and iterm2 which seem to support grapheme clusters but don't report accordingly ?
Thanks.

[rockorager]

Terminal.app

For Terminal.app, there isn't much you can do. I would instead encourage users to use another terminal unfortunately. I will link the best comment I've ever read from notcurses. As the comment suggests, you can check for TERM_PROGRAM=Apple_Terminal

Kitty

Kitty does clustering but doesn't know about ZWJs. The way to calculate widths here is to strip ZWJs and then calculate using standard clustering techniques. I detect kitty in my go library by issuing an XTVERSION query and checking for the presence of "kitty" within the returned string. Kovid has stated he does not want to support mode 2027 style unicode.

iTerm2

I don't use macOS so I haven't tested clustering capabilities on mac. Possibly you could use the XTVERSION query as in kitty.