Is 11 points really 11 points in Wezterm?

[weiying-chen]

This is a zoomed-in screenshot of 3 terminals. All of them have their font size set to 11 points. The third one is Wezterm:

https://i.stack.imgur.com/ibYJW.png

As you can see, Wezterm's font is slightly bigger than the ones on the left (and slightly blurrier).

I wonder why is this.

Note: I'm on Ubuntu 22.10 with an Nvidia GeForce Graphic Card, and I'm using Wayland.

[wez]

Most terminals use pixels for their font size, rather than points. Are you sure that the others in your comparison are using points?

[wez]

In general, you can use wezterm ls-fonts to diagnose or explain font choice.

You can run:

WEZTERM_LOG=wezterm_font::ftwrap=trace,info wezterm ls-fonts --rasterize-ascii --text t

to show some diagnostics about the font selection and size, and preview how it will rasterize. Use WEZTERM_LOG=wezterm_font=trace,info to get very verbose font related diagnostics.

For bitmap fonts, the closest bitmap strike will generally be selected for use.

[weiying-chen]

This is the output. I'm not very sure what to do with the information, though!

DEBUG wezterm_font::ftwrap > set_char_size computing 11 dpi=96 (pixel height=14.666666666666666)
0 t \u{74} x_adv=9 cells=1 glyph=t,320 wezterm.font("JetBrains Mono", {weight="Regular", stretch="Normal", style="Normal"})

Maybe the font is being stretched? Maybe I have to disable stretch?

[wez]

stretch is a font design property; you can ignore that. That line of output shows that wezterm is using 14.6666 pixels as the equivalent for 11 points on your display and dpi. Note that the height shown is for the entire cell height, not just the visible portions of the rendered glyph.

Maybe the difference is that the other terminals round down the font size to an integer number of pixels?
Regardless: I don't have plans to change this as you have a lot of control over the font display already:

• You can use fractional sizes for font_size
• You can adjust freetype's rendering with:
  • https://wezfurlong.org/wezterm/config/lua/config/freetype_load_flags.html
  • https://wezfurlong.org/wezterm/config/lua/config/freetype_load_target.html

[weiying-chen]

Wezterm (up) with sub-pixel looks nearly identical to Gnome Terminal (down) with sub-pixel:

https://i.stack.imgur.com/GbSKa.png

Thanks for the info and quick replies!

Note: enabled like this: freetype_load_target = 'HorizontalLcd'.

Curiosly, the following configuration produces the same effect:

freetype_load_target = "Light",
freetype_render_target = "HorizontalLcd", 

[weiying-chen]

I found out freetype_load_flags = 'FORCE_AUTOHINT' will make Wezterm have exactly the same font shape as Gnome Terminal (not sure why, though). Down to the pixel level:

https://i.stack.imgur.com/gWwmS.png

(Up: Gnome Terminal. Down: Wezterm)

With this, Wezterm's font rendering looks exactly the same as other terminals (maybe a little better). At least with subpixel rendering and in Ubuntu.