Feature request: mapping colors to different fonts

[geofft]

I have a monochrome e-ink screen, which is great for use in bright sunlight, but makes it hard to use applications with syntax highlighting or other use of multiple colors. While the screen does support grayscale, it's hard to visually distinguish more than one or maybe two levels of gray in isolation. (Also the physical refresh rate is lower with grayscale enabled.)

So, I'd like to get my terminal emulator to render the ANSI colors by using distinct fonts/styles instead of color. I can probably distinguish 8-16 unique combinations of typefaces (serif vs. sans, a font with noticeably different x-height, particularly distinctive or novelty fonts, etc.) and styles (small caps, weight, etc.) which would make syntax highlighting usable on a monochrome display. I see that Ghostty already supports rendering multiple fonts via codepoint range, so this seems feasible in theory, though from a quick look at the code it doesn't seem like color info gets plumbed through to font selection, I think.

(While one potential answer is to define a new escape sequence to request a particular font and teach my text editor to use it, there are a lot of apps that use color for output—grep, git, ls, etc.—and I'd like all of them to support this feature, because I can't see colors at all on my e-ink screen. A color-to-font remapping feature would make everything work out of the box.)

Would you be open to this feature? I'd be happy to contribute code for it, though I'd probably need a couple of pointers about how to best structure this change. (I'm in the Discord and happy to chat there.)

Here's a very quick mockup of what it might look like done with CSS and a relatively random choice of fonts:

This is mapping yellow to Recursive mono + casual, red to Doto, and green to Courier Prime, which all have similar enough metrics to JetBrains Mono that the grid works (a full implementation would need to force the metrics to match the primary font exactly).

[frobware]

there are a lot of apps that use color for output—grep, git, ls, etc.—and I'd like all of them to support this feature,

Would setting NO_COLOR=1 help at all? See: https://no-color.org/

[geofft]

No, that would produce an effect largely similar to what I currently have where colored text and uncolored text are indistinguishable on the monochrome display. (You can also do this already at the terminal emulator layer, i.e. for all programs whether or not they respect NO_COLOR, by setting all palette colors to the same color value.)

My goal is a way to distinguish text with different colors on a monochrome display.