macOS: font-thicken behaviour

[vitvly]

Hi!

Thanks for great software. I've been eagerly waiting for it :)

I have a question: how can i make font rendering completely identical to Terminal.app? Consider below:

The image above is Terminal.app, below is Ghostty with font-thicken setting. Same font and size (Menlo 12). Ghostty's version is a bit heavier (and horizontally wider).

[jaredh159]

possibly related: Kitty supports a numeric value for font_thicken, I had mine turned to 0.2, but it seems to be just a bool in Ghostty and turning it on is too thick for me as well, whereas I feel like without it it's too thin.

love ghostty so far and really appreciate all the work!

[vitvly]

Yes, i also recall using Kitty’s font thickening feature, and landing on somewhere between 0.2 and 0.3. However, i was not ever able to figure out the set of options that would produce fonts exactly similar to Terminal.app and TextEdit.

I think it would be great if default font settings in Ghostty were as close to these two apps as possible. However, i understand that font rendering is extremely complicated.

[sampotts]

My 2c: rather than having to rely on font_thicken, can we have some control over the antialiasing on macOS? I feel like it's too strong at the moment, rendering most fonts too thin. Then you have to resort to font_thicken which in turn makes the type not quite as sharp as it should be.

[stancl]

Originally wanted to submit a separate discussion but this is likely related enough

I'm using a particular font and encountering some rendering issues. However, similar behavior happens in some other editors so I'm not sure if this is specifically a bug. It may instead be a feature request.

Essentially, the font renders great in Kitty. See light mode and dark mode.

In Ghostty it renders like this:

• Light mode, no font-thicken looks alright-ish
• Light mode, font-thicken looks very bad
• Dark mode, no font-thicken looks bad
• Dark mode, font-thicken looks best

It's as if font-thicken makes dark mode look almost exactly like Kitty, but makes light mode look worse. I see the other discussion I linked mentioned adding a numeric value for the font-thicken setting — could that be it, or is there more going on in Kitty, like additional font rendering logic that tries to adjust text to its background perhaps? A quick search found this (kovidgoyal/kitty#5969).

For reference, the font also looks kinda ugly in Zed (dark mode, light mode) but a little better I'd say. So with my limited (essentially nonexistent) knowledge of font rendering, I'm inclined to think Kitty puts in extra work into rendering fonts nicely, rather than Ghostty doing something wrong?

[qoobes]

Fonts are pretty awful for me as well compared to kitty. Using the firacode mono nerd font zoomed out to 10px fontsize

[vitvly]

Also: if i recall correctly, in the Changelog podcast about Ghostty (https://changelog.com/podcast/622) it was said that TextEdit is used as a standard to compare against when implementing font rendering on macOS.

I think it's an absolutely correct idea. Given that Ghostty aims at native look & feel, it's important to have a standard macOS font look by default, so that the user doesn't have to tweak any knobs, like font-thicken etc. Or, at least, have a documented away to achieve that default look.

[MrConnorKenway]

With font-thicken = true, some PUA symbols becomes distorted compared with kitty:

kitty:

ghostty w/ font thicken:

ghostty w/o font thicken:

[tortoise10h]

Not sure if it's in the right thread but in Wezterm we have the option that weight = 'DemiBold' it's perfect for me since Bold is too bold. Same as current Ghostty, font-thicken only has 2 options true or false. Turn on the font-thicken seems too bold to me, I wish we had an option like Wezterm

[jcollie]

It's already there:

# The named font style to use for each of the requested terminal font styles.
# This looks up the style based on the font style string advertised by the
# font itself. For example, "Iosevka Heavy" has a style of "Heavy".
#
# You can also use these fields to completely disable a font style. If you set
# the value of the configuration below to literal `false` then that font style
# will be disabled. If the running program in the terminal requests a disabled
# font style, the regular font style will be used instead.
#
# These are only valid if its corresponding font-family is also specified. If
# no font-family is specified, then the font-style is ignored unless you're
# disabling the font style.
font-style = default
font-style-bold = default
font-style-italic = default
font-style-bold-italic = default

[oleksiivelychko]

Yes, it's possible here. I use these settings:

font-thicken = true
font-family = JetBrains Mono
font-style = Light

... and these also suit me too:

font-thicken = false
font-family = JetBrains Mono
font-style = SemiBold

[vitvly]

I've tried both

font-thicken = true
font-style = Light

and

font-thicken = false
font-style = SemiBold

but in both cases the result for Menlo 12 pt is still heavier than in Terminal.app.

[00-kat]

Fixed with #4531, see the new config option font-thicken-strength.

[vitvly]

@00-kat thank you. However, i still don’t understand how to solve my original concern:

how can i make font rendering completely identical to Terminal.app?

Which values of font-thicken-strength should i choose?

[00-kat]

Apologies, I can't help with that as I don't use macOS and hence don't have a copy of Terminal.app to play with; you could try binary search a value for font-thicken-strength perhaps, or hopefully some other macOS user who happened to already configure this stumbles upon this post.

[matthewtodd]

@vitvly here's what I ended up with, Menlo 12 like you.

[vitvly]

@00-kat @matthewtodd thank you! This looks much better.

I wonder though, does this mean that stock Apple apps like TextEdit or Terminal use some hidden font manipulations that third-party apps cannot fully replicate? Would be great if instead of imprecisely arriving at some values that look visually similar, we could be sure that we have it exactly the same.

[yaoyhu]

Anyupdate on it? It seems that font-thicken-strength is not working for me.

Additionally, I want to point out that Ghostty renders the same font differently, such as Fira Code. I had to switch to Fira Code Nerd Font to make the > symbol appear the same as it does in Kitty.

[yaoyhu]

In what way?

I believe this could make it appear clearer. Ghostty(left) looks darker and slimmer in contrast, while Kitty appears whiter and thicker.

# config in ghostty
font-size=17
font-family=FiraCode Nerd Font Mono
font-family=LXGW WenKai
font-thicken = true
font-thicken-strength = 228  # <--- No matter how I adjust this value and reload, it doesn't have any effect.
adjust-cell-width = "-2%"
adjust-cell-height = "6%"

# config in kitty
font_size 17
font_family      family="Fira Code"
bold_font        auto
italic_font      auto
bold_italic_font auto
macos_thicken_font 0.50

[00-kat]

No matter how I adjust this value and reload, it doesn't have any effect.

Oh also could you try restarting Ghostty? It's possible that this is one of those configuration options that can't be hot-reloaded. (You could also try the key you have bound to reset_font_size; ghostty +list-keybinds if you don't know which).

[yaoyhu]

I just changed the value abruptly from 0 to 255 and noticed a very slight difference.

However, my Kitty font thickness is only set to 0.5, which is already thicker than ghossty's 255. Is there a way to make it even thicker?

[gelfand]

@yaoyhu Hey, have you found a solution?

[yaoyhu]

@yaoyhu Hey, have you found a solution?

Nope, switching back to Kitty for now. Waiting for the fixed release.