Fallback sensibly to available tools (if no pandoc, display .md file as plain text with `cat` or alike)

[barracuda156]

There are in fact .md renderers which do not require an exotic compiler, for example this one works, written in C++: https://github.com/ishanawal/TermMark
So ideally it would be nice to have these definable by a user. However at least a sensible fallback to basic available tools will be nice. Currently in my environment README.md are not displayed at all, giving out an error about missing pandoc. But they can be viewed with cat as plain text, for example.
Same goes for scripts (*.sh): I don’t know what is batcat, but for sure these are just plain text files, so simple cat will work fine.

[barracuda156]

@isene Copilot suggests highlight as a fallback for bat and lowdown for pandoc.

[barracuda156]

@isene Thank you!

BTW, colored output can be supported, here I used highlight -O ansi --force --line-numbers @s (Copilot suggestion) for the script and termmark for markdown:

[isene]

@barracuda156 Great news! RTFM already has exactly what you're looking for - a complete plugin system for customizing file viewers!

Using Custom Viewers

When you first run RTFM, it creates ~/.rtfm/preview.rb where you can define your own viewers for any file type. For example, to use the tools you mentioned:

# For syntax highlighting with highlight instead of bat:
txt, rb, py, sh = highlight -O ansi --force --line-numbers @s

# For markdown with termmark instead of pandoc:
md = termmark @s

Check out the plugin documentation in the README (around line 510-540) for more details. I've just updated it with your suggested alternatives as examples!

About the Border Rendering Issue

I noticed in your screenshots that the borders aren't rendering correctly on your Mac - you're getting garbled characters instead of proper box-drawing characters. This appears to be an issue with the underlying rcurses library's terminal detection or character encoding on macOS.

I'll investigate this separately as it's likely related to how rcurses handles Unicode box-drawing characters on different terminals. Could you let me know:

1. What terminal emulator you're using?
2. The output of echo $TERM
3. The output of locale

This will help me fix the border rendering issue properly.

Thanks for the feedback and the screenshots - they're very helpful!

[isene]

@barracuda156 I noticed in your screenshots that the borders weren't rendering correctly - you were seeing garbled characters instead of proper box-drawing characters.

Good news! I've just released rcurses 6.0.2 which fixes this issue. The library now automatically detects whether your terminal supports UTF-8 and falls back to ASCII borders (+, -, |) when needed.

To get the fix, simply update rcurses:

gem update rcurses

If you want to force ASCII borders regardless of your locale, you can also set:

export RCURSES_BORDERS=ascii

This should resolve the border rendering issue you were experiencing on macOS. Let me know if it works better for you now!

[barracuda156]

@isene Awesome, I will try it.

[barracuda156]

@isene Okay, so with 6.0.2 automatic setting of borders worked in Apple Terminal and macterm (both archaic versions), but did not in mlterm (this one is the only modern one, and generally much more usable for TUI stuff).

Forcing to ascii did work for mlterm, however:

Locale output: