Improve font settings for Inter

[cassidyjames]

Not sure what all needs to or can be done, but we're still seeing strange hinting/kerning in places in 6.0 dailies.

Things to try:

• Xsettings hinting (currently slight, see dconf /org/gnome/settings-daemon/plugins/xsettings/hinting)
• antialiasing (currently rgba, probably should change to grayscale)
• Default font size (currently 9, would need to be tweaked in the stylesheet rem() function, too)
• Trying Ubuntu package vs. latest Windows hinted version vs. latest Desktop version
• Freetype settings
  • see: https://bugs.launchpad.net/ubuntu/+source/freetype/+bug/1722508
  • https://www.freetype.org/freetype2/docs/reference/ft2-lcd_rendering.html
  • https://www.freetype.org/freetype2/docs/subpixel-hinting.html

I'm unsure what else could be investigated. I'm aware this is a sort of catch-all issue, but I figured having a public place to investigate and share findings was a better start than opening a whole bunch of issues before we know what we actually need to do.

[cassidyjames]

See this as a demo. @rsms pointed out that MLTAV is a good demo string to ensure kerning is working correctly, which it appears it is. The issue seems to be with hinting. I have tried the Ubuntu package, Windows hinted 3.15, and Desktop 3.15 versions without much visible change with this issue. See the hinting between "ra" and "De" in "Granite Demo" in the HeaderBar:

What's weird is that the hinting changes completely when using 11px or 13px there, and looks much better. Non-integer values near 12px also change how the hinting works. Is this a case of GTK rounding/snapping things to pixels strangely? I'm not sure how all these mechanics work…

[rsms]

It may be so that FreeType or GTK or whatever drives the text renderer enables ClearType-like hinting below a certain text size (or more likely and specifically, rasterization size.)

[rsms]

Font hinting is really a matter of preference, similar to how sub-pixel anti-alias is a matter of preference (btw, note that these things are different concepts.) It may be a good idea to provide these two as user options in system settings. Windows has both these options and macOS has sub-pixel anti-aliasing only as an option (macOS doesn't even implement hinting; they never have. Same with iOS, no hinting.)