Colors broken in fzf preview on Windows (mintty)

[kleymionov]

Checklist

• I have read through the manual page (man fzf)
• I have searched through the existing issues
• For bug reports, I have checked if the bug is reproducible in the latest version of fzf

Output of fzf --version

0.56.3 (tarball)

OS

• Linux
• macOS
• Windows
• Etc.

Shell

• bash
• zsh
• fish

Problem / Steps to reproduce

Syntax and line highlighting produced by bat are incorrectly displayed by fzf preview on mintty:
#> echo | fzf --preview="bat --theme=1337 --highlight-line=2 --color=always test.sh | tee out.txt"

#> cat out.txt

The issue is also reproducible on Alacritty and ConEmu.
Colors are kept intact only on Windows Terminal, but it is unusably slow and laggy.

[junegunn]

Does bat --theme=1337 --highlight-line=2 --color=always test.sh itself produce the right colors?

[t40mas]

I don't know if the behavior is related to my problem, but it seems that fzf is not passing the current appearance to bat or it's not available anymore. Even if I run fzf with --color=dark.

fzf --preview="bat --theme-dark='Catppuccin Mocha' --color=always {}"

If I specify the theme directly, everything works as expected:
fzf --preview="bat --theme='Catppuccin Mocha' --color=always {}";

Many thanks for your work!!!

[kleymionov]

Does bat --theme=1337 --highlight-line=2 --color=always test.sh itself produce the right colors?

Yes, output is similar to shown by cat out.txt.

[kleymionov]

I don't know if the behavior is related to my problem

Yes, this is the same problem: fzf somehow transforms color codes received from bat.

[junegunn]

It is probably because of winpty. Can you try setting export MSYS=enable_pcon?

fzf/src/winpty_windows.go

Lines 18 to 44 in 243a760

	func needWinpty(opts *Options) bool {
	if os.Getenv("TERM_PROGRAM") != "mintty" {
	return false
	}
	if isMintty345() {
	/*
	See: https://github.com/junegunn/fzf/issues/3809
	"MSYS=enable_pcon" allows fzf to run properly on mintty 3.4.5 or later.
	*/
	if strings.Contains(os.Getenv("MSYS"), "enable_pcon") {
	return false
	}
	// Setting the environment variable here unfortunately doesn't help,
	// so we need to start a child process with "MSYS=enable_pcon"
	// os.Setenv("MSYS", "enable_pcon")
	return true
	}
	if opts.NoWinpty {
	return false
	}
	if _, err := exec.LookPath("winpty"); err != nil {
	return false
	}
	return true
	}

Related:

• make fzf work in standard Git Bash Term #3806
• On fzf.vim opening in new cmd Window in Git Bash #3809

[kleymionov]

Can you try setting export MSYS=enable_pcon?

Same result. It's not only mintty related, but also reproducible with Alacritty and ConEmu.

[junegunn]

I don't know if the behavior is related to my problem

Yes, this is the same problem: fzf somehow transforms color codes received from bat.

I don't think it's the same problem. He said "If I specify the theme directly, everything works as expected".

@t40mas It looks like 'bat' somehow fails to detect the terminal theme (dark or light) when run inside the preview window of fzf. --dark option of fzf only changes the colors of fzf, and it does not do anything beyond that.

[kleymionov]

everything works as expected

It seems that together with bat's theme-dark problem, it just happened that 'Catppuccin Mocha' theme colors are not that much warped by fzf pass-through. But there are still slight differences in colors, and --highlight-line, if specified for bat, is not highlighted in preview window with this theme.