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bug#54774: 28.1; ansi-color with no colors in Emacs-28
From: |
Jim Porter |
Subject: |
bug#54774: 28.1; ansi-color with no colors in Emacs-28 |
Date: |
Sat, 9 Apr 2022 10:31:50 -0700 |
On 4/9/2022 12:25 AM, Thierry Volpiatto wrote:
Apart advicing `ansi-color-get-face-1` I couldn't find how to fix my
code as your changes are binding ansi-code 5 to `ansi-color-slow-blink`
face which create unwanted squares.
I had a chance to look into this a bit more. ansi-color.el has
mis-parsed 256-color and 24-bit color escapes for a long time. For
example, you can try this under Emacs 27.2:
(ansi-color-apply "\033[38;5;2mhi\033[0m")
-> #("hi" 0 2 (font-lock-face success))
This should actually be equivalent to the 8-color green value (ANSI SGR
value 32). (Note: Under Emacs 27.2, the "slow blink" face is mapped to
`success', whereas in 28.1, it's mapped to `ansi-color-slow-blink'. In
Emacs 29, this properly sets the foreground to green.)
Normally this isn't an issue, since Emacs' shell/term modes indicate
that they only support 8-color mode, so commands usually don't emit
256-color sequences. However, in your case this looks to be some text
from a web service, so it obviously can't inspect your terminal
capabilities (unless there's a way to send them in the request?).
Looking at your code in more detail, I think you just got lucky that
things worked ok in Emacs 27. See here:
(while (re-search-forward "38;5;\\([0-9]+\\)m" nil t)
;; ...
(replace-match (pcase (match-string 1)
("154" "32")
("190" "31")
("118" "32")
("208" "37")
("202" "34")
("214" "35")
("220" "36")
("226" "33")
(r r))
t t nil 1))
This replaces an ANSI escape like "\033[38;5;154m" with "\033[38;5;32m".
So the 256-color ANSI escape is still there, just slightly transformed.
I think you want the result to be "\033[32m" instead, so that you're not
using 256-color escape sequences at all.
If you adjust the regexp/replacement to remove the "38;5;" bit, I think
your existing code should work fine in both Emacs 27 and 28.